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diff --git a/old/51756-0.txt b/old/51756-0.txt deleted file mode 100644 index b7bf1af..0000000 --- a/old/51756-0.txt +++ /dev/null @@ -1,10191 +0,0 @@ -The Project Gutenberg EBook of The History of Chemistry, Vol II (of 2), by -Thomas Thomson - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms of -the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: The History of Chemistry, Vol II (of 2) - -Author: Thomas Thomson - -Release Date: April 14, 2016 [EBook #51756] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK HISTORY OF CHEMISTRY, VOL II *** - - - - -Produced by MWS, Les Galloway and the Online Distributed -Proofreading Team at http://www.pgdp.net (This file was -produced from images generously made available by The -Internet Archive) - - - - - - - THE - - HISTORY - - OF - - CHEMISTRY. - - - BY - - THOMAS THOMSON, M. D. - F.R.S. L. & E.; F.L.S.; F.G.S., &c. - - REGIUS PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OF GLASGOW. - - - IN TWO VOLUMES. - - VOL. II. - - LONDON: - HENRY COLBURN AND RICHARD BENTLEY, - NEW BURLINGTON STREET. - - 1831. - - - C. WHITING, BEAUFORT HOUSE, STRAND. - - - - - CONTENTS - - OF - - THE SECOND VOLUME. - - - CHAPTER I. Page - - Of the foundation and progress of scientific chemistry in Great - Britain 1 - - - CHAPTER II. - - Of the progress of philosophical chemistry in Sweden 26 - - - CHAPTER III. - - Progress of scientific chemistry in France 75 - - - CHAPTER IV. - - Progress of analytical chemistry 190 - - - CHAPTER V. - - Of electro-chemistry 251 - - - CHAPTER VI. - - Of the atomic theory 277 - - - CHAPTER VII. - - Of the present state of chemistry 309 - - - - - HISTORY OF CHEMISTRY. - - - - -CHAPTER I. - -OF THE FOUNDATION AND PROGRESS OF SCIENTIFIC CHEMISTRY IN GREAT BRITAIN. - - -While Mr. Cavendish was extending the bounds of pneumatic chemistry, -with the caution and precision of a Newton, Dr. Priestley, who had -entered on the same career, was proceeding with a degree of rapidity -quite unexampled; while from his happy talents and inventive faculties, -he contributed no less essentially to the progress of the science, and -certainly more than any other British chemist to its popularity. - -Joseph Priestley was born in 1733, at Fieldhead, about six miles from -Leeds in Yorkshire. His father, Jonas Priestley, was a maker and -dresser of woollen cloth, and his mother, the only child of Joseph -Swift a farmer in the neighbourhood. Dr. Priestley was the eldest -child; and, his mother having children very fast, he was soon committed -to the care of his maternal grandfather. He lost his mother when he -was only six years of age, and was soon after taken home by his father -and sent to school in the neighbourhood. His father being but poor, -and encumbered with a large family, his sister, Mrs. Keighley, a woman -in good circumstances, and without children, relieved him of all care -of his eldest son, by taking him and bringing him up as her own. She -was a dissenter, and her house was the resort of all the dissenting -clergy in the country. Young Joseph was sent to a public school in -the neighbourhood, and, at sixteen, had made considerable progress in -Latin, Greek, and Hebrew. Having shown a passion for books and for -learning at a very early age, his aunt conceived hopes that he would -one day become a dissenting clergyman, which she considered as the -first of all professions; and he entered eagerly into her views: but -his health declining about this period, and something like phthisical -symptoms having come on, he was advised to turn his thoughts to trade, -and to settle as a merchant in Lisbon. This induced him to apply to the -modern languages; and he learned French, Italian, and German, without a -master. Recovering his health, he abandoned his new scheme and resumed -his former plan of becoming a clergyman. In 1752 he was sent to the -academy of Daventry, to study under Dr. Ashworth, the successor of Dr. -Doddridge. He had already made some progress in mechanical philosophy -and metaphysics, and dipped into Chaldee, Syriac, and Arabic. At -Daventry he spent three years, engaged keenly in studies connected with -divinity, and wrote some of his earliest theological tracts. Freedom -of discussion was admitted to its full extent in this academy. The two -masters espoused different sides upon most controversial subjects, and -the scholars were divided into two parties, nearly equally balanced. -The discussions, however, were conducted with perfect good humour -on both sides; and Dr. Priestley, as he tells us himself, usually -supported the heterodox opinion; but he never at any time, as he -assures us, advanced arguments which he did not believe to be good, -or supported an opinion which he did not consider as true. When he -left the academy, he settled at Needham in Suffolk, as an assistant -in a small, obscure dissenting meeting-house, where his income never -exceeded 30_l._ a-year. His hearers fell off, in consequence of their -dislike of his theological opinions; and his income underwent a -corresponding diminution. He attempted a school; but his scheme failed -of success, owing to the bad opinion which his neighbours entertained -of his orthodoxy. His situation would have been desperate, had he not -been occasionally relieved by sums out of charitable funds, procured by -means of Dr. Benson, and Dr. Kippis. - -Several vacancies occurred in his vicinity; but he was treated with -contempt, and thought unworthy to fill any of them. Even the dissenting -clergy in the neighbourhood thought it a degradation to associate -with him, and durst not ask him to preach: not from any dislike to -his theological opinions; for several of them thought as freely as -he did; but because the genteeler part of their audience always -absented themselves when he appeared in the pulpit. A good many years -afterwards, as he informs us himself, when his reputation was very -high, he preached in the same place, and multitudes flocked to hear the -very same sermons, which they had formerly listened to with contempt -and dislike. - -His friends being aware of the disagreeable nature of his situation -at Needham, were upon the alert to procure him a better. In 1758, in -consequence of the interest of Mr. Gill, he was invited to appear as a -candidate for a meeting-house in Sheffield, vacant by the resignation -of Mr. Wadsworth. He appeared accordingly and preached, but was not -approved of. Mr. Haynes, the other minister, offered to procure him a -meeting-house at Nantwich in Cheshire. This situation he accepted, and, -to save expenses, he went from Needham to London by sea. At Nantwich -he continued three years, and spent his time much more agreeably -than he had done at Needham. His opinions were not obnoxious to his -hearers, and controversial discussions were never introduced. Here he -established a school, and found the business of teaching, contrary -to his expectation, an agreeable and even interesting employment. He -taught from seven in the morning, till four in the afternoon; and after -the school was dismissed, he went to the house of Mr. Tomlinson, an -eminent attorney in the neighbourhood, where he taught privately till -seven in the evening. Being thus engaged twelve hours every day in -teaching, he had little time for private study. It is, indeed, scarcely -conceivable how, under such circumstances, he could prepare himself for -Sunday. Here, however, his circumstances began to mend. At Needham it -required the utmost economy to keep out of debt; but at Nantwich, he -was able to purchase a few books and some philosophical instruments, as -a small air-pump, an electrical machine, &c. These he taught his eldest -scholars to keep in order and manage: and by entertaining their parents -and friends with experiments, in which the scholars were generally the -operators, and sometimes the lecturers too, he considerably extended -the reputation of his school. It was at Nantwich that he wrote his -grammar for the use of his school, a book of considerable merit, though -its circulation was never extensive. This latter circumstance was -probably owing to the superior reputation of Dr. Lowth, who published -his well-known grammar about two years afterwards. - -Being boarded in the house of Mr. Eddowes, a very sociable and sensible -man, and a lover of music, Dr. Priestley was induced to play a little -on the English flute; and though he never was a proficient, he informs -us that it contributed more or less to his amusement for many years. He -recommends the knowledge and practice of music to all studious persons, -and thinks it rather an advantage for them if they have no fine ear or -exquisite taste, as they will, in consequence, be more easily pleased, -and less apt to be offended when the performances they hear are but -indifferent. - -The academy at Warrington was instituted while Dr. Priestley was at -Needham, and he was recommended by Mr. Clark, Dr. Benson, and Dr. -Taylor, as tutor in the languages; but Dr. Aiken, whose qualifications -were considered as superior, was preferred before him. However, on -the death of Dr. Taylor, and the advancement of Dr. Aiken to be tutor -in divinity, he was invited to succeed him: this offer he accepted, -though his school at Nantwich was likely to be more gainful; for the -employment at Warrington was more liberal and less painful. In this -situation he continued six years, actively employed in teaching and -in literary pursuits. Here he wrote a variety of works, particularly -his History of Electricity, which first brought him into notice as -an experimental philosopher, and procured him celebrity. After the -publication of this work, Dr. Percival of Manchester, then a student -at Edinburgh, procured him the title of doctor in laws, from that -university. Here he married a daughter of Mr. Isaac Wilkinson, an -ironmonger in Wales; a woman whose qualities he has highly extolled, -and who died after he went to America. - -In the academy he spent his time very happily, but it did not flourish. -A quarrel had broken out between Dr. Taylor and the trustees, in -consequence of which all the friends of that gentleman were hostile -to the institution. This, together with the smallness of his income, -100_l._ a-year, and 15_l._ for each boarder, which precluded him -from making any provision for his family, induced him to accept an -invitation to take charge of Millhill chapel, at Leeds, where he had a -considerable acquaintance, and to which he removed in 1767. - -Here he engaged keenly in the study of theology, and produced a great -number of works, many of them controversial. Here, too, he commenced -his great chemical career, and published his first tract on _air_. -He was led accidentally to think of pneumatic chemistry, by living -in the immediate vicinity of a brewery. Here, too, he published his -history of the Discoveries relative to Light and Colours, as the first -part of a general history of experimental philosophy; but the expense -of this book was so great, and its sale so limited, that he did not -venture to prosecute the undertaking. Here, likewise, he commenced and -published three volumes of a periodical work, entitled "The Theological -Repository," which he continued after he settled in Birmingham. - -After he had been six years at Leeds, the Earl of Shelburne (afterwards -Marquis of Lansdowne), engaged him, on the recommendation of Dr. -Price, to live with him as a kind of librarian and literary companion, -at a salary of 250_l._ a-year, with a house. With his lordship he -travelled through Holland, France, and a part of Germany, and spent -some time in Paris. He was delighted with this excursion, and expressed -himself thoroughly convinced of the great advantages to be derived -from foreign travel. The men of science and politicians in Paris were -unbelievers, and even professed atheists, and as Dr. Priestley chose -to appear before them as a Christian, they told him that he was the -first person they had met with, of whose understanding they had any -opinion, who was a believer of Christianity; but, upon interrogating -them closely, he found that none of them had any knowledge either of -the nature or principles of the Christian religion.--While with Lord -Shelburne, he published the first three volumes of his Experiments on -Air, and had collected materials for a fourth, which he published soon -after settling in Birmingham. At this time also he published his attack -upon Drs. Reid, Beattie, and Oswald; a book which, he tells us, he -finished in a fortnight: but of which he afterwards, in some measure, -disapproved. Indeed, it was impossible for any person of candour to -approve of the style of that work, and the way in which he treated Dr. -Reid, a philosopher certainly much more deeply skilled than himself in -metaphysics. - -After some years Lord Shelburne began to be weary of his associate, -and, on his expressing a wish to settle him in Ireland, Dr. Priestley -of his own accord proposed a separation, to which his lordship -consented, after settling on him an annuity of 150_l._, according to a -previous stipulation. This annuity he continued regularly to pay during -the remainder of the life of Dr. Priestley. - -His income being much diminished by his separation from Lord Shelburne, -and his family increasing, he found it now difficult to support -himself. At this time Mrs. Rayner made him very considerable presents, -particularly at one period a sum of 400_l._; and she continued her -contributions to him almost annually. Dr. Fothergill had proposed a -subscription, in order that he might prosecute his experiments to their -utmost extent, and be enabled to live without sacrificing his time to -his pupils. This he accepted. It amounted at first to 40_l._ per annum, -and was afterwards much increased. Dr. Watson, Mr. Wedgewood, Mr. -Galton, and four or five more, were the gentlemen who joined with Dr. -Fothergill in this generous subscription. - -Soon after, he settled in a meeting-house in Birmingham, and continued -for several years engaged in theological and chemical investigations. -His apparatus, by the liberality of his friends, had become excellent, -and his income was so good that he could prosecute his researches to -their full extent. Here he published the three last volumes of his -Experiments on Air, and various papers on the same subject in the -Philosophical Transactions. Here, too, he continued his Theological -Repository, and published a variety of tracts on his peculiar opinions -in religion, and upon the history of the primitive church. He now -unluckily engaged in controversy with the established clergy of the -place; and expressed his opinions on political subjects with a degree -of freedom, which, though it would have been of no consequence at -any former period, was ill suited to the peculiar circumstances that -were introduced into this country by the French revolution, and to -the political maxims of Mr. Pitt and his administration. His answer -to Mr. Burke's book on the French revolution excited the violent -indignation of that extraordinary man, who inveighed against his -character repeatedly, and with peculiar virulence, in the house of -commons. The clergy of the church of England, too, who began about this -time to be alarmed for their establishment, of which Dr. Priestley -was the open enemy, were particularly active; the press teemed with -their productions against him, and the minds of their hearers seem to -have been artificially excited; indeed some of the anecdotes told of -the conduct of the clergy of Birmingham, were highly unbecoming their -character. Unfortunately, Dr. Priestley did not seem to be aware of -the state of the nation, and of the plan of conduct laid down by Mr. -Pitt and his political friends; and he was too fond of controversial -discussions to yield tamely to the attacks of his antagonists. - -These circumstances seem in some measure to explain the disgraceful -riots which took place in Birmingham in 1791, on the day of the -anniversary of the French revolution. Dr. Priestley's meeting-house and -his dwelling-house were burnt; his library and apparatus destroyed, -and many manuscripts, the fruits of several years of industry, were -consumed in the conflagration. The houses of several of his friends -shared the same fate, and his son narrowly escaped death, by the care -of a friend who forcibly concealed him for several days. Dr. Priestley -was obliged to make his escape to London, and a seat was taken for him -in the mail-coach under a borrowed name. Such was the ferment against -him that it was believed he would not have been safe any where else; -and his friends would not allow him, for several weeks, to walk through -the streets. - -He was invited to Hackney, to succeed Dr. Price in the meeting-house -of that place. He accepted the office, but such was the dread of his -unpopularity, that nobody would let him a house, from an apprehension -that it would be burnt by the populace as soon as it was known that he -inhabited it. He was obliged to get a friend to take a lease of a house -in another name; and it was with the utmost difficulty that he could -prevail with the landlord to allow the lease to be transferred to him. -The members of the Royal Society, of which he was a fellow, declined -admitting him into their company; and he was obliged to withdraw his -name from the society. - -When we look back upon this treatment of a man of Dr. Priestley's -character, after an interval of forty years, it cannot fail to strike -us with astonishment; and it must be owned, I think, that it reflects -an indelible stain upon that period of the history of Great Britain. -To suppose that he was in the least degree formidable to so powerful -a body as the church of England, backed as it was by the aristocracy, -by the ministry, and by the opinions of the people, is perfectly -ridiculous. His theological sentiments, indeed, were very different -from those of the established church; but so were those of Milton, -Locke, and Newton. Nay, some of the members of the church itself -entertained opinions, not indeed so decided or so openly expressed as -those of Dr. Priestley, but certainly having the same tendency. To be -satisfied of this it is only necessary to recollect the book which -Dr. Clarke published on the Trinity. Nay, some of the bishops, unless -they are very much belied, entertained opinions similar to those of -Dr. Clarke. The same observation applies to Dr. Lardner, Dr. Price, -and many others of the dissenters. Yet, the church of England never -attempted to persecute these respectable and meritorious men, nor did -they consider their opinions as at all likely to endanger the stability -of the church. Besides, Dr. Horsley had taken up the pen against Dr. -Priestley's theological opinions, and had refuted them so completely in -the opinion of the members of the church, that it was thought right to -reward his meritorious services by a bishopric. - -It could hardly, therefore, be the dread of Dr. Priestley's theological -opinions that induced the clergy of the church of England to bestir -themselves against him with such alacrity. Erroneous opinions advanced -and refuted, so far from being injurious, have a powerful tendency to -support and strengthen the cause which they were meant to overturn. -Or, if there existed any latent suspicion that the refutation of -Horsley was not so complete as had been alleged, surely persecution -was not the best means of supporting weak arguments; and indeed it was -rather calculated to draw the attention of mankind to the theological -opinions of Priestley; as has in fact been the consequence. - -Neither can the persecutions which Dr. Priestley was subjected to be -accounted for by his political opinions, even supposing it not to be -true, that in a free country like Great Britain, any man is at liberty -to maintain whatever theoretic opinions of government he thinks proper, -provided he be a peaceable subject and obey rigorously all the laws of -his country. - -Dr. Priestley was an advocate for the perfectibility of the human -species, or at least its continually increasing tendency to -improvement--a doctrine extremely pleasing in itself, and warmly -supported by Franklin and Price; but which the wild principles of -Condorcet, Godwin, and Beddoes at last brought into discredit. This -doctrine was taught by Priestley in the outset of his Treatise on -Civil Government, first published in 1768. It is a speculation of so -very agreeable a nature, so congenial to our warmest wishes, and so -flattering to the prejudices of humanity, that one feels much pain -at being obliged to give it up. Perhaps it may be true, and I am -willing to hope so, that improvements once made are never entirely -lost, unless they are superseded by something much more advantageous, -and that therefore the knowledge of the human race, upon the whole, -is progressive. But political establishments, at least if we are to -judge from the past history of mankind, have their uniform periods of -progress and decay. Nations seem incapable of profiting by experience. -Every nation seems destined to run the same career, and the history -may be comprehended under the following heads: Poverty, liberty, -industry, wealth, power, dissipation, anarchy, destruction. We have no -example in history of a nation running through this career and again -recovering its energy and importance. Greece ran through it more than -two thousand years ago: she has been in a state of slavery ever since. -An opportunity is now at last given her of recovering her importance: -posterity will ascertain whether she will embrace it. - -Dr. Priestley's short Essay on the First Principles of Civil Government -was published in 1768. In it he lays down as the foundation of his -reasoning, that "it must be understood, whether it be expressed or -not, that all people live in society for their mutual advantage; so -that the good and happiness of the members, that is the majority of -the members of any state, is the great standard by which every thing -relating to that state must be finally determined; and though it may be -supposed that a body of people may be bound by a voluntary resignation -of all their rights to a single person or to a few, it can never be -supposed that the resignation is obligatory on their posterity, because -it is manifestly contrary to the good of the whole that it should be -so." From this first principle he deduces all his political maxims. -Kings, senators, and nobles, are merely the servants of the public; -and when they abuse their power, in the people lies the right of -deposing and consequently of punishing them. He examines the expediency -of hereditary sovereignty, of hereditary rank and privileges, of the -duration of parliament, and of the right of voting, with an evident -tendency to democratical principles, though he does not express himself -very clearly on the subject. - -Such were his political principles in 1768, when his book was -published. They excited no alarm and drew but little attention; -these principles he maintained ever after, or indeed he may be said -to have become more moderate instead of violent. Though he approved -of a republic in the abstract; yet, considering the prejudices and -habits of the people of Great Britain, he laid it down as a principle -that their present form of government was best suited to them. He -thought, however, that there should be a reform in parliament; and that -parliaments should be triennial instead of septennial. He was an enemy -to all violent reforms, and thought that the change ought to be brought -about gradually and peaceably. When the French revolution broke out he -took the side of the patriots, as he had done during the American war; -and he wrote a refutation of Mr. Burke's extraordinary performance. -Being a dissenter, it is needless to say that he was an advocate for -complete religious freedom. He was ever hostile to all religious -establishments, and an open enemy to the church of England. - -How far these opinions were just and right this is not the place to -inquire; but that they were perfectly harmless, and that many other -persons in this country during the last century, and even at present, -have adopted similar opinions without incurring any odium whatever, -and without exciting the jealousy or even the attention of government, -is well known to every person. It comes then to be a question of some -curiosity at least, to what we are to ascribe the violent persecutions -raised against Dr. Priestley. It seems to have been owing chiefly to -the alarm caught by the clergy of the established church that their -establishment was in danger;--and, considering the ferment excited -soon after the breaking out of the French revolution, and the rage -for reform, which pervaded all ranks, the almost general alarm of the -aristocracy, at least, was not entirely without foundation. I cannot, -however, admit that there was occasion for the violent alarm caught by -Mr. Pitt and his political friends, and for the very despotic measures -which they adopted in consequence. The disease would probably have -subsided of itself, or it would have been cured by a much gentler -treatment. As Dr. Priestley was an open enemy to the establishment, -its clergy naturally conceived a prejudice against him, and this -prejudice was violently inflamed by the danger to which they thought -themselves exposed; their influence with the ministry was very great, -and Mr. Pitt and his friends naturally caught their prejudices and -opinions. Mr. Burke, too, who had changed his political principles, -and who was inflamed with the burning zeal which distinguishes all -converts, was provoked at Dr. Priestley's answer to his book on the -French revolution, and took every opportunity to inveigh against him -in the house of commons. The conduct of the French, likewise, who made -Dr. Priestley a citizen of France, and chose him a member of their -assembly, though intended as a compliment, was injurious to him in -Great Britain. It was laid hold of by his antagonists to convince the -people that he was an enemy to his country; that he had abjured his -rights as an Englishman; and that he had adopted the principles of -the hereditary enemies of Great Britain. These causes, and not his -political opinions, appear to me to account for the persecution which -was raised against him. - -His sons, disgusted with this persecution of their father, had -renounced their native country and gone over to France; and, on the -breaking out of the war between this country and the French republic, -they emigrated to America. It was this circumstance, joined to the -state of insulation in which he lived, that induced Dr. Priestley, -after much consideration, to form the resolution of following his sons -and emigrating to America. He published his reasons in the preface -to a Fast-day Sermon, printed in 1794, one of the gravest and most -forcible pieces of composition I have ever read. He left England in -April, 1795, and reached New York in June. In America he was received -with much respect by persons of all ranks; and was immediately offered -the situation of professor of chemistry in the College of Philadelphia; -which, however, he declined, as his circumstances, by the liberality -of his friends in England, continued independent. He settled, finally, -in Northumberland, about 130 miles from Philadelphia, where he built -a house, and re-established his library and laboratory, as well as -circumstances permitted. Here he published a considerable number of -chemical papers, some of them under the form of pamphlets, and the rest -in the American Transactions, the New York Medical Repository, and -Nicholson's Journal of Natural Philosophy and Chemistry. Here, also, -he continued keenly engaged in theological pursuits; and published, or -republished, a great variety of books on theological subjects. Here he -lost his wife and his youngest and favourite son, who, he had flattered -himself, was to succeed him in his literary career:--and here he died, -in 1804, after having been confined only two days to bed, and but a -few hours after having arranged his literary concerns, inspected some -proof-sheets of his last theological work, and given instructions to -his son how it should be printed. - -During the latter end of the presidency of Mr. Adams, the same kind of -odium which had banished Dr. Priestley from England began to prevail -in America. He was threatened with being sent out of the country -as an alien. Notwithstanding this, he declined being naturalized; -resolving, as he said, to die as he had lived, an Englishman. When his -friend Mr. Jefferson, whose political opinions coincided with his own, -became president, the odium against him wore off, and he became as much -respected as ever. - -As to the character of Dr. Priestley, it is so well marked by his -life and writings, that it is difficult to conceive how it could -have been mistaken by many eminent men in this kingdom. Industry was -his great characteristic; and this quality, together with a facility -of composition, acquired, as he tells us, by a constant habit while -young of drawing out an abstract of the sermons which he had preached, -and writing a good deal in verse, enabled him to do so much: yet, he -informs us that he never was an intense student, and that his evenings -were usually passed in amusement or company. He was an early riser, -and always lighted his own fire before any one else was stirring: it -was then that he composed all his works. It is obvious, from merely -glancing into his books, that he was precipitate; and indeed, from -the way he went on thinking as he wrote, and writing only one copy, -it was impossible he could be otherwise: but, as he was perfectly -sincere and anxious to obtain the truth, he freely acknowledged his -mistakes as soon as he became sensible of them. This candour is very -visible in his philosophical speculations; but in his theological -writings it was not so much to be expected. He was generally engaged -in controversy in theology; and his antagonists were often insolent, -and almost always angry. We all know the effect of such opposition; and -need not be surprised that it operated upon Dr. Priestley, as it would -do upon any other man. By all accounts his powers of conversation -were very great, and his manners in every respect very agreeable. That -this must have been the case is obvious from the great number of his -friends, and the zeal and ardour with which they continued to serve -him, notwithstanding the obloquy under which he lay, and even the -danger that might be incurred by appearing to befriend him. As for his -moral character, even his worst enemies have been obliged to allow that -it was unexceptionable. Many of my readers will perhaps smile, when I -say that he was not only a sincere, but a zealous Christian, and would -willingly have died a martyr to the cause. Yet I think the fact is of -easy proof; and his conduct through life, and especially at his death, -affords irrefragable proofs of it. His tenets, indeed, did not coincide -with those of the majority of his countrymen; but though he rejected -many of the doctrines, he admitted the whole of the sublime morality -and the divine origin of the Christian religion; which may charitably -be deemed sufficient to constitute a true Christian. Of vanity he seems -to have possessed rather more than a usual share; but perhaps he was -deficient in pride. - -His writings were exceedingly numerous, and treated of science, -theology, metaphysics, and politics. Of his theological, metaphysical, -and political writings it is not our business in this work to take any -notice. His scientific works treat of _electricity_, _optics_, and -_chemistry_. As an electrician he was respectable; as an optician, -a compiler; as a chemist, a discoverer. He wrote also a book on -perspective which I have never had an opportunity of perusing. - -It is to his chemical labours that he is chiefly indebted for the -great reputation which he acquired. No man ever entered upon any -undertaking with less apparent means of success than Dr. Priestley -did on the chemical investigation of _airs_. He was unacquainted with -chemistry, excepting that he had, some years before, attended an -elementary course delivered by Mr. Turner, of Liverpool. He was not in -possession of any apparatus, nor acquainted with the method of making -chemical experiments; and his circumstances were such, that he could -neither lay out a great deal of money on experiments, nor could he -hope, without a great deal of expense, to make any material progress -in his investigations. These circumstances, which, at first sight, -seem so adverse, were, I believe, of considerable service to him, and -contributed very much to his ultimate success. The branch of chemistry -which he selected was new: an apparatus was to be invented before any -thing of importance could be effected; and, as simplicity is essential -in every apparatus, _he_ was most likely to contrive the best, whose -circumstances obliged him to attend to economical considerations. - -Pneumatic chemistry had been begun by Mr. Cavendish in his valuable -paper on carbonic acid and hydrogen gases, published in the -Philosophical Transactions for 1766. The apparatus which he employed -was similar to that used about a century before by Dr. Mayow of -Oxford. Dr. Priestley contrived the apparatus still used by chemists -in pneumatic investigations; it is greatly superior to that of -Mr. Cavendish, and, indeed, as convenient as can be desired. Were -we indebted to him for nothing else than this apparatus, it would -deservedly give him high consideration as a pneumatic chemist. - -His discoveries in pneumatic chemistry are so numerous, that I must -satisfy myself with a bare outline; to enumerate every thing, would -be to transcribe his three volumes, into which he digested his -discoveries. His first paper was published in 1772, and was on the -method of impregnating water with carbonic acid gas; the experiments -contained in it were the consequence of his residing near a brewery in -Leeds. This pamphlet was immediately translated into French; and, at -a meeting of the College of Physicians in London, they addressed the -Lords of the Treasury, pointing out the advantage that might result -from water impregnated with carbonic acid gas in cases of scurvy at -sea. His next essay was published in the Philosophical Transactions, -and procured him the Copleyan medal. His different volumes on air were -published in succession, while he lived with Lord Shelburne, and while -he was settled at Birmingham. They drew the attention of all Europe, -and raised the reputation of this country to a great height. - -The first of his discoveries was _nitrous gas_, now called _deutoxide -of azote_, which had, indeed, been formed by Dr. Hales; but that -philosopher had not attempted to investigate its properties. Dr. -Priestley ascertained its properties with much sagacity, and almost -immediately applied it to the analysis of air. It contributed very much -to all subsequent investigations in pneumatic chemistry, and may be -said to have led to our present knowledge of the constitution of the -atmosphere. - -The next great discovery was _oxygen gas_, which was made by him on -the 1st of August, 1774, by heating the red oxide of mercury, and -collecting the gaseous matter given out by it. He almost immediately -detected the remarkable property which this gas has of supporting -combustion better, and animal life longer, than the same volume of -common air; and likewise the property which it has of condensing into -red fumes when mixed with nitrous gas. Lavoisier, likewise, laid -claim to the discovery of oxygen gas; but his claim is entitled to -no attention whatever; as Dr. Priestley informs us that he prepared -this gas in M. Lavoisier's house, in Paris, and showed him the method -of procuring it in the year 1774, which is a considerable time before -the date assigned by Lavoisier for his pretended discovery. Scheele, -however, actually obtained this gas without any previous knowledge of -what Priestley had done; but the book containing this discovery was not -published till three years after Priestley's process had become known -to the public. - -Dr. Priestley first made known sulphurous acid, fluosilicic acid, -muriatic acid, and ammonia in the gaseous form; and pointed out easy -methods of procuring them: he describes with exactness the most -remarkable properties of each. He likewise pointed out the existence -of carburetted hydrogen gas; though he made but few experiments to -determine its nature. His discovery of protoxide of azote affords -a beautiful example of the advantages resulting from his method of -investigation, and the sagacity which enabled him to follow out -any remarkable appearances which occurred. Carbonic oxide gas was -discovered by him while in America, and it was brought forward by him -as an incontrovertible refutation of the antiphlogistic theory. - -Though he was not strictly the discoverer of hydrogen gas, yet his -experiments on it were highly interesting, and contributed essentially -to the revolution which chemistry soon after underwent. Nothing, -for example, could be more striking, than the reduction of oxide of -iron, and the disappearance of the hydrogen when the oxide is heated -sufficiently in contact with hydrogen gas. Azotic gas was known before -he began his career; but we are indebted to him for most of the -properties of it yet known. To him, also, we owe the knowledge of the -fact, that an acid is formed when electric sparks are made to pass -for some time through a given bulk of common air; a fact which led -afterwards to Mr. Cavendish's great discovery of the composition of -nitric acid. - -He first discovered the great increase of bulk which takes place -when electric sparks are made to pass through ammoniacal gas--a fact -which led Berthollet to the analysis of this gas. He merely repeated -Priestley's experiment, determined the augmentation of bulk, and the -nature of the gases evolved by the action of the electricity. His -experiments on the amelioration of atmospherical air by the vegetation -of plants, on the oxygen gas given out by their leaves, and on the -respiration of animals, are not less curious and interesting. - -Such is a short view of the most material facts for which chemistry -is indebted to Dr. Priestley. As a discoverer of new substances, his -name must always stand very high in the science; but as a reasoner or -theorist his position will not be so favourable. It will be observed -that almost all his researches and discoveries related to gaseous -bodies. He determined the different processes, by means of which the -different gases can be procured, the substances which yield them, and -the effects which they are capable of producing on other bodies. Of -the other departments of chemistry he could hardly be said to know any -thing. As a pneumatic chemist he stands high; as an analytical chemist -he can scarcely claim any rank whatever. In his famous experiments on -the formation of water by detonating mixtures of oxygen and hydrogen -in a copper globe, the copper was found acted upon, and a blue liquid -was obtained, the nature of which he was unable to ascertain; but Mr. -Keir, whose assistance he solicited, determined it to be a solution of -nitrate of copper in water. This formation of nitric acid induced him -to deny that water was a compound of oxygen and hydrogen. The same acid -was formed in the experiments of Mr. Cavendish; but he investigated -the circumstances of the formation, and showed that it depended upon -the presence of azotic gas in the gaseous mixture. Whenever azotic -gas is present, nitric acid is formed, and the quantity of this acid -depends upon the relative proportion of the azotic and hydrogen gases -in the mixture. When no hydrogen gas is present, nothing is formed -but nitric acid: when no azotic gas is present, nothing is formed -but water. These facts, determined by Cavendish, invalidate the -reasoning of Priestley altogether; and had he possessed the skill, like -Cavendish, to determine with sufficient accuracy the proportions of the -different gases in his mixtures, and the relative quantities of nitric -acid formed, he would have seen the inaccuracy of his own conclusions. - -He was a firm believer in the existence of phlogiston; but he seems, -at least ultimately, to have adopted the view of Scheele, and many -other eminent contemporary chemists--indeed, the view of Cavendish -himself--that hydrogen gas is phlogiston in a separate and pure state. -Common air he considered as a compound of oxygen and phlogiston. -Oxygen, in his opinion, was air quite free from phlogiston, or air in -a simple and pure state; while _azotic gas_ (the other constituent of -common air) was air saturated with phlogiston. Hence he called oxygen -_dephlogisticated_, and azote _phlogisticated air_. The facts that -when common air is converted into azotic gas its bulk is diminished -about one-fifth part, and that azotic gas is lighter than common air or -oxygen gas, though not quite unknown to him, do not seem to have drawn -much of his attention. He was not accustomed to use a balance in his -experiments, nor to attend much to the alterations which took place in -the weight of bodies. Had he done so, most of his theoretical opinions -would have fallen to the ground. - -When a body is allowed to burn in a given quantity of common air, it is -known that the quality of the common air is deteriorated; it becomes, -in his language, more phlogisticated. This, in his opinion, was owing -to an affinity which existed between phlogiston and air. The presence -of air is necessary to combustion, in consequence of the affinity which -it has for phlogiston. It draws phlogiston out of the burning body, -in order to combine with it. When a given bulk of air is saturated -with phlogiston, it is converted into azotic gas, or _phlogisticated -air_, as he called it; and this air, having no longer any affinity for -phlogiston, can no longer attract that principle, and consequently -combustion cannot go on in such air. - -All combustible bodies, in his opinion, contain hydrogen. Of course -the metals contain it as a constituent. The calces of metals are those -bodies deprived of phlogiston. To prove the truth of this opinion, he -showed that when the oxide of iron is heated in hydrogen gas, that gas -is absorbed, while the calx is reduced to the metallic state. Finery -cinder, which he employed in these experiments, is, in his opinion, -iron not quite free from phlogiston. Hence it still retains a quantity -of hydrogen. To prove this, he mixed together finery cinder and -carbonates of lime, barytes and strontian, and exposed the mixture to a -strong heat; and by this process obtained inflammable gas in abundance. -In his opinion every inflammable gas contains hydrogen in abundance. -Hence this experiment was adduced by him as a demonstration that -hydrogen is a constituent of finery cinder. - -All these processes of reasoning, which appear so plausible as Dr. -Priestley states them, vanish into nothing, when his experiments are -made, and the weights of every thing determined by means of a balance: -it is then established that a burning body becomes heavier during its -combustion, and that the surrounding air loses just as much weight as -the burning body gains. Scheele and Lavoisier showed clearly that the -loss of weight sustained by the air is owing to a quantity of oxygen -absorbed from it, and condensed in the burning body. Cruikshank first -elucidated the nature of the inflammable gas, produced by the heating -a mixture of finery cinder and carbonate of lime, or other earthy -carbonate. He found that iron filings would answer better than finery -cinder. The gas was found to contain no hydrogen, and to be in fact -a compound of oxygen and carbon. It was shown to be derived from the -carbonic acid of the earthy carbonate, which was deprived of half its -oxygen by the iron filings or finery cinder. Thus altered, it no longer -preserved its affinity for the lime, but made its escape in the gaseous -form, constituting the gas now known by the name of carbonic oxide. - -Though the consequence of the Birmingham riots, which obliged Dr. -Priestley to leave England and repair to America, is deeply to be -lamented, as fixing an indelible disgrace upon the country; perhaps -it was not in reality so injurious to Dr. Priestley as may at first -sight appear. He had carried his peculiar researches nearly as far -as they could go. To arrange and methodize, and deduce from them the -legitimate consequences, required the application of a different -branch of chemical science, which he had not cultivated, and which his -characteristic rapidity, and the time of life to which he had arrived, -would have rendered it almost impossible for him to acquire. In all -probability, therefore, had he been allowed to prosecute his researches -unmolested, his reputation, instead of an increase, might have -suffered a diminution, and he might have lost that eminent situation as -a man of science which he had so long occupied. - -With Dr. Priestley closes this period of the History of British -Chemistry--for Mr. Cavendish, though he had not lost his activity, had -abandoned that branch of science, and turned his attention to other -pursuits. - - - - -CHAPTER II. - -OF THE PROGRESS OF PHILOSOPHICAL CHEMISTRY IN SWEDEN. - - -Though Sweden, partly in consequence of her scanty population, and the -consequent limited sale of books in that country, and partly from the -propensity of her writers to imitate the French, which has prevented -that originality in her poets and historians that is requisite for -acquiring much eminence--though Sweden, for these reasons, has never -reached a very high rank in literature; yet the case has been very -different in science. She has produced men of the very first eminence, -and has contributed more than her full share in almost every department -of science, and in none has she shone with greater lustre than in the -department of Chemistry. Even in the latter part of the seventeenth -century, before chemistry had, properly speaking, assumed the rank of a -science, we find Hierne in Sweden, whose name deserves to be mentioned -with respect. Moreover, in the earlier part of the eighteenth century, -Brandt, Scheffer, and Wallerius, had distinguished themselves by their -writings. Cronstedt, about the middle of the eighteenth century, may -be said to have laid the foundation of systematic mineralogy upon -chemical principles, by the publication of his System of Mineralogy. -But Bergman is entitled to the merit of being the first person who -prosecuted chemistry in Sweden on truly philosophical principles, -and raised it to that high estimation to which its importance justly -entitles it. - -Torbern Bergman was born at Catherinberg, in West Gothland, on the -20th of March, 1735. His father, Barthold Bergman, was receiver of the -revenues of that district, and his mother, Sara Hägg, the daughter of -a Gotheborg merchant. A receiver of the revenues was at that time, -in Sweden, a post both disagreeable and hazardous. The creatures of -a party which had had the ascendancy in one diet, they were exposed -to the persecution of the diet next following, in which an opposite -party usually had the predominance. This circumstance induced Bergman -to advise his son to turn his attention to the professions of law or -divinity, which were at that time the most lucrative in Sweden. After -having spent the usual time at school, and acquired those branches of -learning commonly taught in Sweden, in the public schools and academies -to which Bergman was sent, he went to the University of Upsala, in the -autumn of 1752, where he was placed under the guidance of a relation, -whose province it was to superintend his studies, and direct them to -those pursuits that were likely to lead young Bergman to wealth and -distinction. Our young student showed at once a decided predilection -for mathematics, and those branches of physics which were connected -with mathematics, or depended upon them. But these were precisely -the branches of study which his relation was anxious to prevent his -indulging in. Bergman attempted at once to indulge his own inclination, -and to gratify the wishes of his relation. This obliged him to study -with a degree of ardour and perseverance which has few examples. -His mathematical and physical studies claimed the first share of his -attention; and, after having made such progress in them as would -alone have been sufficient to occupy the whole time of an ordinary -student--to satisfy his relation, Jonas Victorin, who was at that -time a _magister docens_ in Upsala, he thought it requisite to study -some law books besides, that he might be able to show that he had not -neglected his advice, nor abandoned the views which he had held out. - -He was in the habit of rising to his studies every morning at four -o'clock, and he never went to bed till eleven at night. The first year -of his residence at Upsala, he had made himself master of Wolf's Logic, -of Wallerius's System of Chemistry, and of twelve books of Euclid's -Elements: for he had already studied the first book of that work in -the Gymnasium before he went to college. He likewise perused Keil's -Lectures on Astronomy, which at that time were considered as the best -introduction to physics and astronomy. His relative disapproved of his -mathematical and physical studies altogether; but, not being able to -put a stop to them, he interdicted the books, and left his young charge -merely the choice between law and divinity. Bergman got a small box -made, with a drawer, into which he put his mathematical and physical -books, and over this box he piled the law books which his relative had -urged him to study. At the time of the daily visits of his relative, -the mathematical and physical books were carefully locked up in the -drawer, and the law books spread upon the table; but no sooner was his -presence removed, than the drawer was opened, and the mathematical -studies resumed. - -This incessant study; this necessity under which he found himself to -consult his own inclinations and those of his relative; this double -portion of labour, without time for relaxation, exercise, or amusement, -proved at last injurious to young Bergman's health. He fell ill, and -was obliged to leave the university and return home to his father's -house in a state of bad health. There constant and moderate exercise -was prescribed him, as the only means of restoring his health. That his -time here might not be altogether lost to him, he formed the plan of -making his walks subservient to the study of botany and entomology. - -At this time Linnæus, after having surmounted obstacles which would -have crushed a man of ordinary energy, was in the height of his glory; -and was professor of botany and natural history in the University of -Upsala. His lectures were attended by crowds of students from every -country in Europe: he was enthusiastically admired and adored by -his students. This influence on the minds of his pupils was almost -unbounded; and at Upsala, every student was a natural historian. -Bergman had studied botany before he went to college, and he had -acquired a taste for entomology from the lectures of Linnæus himself. -Both of these pursuits he continued to follow after his return home -to West Gothland; and he made a collection of plants and of insects. -Grasses and mosses were the plants to which he turned the most of his -attention, and of which he collected the greatest number. But he felt -a predilection for the study of insects, which was a field much less -explored than the study of plants. - -Among the insects which he collected were several not to be found in -the _Fauna Suecica_. Of these he sent specimens to Linnæus at Upsala, -who was delighted with the present. All of them were till then unknown -as Swedish insects, and several of them were quite new. The following -were the insects at this time collected by Bergman, and sent to Upsala, -as they were named by Linnæus: - - _Phalæna._ Bombyx monacha, camelina. - Noctua Parthenias, conspicillaris. - Perspicillaris, flavicornis, Plebeia. - Geometra pennaria. - Tortrix Bergmanniana, Lediana. - Tinea Harrisella, Pedella, Punctella. - _Tenthredo._ Vitellina, ustulata. - _Ichneumon._ Jaculator niger. - _Tipula._ Tremula. - -When Bergman's health was re-established, he returned to Upsala with -full liberty to prosecute his studies according to his own wishes, and -to devote the whole of his time to mathematics, physics, and natural -history. His relations, finding it in vain to combat his predilections -for these studies, thought it better to allow him to indulge them. - -He had made himself known to Linnæus by the collection of insects -which he had sent him from Catherinberg; and, drawn along by the -glory with which Linnæus was surrounded, and the zeal with which his -fellow-students prosecuted such studies, he devoted a great deal of -his attention to natural history. The first paper which he wrote upon -the subject contained a discovery. There was a substance observed in -some ponds not far from Upsala, to which the name of _coccus aquaticus_ -was given, but its nature was unknown. Linnæus had conjectured that -it might be the _ovarium_ of some insect; but he left the point to be -determined by future observations. Bergman ascertained that it was the -ovum of a species of leech, and that it contained from ten to twelve -young animals. When he stated what he had ascertained to Linnæus, that -great naturalist refused to believe it; but Bergman satisfied him -of the truth of his discovery by actual observation. Linnæus, thus -satisfied, wrote under the paper of Bergman, _Vidi et obstupui_, and -sent it to the academy of Stockholm with this flattering panegyric. It -was printed in the Memoirs of that learned body for 1756 (p. 199), and -was the first paper of Bergman's that was committed to the press. - -He continued to prosecute the study of natural history as an amusement; -though mathematics and natural philosophy occupied by far the greatest -part of his time. Various useful papers of his, connected with -entomology, appeared from time to time in the Memoirs of the Stockholm -Academy; in particular, a paper on the history of insects which attack -fruit-trees, and on the methods of guarding against their ravages: on -the method of classing these insects from the forms of their larvæ, a -time when it would be most useful for the agriculturist to know, in -order to destroy those that are hurtful: a great number of observations -on this class of animals, so various in their shape and their -organization, and so important for man to know--some of which he has -been able to overcome, while others, defended by their small size, and -powerful by their vast numbers, still continue their ravages; and which -offer so interesting a sight to the philosopher by their labours, their -manners, and their foresight.--Bergman was fond of these pursuits, -and looked back upon them in afterlife with pleasure. Long after, he -used to mention with much satisfaction, that by the use of the method -pointed out by him, no fewer than seven millions of destructive insects -were destroyed in a single garden, and during the course of a single -summer. - -About the year 1757 he was appointed tutor to the only son of Count -Adolf Frederick Stackelberg, a situation which he filled greatly to the -satisfaction both of the father and son, as long as the young count -stood in need of an instructor. He took his master's degree in 1758, -choosing for the subject of his thesis on _astronomical interpolation_. -Soon after, he was appointed _magister docens_ in natural philosophy, -a situation peculiar to the University of Upsala, and constituting a -kind of assistant to the professor. For his promotion to this situation -he was obliged to M. Ferner, who saw how well qualified he was for it, -and how beneficial his labours would be to the University of Upsala. In -1761 he was appointed _adjunct_ in mathematics and physics, which, I -presume, means that he was raised to the rank of an associate with the -professor of these branches of science. In this situation it was his -business to teach these sciences to the students of Upsala, a task for -which he was exceedingly well fitted. During this period he published -various tracts on different branches of physical science, particularly -on the _rainbow_, the crepuscula, the aurora-borealis, the electrical -phenomena of Iceland spar, and of the tourmalin. We find his name -among the astronomers who observed the first transit of Venus over the -sun, in 1761, whose results deserve the greatest confidence.[1] His -observations on the electricity of the tourmalin are important. It was -he that first established the true laws that regulate these curious -phenomena. - - [1] See Phil. Trans., vol. lii. p. 227, and vol. lvi. p. 85. - -During the whole of this period he had been silently studying chemistry -and mineralogy, though nobody suspected that he was engaged in any -such pursuits. But in 1767 John Gottschalk Wallerius, who had long -filled the chair of chemistry in the University of Upsala, with high -reputation, resigned his chair. Bergman immediately offered himself -as a candidate for the vacant professorship: and, to show that he -was qualified for the office, published two dissertations on the -Manufacture of Alum, which probably he had previously drawn up, and had -lying by him. Wallerius intended to resign his chair in favour of a -pupil or relation of his own, whom he had destined to succeed him. He -immediately formed a party to oppose the pretensions of Bergman; and -his party was so powerful and so malignant, that few doubted of their -success: for it was joined by all those who, despairing of equalling -the industry and reputation of Bergman, set themselves to oppose and -obstruct his success. Such men unhappily exist in all colleges, and -the more eminent a professor is, the more is he exposed to their -malignant activity. Many of those who cannot themselves rise to any -eminence, derive pleasure from the attempt to pull down the eminent -to their own level. In these attempts, however, they seldom succeed, -unless from some want of prudence and steadiness in the individual -whom they assail. Bergman's Dissertations on Alum were severely -handled by Wallerius and his party: and such was the influence of the -ex-professor, that every body thought Bergman would be crushed by him. - -Fortunately, Gustavus III. of Sweden, at that time crown prince, -was chancellor of the university. He took up the cause of Bergman, -influenced, it is said, by the recommendation of Von Swab, who pledged -himself for his qualifications, and was so keen on the subject that he -pleaded his cause in person before the senate. Wallerius and his party -were of course baffled, and Bergman got the chair. - -For this situation his previous studies had fitted him in a peculiar -manner. His mathematical, physical, and natural-historical knowledge, -so far from being useless, contributed to free him from prejudices, and -to emancipate him from that spirit of routine under which chemistry -had hitherto suffered. They gave to his ideas a greater degree of -precision, and made his views more correct. He saw that mathematics -and chemistry divided between them the whole extent of natural -science, and that its bounds required to be enlarged, to enable it -to embrace all the different branches of science with which it was -naturally connected, or which depended upon it. He saw the necessity -of banishing from chemistry all vague hypotheses and explanations, -and of establishing the science on the firm basis of experiment. He -was equally convinced of the necessity of reforming the nomenclature -of chemistry, and of bringing it to the same degree of precision that -characterized the language of the other branches of natural philosophy. - -His first care, after getting the chair, was to make as complete a -collection as he could of mineral substances, and to arrange them in -order according to the nature of their constituents, as far as they -had been determined by experiment. To another cabinet he assigned the -Swedish minerals, ranged in a geographical manner according to the -different provinces which furnished them. - -When I was at Upsala, in 1812, the first of these collections still -remained, greatly augmented by his nephew and successor, Afzelius. -But no remains existed of the geographical collection. However, there -was a very considerable collection of this kind in the apartments -of the Swedish school of mines at Stockholm, under the care of Mr. -Hjelm, which I had an opportunity of inspecting. It is not improbable -that Bergman's collection might have formed the nucleus of this. A -geographical collection of minerals, to be of much utility, should -exhibit all the different formations which exist in the kingdom: and -in a country so uniform in its nature as Sweden, the minerals of one -county are very nearly similar to those of the other counties; with -the exception of certain peculiarities derived from the mines, or from -some formations which may belong exclusively to certain parts of the -country, as, for example, the coal formations in the south corner of -Sweden, near Helsinburg, and the porphyry rocks, in Elfsdale. - -Bergman attempted also to make a collection of models of the apparatus -employed in the different chemical manufactories, to be enabled to -explain these manufactures with greater clearness to his students. I -was informed by M. Ekeberg, who, in 1812, was _magister docens_ in -chemistry at Upsala, that these models were never numerous. Nor is it -likely that they should be, as Sweden cannot boast of any great number -of chemical manufactories, and as, in Bergman's time, the processes -followed in most of the chemical manufactories of Europe were kept as -secret as possible. - -Thus it was Bergman's object to exhibit to his pupils specimens of all -the different substances which the earth furnishes, with the order in -which these productions are arranged on the globe--to show them the -uses made of all these different productions--how practice had preceded -theory and had succeeded in solving many chemical problems of the most -complicated nature. - -His lectures are said to have been particularly valuable. He drew -around him a considerable number of pupils, who afterwards figured as -chemical discoverers themselves. Of all these Assessor Gahn, of Fahlun, -was undoubtedly the most remarkable; but Hjelm, Gadolin, the Elhuyarts, -and various other individuals, likewise distinguished themselves as -chemists. - -After his appointment to the chemical chair at Upsala, the remainder -of his life passed with very little variety; his whole time was -occupied with his favourite studies, and not a year passed that he -did not publish some dissertation or other upon some more or less -important branch of chemistry. His reputation gradually extended itself -over Europe, and he was enrolled among the number of the members -of most scientific academies. Among other honourable testimonies -of the esteem in which he was held, he was elected rector of the -University of Upsala. This university is not merely a literary body, -but owns extensive estates, over which it possesses great authority, -and, having considerable control over its students, and enjoying -considerable immunities and privileges (conferred in former times as -an encouragement to learning, though, in reality, they serve only to -cramp its energies, and throw barriers in the way of its progress), -constitutes, therefore, a kind of republic in the midst of Sweden: the -professors being its chiefs. But while, in literary establishments, -all the institutions ought to have for an object to maintain peace, -and free their members from every occupation unconnected with letters, -the constitution of that university obliges its professors to attend -to things very inconsistent with their usual functions; while it -gives men of influence and ambition a desire to possess the power and -patronage, though they may not be qualified to perform the duties, of -a professor. Such temptations are very injurious to the true cause -of science; and it were to be wished, that no literary body, in any -part of the world, were possessed of such powers and privileges. When -Bergman was rector, the university was divided into two great parties, -the one consisting of the theological and law faculties, and the other -of the scientific professors. Bergman's object was to preserve peace -and agreement between these two parties, and to convince them that it -was the interest of all to unite for the good of the university and the -promotion of letters. The period of his magistracy is remarkable in the -annals of the university for the small number of deliberations, and the -little business recorded in the registers; and for the good sense and -good behaviour of the students. The students in Upsala are numerous, -and most of them are young men. They had been accustomed frequently to -brave or elude the severity of the regulations; but during Bergman's -rectorship they were restrained effectually by their respect for his -genius, and their admiration of his character and conduct. - -When the reputation of Bergman was at its height, in the year 1776, -Frederick the Great of Prussia formed the wish to attach him to the -Academy of Sciences of Berlin, and made him offers of such a nature -that our professor hesitated for a short time as to whether he ought -not to accept them. His health had been injured by the assiduity -with which he had devoted himself to the double duty of teaching and -experimenting. He might look for an alleviation of his ailments, if -not a complete recovery, in the milder climate of Prussia, and he -would be able to devote himself entirely to his academical duties; but -other considerations prevented him from acceding to this proposal, -tempting as it was. The King of Sweden had been his benefactor, and it -was intimated to him that his leaving the kingdom would afflict that -monarch. This information induced him, without further hesitation, -to refuse the proposals of the King of Prussia. He requested of the -king, his master, not to make him lose the merit of his sacrifice -by augmenting his income; but to this demand the King of Sweden very -properly refused to accede. - -In the year 1771, Professor Bergman married a widow lady, Margaretha -Catharina Trast, daughter of a clergyman in the neighbourhood of -Upsala. By her he had two sons; but both of them died when infants. -This lady survived her husband. The King of Sweden settled on her an -annuity of 200 rix dollars, on condition that she gave up the library -and apparatus of her late husband to the Royal Society of Upsala. - -Bergman's health had been always delicate; indeed he seems never to -have completely recovered the effects of his first year's too intense -study at Upsala. He struggled on, however, with his ailments; and, by -way of relaxation, was accustomed sometimes, in summer, to repair to -the waters of Medevi--a celebrated mineral spring in Sweden, situated -near the banks of the great inland lake, Wetter. One of these visits -seems to have restored him to health for the time. But his malady -returned in 1784 with redoubled violence. He was afflicted with -hemorrhoids, and his daily loss of blood amounted to about six ounces. -This constant drain soon exhausted him, and on the 8th of July, 1784, -he died at the baths of Medevi, to which he had repaired in hopes of -again benefiting by these waters. - -The different tracts which he published, as they have been enumerated -by Hjelm, who gave an interesting account of Bergman to the Stockholm -Academy in the year 1785, amount to 106. They have been all collected -into six octavo volumes entitled "Opuscula Torberni Bergman Physica et -Chemica"--with the exception of his notes on Scheffer, his Sciagraphia, -and his chapter on Physical Geography, which was translated into -French, and published in the Journal des Mines (vol. iii. No. 15, p. -55). His Sciagraphia, which is an attempt to arrange minerals according -to their composition, was translated into English by Dr. Withering. -His notes on Scheffer were interspersed in an edition of the "Chemiske -Föreläsningar" of that chemist, published in 1774, which he seems to -have employed as a text-book in his lectures: or, at all events, the -work was published for the use of the students of chemistry at Upsala. -There was a new edition of it published, after Bergman's death, in the -year 1796, to which are appended Bergman's Tables of Affinities. - -The most important of Bergman's chemical papers were collected by -himself, and constitute the three first volumes of his Opuscula. The -three last volumes of that work were published after his death. The -fourth volume was published at Leipsic, in 1787, by Hebenstreit, and -contains the rest of his chemical papers. The fifth volume was given -to the world in 1788, by the same editor. It contains three chemical -papers, and the rest of it is made up with papers on natural history, -electricity, and other branches of physics, which Bergman had published -in the earlier part of his life. The same indefatigable editor -published the sixth volume in 1790. It contains three astronomical -papers, two chemical, and a long paper on the means of preventing any -injurious effects from lightning. This was an oration, delivered before -the Royal Academy of Sciences of Stockholm, in 1764, probably at the -time of his admission into the academy. - -It would serve little purpose in the present state of chemical -knowledge, to give a minute analysis of Bergman's papers. To judge -of their value, it would be necessary to compare them, not with our -present chemical knowledge, but with the state of the science when -his papers were published. A very short general view of his labours -will be sufficient to convey an idea of the benefits which the science -derived from them. - -1. His first paper, entitled "On the Aerial Acid," that is, _carbonic -acid_, was published in 1774. In it he gives the properties of this -substance in considerable detail, shows that it possesses acid -qualities, and that it is capable of combining with the bases, and -forming salts. What is very extraordinary, in giving an account of -carbonate of lime and carbonate of magnesia, he never mentions the name -of Dr. Black; though it is very unlikely that a controversy, which had -for years occupied the attention of chemists, should have been unknown -to him. Mr. Cavendish's name never once appears in the whole paper; -though that philosopher had preceded him by seven or eight years. He -informs us, that he had made known his opinions respecting the nature -of this substance, to various foreign correspondents, among others -to Dr. Priestley, as early as the year 1770, and that Dr. Priestley -had mentioned his views on the subject, in a paper inserted in the -Philosophical Transactions for 1772. Bergman found the specific gravity -of carbonic acid gas rather higher than 1·5, that of air being 1. -His result is not far from the truth. He obtained his gas, by mixing -calcareous spar with dilute sulphuric acid. He shows that this gas -has a sour taste, that it reddens the infusion of litmus, and that -it combines with bases. He gives figures of the apparatus which he -used. This apparatus demands attention. Though far inferior to the -contrivances of Priestley, it answered pretty well, enabling him to -collect the gas, and examine its properties. - -It is unnecessary to enter into any further details respecting this -paper. Whoever will take the trouble to compare it with Cavendish's -paper on the same subject, will find that he had been anticipated by -that philosopher in a great many of his most important facts. Under -these circumstances, I consider as singular his not taking any notice -of Cavendish's previous labours. - -2. His next paper, "On the Analyses of Mineral Waters," was first -published in 1778, being the subject of a thesis, supported by J. -P. Scharenberg. This dissertation, which is of great length, is -entitled to much praise. He lays therein the foundation of the mode of -analyzing waters, such as is followed at present. He points out the -use of different reagents, for detecting the presence of the various -constituents in mineral water, and then shows how the quantity of each -is to be determined. It would be doing great injustice to Bergman, to -compare his analyses with those of any modern experimenter. At that -time, the science was not in possession of any accurate analyses of -the neutral salts, which exist in mineral waters. Bergman undertook -these necessary analyses, without which, the determination of the -saline constituents of mineral waters was out of the question. His -determinations were not indeed accurate, but they were so much -better than those that preceded them, and Bergman's character as an -experimenter stood so high, that they were long referred to as a -standard by chemists. The first attempt to correct them was by Kirwan. -But Bergman's superior reputation as a chemist enabled his results -still to keep their ground, till his character for accuracy was finally -destroyed by the very accurate experiments which the discovery of -the atomic theory rendered it necessary to make. These, when once -they became generally known, were of course preferred, and Bergman's -analyses were laid aside. - -It is a curious and humiliating fact, as it shows how much chemical -reputation depends upon situation, or accidental circumstances, that -Wenzel had, in 1766, in his book on _affinity_, published much more -accurate analyses of all these salts, than Bergman's--analyses indeed -which were almost perfectly correct, and which have scarcely been -surpassed, by the most careful ones of the present day. Yet these -admirable experiments scarcely drew the attention of chemists; while -the very inferior ones of Bergman were held up as models of perfection. - -3. Bergman, not satisfied with pointing out the mode of analyzing -mineral waters, attempted to imitate them artificially by chemical -processes, and published two essays on the subject; in the first he -showed the processes by which cold mineral waters might be imitated, -and in the other, the mode of imitating hot mineral waters. The attempt -was valuable, and served to extend greatly the chemical knowledge of -mineral waters, and of the salts which they contain; but it was made -at too early a period of the analytical art, to approach perfection. -A similar remark applies to his analysis of sea-water. The water -examined was brought by Sparmann from a depth of eighty fathoms, near -the latitude of the Canaries: Bergman found in it only common salt, -muriate of magnesia, and sulphate of lime. His not having discovered -the presence of sulphate of magnesia is a sufficient proof of the -imperfection of his analytical methods; the other constituents exist -in such small quantity in sea-water that they might easily have been -overlooked, but the quantity of sulphate of magnesia in sea-water is -considerable. - -4. I shall pass over the paper on oxalic acid, which constituted the -subject of a thesis, supported in 1776, by John Afzelius Arfvedson. -It is now known that oxalic acid was discovered by Scheele, not by -Bergman. It is impossible to say how many of the numerous facts -stated in this thesis were ascertained by Scheele, and how many -by Afzelius. For, as Afzelius was already a _magister docens_ in -chemistry, there can be little doubt that he would himself ascertain -the facts which were to constitute the foundation of his thesis. It -is indeed now known that Bergman himself intrusted all the details of -his experiments to his pupils. He was the contriver, while his pupils -executed his plans. That Scheele has nowhere laid claim to a discovery -of so much importance as that of oxalic acid, and that he allowed -Bergman peaceably to bear away the whole credit, constitutes one of -the most remarkable facts in the history of chemistry. Moreover, while -it reflects so much credit on Scheele for modesty and forbearance, -it seems to bear a little hard upon the character of Bergman. When -he published the essay in the first volume of his Opuscula, in 1779, -why did he not in a note inform the world that Scheele was the -true discoverer of this acid? Why did he allow the discovery to be -universally assigned to him, without ever mentioning the true state of -the case? All this appeared so contrary to the character of Bergman, -that I was disposed to doubt the truth of the statement, that Scheele -was the discoverer of oxalic acid. When I was at Fahlun, in the year -1812, I took an opportunity of putting the question to Assessor Gahn, -who had been the intimate friend of Scheele, and the pupil, and -afterwards the friend of Bergman. He assured me that Scheele really was -the discoverer of oxalic acid, and ascribed the omission of Bergman to -inadvertence. Assessor Gahn showed me a volume of Scheele's letters -to him, which he had bound up: they contained the history of all his -chemical labours. I have little doubt that an account of oxalic acid -would be found in these letters. If the son of Assessor Gahn, in whose -possession these letters must now be, would take the trouble to inspect -the volume in question, and to publish any notices respecting this acid -which they may contain, he would confer an important favour on every -person interested in the history of chemistry. - -5. The dissertation on the manufacture of alum has been mentioned -before. Bergman shows himself well acquainted with the processes -followed, at least in Sweden, for making alum. He had no notion of -the true constitution of alum; nor was that to be expected, as the -discovery was thereby years later in being made. He thought that the -reason why alum leys did not crystallize well was, that they contained -an excess of acid, and that the addition of potash gave them the -property of crystallizing readily, merely by saturating that excess -of acid. Alum is a double salt, composed of three integrant particles -of sulphate of alumina, and one integrant particle of sulphate of -potash, or sulphate of ammonia. In some cases, the alum ore contains -all the requisite ingredients. This is the case with the ore at Tolfa, -in the neighbourhood of Rome. It seems, also, to be the case with -respect to some of the alum ores in Sweden; particularly at Hœnsœter -on Kinnekulle, in West Gothland, which I visited in 1812. If any -confidence can be put in the statements of the manager of those works, -no alkaline salt whatever is added; at least, I understood him to say -so when I put the question. - -6. In his dissertation on tartar-emetic, he gives an interesting -historical account of this salt and its uses. His notions respecting -the antimonial preparations best fitted to form it, are not accurate: -nor, indeed, could they be expected to be so, till the nature and -properties of the different oxides of antimony were accurately -known. Antimony forms three _oxides_: now it is the protoxide alone -that is useful in medicine, and that enters into the composition -of tartar-emetic; the other two oxides are inert, or nearly so. -Bergman was aware that tartar-emetic is a double salt, and that its -constituents are tartaric acid, potash, and oxide of antimony; but it -was not possible, in 1773, when his dissertation was published, to have -determined the true constituents of this salt by analysis. - -7. Bergman's paper on magnesia was also a thesis defended in 1775, -by Charles Norell, of West Gothland, who in all probability made the -experiments described in the essay. In the introduction we have a -history of the discovery of magnesia, and he mentions Dr. Black as the -person who first accurately made out its peculiar chemical characters, -and demonstrated that it differs from lime. This essay contains a -pretty full and accurate account of the salts of magnesia, considering -the state of chemistry at the time when it was published. There is no -attempt to analyze any of the magnesian salts; but, in his treatise on -the analysis of mineral waters, he had stated the quantity of magnesia -contained in one hundred parts of several of them. - -8. His paper on the _shapes of crystals_, published in 1773, contains -the germ of the whole theory of crystallization afterwards developed by -M. Hauy. He shows how, from a very simple primary form of a mineral, -other shapes may proceed, which seem to have no connexion with, or -resemblance to the primary form. His view of the subject, so far as -it goes, is the very same afterwards adopted by Hauy: and, what is -very curious, Hauy and Bergman formed their theory from the very -same crystalline shape of calcareous spar--from which, by mechanical -divisions, the same rhombic nucleus was extracted by both. Nothing -prevented Bergman from anticipating Hauy but a sufficient quantity of -crystals to apply his theory to.[2] - - [2] I shall mention afterwards that the real discoverer of this fact - was Assessor Gahn, of Fahlun. - -9. In his paper on silica he gives us a history of the progress of -chemical knowledge respecting this substance. Its nature was first -accurately pointed out by Pott; though Glauber, and before him Van -Helmont, were acquainted with the _liquor silicus_, or the combination -of silica and potash, which is soluble in water. Bergman gives a -detailed account of its properties; but he does not suspect it to -possess acid properties. This great discovery, which has thrown a -new light upon mineral bodies, and shown them all to be chemical -combinations, was reserved for Mr. Smithson. - -10. Bergman's experiments on the precious stones constitute the first -rudiments of the method of analyzing stony bodies. His processes are -very imperfect, and his apparatus but ill adapted to the purpose. We -need not be surprised, therefore, that the results of his analyses -are extremely wide of the truth. Yet, if we study his processes, we -shall find in them the rudiments of the very methods which we follow -at present. The superiority of the modern analyses over those of -Bergman must in a great measure be ascribed to the platinum vessels -which we now employ, and to the superior purity of the substances which -we use as reagents in our analyses. The methods, too, are simplified -and perfected. But we must not forget that this paper of Bergman's, -imperfect as it is, constitutes the commencement of the art, and that -fully as much genius and invention may be requisite to contrive the -first rude processes, how imperfect soever they may be, as are required -to bring these processes when once invented to a state of comparative -perfection. The great step in analyzing minerals is to render them -soluble in acids. Bergman first thought of the method for accomplishing -this which is still followed, namely, fusing them or heating them to -redness with an alkali or alkaline carbonate. - -11. The paper on fulminating gold goes a great way to explain the -nature of that curious compound. He describes the properties of this -substance, and the effects of alkaline and acid bodies on it. He -shows that it cannot be formed without ammonia, and infers from his -experiments that it is a compound of oxide of gold and ammonia. He -explains the fulmination by the elastic fluid suddenly generated by the -decomposition of the ammonia. - -12. The papers on platinum, carbonate of iron, nickel, arsenic, and -zinc, do not require many remarks. They add considerably to the -knowledge which chemists at that time possessed of these bodies; though -the modes of analysis are not such as would be approved of by a modern -chemist; nor were the results obtained possessed of much precision. - -13. The Essay on the Analysis of Metallic Ores by the wet way, or by -solution, constitutes the first attempt to establish a regular method -of analyzing metallic ores. The processes are all imperfect, as might -be expected from the then existing state of analytical chemistry, and -the imperfect knowledge possessed, of the different metallic ores. -But this essay constituted a first beginning, for which the author is -entitled to great praise. The subject was taken up by Klaproth, and -speedily brought to a great degree of improvement by the labours of -modern chemists. - -14. The experiments on the way in which minerals behave before the -blowpipe, which Bergman published, were made at Bergman's request -by Assessor Gahn, of Fahlun, who was then his pupil. They constitute -the first results obtained by that very ingenious and amiable man. He -afterwards continued the investigation, and added many improvements, -simplifying the reagents and the manner of using them. But he was too -indolent a man to commit the results of his investigations to writing. -Berzelius, however, had the good sense to see the importance of the -facts which Gahn had ascertained. He committed them to writing, and -published them for the use of mineralogists. They constitute the book -entitled "Berzelius on the Blowpipe," which has been translated into -English. - -15. The object of the Essay on Metallic Precipitates is to determine -the quantity of phlogiston which each metal contains, deduced from -the quantity of one metal necessary to precipitate a given weight of -another. The experiments are obviously made with little accuracy: -indeed they are not susceptible of very great precision. Lavoisier -afterwards made use of the same method to determine the quantity of -oxygen in the different metallic oxides; but his results were not more -successful than those of Bergman. - -16. Bergman's paper on iron is one of the most important in his whole -works, and contributed very materially to advance the knowledge of -the cause of the difference between iron and steel. He employed -his pupils to collect specimens of iron from the different Swedish -forges, and gave them directions how to select the proper pieces. -All these specimens, to the number of eighty-nine, he subjected to a -chemical examination, by dissolving them in dilute sulphuric acid. He -measured the volume of hydrogen gas, which he obtained by dissolving -a given weight of each, and noted the quantity and the nature of the -undissolved residue. The general result of the whole investigation -was that pure malleable iron yielded most hydrogen gas; steel less, -and cast-iron least of all. Pure malleable iron left the smallest -quantity of insoluble matter, steel a greater quantity, and cast-iron -the greatest of all. From these experiments he drew conclusions with -respect to the difference between iron, steel, and cast-iron. Nothing -more was necessary than to apply the antiphlogistic theory to these -experiments, (as was done soon after by the French chemists,) in -order to draw important conclusions respecting the nature of these -bodies. Iron is a simple body; steel is a compound of iron and carbon; -and cast-iron of iron and a still greater proportion of carbon. The -defective part of the experiments of Bergman in this important paper -is his method of determining the quantity of _manganese_ in iron. In -some specimens he makes the manganese amount to considerably more than -a third part of the weight of the whole. Now we know that a mixture of -two parts iron and one part manganese is brittle and useless. We are -sure, therefore, that no malleable iron whatever can contain any such -proportion of manganese. The fact is, that Bergman's mode of separating -manganese from iron was defective. What he considered as manganese was -chiefly, and might be in many cases altogether, oxide of iron. Many -years elapsed before a good process for separating iron from manganese -was discovered. - -17. Bergman's experiments to ascertain the cause of the brittleness of -cold-short iron need not occupy much of our attention. He extracted -from it a white powder, by dissolving the cold-short iron in dilute -sulphuric acid. This white powder he succeeded in reducing to the state -of a white brittle metal, by fusing it with a flux and charcoal. -Klaproth soon after ascertained that this metal was a phosphuret of -iron, and that the white powder was a phosphate of iron: and Scheele, -with his usual sagacity, hit on a method of analyzing this phosphate, -and thus demonstrating its nature. Thus Bergman's experiments led to -the knowledge of the fact that cold-short iron owes its brittleness to -a quantity of phosphorus which it contains. It ought to be mentioned -that Meyer, of Stettin, ascertained the same fact, and made it known to -chemists at about the same time with Bergman. - -18. The dissertation on the products of volcanoes, first published in -1777, is one of the most striking examples of the sagacity of Bergman -which we possess. He takes a view of all the substances certainly known -to have been thrown out of volcanoes, attempts to subject them to a -chemical analysis, and compares them with the basalt, and greenstone or -trap-rocks, the origin of which constituted at that time a keen matter -of dispute among geologists. He shows the identity between lavas and -basalt and greenstone, and therefore infers the identity of formation. -This is obviously the true mode of proceeding, and, had it been adopted -at an earlier period, many of those disputes respecting the nature of -trap-rocks, which occupied geologists for so long a period, would never -have been agitated; or, at least, would have been speedily decided. The -whole dissertation is filled with valuable matter, still well entitled -to the attention of geologists. His observations on _zeolites_, which -he considered as unconnected with volcanic products, were very natural -at the time when he wrote: though the subsequent experiments of Sir -James Hall, and Mr. Gregory Watt, and, above all, an accurate attention -to the scoriæ from different smelting-houses, have thrown a new light -on the subject, and have shown the way in which zeolitic crystals -might easily have been formed in melted lava, provided circumstances -were favourable. In fact, we find abundant cavities in real lava from -Vesuvius, filled with zeolitic crystals. - -19. The last of the labours of Bergman which I shall notice here is -his Essay on Elective Attractions, which was originally published -in 1775, but was much augmented and improved in the third volume of -his Opuscula, published in 1783. An English translation of this last -edition of the Essay was made by Dr. Beddoes, and was long familiar to -the British chemical world. The object of this essay was to elucidate -and explain the nature of chemical affinity, and to account for all the -apparent anomalies that had been observed. He laid it down as a first -principle, that all bodies capable of combining chemically with each -other, have an attraction for each other, and that this attraction is -a definite and fixed force which may be represented by a number. Now -the bodies which have the property of uniting together are chiefly the -acids and the alkalies, or bases. Every acid has an attraction for each -of the alkalies or bases; but the force of this attraction differs in -each. Some bases have a strong attraction for acids, and others a weak; -but the attractive force of each may be expressed by numbers. - -Now, suppose that an acid _a_ is united with a base _m_ with a certain -force, if we mix the compound _a m_ with a certain quantity of the -base _n_, which has a stronger attraction for _a_ than _m_ has, the -consequence will be, that _a_ will leave _m_ and unite with _n_;--_n_ -having a stronger attraction for _a_ than _m_ has, will disengage it -and take its place. In consequence of this property, which Bergman -considered as the foundation of the whole of the science, the -strength of affinity of one body for another is determined by these -decompositions and combinations. If _n_ has a stronger affinity for -_a_ than _m_ has, then if we mix together _a_, _m_, and _n_ in the -requisite proportions, _a_ and _n_ will unite together, leaving _m_ -uncombined: or if we mix _n_ with the compound _a m_, _m_ will be -disengaged. Tables, therefore, may be drawn up, exhibiting the strength -of these affinities. At the top of a column is put the name of an -_acid_ or a _base_, and below it are put the names of all the _bases_ -or _acids_ in the order of their affinity. The following little table -will exhibit a specimen of these columns: - - _Sulphuric Acid._ - Barytes - Strontian - Potash - Soda - Lime - Magnesia. - -Here sulphuric acid is the substance placed at the head of the column, -and under it are the names of the bases capable of uniting with it in -the order of their affinity. Barytes, which is highest up, has the -strongest affinity, and magnesia, which is lowest down, has the weakest -affinity. If sulphuric acid and magnesia were combined together, all -the bases whose names occur in the table above magnesia would be able -to separate the sulphuric acid from it. Potash would be disengaged from -sulphuric acid by barytes and strontian, but not by soda, lime, and -magnesia. - -Such tables then exhibited to the eye the strength of affinity of all -the different bodies that are capable of uniting with one and the same -substance, and the order in which decompositions are effected. Bergman -drew up tables of affinity according to these views in fifty-nine -columns. Each column contained the name of a particular substance, -and under it was arranged all the bodies capable of uniting with it, -each in the order of its affinity. Now bodies may be made to unite, -either by mixing them together, and then exposing them to heat, or -by dissolving them in water and mixing the respective solutions -together. The first of these ways is usually called the _dry way_, -the second the _moist way_. The order of decompositions often varies -with the mode employed. On this account, Bergman divided each of his -fifty-nine columns into two. In the first, he exhibited the order of -decompositions in the moist way, in the second in the dry. He explained -also the cases of double decomposition, by means of these unvarying -forces acting together or opposing each other--and gave sixty-four -cases of such double decompositions. - -These views of Bergman's were immediately acceded to by the chemical -world, and continued to regulate their processes till Berthollet -published his Chemical Statics in 1802. He there called in question the -whole doctrine of Bergman, and endeavoured to establish one of the very -opposite kind. I shall have occasion to return to the subject when I -come to give an account of the services which Berthollet conferred upon -chemistry. - -I have already observed, that we are under obligations to Bergman, not -merely for the improvements which he himself introduced into chemistry, -but for the pupils whom he educated as chemists, and the discoveries -which were made by those persons, whose exertions he stimulated and -encouraged. Among those individuals, whose chemical discoveries were -chiefly made known to the world by his means, was Scheele, certainly -one of the most extraordinary men, and most sagacious and industrious -chemists that ever existed. - -Charles William Scheele was born on the 19th of December, 1742, at -Stralsund, the capital of Swedish Pomerania, where his father was a -tradesman. He received the first part of his education at a private -academy in Stralsund, and was afterwards removed to a public school. -At a very early period he expressed a strong desire to study pharmacy, -and obtained his father's consent to make choice of this profession. -He was accordingly bound an apprentice for six years to Mr. Bouch, an -apothecary in Gotheborg, and after his time was out, he remained with -him still, two years longer. - -It was here that he laid the groundwork of all his future celebrity, -as we are informed by Mr. Grunberg, who was his fellow-apprentice, -and afterwards settled as an apothecary in Stralsund. He was at that -time very reserved and serious, but uncommonly diligent. He attended -minutely to all the processes, reflected upon them while alone, and -studied the writings of Neumann, Lemery, Kunkel, and Stahl, with -indefatigable industry. He likewise exercised himself a good deal -in drawing and painting, and acquired some proficiency in these -accomplishments without a master. Kunkel's Laboratorium was his -favourite book, and he was in the habit of repeating experiments out of -it secretly during the night-time. On one occasion, as he was employed -in making pyrophorus, his fellow-apprentice was malicious enough to -put a quantity of fulminating powder into the mixture. The consequence -was a violent explosion, which, as it took place in the night, threw -the whole family into confusion, and brought a very severe rebuke -upon our young chemist. But this did not put a stop to his industry, -which he pursued so constantly and judiciously, that, by the time his -apprenticeship was ended, there were very few chemists indeed who -excelled him in knowledge and practical skill. His fellow-apprentice, -Mr. Grunberg, wrote to him in 1774, requesting to know by what means he -had become such a proficient in chemistry, and received the following -answer: "I look upon you, my dear friend, as my first instructor, -and as the author of all I know on the subject, in consequence of -your advising me to read Neumann's Chemistry. The perusal of this -book first gave me a taste for experimenting, myself; and I very well -remember, that upon mixing some oil of cloves and smoking spirit of -nitre together, they took fire. However, I kept this matter secret. -I have also before my eyes the unfortunate experiment which I made -with pyrophorus. Such accidents only served to increase my passion for -making experiments." - -In 1765 Scheele went to Malmo, to the house of an apothecary, called -Mr. Kalstrom. After spending two years in that place, he went to -Stockholm, to superintend the apothecary's shop of Mr. Scharenberg. In -1773 he exchanged this situation for another at Upsala, in the house of -Mr. Loock. It was here that he accidentally formed an acquaintance with -Assessor Gahn, of Fahlun, who was at that time a student at Upsala, and -a zealous chemist. Mr. Gahn happening to be one day in the shop of Mr. -Loock, that gentleman mentioned to him a circumstance which had lately -occurred to him, and of which he was anxious to obtain an explanation. -If a quantity of saltpetre be put into a crucible and raised to such a -temperature as shall not merely melt it, but occasion an agitation in -it like boiling, and if, after a certain time, the crucible be taken -out of the fire and allowed to cool, the saltpetre still continues -neutral; but its properties are altered: for, if distilled vinegar be -poured upon it, red fumes are given out, while vinegar produces no -effect upon the saltpetre before it has been thus heated. Mr. Loock -wished from Gahn an explanation of the cause of this phenomenon: Gahn -was unable to explain it; but promised to put the question to Professor -Bergman. He did so accordingly, but Bergman was as unable to find an -explanation as himself. On returning a few days after to Mr. Loock's -shop, Gahn was informed that there was a young man in the shop who had -given an explanation of the phenomenon. This young man was Scheele, who -had informed Mr. Loock that there were two species of acids confounded -under the name of _spirit of nitre_; what we at present call _nitric_ -and _hyponitrous_ acids. Nitric acid has a stronger affinity for potash -than vinegar has; but hyponitrous acid has a weaker. The heat of the -fire changes the _nitric_ acid of the saltpetre to _hyponitrous_: hence -the phenomenon. - -Gahn was delighted with the information, and immediately formed an -acquaintance with Scheele, which soon ripened into friendship. When he -informed Bergman of Scheele's explanation, the professor was equally -delighted, and expressed an eager desire to be made acquainted with -Scheele; but when Gahn mentioned the circumstance to Scheele, and -offered to introduce him to Bergman, our young chemist rejected the -proposal with strong feelings of dislike. - -It seems, that while Scheele was in Stockholm, he had made experiments -on cream of tartar, and had succeeded in separating from it tartaric -acid, in a state of purity. He had also determined a number of the -properties of tartaric acid, and examined several of the tartrates. He -drew up an account of these results, and sent it to Bergman. Bergman, -seeing a paper subscribed by the name of a person who was unknown to -him, laid it aside without looking at it, and forgot it altogether. -Scheele was very much provoked at this contemptuous and unmerited -treatment. He drew up another account of his experiments and gave it to -Retzius, who sent it to the Stockholm Academy of Sciences (with some -additions of his own), in whose Memoirs it was published in the year -1770.[3] It cost Assessor Gahn considerable trouble to satisfy Scheele -that Bergman's conduct was merely the result of inadvertence, and that -he had no intention whatever of treating him either with contempt or -neglect. After much entreaty, he prevailed upon Scheele to allow him -to introduce him to the professor of chemistry. The introduction took -place accordingly, and ever after Bergman and Scheele continued steady -friends--Bergman facilitating the researches of Scheele by every means -in his power. - - [3] Konig. Vetensk. Acad. Handl. 1770, p. 207. - -So high did the character of Scheele speedily rise in Upsala, that when -the Duke of Sudermania visited the university soon after, in company -with Prince Henry of Prussia, Scheele was appointed by the university -to exhibit some chemical processes before him. He fulfilled his charge, -and performed in different furnaces several curious and striking -experiments. Prince Henry asked him various questions, and expressed -satisfaction at the answers given. He was particularly pleased -when informed that he was a native of Stralsund. These two princes -afterwards stated to the professors that they would take it as a favour -if Scheele could have free access to the laboratory of the university -whenever he wished to make experiments. - -In the year 1775, on the death of Mr. Popler, apothecary at Köping (a -small place on the north side of the lake Mæler), he was appointed by -the Medical College _provisor_ of the apothecary's shop. In Sweden all -the apothecaries are under the control of the Medical College, and no -one can open a shop without undergoing an examination and receiving -licence from that learned body. In the course of the examinations -which he was obliged to undergo, Scheele gave great proofs of his -abilities, and obtained the appointment. In 1777 the widow sold him -the shop and business, according to a written agreement made between -them; but they still continued housekeeping at their joint expense. He -had already distinguished himself by his discovery of fluoric acid, -and by his admirable paper on manganese. It is said, too, that it was -he who made the experiments on carbonic acid gas, which constitute the -substance of Bergman's paper on the subject, and which confirmed and -established Bergman's idea that it was an acid. At Köping he continued -his researches with unremitting perseverance, and made more discoveries -than all the chemists of his time united together. It was here that he -made the experiments on air and fire, which constitute the materials of -his celebrated work on these subjects. The theory which he formed was -indeed erroneous; but the numerous discoveries which the book contains -must always excite the admiration of every chemist. His discovery of -oxygen gas had been anticipated by Priestley; but his analysis of -atmospheric air was new and satisfactory--was peculiarly his own. The -processes by means of which he procured oxygen gas were also new, -simple, and easy, and are still followed by chemists in general. During -his residence at Köping he published a great number of chemical papers, -and every one of them contained a discovery. The whole of his time was -devoted to chemical investigations. Every action of his life had a -tendency to forward the advancement of his favourite science; all his -thoughts were turned to the same object; all his letters were devoted -to chemical observations and chemical discussions. Crell's Annals was -at that time the chief periodical work on chemistry in Germany. He got -the numbers regularly as they were published, and was one of Crell's -most constant and most valuable correspondents. Every one of his -letters published in that work either contains some new chemical fact, -or exposes the errors and mistakes of some one or other of Crell's -numerous correspondents. - -Scheele's outward appearance was by no means prepossessing. He seldom -joined in the usual conversations and amusements of society, having -neither leisure nor inclination for them. What little time he had to -spare from the hurry of his profession was always employed in making -experiments. It was only when he received visits from his friends, -with whom he could converse on his favourite science, that he indulged -himself in a little relaxation. For such intimate friends he had -a sincere affection. This regard was extended to all the zealous -cultivators of chemistry in every part of the world, whether personally -known to him or not. He kept up a correspondence with several; though -this correspondence was much limited by his ignorance of all languages -except German; for at least he could not write fluently in any other -language. His chemical papers were always written in German, and -translated into Swedish, before they were inserted in the Memoirs of -the Stockholm Academy, where most of them appeared. - -He was kind and affable to all. Before he adopted an opinion in -science, he reflected maturely on it; but, after he had once embraced -it, his opinions were not easily shaken. However, he did not hesitate -to give up an opinion as soon as it had been proved to be erroneous. -Thus, he entirely renounced the notion which he once entertained that -_silica_ is a compound of _water_ and _fluoric acid_; because it was -demonstrated, by Meyer and others, that this _silica_ was derived -from the glass vessels in which the fluoric acid was prepared; that -these glass vessels were speedily corroded into holes; and that, if -fluoric acid was prepared in metallic vessels, and not allowed to come -in contact with glass or any substance containing silica, it might be -mixed with water without any deposition of silica whatever. - -It appears also by a letter of his, published in Crell's Annals, that -he was satisfied of the accuracy of Mr. Cavendish's experiments, -showing that water was a compound of oxygen and hydrogen gases, and -of Lavoisier's repetition of them. He attempted to reconcile this -fact with his own notion, that heat is a compound of oxygen and -hydrogen. But his arguments on that subject, though ingenious, are not -satisfactory; and there is little doubt that if he had lived somewhat -longer, and had been able to repeat his own experiments, and compare -them with those of Cavendish and Lavoisier, he would have given up -his own theory and adopted that of Lavoisier, or, at any rate, the -explanation of Cavendish, which, being more conformable to his own -preconceived notions, might have been embraced by him in preference. - -It is said by Dr. Crell that Scheele was invited over to England, with -an offer of an easy and advantageous situation; but that his love of -quiet and retirement, and his partiality for Sweden, where he had -spent the greatest part of his life, threw difficulties in the way -of these overtures, and that a change in the English ministry put a -stop to them for the time. The invitation, Crell says, was renewed -in 1786, with the offer of a salary of 300_l._ a-year; but Scheele's -death put a final stop to it. I have very great doubts about the truth -of this statement; and, many years ago, during the lifetime of Sir -Joseph Banks, Mr. Cavendish, and Mr. Kirwan, I made inquiry about the -circumstance; but none of the chemists in Great Britain, who were at -that time numerous and highly respectable, had ever heard of any such -negotiation. I am utterly at a loss to conceive what one individual -in any of the ministries of George III. was either acquainted with -the science of chemistry, or at all interested in its progress. They -were all so intent upon accomplishing their own objects, or those of -their sovereign, that they had neither time nor inclination to think -of science, and certainly no money to devote to any of its votaries. -What minister in Great Britain ever attempted to cherish the sciences, -or to reward those who cultivate them with success? If we except Mr. -Montague, who procured the place of master of the Mint for Sir Isaac -Newton, I know of no one. While in every other nation in Europe science -is directly promoted, and considerable sums are appropriated for its -cultivation, and for the support of a certain number of individuals -who have shown themselves capable of extending its boundaries, not a -single farthing has been devoted to any such purpose in Great Britain. -Science has been left entirely to itself; and whatever has been done -by way of promoting it has been performed by the unaided exertions of -private individuals. George III. himself was a patron of literature -and an encourager of _botany_. He might have been disposed to reward -the unrivalled eminence which Scheele had attained; but this he could -only have done by bestowing on him a pension out of his privy purse. -No situation which Scheele could fill was at his disposal. The -universities and the church were both shut against a Lutheran; and no -pharmaceutical places exist in this country to which Scheele could have -been appointed. If any such project ever existed, it must have been an -idea which struck some man of science that such a proposal to a man -of Scheele's eminence would redound to the credit of the country. But -that such a project should have been broached by a British ministry, or -by any man of great political influence, is an opinion that no person -would adopt who has paid any attention to the history of Great Britain -since the Revolution to the present time. - -Scheele fell at last a sacrifice to his ardent love for his science. He -was unable to abstain from experimenting, and many of his experiments -were unavoidably made in his shop, where he was exposed during winter, -in the ungenial climate of Sweden, to cold draughts of air. He caught -rheumatism in consequence, and the disease was aggravated by his ardour -and perseverance in his pursuits. When he purchased the apothecary's -shop in which his business was carried on, he had formed the resolution -of marrying the widow of his predecessor, and he had only delayed -it from the honourable principle of acquiring, in the first place, -sufficient property to render such an alliance desirable on her part. -At length, in the month of March, 1786, he declared his intention of -marrying her; but his disease at this time increased very fast, and -his hopes of recovery daily diminished. He was sensible of this; but -nevertheless he performed his promise, and married her on the 19th of -May, at a time when he lay on his deathbed. On the 21st, he left her by -his will the disposal of the whole of his property; and, the same day -on which he so tenderly provided for her, he died. - -I shall now endeavour to give the reader an idea of the principal -chemical discoveries for which we are indebted to Scheele: his papers, -with the exception of his book on _air and fire_, which was published -separately by Bergman, are all to be found either in the Memoirs of -the Stockholm Academy of Science, or in Crell's Journal; they were -collected, and a Latin translation of them, made by Godfrey Henry -Schaefer, published at Leipsic, in 1788, by Henstreit, the editor of -the three last volumes of Bergman's Opuscula. A French translation of -them was made in consequence of the exertions of M. Morveau; and an -English translation of them, in 1786, by means of Dr. Beddoes, when he -was a student in Edinburgh. There are also several German translations, -but I have never had an opportunity of seeing them. - -1. Scheele's first paper was published by Retzius, in 1770; it gives a -method of obtaining pure tartaric acid: the process was to decompose -cream of tartar by means of chalk. One half of the tartaric acid unites -to the lime, and falls down in the state of a white insoluble powder, -being _tartrate of lime_. The cream of tartar, thus deprived of half -its acid, is converted into the neutral salt formerly distinguished -by the name of _soluble tartar_, from its great solubility in water: -it dissolves, and may be obtained in crystals, by the usual method of -crystallizing salts. The tartrate of lime is washed with water, and -then mixed with a quantity of dilute sulphuric acid, just capable of -saturating the lime contained in the tartrate of lime; the mixture -is digested for some time; the sulphuric acid displaces the tartaric -acid, and combines with the lime; and, as the sulphate of lime is but -very little soluble in water, the greatest part of it precipitates, -and the clear liquor is drawn off: it consists of tartaric acid, -held in solution by water, but not quite free from sulphate of lime. -By repeated concentrations, all the sulphate of lime falls down, -and at last the tartaric acid itself is obtained in large crystals. -This process is still followed by the manufacturers of this country; -for tartaric acid is used to a very considerable extent by the -calico-printers, in various processes; for example, it is applied, -thickened with gum, to different parts of cloth dyed Turkey red; the -cloth is then passed through water containing the requisite quantity of -chloride of lime: the tartaric acid, uniting with the lime, sets the -chlorine at liberty, which immediately destroys the red colour wherever -the tartaric acid has been applied, but leaves all the other parts of -the cloth unchanged. - -2. The paper on _fluoric acid_ appeared in the Memoirs of the Stockholm -Academy, for 1771, when Scheele was in Scharenberg's apothecary's -shop in Stockholm, where, doubtless, the experiments were made. Three -years before, Margraaf had attempted an analysis of fluor spar, but -had discovered nothing. Scheele demonstrated that it is a compound of -lime and a peculiar acid, to which he gave the name of _fluoric_ acid. -This acid he obtained in solution in water; it was separated from -the fluor spar by sulphuric, muriatic, nitric, and phosphoric acids. -When the fluoric acid came in contact with water, a white crust was -formed, which proved, on examination, to be silica. Scheele at first -thought that this silica was a compound of fluoric acid and water; but -it was afterwards proved by Weigleb and by Meyer, that this notion is -inaccurate, and that the silica was corroded from the retort into which -the fluor spar and sulphuric acid were put. Bergman, who had adopted -Scheele's theory of the nature of silica, was so satisfied by these -experiments, that he gave it up, as Scheele himself did soon after. - -Scheele did not obtain fluoric acid in a state of purity, put only -_fluosilicic acid_; nor were chemists acquainted with the properties -of fluoric acid till Gay-Lussac and Thenard published their Recherches -Physico-chimiques, in 1811. - -3. Scheele's experiments on _manganese_ were undertaken at the request -of Bergman, and occupied him three years; they were published in the -Memoirs of the Stockholm Academy, for 1774, and constitute the most -memorable and important of all his essays, since they contain the -discovery of two new bodies, which have since acted so conspicuous a -part, both in promoting the progress of the science, and in improving -the manufactures of Europe. These two substances are _chlorine_ and -_barytes_, the first account of both of which occur in this paper. - -The ore of manganese employed in these experiments was the _black -oxide_, or _deutoxide_, of manganese, as it is now called. Scheele's -method of proceeding was to try the effect of all the different -reagents on it. It dissolved in sulphurous and nitrous acids, and the -solution was colourless. Dilute sulphuric acid did not act upon it, -nor nitric acid; but concentrated sulphuric acid dissolved it by the -assistance of heat. The solution of sulphate of manganese in water was -colourless and crystallized in very oblique rhomboidal prisms, having -a bitter taste. Muriatic acid effervesced with it, when assisted by -heat, and the elastic fluid that passed off had a yellowish colour, and -the smell of aqua regia. He collected quantities of this elastic fluid -(_chlorine_) in bladders, and determined some of its most remarkable -properties: it destroyed colours, and tinged the bladder yellow, -as nitric acid does. This elastic fluid, in Scheele's opinion, was -muriatic acid deprived of phlogiston. By phlogiston Scheele meant, in -this place, hydrogen gas. He considered muriatic acid as a compound -of chlorine and hydrogen. Now this is the very theory that was -established by Davy in consequence of his own experiments and those of -Gay-Lussac and Thenard. Scheele's mode of collecting chlorine gas in a -bladder, did not enable him to determine its characters with so much -precision as was afterwards done. But his accuracy was so great, that -every thing which he stated respecting it was correct so far as it went. - -Most of the specimens of manganese ore which Scheele examined, -contained more or less barytes, as has since been determined, in -combination with the oxide. He separated this barytes, and determined -its peculiar properties. It dissolved in nitric and muriatic acids, -and formed salts capable of crystallizing, and permanent in the air. -Neither potash, soda, nor lime, nor any _base_ whatever, was capable of -precipitating it from these acids. But the alkaline carbonates threw it -down in the state of a white powder, which dissolved with effervescence -in acids. Sulphuric acid and all the sulphates threw it down in the -state of a white powder, which was insoluble in water and in acids. -This sulphate cannot be decomposed by any acid or base whatever. The -only practicable mode of proceeding is to convert the sulphuric acid -into sulphur, by heating the salt with charcoal powder, along with a -sufficient quantity of potash, to bring the whole into fusion. The -fused mass, edulcorated, is soluble in nitric or muriatic acid, and -thus may be freed from charcoal, and the barytes obtained in a state -of purity. Scheele detected barytes, also, in the potash made from -trees or other smaller vegetables; but at that time he was unacquainted -with _sulphate of barytes_, which is so common in various parts of the -earth, especially in lead-mines. - -To point out all the new facts contained in this admirable essay, -it would be necessary to transcribe the whole of it. He shows the -remarkable analogy between manganese and metallic oxides. Bergman, in -an appendix affixed to Scheele's paper, states his reasons for being -satisfied that it is really a metallic oxide. Some years afterwards, -Assessor Gahn succeeded in reducing it to the metallic state, and thus -dissipating all remaining doubts on the subject. - -4. In 1775 he gave a new method of obtaining benzoic acid from benzoin. -His method was, to digest the benzoin with pounded chalk and water, -till the whole of the acid had combined with lime, and dissolved in the -water. It is requisite to take care to prevent the benzoin from running -into clots. The liquid thus containing benzoate of lime in solution is -filtered, and muriatic acid added in sufficient quantity to saturate -the lime. The benzoic acid is separated in white flocks, which may be -easily collected and washed. This method, though sufficiently easy, is -not followed by practical chemists, at least in this country. The acid -when procured by precipitation is not so beautiful as what is procured -by sublimation; nor is the process so cheap or so rapid. For these -reasons, Scheele's process has not come into general use. - -5. During the same year, 1775, his essay on arsenic and its acid was -also published in the Memoirs of the Stockholm Academy. In this essay -he shows various processes, by means of which white arsenic may be -converted into an acid, having a very sour taste, and very soluble in -water. This is the acid to which the name of _arsenic acid_ has been -since given. Scheele describes the properties of this acid, and the -salts which it forms, with the different bases. He examines, also, the -action of white arsenic upon different bodies, and throws light upon -the arsenical salt of Macquer. - -6. The object of the little paper on silica, clay, and alum, published -in the Memoirs of the Stockholm Academy, for 1776, is to prove that -alumina and silica are two perfectly distinct bodies, possessed -of different properties. This he does with his usual felicity of -experiment. He shows, also, that alumina and lime are capable of -combining together. - -7. The same year, and in the same volume of the Stockholm Memoirs, he -published his experiments on a urinary calculus. The calculus upon -which his experiments were made, happened to be composed of _uric -acid_. He determined the properties of this new acid, particularly -the characteristic one of dissolving in nitric acid, and leaving a -beautiful pink sediment when the solution is gently evaporated to -dryness. - -8. In 1778 appeared his experiments on molybdena. What is now called -_molybdena_ is a soft foliated mineral, having the metallic lustre, -and composed of two atoms sulphur united to one atom of metallic -molybdenum. It was known before, from the experiments of Quest, that -this substance contains sulphur. Scheele extracted from it a white -powder, which he showed to possess acid properties, though it was -insoluble in water. He examined the characters of this acid, called -molybdic acid, and the nature of the salts which it is capable of -forming by uniting with bases. - -9. In the year 1777 was published the Experiments of Scheele on Air -and Fire, with an introduction, by way of preface, from Bergman, who -seems to have superintended the publication. This work is undoubtedly -the most extraordinary production that Scheele has left us; and is -really wonderful, if we consider the circumstances under which it was -produced. Scheele ascertained that common air is a mixture of two -distinct elastic fluids, one of which alone is capable of supporting -combustion, and which, therefore, he calls _empyreal air_; the -other, being neither capable of maintaining combustion, nor of being -breathed, he called _foul air_. These are the _oxygen_ and _azote_ -of modern chemists. Oxygen he showed to be heavier than common air; -bodies burnt in it with much greater splendour than in common air. -Azote he found lighter than common air; bodies would not burn in it at -all. He showed that metallic _calces_, or metallic _oxides_, as they -are now called, contain oxygen as a constituent, and that when they -are reduced to the metallic state, oxygen gas is disengaged. In his -experiments on fulminating gold he shows, that during the fulmination -a quantity of azotic gas is disengaged; and he deduces from a great -many curious facts, which are stated at length, that ammonia is a -compound of _azote_ and _hydrogen_. His apparatus was not nice enough -to enable him to determine the proportions of the various ingredients -of the bodies which he analyzed: accordingly that is seldom attempted; -and when it is, as was the case with common air, the results are very -unsatisfactory. He deduces from his experiments, that the volume of -oxygen gas, in common air, is between a third and a fourth: we now know -that it is exactly a fifth. - -In this book, also, we have the first account of sulphuretted -hydrogen gas, and of its properties. He gives it the name of stinking -sulphureous air. - -The observations and new views respecting heat and light in this -work are so numerous, that I am obliged to omit them: nor do I think -it necessary to advert to his theory, which, when his book was -published, was exceedingly plausible, and undoubtedly constituted -a great step towards the improvements which soon after followed. -His own experiments, had he attended a little more closely to the -_weights_, and the alterations of them, would have been sufficient -to have overturned the whole doctrine of phlogiston. Upon the whole -it may be said, with confidence, that there is no chemical book in -existence which contains a greater number of new and important facts -than this work of Scheele, at the time it was published. Yet most of -his discoveries were made, also, by others. Priestley and Lavoisier, -from the superiority of their situations, and their greater means of -making their labours speedily known to the public, deprived him of -much of that reputation to which, in common circumstances, he would -have been entitled. Priestley has been blamed for the rapidity of his -publications, and the crude manner in which he ushered his discoveries -to the world. But had he kept them by him till he had brought them to -a sufficient degree of maturity, it is obvious that he would have been -anticipated in the most important of them by Scheele. - -10. In the Memoirs of the Stockholm Academy, for 1779, there is a -short but curious paper of Scheele, giving an account of some results -which he had obtained. If a plate of iron be moistened by a solution -of common salt, or of sulphate of soda, and left for some weeks in a -moist cellar, an efflorescence of carbonate of soda covers the surface -of the plate. The same decomposition of common salt and evolution of -soda takes place when unslacked quicklime is moistened with a solution -of common salt, and left in a similar situation. These experiments led -afterwards to various methods of decomposing common salt, and obtaining -from it carbonate of soda. The phenomena themselves are still wrapped -up in considerable obscurity. Berthollet attempted an explanation -afterwards in his Chemical Statics; but founded on principles not -easily admissible. - -11. During the same year, his experiments on _plumbago_ were published. -This substance had been long employed for making black-lead pencils; -but nothing was known concerning its nature. Scheele, with his usual -perseverance, tried the effect of all the different reagents, and -showed that it consisted chiefly of _carbon_, but was mixed with a -certain quantity of iron. It was concluded from these experiments, -that plumbago is a carburet of iron. But the quantity of iron differs -so enormously in different specimens, that this opinion cannot be -admitted. Sometimes the iron amounts only to one-half per cent., and -sometimes to thirty per cent. Plumbago, then, is carbon mixed with a -variable proportion of iron, or carburet of iron. - -12. In 1780 Scheele published his experiments on milk, and showed that -sour milk contains a peculiar acid, to which the name of _lactic_ acid -has been given. - -He found that when sugar of milk is dissolved in nitric acid, and the -solution allowed to cool, small crystalline grains were deposited. -These grains have an acid taste, and combine with bases: they have -peculiar properties, and therefore constitute a particular acid, to -which the name of _saclactic_ was given. It is formed, also, when -gum is dissolved in nitric acid; on this account it has been called, -_mucic_ acid. - -13. In 1781 his experiments on a heavy mineral called by the Swedes -_tungsten_, were published. This substance had been much noticed on -account of its great weight; but nothing was known respecting its -nature. Scheele, with his usual skill and perseverance, succeeded in -proving that it was a compound of lime and a peculiar acid, to which -the name of _tungstic acid_ was given. Tungsten was, therefore, a -tungstate of lime. Bergman, from its great weight, suspected that -tungstic acid was in reality the oxide of a metal, and this conjecture -was afterwards confirmed by the Elhuyarts, who extracted the same acid -from wolfram, and succeeded in reducing it to the metallic state. - -14. In 1782 and 1783 appeared his experiments on _Prussian blue_, in -order to discover the nature of the colouring matter. These experiments -were exceedingly numerous, and display uncommon ingenuity and sagacity. -He succeeded in demonstrating that _prussic acid_, the name at that -time given to the colouring principle, was a compound of _carbon_ and -_azote_. He pointed out a process for obtaining prussic acid in a -separate state, and determined its properties. This paper threw at once -a ray of light on one of the obscurest parts of chemistry. If he did -not succeed in elucidating this difficult department completely, the -fault must not be ascribed to him, but to the state of chemistry when -his experiments were made; in fact, it would have been impossible to -have gone further, till the nature of the different elastic fluids at -that time under investigation had been thoroughly established. Perhaps -in 1783 there was scarcely any other individual who could have carried -this very difficult investigation so far as it was carried by Scheele. - -15. In 1783 appeared his observations on the _sweet principle of oils_. -He observed, that when olive oil and litharge are combined together, -a sweet substance separates from the oil and floats on the surface. -This substance, when treated with nitric acid, yields _oxalic acid_. It -was therefore closely connected with sugar in its nature. He obtained -the same sweet matter from linseed oil, oil of almonds, of rape-seed, -from hogs' lard, and from butter. He therefore concluded that it was a -principle contained in all the expressed or fixed oils. - -16. In 1784 he pointed out a method by which _citric acid_ may be -obtained in a state of purity from lemon-juice. He likewise determined -its characters, and showed that it was entitled to rank as a peculiar -acid. - -It was during the same year that he observed a white earthy matter, -which may be obtained by washing rhubarb, in fine powder, with a -sufficient quantity of water. This earthy matter he decomposed, and -ascertained that it was a neutral salt, composed of oxalic acid, -combined with lime. In a subsequent paper he showed, that the same -oxalate of lime exists in a great number of roots of various plants. - -17. In 1786 he showed that apples contain a peculiar acid, the -properties of which he determined, and to which the name of _malic -acid_ has been given. In the same paper he examined all the common acid -fruits of this country--gooseberries, currants, cherries, bilberries, -&c., and determined the peculiar acids which they contain. Some owe -their acidity to malic acid, some to citric acid, and some to tartaric -acid; and not a few hold two, or even three, of these acids at the same -time. - -The same year he showed that the syderum of Bergman was phosphuret of -iron, and the _acidum perlatum_ of Proust _biphosphate of soda_. - -The only other publication of Scheele, during 1785, was a short -notice respecting a new mode of preparing _magnesia alba_. If -sulphate of magnesia and common salt, both in solution, be mixed in -the requisite proportions, a double decomposition takes place, and -there will be formed sulphate of soda and muriate of magnesia. The -greatest part of the former salt may be obtained out of the mixed ley -by crystallization, and then the magnesia alba may be thrown down, -from the muriate of magnesia, by means of an alkaline carbonate. The -advantage of this new process is, the procuring of a considerable -quantity of sulphate of soda in exchange for common salt, which is a -much cheaper substance. - -18. The last paper which Scheele published appeared in the Memoirs -of the Stockholm Academy, for 1786: in it he gave an account of the -characters of gallic acid, and the method of obtaining that acid from -nutgalls. - -Such is an imperfect sketch of the principal discoveries of Scheele. -I have left out of view his controversial papers, which have now lost -their interest; and a few others of minor importance, that this notice -might not be extended beyond its due length. It will be seen that -Scheele extended greatly the number of acids; indeed, he more than -doubled the number of these bodies known when he began his chemical -labours. The following acids were discovered by him; or, at least, it -was he that first accurately pointed out their characters: - - Fluoric acid - Molybdic acid - Tungstic acid - Arsenic acid - Lactic acid - Gallic acid - Tartaric acid - Oxalic acid - Citric acid - Malic acid - Saclactic - Chlorine. - -To him, also, we owe the first knowledge of barytes, and of the -characters of manganese. He determined the nature of the constituents -of ammonia and prussic acid: he first determined the compound nature of -common air, and the properties of the two elastic fluids of which it is -composed. What other chemist, either a contemporary or predecessor of -Scheele, can be brought in competition with him as a discoverer? And -all was performed under the most unpropitious circumstances, and during -the continuance of a very short life, for he died in the 44th year of -his age. - - - - -CHAPTER III. - -PROGRESS OF SCIENTIFIC CHEMISTRY IN FRANCE. - - -I have already given an account of the state of chemistry in France, -during the earlier part of the eighteenth century, as it was cultivated -by the Stahlian school. But the new aspect which chemistry put on in -Britain in consequence of the discoveries of Black, Cavendish, and -Priestley, and the conspicuous part which the gases newly made known -was likely to take in the future progress of the science, drew to -the study of chemistry, sometime after the middle of the eighteenth -century, a man who was destined to produce a complete revolution, and -to introduce the same precision, and the same accuracy of deductive -reasoning which distinguishes the other branches of natural science. -This man was Lavoisier. - -Antoine Laurent Lavoisier was born in Paris on the 26th of August, -1743. His father being a man of opulence spared no expense on his -education. His taste for the physical sciences was early displayed, and -the progress which he made in them was uncommonly rapid. In the year -1764 a prize was offered by the French government for the best and most -economical method of lighting the streets of an extensive city. Young -Lavoisier, though at that time only twenty-one years of age, drew up a -memoir on the subject which obtained the gold medal. This essay was -inserted in the Memoirs of the French Academy of Sciences, for 1768. It -was during that year, when he was only twenty-five years of age that -he became a member of that scientific body. By this time he was become -fully conscious of his own strength; but he hesitated for some time to -which of the sciences he should devote his attention. He tried pretty -early to determine, experimentally, some chemical questions which at -that time drew the attention of practical chemists. For example: an -elaborate paper of his appeared in the Memoirs of the French Academy, -for 1768, on the composition of _gypsum_--a point at that time not -settled; but which Lavoisier proved, as Margraaf had done before him, -to be a compound of sulphuric acid and lime. In the Memoirs of the -Academy, for 1770, two papers of his appeared, the object of which -was to determine whether water could, as Margraaf had pretended, be -converted into _silica_ by long-continued digestion in glass vessels. -Lavoisier found, as Margraaf stated, that when water is digested for a -long time in a glass retort, a little silica makes its appearance; but -he showed that this silica was wholly derived from the retort. Glass, -it is well known, is a compound of silica and a fixed alkali. When -water is long digested on it the glass is slightly corroded, a little -alkali is dissolved in the water and a little silica separated in the -form of a powder. - -He turned a good deal of his attention also to geology, and made -repeated journeys with Guettard into almost every part of France. -The object in view was an accurate description of the mineralogical -structure of France--an object accomplished to a considerable extent by -the indefatigable exertions of Guettard, who published different papers -on the subject in the Memoirs of the French Academy, accompanied with -geological maps; which were at that time rare. - -The mathematical sciences also engrossed a considerable share of his -attention. In short he displayed no great predilection for one study -more than another, but seemed to grasp at every branch of science with -equal avidity. While in this state of suspension he became acquainted -with the new and unexpected discoveries of Black, Cavendish, and -Priestley, respecting the gases. This opened a new creation to his -view, and finally determined him to devote himself to scientific -chemistry. - -In the year 1774 he published a volume under the title of "Essays -Physical and Chemical." It was divided into two parts. The first part -contained an historical detail of every thing that had been done on -the subject of airs, from the time of Paracelsus down to the year -1774. We have the opinions and experiments of Van Helmont, Boyle, -Hales, Boerhaave, Stahl, Venel, Saluces, Black, Macbride, Cavendish, -and Priestley. We have the history of Meyer's acidum pingue, and the -controversy carried on in Germany, between Jacquin on the one hand, and -Crans and Smeth on the ether. - -In the second part Lavoisier relates his own experiments upon gaseous -substances. In the first four chapters he shows the truth of Dr. -Black's theory of fixed air. In the 4th and 5th chapters he proves that -when metallic calces are reduced, by heating them with charcoal, an -elastic fluid is evolved, precisely of the same nature with carbonic -acid gas. In the 6th chapter he shows that when metals are calcined -their weight increases, and that a portion of air equal to their -increase in weight is absorbed from the surrounding atmosphere. He -observed that in a given bulk of air calcination goes on to a certain -point and then stops altogether, and that air in which metals have -been calcined does not support combustion so well as it did before any -such process was performed in it. He also burned phosphorus in a given -volume of air, observed the diminution of volume of the air and the -increase of the weight of the phosphorus. - -Nothing in these essays indicates the smallest suspicion that air -was a mixture of two distinct fluids, and that only one of them was -concerned in combustion and calcination; although this had been already -deduced by Scheele from his own experiments, and though Priestley had -already discovered the existence and peculiar properties of oxygen -gas. It is obvious, however, that Lavoisier was on the way to make -these discoveries, and had neither Scheele nor Priestley been fortunate -enough to hit upon oxygen gas, it is exceedingly likely that he would -himself have been able to have made that discovery. - -Dr. Priestley, however, happened to be in Paris towards the end of -1774, and exhibited to Lavoisier, in his own laboratory in Paris, -the method of procuring oxygen gas from red oxide of mercury. This -discovery altered all his views, and speedily suggested not only -the nature of atmospheric air, but also what happens during the -calcination of metals and the combustion of burning bodies in general. -These opinions when once formed he prosecuted with unwearied industry -for more than twelve years, and after a vast number of experiments, -conducted with a degree of precision hitherto unattempted in chemical -investigations, he boldly undertook to disprove the existence of -phlogiston altogether, and to explain all the phenomena hitherto -supposed to depend upon that principle by the simple combination or -separation of oxygen from bodies. - -In these opinions he had for some years no coadjutors or followers, -till, in 1785, Berthollet at a meeting of the Academy of Sciences, -declared himself a convert. He was followed by M. Fourcroy, and soon -after Guyton de Morveau, who was at that time the editor of the -chemical department of the Encyclopédie Méthodique, was invited to -Paris by Lavoisier and prevailed upon to join the same party. This was -followed by a pretty vigorous controversy, in which Lavoisier and his -associates gained a signal victory. - -Lavoisier, after Buffon and Tillet, was treasurer to the academy, -into the accounts of which he introduced both economy and order. He -was consulted by the National Convention on the most eligible means -of improving the manufacture of assignats, and of augmenting the -difficulty of forging them. He turned his attention also to political -economy, and between 1778 and 1785 he allotted 240 arpents in the -Vendomois to experimental agriculture, and increased the ordinary -produce by one-half. In 1791 the Constituent Assembly invited him -to draw up a plan for rendering more simple the collection of the -taxes, which produced an excellent report, printed under the title of -"Territorial Riches of France." - -In 1776 he was employed by Turgot to inspect the manufactory of -gunpowder; which he made to carry 120 toises, instead of 90. It is -pretty generally known, that during the war of the American revolution, -the French gunpowder was much superior to the British; but it is -perhaps not so generally understood, that for this superiority the -French government were indebted to the abilities of Lavoisier. During -the war of the French revolution, the quality of the powder of the two -nations was reversed; the English being considerably superior to that -of the French, and capable of carrying further. This was put to the -test in a very remarkable way at Cadiz. - -During the horrors of the dictatorship of Robespierre, Lavoisier began -to suspect that he would be stripped of his property, and informed -Lalande that he was extremely willing to work for his subsistence. It -was supposed that he meant to pursue the profession of an apothecary, -as most congenial to his studies: but he was accused, along with the -other _farmers-general_, of defrauding the revenue, and thrown into -prison. During that sanguinary period imprisonment and condemnation -were synonymous terms. Accordingly, on the 8th of May, 1794, he -suffered on the scaffold, with twenty-eight farmers-general, at the -early age of fifty-one. It has been, alleged that Fourcroy, who at that -time possessed considerable influence, might have saved him had he been -disposed to have exerted himself. But this accusation has never been -supported by any evidence. Lavoisier was a man of too much eminence -to be overlooked, and no accused person at that time could be saved -unless he was forgotten. A paper was presented to the tribunal, drawn -up by M. Hallé, giving a catalogue of the works, and a recapitulation -of the merits of Lavoisier; but it was thrown aside without even being -read, and M. Hallé had reason to congratulate himself that his useless -attempts to save Lavoisier did not terminate in his own destruction. - -Lavoisier was tall, and possessed a countenance full of benignity, -through which his genius shone forth conspicuous. He was mild, humane, -sociable, obliging, and he displayed an incredible degree of activity. -His influence was great, on account of his fortune, his reputation, -and the place which he held in the treasury; but all the use which -he made of it was to do good. His wife, whom he married in 1771, -was Marie-Anna-Pierette-Paulze, daughter of a farmer-general, who -was put to death at the same time with her husband; she herself was -imprisoned, but saved by the fortunate destruction of the dictator -himself, together with his abettors. It would appear that she was able -to save a considerable part of her husband's fortune: she afterwards -married Count Rumford, whom she survived. - -Besides his volume of Physical and Chemical Essays, and his Elements of -Chemistry, published in 1789, Lavoisier was the author of no fewer than -sixty memoirs, which were published in the volumes of the Academy of -Sciences, from 1772, to 1788, or in other periodical works of the time. -I shall take a short review of the most important of these memoirs, -dividing them into two parts: I. Those that are not connected with his -peculiar chemical theory; II. Those which were intended to disprove the -existence of phlogiston, and establish the antiphlogistic theory. - -I. I have already mentioned his paper on gypsum, published in the -Memoirs of the Academy, for 1768. He proves, by very decisive -experiments, that this salt is a compound of sulphuric acid, lime, -and water. But this had been already done by Margraaf, in a paper -inserted into the Memoirs of the Berlin Academy, for 1750, entitled -"An Examination of the constituent parts of the Stones that become -luminous." The most remarkable circumstance attending this paper is, -that an interval of eighteen years should elapse without Lavoisier's -having any knowledge of this important paper of Margraaf; yet he quotes -Pott and Cronstedt, who had written on the same subject later than -Margraaf, at least Cronstedt. What makes this still more singular and -unaccountable is, that a French translation of Margraaf's Opuscula had -been published in Paris, in the year 1762. That a man in Lavoisier's -circumstances, who, as appears from his paper, had paid considerable -attention to chemistry, should not have perused the writings of one -of the most eminent chemists that had ever existed, when they were -completely within his power, constitutes, I think, one of the most -extraordinary phenomena in the history of science. - -2. If a want of historical knowledge appears conspicuous in Lavoisier's -first chemical paper, the same remark cannot be applied to his second -paper, "On the Nature of Water, and the Experiments by which it has -been attempted to prove the possibility of changing it into Earth," -which was inserted in the Memoirs of the French Academy, for 1770. This -memoir is divided into two parts. In the first he gives a history of -the progress of opinions on the subject, beginning with Van Helmont's -celebrated experiment on the willow; then relating those of Boyle, -Triewald, Miller, Eller, Gleditch, Bonnet, Kraft, Alston, Wallerius, -Hales, Duhamel, Stahl, Boerhaave, Geoffroy, Margraaf, and Le Roy. This -first part is interesting, in an historical point of view, and gives -a very complete account of the progress of opinions upon the subject -from the very first dawn of scientific chemistry down to his own time. -There is, it is true, a remarkable difference between the opinions -of his predecessors respecting the conversion of water into earth, -and the experiments of Margraaf on the composition of _selenite_. The -former were inaccurate, and were recorded by him that they might be -refuted; but the experiments of Margraaf were accurate, and of the -same nature with his own. The second part of this memoir contains his -own experiments, made with much precision, which went to show that -the earth was derived from the retort in which the experiments of -Margraaf were made, and that we have no proof whatever that water may -be converted into earth. - -But these experiments of Lavoisier, though they completely disproved -the inferences that Margraaf drew from his observations, by no means -demonstrated that water might not be converted into different animal -and vegetable substances by the processes of digestion. Indeed there -can be no doubt that this is the case, and that the oxygen and hydrogen -of which it is composed, enter into the composition of by far the -greater number of animal and vegetable bodies produced by the action -of the functions of living animals and vegetables. We have no evidence -that the carbon, another great constituent of vegetable bodies, -and the carbon and azote which constitute so great a proportion of -animal substances, have their origin from water. They are probably -derived from the food of plants and animals, and from the atmosphere -which surrounds them, and which contains both of these principles in -abundance. - -Whether the silica, lime, alumina, magnesia, and iron, that exist in -small quantity in plants, be derived from water and the atmosphere, is -a question which we are still unable to answer. But the experiments -of Schrader, which gained the prize offered by the Berlin Academy, -in the year 1800, for the best essay on the following subject: _To -determine the earthy constituents of the different kinds of corn, and -to ascertain whether these earthy parts are formed by the processes of -vegetation_, show at least that we cannot account for their production -in any other way. Schrader analyzed the seeds of wheat, rye, barley, -and oats, and ascertained the quantity of earthy matter which each -contained. He then planted these different seeds in flowers of sulphur, -and in oxides of antimony and zinc, watering them regularly with -distilled water. They vegetated very well. He then dried the plants, -and analyzed what had been the produce of a given weight of seed, and -he found that the earthy matter in each was greater than it had been in -the seeds from which they sprung. Now as the sulphur and oxides of zinc -and antimony could furnish no earthy matter, no other source remains -but the water with which the plants were fed, and the atmosphere -with which they were surrounded. It may be said, indeed, that earthy -matter is always floating about in the atmosphere, and that in this -way they may have obtained all the addition of these principles which -they contained. This is an objection not easily obviated, and yet it -would require to be obviated before the question can be considered as -answered. - -3. Lavoisier's next paper, inserted in the Memoirs of the Academy, for -1771, was entitled "Calculations and Observations on the Project of -the establishment of a Steam-engine to supply Paris with Water." This -memoir, though long and valuable, not being strictly speaking chemical, -I shall pass over. Mr. Watt's improvements seem to have been unknown -to Lavoisier, indeed as his patent was only taken out in 1769, and as -several years elapsed before the merits of his new steam-engine became -generally known, Lavoisier's acquaintance with it in 1771 could hardly -be expected. - -4. In 1772 we find a paper, by Lavoisier, in the Memoirs of the -Academy, "On the Use of Spirit of Wine in the analysis of Mineral -Waters." He shows how the earthy muriates may be separated from the -sulphates by digesting the mixed mass in alcohol. This process no doubt -facilitates the separation of the salts from each other: but it is -doubtful whether the method does not occasion new inaccuracies that -more than compensate the facility of such separations. When different -salts are dissolved in water in small quantities, it may very well -happen that they do not decompose each other, being at too great a -distance from each other to come within the sphere of mutual action. -Thus it is possible that sulphate of soda and muriate of lime may exist -together in the same water. But if we concentrate this water very -much, and still more, if we evaporate to dryness, the two salts will -gradually come into the sphere of mutual action, a double decomposition -will take place, and there will be formed sulphate of lime and common -salt. If upon the dry residue we pour as much distilled water as was -driven off by the evaporation, we shall not be able to dissolve the -saline matter deposited; a portion of sulphate of lime will remain -in the state of a powder. Yet before the evaporation, all the saline -contents of the water were in solution, and they continued in solution -till the water was very much concentrated. This is sufficient to show -that the nature of the salts was altered by the evaporation. If we -digest the dry residue in spirit of wine, we may dissolve a portion of -muriate of lime, if the quantity of that salt in the original water was -greater than the sulphate of soda was capable of decomposing: but if -the quantity was just what the sulphate of soda could decompose, the -alcohol will dissolve nothing, if it be strong enough, or nothing but a -little common salt, if its specific gravity was above 0·820. We cannot, -therefore, depend upon the salts which we obtain after evaporating a -mineral water to dryness, being the same as those which existed in the -mineral water itself. The nature of the salts must always be determined -some other way. - -5. In the Memoirs of the Academy, for 1772 (published in 1776), are -inserted two elaborate papers of Lavoisier, on the combustion of the -diamond. The combustibility of the diamond was suspected by Newton, -from its great refractive power. His suspicion was confirmed in -1694, by Cosmo III., Grand Duke of Tuscany, who employed Averani and -Targioni to try the effect of powerful burning-glasses upon diamonds. -They were completely dissipated by the heat. Many years after, the -Emperor Francis I. caused various diamonds to be exposed to the heat -of furnaces. They also were dissipated, without leaving any trace -behind them. M. Darcet, professor of chemistry at the Royal College -of Paris, being employed with Count Lauragais in a set of experiments -on the manufacture of porcelain, took the opportunity of trying what -effect the intense heat of the porcelain furnaces produced upon -various bodies. Diamonds were not forgotten. He found that they were -completely dissipated by the heat of the furnace, without leaving any -traces behind them. Darcet found that a violent heat was not necessary -to volatilize diamonds. The heat of an ordinary furnace was quite -sufficient. In 1771 a diamond, belonging to M. Godefroi Villetaneuse, -was exposed to a strong heat by Macquer. It was placed upon a cupel, -and raised to a temperature high enough to melt copper. It was observed -to be surrounded with a low red flame, and to be more intensely red -than the cupel. In short, it exhibited unequivocal marks of undergoing -real combustion. - -These experiments were soon after repeated by Lavoisier before a -large company of men of rank and science. The real combustion of the -diamond was established beyond doubt; and it was ascertained also, -that if it be completely excluded from the air, it may be exposed to -any temperature that can be raised in a furnace without undergoing -any alteration. Hence it is clear that the diamond is not a volatile -substance, and that it is dissipated by heat, not by being volatilized, -but by being burnt. - -The object of Lavoisier in his experiments was to determine the nature -of the substance into which the diamond was converted by burning. In -the first part he gives as usual a history of every thing which had -been done previous to his own experiments on the combustion of the -diamond. In the second part we have the result of his own experiments -upon the same subject. He placed diamonds on porcelain supports in -glass jars standing inverted over water and over mercury; and filled -with common air and with oxygen gas.[4] - - [4] The reader will bear in mind that though the memoir was inserted - in the Mem. de l'Acad., for 1772, it was in fact published in 1776, - and the experiments were made in 1775 and 1776. - -The diamonds were consumed by means of burning-glasses. No _water_ or -_smoke_ or _soot_ made their appearance, and no alteration took place -on the bulk of the air when the experiments were made over mercury. -When they were made over water, the bulk of the air was somewhat -diminished. It was obvious from this that diamond when burnt in air or -oxygen gas, is converted into a gaseous substance, which is absorbed by -water. On exposing air in which diamond had been burnt, to lime-water, -a portion of it was absorbed, and the lime-water was rendered milky. -From this it became evident, that when diamond is burnt, _carbonic -acid_ is formed, and this was the only product of the combustion that -could be discovered. - -Lavoisier made similar experiments with charcoal, burning it in air and -oxygen gas, by means of a burning-glass. The results were the same: -carbonic acid gas was formed in abundance, and nothing else. These -experiments might have been employed to support and confirm Lavoisier's -peculiar theory, and they were employed by him for that purpose -afterwards. But when they were originally published, no such intention -appeared evident; though doubtless he entertained it. - -6. In the second volume of the Journal de Physique, for 1772, there -is a short paper by Lavoisier on the conversion of water into ice. M. -Desmarets had given the academy an account of Dr. Black's experiments, -to determine the latent heat of water. This induced Lavoisier to relate -his experiments on the same subject. He does not inform us whether -they were made in consequence of his having become acquainted with Dr. -Black's theory, though there can be no doubt that this must have been -the case. The experiments related in this short paper are not of much -consequence. But I have thought it worth while to notice it because it -authenticates a date at which Lavoisier was acquainted with Dr. Black's -theory of latent heat. - -7. In the third volume of the Journal de Physique, there is an account -of a set of experiments made by Bourdelin, Malouin, Macquer, Cadet, -Lavoisier, and Baumé on the _white-lead ore_ of Pullowen. The report -is drawn up by Baumé. The nature of the ore is not made out by these -experiments. They were mostly made in the dry way, and were chiefly -intended to show that the ore was not a chloride of lead. It was most -likely a phosphate of lead. - -8. In the Memoirs of the Academy, for 1774, we have the experiments of -Trudaine, de Montigny, Macquer, Cadet, Lavoisier, and Brisson, with -the great burning-glass of M. Trudaine. The results obtained cannot be -easily abridged, and are not of sufficient importance to be given in -detail. - -9. Analysis of some waters brought from Italy by M. Cassini, junior. -This short paper appeared in the Memoirs of the Academy, for 1777. The -waters in question were brought from alum-pits, and were found to -contain alum and sulphate of iron. - -10. In the same volume of the Memoirs of the Academy, appeared his -paper "On the Ash employed by the Saltpetre-makers of Paris, and on its -use in the Manufacture of Saltpetre." This is a curious and valuable -paper; but not sufficiently important to induce me to give an abstract -of it here. - -11. In the Memoirs of the Academy, for 1777, appeared an elaborate -paper, by Lavoisier, "On the Combination of the matter of Fire, with -Evaporable Fluids, and the Formation of Elastic aeriform Fluids." In -this paper he adopts precisely the same theory as Dr. Black had long -before established. It is remarkable that the name of Dr. Black never -occurs in the whole paper, though we have seen that Lavoisier had -become acquainted with the doctrine of latent heat, at least as early -as the year 1772, as he mentioned the circumstance in a short paper -inserted that year in the Journal de Physique, and previously read to -the academy. - -12. In the same volume of the Memoirs of the Academy, we have a paper -entitled "Experiments made by Order of the Academy, on the Cold -of the year 1775, by Messrs. Bezout, Lavoisier, and Vandermond." -It is sufficiently known that the beginning of the year 1776 was -distinguished in most parts of Europe by the weather. The object -of this paper, however, is rather to determine the accuracy of the -different thermometers at that time used in France, than to record the -lowest temperature which had been observed. It has some resemblance to -a paper drawn up about the same time by Mr. Cavendish, and published in -the Philosophical Transactions. - -13. In the Memoirs of the Academy, for 1778, appeared a paper entitled -"Analysis of the Waters of the Lake Asphaltes, by Messrs. Macquer, -Lavoisier, and Sage." This water is known to be saturated with _salt_. -It is needless to state the result of the analysis contained in this -paper, because it is quite inaccurate. Chemical analysis had not at -that time made sufficient progress to enable chemists to analyze -mineral waters with precision. - -The observation of Lavoisier and Guettard, which appeared at the -same time, on a species of steatite, which is converted by the fire -into a fine biscuit of porcelain, and on two coal-mines, the one in -Franche-Comté, the other in Alsace, do not require to be particularly -noticed. - -14. In the Mem. de l'Académie, for 1780 (published in 1784), we have -a paper, by Lavoisier, "On certain Fluids which may be obtained in -an aeriform State, at a degree of Heat not much higher than the mean -Temperature of the Earth." These fluids are sulphuric ether, alcohol, -and water. He points out the boiling temperature of these liquids, and -shows that at that temperature the vapour of these bodies possesses -the elasticity of common air, and is permanent as long as the high -temperature continues. He burnt a mixture of vapour of ether and oxygen -gas, and showed that during the combustion carbonic acid gas is formed. -Lavoisier's notions respecting these vapours, and what hindered the -liquids at the boiling temperature from being all converted into vapour -were not quite correct. Our opinions respecting steam and vapours in -general were first rectified by Mr. Dalton. - -15. In the Mem. de l'Académie, for 1780, appeared also the celebrated -paper on _heat_, by Lavoisier and Laplace. The object of this paper was -to determine the specific heat of various bodies, and to investigate -the proposals that had been made by Dr. Irvine for determining the -point at which a thermometer would stand, if plunged into a body -destitute of heat. This point is usually called the real zero. -They begin by describing an instrument which they had contrived to -measure the quantity of heat which leaves a body while it is cooling -a certain number of degrees. To this instrument they gave the name of -_calorimeter_. It consisted of a kind of hollow, surrounded on every -side by ice. The hot body was put into the centre. The heat which it -gave out while cooling was all expended in melting the ice, which was -of the temperature of 32°, and the quantity of heat was proportional -to the quantity of ice melted. Hence the quantity of ice melted, while -equal weights of hot bodies were cooling a certain number of degrees, -gave the direct ratios of the specific heats of each. In this way they -obtained the following specific heats: - - Specific heat. - - Water 1 - Sheet-iron 0·109985 - Glass without lead (crystal) 0·1929 - Mercury 0·029 - Quicklime 0·21689 - Mixture of 9 water with 16 lime 0·439116 - Sulphuric acid of 1·87058 0·334597 - 4 sulphuric acid, 3 water 0·603162 - 4 sulphuric acid, 5 water 0·663102 - Nitric acid of 1·29895 0·661391 - 9⅓ nitric acid, 1 lime 0·61895 - 1 saltpetre, 8 water 0·8167 - -Their experiments were inconsistent with the conclusions drawn by Dr. -Irvine, respecting the real zero, from the diminution of the specific -heat, and the heat evolved when sulphuric acid was mixed with various -proportions of water, &c. If the experiments of Lavoisier and Laplace -approached nearly to accuracy, or, indeed, unless they were quite -inaccurate, it is obvious that the conclusions of Irvine must be quite -erroneous. It is remarkable that though the experiments of Crawford, -and likewise those of Wilcke, and of several others, on specific heat -had been published before this paper made its appearance, no allusion -whatever is made to these publications. Were we to trust to the -information communicated in the paper, the doctrine of specific heat -originated with Lavoisier and Laplace. It is true that in the fourth -part of the paper, which treats of combustion and respiration, Dr. -Crawford's, theory of animal heat is mentioned, showing clearly that -our authors were acquainted with his book on the subject. And, as this -theory is founded on the different specific heats of bodies, there -could be no doubt that he was acquainted with that doctrine. - -16. In the Mem. de l'Académie, for 1780, occur the two following -memoirs: - -Report made to the Royal Academy of Sciences on the Prisons. By Messrs. -Duhamel, De Montigny, Le Roy, Tenon, Tillet, and Lavoisier. - -Report on the Process for separating Gold and Silver. By Messrs. -Macquer, Cadet, Lavoisier, Baumé, Cornette, and Berthollet. - -17. In the Mem. de l'Académie, for 1781, we find a memoir by Lavoisier -and Laplace, on the electricity evolved when bodies are evaporated or -sublimed. The result of these experiments was, that when water was -evaporated electricity was always evolved. They concluded from these -observations, that whenever a body changes its state electricity -is always evolved. But when Saussure attempted to repeat these -observations, he could not succeed. And, from the recent experiments -of Pouillet, it seems to follow that electricity is evolved only when -bodies undergo chemical decomposition or combination. Such experiments -depend so much upon very minute circumstances, which are apt to escape -the attention of the observer, that implicit confidence cannot be -put in them till they have been often repeated, and varied in every -possible manner. - -18. In the Memoires de l'Académie, for 1781, there is a paper by -Lavoisier on the comparative value of the different substances -employed as articles of fuel. The substances compared to each other -are pit-coal, coke, charcoal, and wood. It would serve no purpose to -state the comparison here, as it would not apply to this country; nor, -indeed, would it at present apply even to France. - -We have, in the same volume, his paper on the mode of illuminating -theatres. - -19. In the Memoires de l'Académie, for 1782 (printed in 1785), we -have a paper by Lavoisier on a method of augmenting considerably the -action of fire and of heat. The method which he proposes is a jet of -oxygen gas, striking against red-hot charcoal. He gives the result -of some trials made in this way. Platinum readily melted. Pieces of -ruby or sapphire were softened sufficiently to run together into one -stone. Hyacinth lost its colour, and was also softened. Topaz lost its -colour, and melted into an opaque enamel. Emeralds and garnets lost -their colour, and melted into opaque coloured glasses. Gold and silver -were volatilized; all the other metals, and even the metallic oxides, -were found to burn. Barytes also burns when exposed to this violent -heat. This led Lavoisier to conclude, as Bergman had done before him, -that Barytes is a metallic oxide. This opinion has been fully verified -by modern chemists. Both silica and alumina were melted. But he could -not fuse lime nor magnesia. We are now in possession of a still more -powerful source of heat in the oxygen and hydrogen blowpipe, which is -capable of fusing both lime and magnesia, and, indeed, every substance -which can be raised to the requisite heat without burning or being -volatilized. This subject was prosecuted still further by Lavoisier -in another paper inserted in a subsequent volume of the Memoires de -l'Académie. He describes the effect on rock-crystal, quartz, sandstone, -sand, phosphorescent quartz, milk quartz, agate, chalcedony, cornelian, -flint, prase, nephrite, jasper, felspar, &c. - -20. In the same volume is inserted a memoir "On the Nature of the -aeriform elastic Fluids which are disengaged from certain animal -Substances in a state of Fermentation." He found that a quantity of -recent human fæces, amounting to about five cubic inches, when kept -at a temperature approaching to 60° emitted, every day for a month, -about half a cubic inch of gas. This gas was a mixture of eleven parts -carbonic acid gas, and one part of an inflammable gas, which burnt -with a blue flame, and was therefore probably carbonic oxide. Five -cubic inches of old human fæces from a necessary kept in the same -temperature, during the first fifteen days emitted about a third of -a cubic inch of gas each day; and during each of the second fifteen -days, about one fourth of a cubic inch. This gas was a mixture of -thirty-eight volumes of carbonic acid gas, and sixty-two volumes of a -combustible gas, burning with a blue flame, and probably carbonic oxide. - -Fresh fæces do not effervesce with dilute sulphuric acid, but old moist -fæces do, and emit about eight times their volume of carbonic acid -gas. Quicklime, or caustic potash, mixed with fæces, puts a stop to -the evolution of gas, doubtless by preventing all fermentation. During -effervescence of fæcal matter the air surrounding it is deprived of a -little of its oxygen, probably in consequence of its combining with the -nascent inflammable gas which is slowly disengaged. - -II. We come now to the new theory of combustion of which Lavoisier -was the author, and upon which his reputation with posterity will -ultimately depend. Upon this subject, or at least upon matters more -or less intimately connected with it, no fewer than twenty-seven -memoirs of his, many of them of a very elaborate nature, and detailing -expensive and difficult experiments, appeared in the different -volumes of the academy between 1774 and 1788. The analogy between the -combustion of bodies and the calcination of metals had been already -observed by chemists, and all admitted that both processes were -owing to the same cause; namely, the emission of _phlogiston_ by the -burning or calcining body. The opinion adopted by Lavoisier was, that -during burning and calcination nothing whatever left the bodies, but -that they simply united with a portion of the air of the atmosphere. -When he first conceived this opinion he was ignorant of the nature -of atmospheric air, and of the existence of oxygen gas. But after -that principle had been discovered, and shown to be a constituent of -atmospherical air, he soon recognised that it was the union of oxygen -with the burning and calcining body that occasioned the phenomena. Such -is the outline of the Lavoisierian theory stated in the simplest and -fewest words. It will be requisite to make a few observations on the -much-agitated question whether this theory originated with him. - -It is now well known that John Rey, a physician at Bugue, in Perigord, -published a book in 1630, in order to explain the cause of the increase -of weight which lead and tin experience during their calcination. After -refuting in succession all the different explanations of this increase -of weight which had been advanced, he adds, "To this question, then, -supported on the grounds already mentioned, I answer, and maintain -with confidence, that the increase of weight arises from the air, -which is condensed, rendered heavy and adhesive by the violent and -long-continued heat of the furnace. This air mixes itself with the calx -(frequent agitation conducing), and attaches itself to the minutest -molecules, in the same manner as water renders heavy sand which is -agitated with it, and moistens and adheres to the smallest grains." -There cannot be the least doubt from this passage that Rey's opinion -was precisely the same as the original one of Lavoisier, and had -Lavoisier done nothing more than merely state in general terms that -during calcination air unites with the calcining bodies, it might have -been suspected that he had borrowed his notions from those of Rey. But -the discovery of oxygen, and the numerous and decisive proofs which -he brought forward that during burning and calcination oxygen unites -with the burning and calcining body, and that this oxygen may be again -separated and exhibited in its original elastic state oblige us to -alter our opinion. And whether we admit that he borrowed his original -notion from Rey, or that it suggested itself to his own mind, the case -will not be materially altered. For it is not the man who forms the -first vague notion of a thing that really adds to the stock of our -knowledge, but he who demonstrates its truth and accurately determines -its nature. - -Rey's book and his opinions were little known. He had not brought -over a single convert to his doctrine, a sufficient proof that he had -not established it by satisfactory evidence. We may therefore believe -Lavoisier's statement, when he assures us that when he first formed his -theory he was ignorant of Rey, and never had heard that any such book -had been published. - -The theory of combustion advanced by Dr. Hook, in 1665, in his -Micrographia, approaches still nearer to that of Lavoisier than -the theory of Rey, and indeed, so far as he has explained it, the -coincidence is exact. According to Hook there exists in common air a -certain substance which is like, if not the very same with that which -is fixed in saltpetre. This substance has the property of dissolving -all combustibles; but only when their temperature is sufficiently -raised. The solution takes place with such rapidity that it occasions -fire, which in his opinion is mere _motion_. The dissolved substance -may be in the state of air, or coagulated in a liquid or solid form. -The quantity of this solvent in a given bulk of air is incomparably -less than in the same bulk of saltpetre. Hence the reason why a -combustible continues burning but a short time in a given bulk of air: -the solvent is soon saturated, and then of course the combustion is -at an end. This explains why combustion requires a constant supply -of fresh air, and why it is promoted by forcing in air with bellows. -Hook promised to develop this theory at greater length in a subsequent -work; but he never fulfilled his promise; though in his Lampas, -published about twelve years afterwards, he gives a beautiful chemical -explanation of flame, founded on the very same theory. - -From the very general terms in which Hook expresses himself, we cannot -judge correctly of the extent of his knowledge. This theory, so far as -it goes, coincides exactly with our present notions on the subject. -His solvent is oxygen gas, which constitutes one-fifth part of the -volume of the air, but exists in much greater quantity in saltpetre. -It combines with the burning body, and the compound formed may either -be a gas, a liquid, or a solid, according to the nature of the body -subjected to combustion. - -Lavoisier nowhere alludes to this theory of Hook nor gives the least -hint that he had ever heard of it. This is the more surprising, -because Hook was a man of great celebrity; and his Micrographia, as -containing the original figures and descriptions of many natural -objects, is well known, not merely in Great Britain, but on the -continent. At the same time it must be recollected that Hook's theory -is supported by no evidence; that it is a mere assertion, and that -nobody adopted it. Even then, if we were to admit that Lavoisier was -acquainted with this theory, it would derogate very little from his -merit, which consisted in investigating the phenomena of combustion and -calcination, and in showing that oxygen became a constituent of the -burnt and calcined bodies. - -About ten years after the publication of the Micrographia, Dr. Mayow, -of Oxford, published his Essays. In the first of which, De Sal-nitro -et Spiritu Nitro-aëreo, he obviously adopts Dr. Hook's theory of -combustion, and he applies it with great ingenuity to explain the -nature of respiration. Dr. Mayow's book had been forgotten when the -attention of men of science was attracted to it by Dr. Beddoes. Dr. -Yeats, of Bedford, published a very interesting work on the merits of -Mayow, in 1798. It will be admitted at once by every person who takes -the trouble of perusing Mayow's tract, that he was not satisfied with -mere theory; but proved by actual experiment that air was absorbed -during combustion, and altered during respiration. He has given -figures of his apparatus, and they are very much of the same nature -with those afterwards made use of by Lavoisier. It would be wrong, -therefore, to deprive Mayow of the reputation to which he is entitled -for his ingeniously-contrived and well-executed experiments. It must be -admitted that he proved both the absorption of air during combustion -and respiration; but even this does not take much from the fair -fame of Lavoisier. The analysis of air and the discovery of oxygen -gas really diminish the analogy between the theories of Mayow and -Lavoisier, or at any rate the full investigation of the subject and the -generalization of it belong exclusively to Lavoisier. - -Attempts were made by the other French chemists, about the beginning -of the revolution, to associate themselves with Lavoisier, as equally -entitled with himself to the merit of the antiphlogistic theory; but -Lavoisier himself has disclaimed the partnership. Some years before his -death, he had formed the plan of collecting together all his papers -relating to the antiphlogistic theory and publishing them in one work; -but his death interrupted the project. However, his widow afterwards -published the first two volumes of the book, which were complete at the -time of his death. In one of these volumes Lavoisier claims for himself -the exclusive discovery of the cause of the augmentation of weight -which bodies undergo during combustion and calcination. He informs us -that a set of experiments, which he made in 1772, upon the different -kinds of air which are disengaged in effervescence, and a great number -of other chemical operations discovered to him demonstratively the -cause of the augmentation of weight which metals experience when -exposed to heat. "I was young," says he, "I had newly entered the lists -of science, I was desirous of fame, and I thought it necessary to -take some steps to secure to myself the property of my discovery. At -that time there existed an habitual correspondence between the men of -science of France and those of England. There was a kind of rivality -between the two nations, which gave importance to new experiments, -and which sometimes was the cause that the writers of the one or the -other of the nations disputed the discovery with the real author. -Consequently, I thought it proper to deposit on the 1st of November, -1772, the following note in the hands of the secretary of the academy. -This note was opened on the 1st of May following, and mention of these -circumstances marked at the top of the note. It was in the following -terms: - -"About eight days ago I discovered that sulphur in burning, far from -losing, augments in weight; that is to say, that from one pound of -sulphur much more than one pound of vitriolic acid is obtained, without -reckoning the humidity of the air. Phosphorus presents the same -phenomenon. This augmentation of weight arises from a great quantity of -air, which becomes fixed during the combustion, and which combines with -the vapours. - -"This discovery, which I confirmed by experiments which I regard as -decisive, led me to think that what is observed in the combustion of -sulphur and phosphorus, might likewise take place with respect to all -the bodies which augment in weight by combustion and calcination; -and I was persuaded that the augmentation of weight in the calces of -metals proceeded from the same cause. The experiment fully confirmed my -conjectures. I operated the reduction of litharge in close vessels with -Hales's apparatus, and I observed, that at the moment of the passage -of the calx into the metallic state, there was a disengagement of air -in considerable quantity, and that this air formed a volume at least -one thousand times greater than that of the litharge employed. As this -discovery appears to me one of the most interesting which has been made -since Stahl, I thought it expedient to secure to myself the property, -by depositing the present note in the hands of the secretary of the -academy, to remain secret till the period when I shall publish my -experiments. - - "LAVOISIER. - -"_Paris, November 11, 1772._" - -This note leaves no doubt that Lavoisier had conceived his theory, and -confirmed it by experiment, at least as early as November, 1772. But at -that time the nature of air and the existence of oxygen were unknown. -The theory, therefore, as he understood it at that time, was precisely -the same as that of John Rey. It was not till the end of 1774 that his -views became more precise, and that he was aware that oxygen is the -portion of the air which unites with bodies during combustion, and -calcination. - -Nothing can be more evident from the whole history of the academy, -and of the French chemists during this eventful period, for the -progress of the science, that none of them participated in the views -of Lavoisier, or had the least intention of giving up the phlogistic -theory. It was not till 1785, after his experiments had been almost all -published, and after all the difficulties had been removed by the two -great discoveries of Mr. Cavendish, that Berthollet declared himself a -convert to the Lavoisierian opinions. This was soon followed by others, -and within a very few years almost all the chemists and men of science -in France enlisted themselves on the same side. Lavoisier's objection, -then, to the phrase _La Chimie Française_, is not without reason, the -term _Lavoisierian Chemistry_ should undoubtedly be substituted for -it. This term, _La Chimie Française_ was introduced by Fourcroy. Was -Fourcroy anxious to clothe himself with the reputation of Lavoisier, -and had this any connexion with the violent death of that illustrious -man? - -The first set of experiments which Lavoisier published on his peculiar -views, was entitled, "A Memoir on the Calcination of Tin in close -Vessels; and on the Cause of the increase of Weight which the Metal -acquires during this Process." It appeared in the Memoirs of the -Academy, for 1774. In this paper he gives an account of several -experiments which he had made on the calcination of tin in glass -retorts, hermetically sealed. He put a quantity of tin (about half a -pound) into a glass retort, sometimes of a larger and sometimes of a -smaller size, and then drew out the beak into a capillary tube. The -retort was now placed upon the sand-bath, and heated till the tin just -melted. The extremity of the capillary beak of the retort was now -fused so as to seal it hermetically. The object of this heating was to -prevent the retort from bursting by the expansion of the air during the -process. The retort, with its contents, was now carefully weighed, and -the weight noted. It was put again on the sand-bath, and kept melted -till the process of calcination refused to advance any further. He -observed, that if the retort was small, the calcination always stopped -sooner than it did if the retort was large. Or, in other words, the -quantity of tin calcined was always proportional to the size of the -retort. - -After the process was finished, the retort (still hermetically sealed) -was again weighed, and was always found to have the same weight exactly -as at first. The beak of the retort was now broken off, and a quantity -of air entered with a hissing noise. The increase of weight was now -noted: it was obviously owing to the air that had rushed in. The weight -of air that had been at first driven out by the fusion of the tin had -been noted, and it was now found that a considerably greater quantity -had entered than had been driven out at first. In some experiments, -as much as 10·06 grains, in others 9·87 grains, and in some less than -this, when the size of the retort was small. The tin in the retort was -mostly unaltered, but a portion of it had been converted into a black -powder, weighing in some cases above two ounces. Now it was found in -all cases, that the weight of the tin had increased, and the increase -of weight was always exactly equal to the diminution of weight which -the air in the retort had undergone, measured by the quantity of new -air which rushed in when the beak of the retort was broken, minus the -air that had been driven out when the tin was originally melted before -the retort was hermetically sealed. - -Thus Lavoisier proved by these first experiments, that when tin -is calcined in close vessels a portion of the air of the vessel -disappears, and that the tin increases in weight just as much as is -equivalent to the loss of weight which the air has sustained. He -therefore inferred, that this portion of air had united with the tin, -and that calx of tin is a compound of tin and air. In this first paper -there is nothing said about oxygen, nor any allusion to lead to the -suspicion that air is a compound of different elastic fluids. These, -therefore, were probably the experiments to which Lavoisier alludes in -the note which he lodged with the secretary of the academy in November, -1772. - -He mentions towards the end of the Memoir that he had made similar -experiments with lead; but he does not communicate any of the numerical -results: probably because the results were not so striking as those -with tin. The heat necessary to melt lead is so high that satisfactory -experiments on its calcination could not easily be made in a glass -retort. - -Lavoisier's next Memoir appeared in the Memoirs of the Academy, for -1775, which were published in 1778. It is entitled, "On the Nature of -the Principle which combines with the Metals during their Calcination, -and which augments their Weight." He observes that when the metallic -calces are reduced to the metallic state it is found necessary to -heat them along with charcoal. In such cases a quantity of carbonic -acid gas is driven off, which he assures us is the charcoal united to -the elastic fluid contained in the calx. He tried to reduce the calx -of iron by means of burning-glasses, while placed under large glass -receivers standing over mercury; but as the gas thus evolved was mixed -with a great deal of common air which was necessarily left in the -receiver, he was unable to determine its nature. This induced him to -have recourse to red oxide of mercury. He showed in the first place -that this substance (_mercurius præcipitatus per se_) was a true calx, -by mixing it with charcoal powder in a retort and heating it. The -mercury was reduced and abundance of carbonic acid gas was collected -in an inverted glass jar standing in a water-cistern into which the -beak of the retort was plunged. On heating the red oxide of mercury -by itself it was reduced to the metallic state, though not so easily, -and at the same time a gas was evolved which possessed the following -properties: - -1. It did not combine with water by agitation. - -2. It did not precipitate lime-water. - -3. It did not unite with fixed or volatile alkalies. - -4. It did not at all diminish their caustic quality. - -5. It would serve again for the calcination of metals. - -6. It was diminished like common air by addition of one-third of -nitrous gas. - -7. It had none of the properties of carbonic acid gas. Far from being -fatal, like that gas, to animals, it seemed on the contrary more proper -for the purposes of respiration. Candles and burning bodies were not -only not extinguished by it, but burned with an enlarged flame in -a very remarkable manner. The light they gave was much greater and -clearer than in common air. - -He expresses his opinion that the same kind of air would be obtained by -heating nitre without addition, and this opinion is founded on the fact -that when nitre is detonated with charcoal it gives out abundance of -carbonic acid gas. - -Thus Lavoisier shows in this paper that the kind of air which unites -with metals during their calcination is purer and fitter for combustion -than common air. In short it is the gas which Dr. Priestley had -discovered in 1774, and which is now known by the name of oxygen gas. - -This Memoir deserves a few animadversions. Dr. Priestley discovered -oxygen gas in August, 1774; and he informs us in his life, that in -the autumn of that year he went to Paris and exhibited to Lavoisier, -in his own laboratory the mode of obtaining oxygen gas by heating -red oxide of mercury in a gun-barrel, and the properties by which -this gas is distinguished--indeed the very properties which Lavoisier -himself enumerates in his paper. There can, therefore, be no doubt that -Lavoisier was acquainted with oxygen gas in 1774, and that he owed his -knowledge of it to Dr. Priestley. - -There is some uncertainty about the date of Lavoisier's paper. In the -History of the Academy, for 1775, it is merely said about it, "Read at -the resumption (_rentrée_) of the Academy, on the 26th of April, by M. -Lavoisier," without naming the year. But it could not have been before -1775, because that is the year upon the volume of the Memoirs; and -besides, we know from the Journal de Physique (v. 429), that 1775 was -the year on which the paper of Lavoisier was read. - -Yet in the whole of this paper the name of Dr. Priestley never occurs, -nor is the least hint given that he had already obtained oxygen gas by -heating red oxide of mercury. So far from it, that it is obviously the -intention of the author of the paper to induce his readers to infer -that he himself was the discoverer of oxygen gas. For after describing -the process by which oxygen gas was obtained by him, he says nothing -further remained but to determine its nature, and "I discovered with -_much surprise_ that it was not capable of combination with water -by agitation," &c. Now why the expression of surprise in describing -phenomena which had been already shown? And why the omission of all -mention of Dr. Priestley's name? I confess that this seems to me -capable of no other explanation than a wish to claim for himself the -discovery of oxygen gas, though he knew well that that discovery had -been previously made by another. - -The next set of experiments made by Lavoisier to confirm or extend -his theory, was "On the Combustion of Phosphorus, and the Nature of -the Acid which results from that Combustion." It appeared in the -Memoirs of the Academy, for 1777. The result of these experiments -was very striking. When phosphorus is burnt in a given bulk of air -in sufficient quantity, about four-fifths of the volume of the air -disappears and unites itself with the phosphorus. The residual portion -of the air is incapable of supporting combustion or maintaining animal -life. Lavoisier gave it the name of _mouffette atmospherique_, and he -describes several of its properties. The phosphorus by combining with -the portion of air which has disappeared, is converted into phosphoric -acid, which is deposited on the inside of the receiver in which the -combustion is performed, in the state of fine white flakes. One grain -by this process is converted into two and a half grains of phosphoric -acid. These observations led to the conclusion that atmospheric air -is a mixture or compound of two distinct gases, the one (_oxygen_) -absorbed by burning phosphorus, the other (_azote_) not acted on by -that principle, and not capable of uniting with or calcining metals. -These conclusions had already been drawn by Scheele from similar -experiments, but Lavoisier was ignorant of them. - -In the second part of this paper, Lavoisier describes the properties -of phosphoric acid, and gives an account of the salts which it forms -with the different bases. The account of these salts is exceedingly -imperfect, and it is remarkable that Lavoisier makes no distinction -between phosphate of potash and phosphate of soda; though the different -properties of these two salts are not a little striking. But these were -not the investigations in which Lavoisier excelled. - -The next paper in which the doctrines of the antiphlogistic theory -were still further developed, was inserted in the Memoirs of the -Academy, for 1777. It is entitled, "On the Combustion of Candles in -atmospherical Air, and in Air eminently Respirable." This paper is -remarkable, because in it he first notices Dr. Priestley's discovery of -oxygen gas; but without any reference to the preceding paper, or any -apology for not having alluded in it to the information which he had -received from Dr. Priestley. - -He begins by saying that it is necessary to distinguish four different -kinds of air. 1. Atmospherical air in which we live, and which we -breath. 2. Pure air (_oxygen_), alone fit for breathing, constituting -about the fourth of the volume of atmospherical air, and called by Dr. -Priestley _dephlogisticated air_. 3. Azotic gas, which constitutes -about three-fourths of the volume of atmospherical air, and whose -properties are still unknown. 4. Fixed air, which he proposed to call -(as Bucquet had done) _acide crayeux_, _acid of chalk_. - -In this paper Lavoisier gives an account of a great many trials that -he made by burning candles in given volumes of atmospherical air and -oxygen gas enclosed in glass receivers, standing over mercury. The -general conclusion which he deduces from these experiments are--that -the azotic gas of the air contributes nothing to the burning of -the candle; but the whole depends upon the oxygen gas of the air, -constituting in his opinion one-fourth of its volume; that during the -combustion of a candle in a given volume of air only two-fifths of -the oxygen are converted into carbonic acid gas, while the remaining -three-fifths remain unaltered; but when the combustion goes on in -oxygen gas a much greater proportion (almost the whole) of this gas -is converted into carbonic acid gas. Finally, that phosphorus, when -burnt in air acts much more powerfully on the oxygen of the air than a -lighted candle, absorbing four-fifths of the oxygen and converting it -into phosphoric acid. - -It is evident that at the time this paper was written, Lavoisier's -theory was nearly complete. He considered air as a mixture of three -volumes of azotic gas, and one volume of oxygen gas. The last alone -was concerned in combustion and calcination. During these processes a -portion of the oxygen united with the burning body, and the compound -formed constituted the acid or the calx. Thus he was able to account -for combustion and calcination without having recourse to phlogiston. -It is true that several difficulties still lay in his way, which he -was not yet able to obviate, and which prevented any other person from -adopting his opinions. One of the greatest of these was the fact that -hydrogen gas was evolved during the solution of several metals in -dilute sulphuric or muriatic acid; that by this solution these metals -were converted into calces, and that calces, when heated in hydrogen -gas, were reduced to the metallic state while the hydrogen disappeared. -The simplest explanation of these phenomena was the one adopted by -chemists at the time. Hydrogen was considered as phlogiston. By -dissolving metals in acids, the phlogiston was driven off and the calx -remained: by heating the calx in hydrogen, the phlogiston was again -absorbed and the calx reduced to the metallic state. - -This explanation was so simple and appeared so satisfactory, that it -was universally adopted by chemists with the exception of Lavoisier -himself. There was a circumstance, however, which satisfied him that -this explanation, however plausible, was not correct. The calx was -_heavier_ than the metal from which it had been produced. And hydrogen, -though a light body, was still possessed of weight. It was obviously -impossible, then, that the metal could be a combination of the calx and -hydrogen. Besides, he had ascertained by direct experiment, that the -calces of mercury, tin, and lead are compounds of the respective metals -and oxygen. And it was known that when the other calces were heated -with charcoal, they were reduced to the metallic state, and at the same -time carbonic acid gas is evolved. The very same evolution takes place -when calces of mercury, tin, and lead, are heated with charcoal powder. -Hence the inference was obvious that carbonic acid is a compound of -charcoal and oxygen, and therefore that all calces are compounds of -their respective metals and oxygen. - -Thus, although Lavoisier was unable to account for the phenomena -connected with the evolution and absorption of hydrogen gas, he had -conclusive evidence that the orthodox explanation was not the true one. -He wisely, therefore, left it to time to throw light upon those parts -of the theory that were still obscure. - -His next paper, which was likewise inserted in the Memoirs of the -Academy, for 1777, had some tendency to throw light on this subject, -or at least it elucidated the constitution of sulphuric acid, which -bore directly upon the antiphlogistic theory. It was entitled, "On the -Solution of Mercury in vitriolic Acid, and on the Resolution of that -Acid into aeriform sulphurous Acid, and into Air eminently Respirable." - -He had already proved that sulphuric acid is a compound of sulphur and -oxygen; and had even shown how the oxygen which the acid contained -might be again separated from it, and exhibited in a separate state. -Dr. Priestley had by this time made known the method of procuring -sulphurous acid gas, by heating a mixture of mercury and sulphuric -acid in a phial. This was the process which Lavoisier analyzed in the -present paper. He put into a retort a mixture of four ounces mercury -and six ounces concentrated sulphuric acid. The beak of the retort was -plunged into a mercurial cistern, to collect the sulphurous acid gas -as it was evolved; and heat being applied to the belly of the retort, -sulphurous acid gas passed over in abundance, and sulphate of mercury -was formed. The process was continued till the whole liquid contents -of the retort had disappeared: then a strong heat was applied to the -salt. In the first place, a quantity of sulphurous acid gas passed -over, and lastly a portion of oxygen gas. The quicksilver was reduced -to the metallic state. Thus he resolved sulphuric acid into sulphurous -acid and oxygen. Hence it followed as a consequence, that sulphurous -acid differs from sulphuric merely by containing a smaller quantity of -oxygen. - -The object of his next paper, published at the same time, was to throw -light upon the pyrophorus of Homberg, which was made by kneading -alum into a cake, with flour, or some substance containing abundance -of carbon, and then exposing the mixture to a strong heat in close -vessels, till it ceased to give out smoke. It was known that a -pyrophorus thus formed takes fire of its own accord, and burns when it -comes in contact with common air. It will not be necessary to enter -into a minute analysis of this paper, because, though the experiments -were very carefully made, yet it was impossible, at the time when the -paper was drawn, to elucidate the phenomena of this pyrophorus in a -satisfactory manner. There can be little doubt that the pyrophorus owes -its property of catching fire, when in contact with air or oxygen, -to a little potassium, which has been reduced to the metallic state -by the action of the charcoal and sulphur on the potash in the alum. -This substance taking fire, heat enough is produced to set fire to the -carbon and sulphur which the pyrophorus contains. Lavoisier ascertained -that during its combustion a good deal of carbonic acid was generated. - -There appeared likewise another paper by Lavoisier, in the same volume -of the academy, which may be mentioned, as it served still further to -demonstrate the truth of the antiphlogistic theory. It is entitled, "On -the Vitriolization of Martial Pyrites." Iron pyrites is known to be a -compound of _iron_ and _sulphur_. Sometimes this mineral may be left -exposed to the air without undergoing any alteration, while at other -times it speedily splits, effloresces, swells, and is converted into -sulphate of iron. There are two species of pyrites; the one composed -of two atoms of sulphur and one atom of iron, the other of one atom of -sulphur and one atom of iron. The first of these is called bisulphuret -of iron; the second protosulphuret, or simply sulphuret of iron. The -variety of pyrites which undergoes spontaneous decomposition in the -air, is known to be a compound, or rather mixture of the two species of -pyrites. - -Lavoisier put a quantity of the decomposing pyrites under a glass jar, -and found that the process went on just as well as in the open air. -He found that the air was deprived of the whole of its oxygen by the -process, and that nothing was left but azotic gas. Hence the nature -of the change became evident. The sulphur, by uniting with oxygen, -was converted into sulphuric acid, while the iron became oxide of -iron, and both uniting, formed sulphate of iron. There are still some -difficulties connected with this change that require to be elucidated. - -We have still another paper by Lavoisier, bearing on the antiphlogistic -theory, published in the same volume of the Memoirs of the Academy, -for 1778, entitled, "On Combustion in general." He establishes that -the only air capable of supporting combustion is oxygen gas: that -during the burning of bodies in common air, a portion of the oxygen of -the atmosphere disappears, and unites with the burning body, and that -the new compound formed is either an acid or a metallic calx. When -sulphur is burnt, sulphuric acid is formed; when phosphorus, phosphoric -acid; and when charcoal, carbonic acid. The calcination of metals is -a process analogous to combustion, differing chiefly by the slowness -of the process: indeed when it takes place rapidly, actual combustion -is produced. After establishing these general principles, which are -deduced from his preceding papers, he proceeds to examine the Stahlian -theory of phlogiston, and shows that no evidence of the existence of -any such principle can be adduced, and that the phenomena can all be -explained without having recourse to it. Powerful as these arguments -were, they produced no immediate effects. Nobody chose to give up the -phlogistic theory to which he had been so long accustomed. - -The next two papers of Lavoisier require merely to be mentioned, as -they do not bear immediately upon the antiphlogistic theory. They -appeared in the Memoirs of the Academy, for 1780. These memoirs were, - -1. Second Memoir on the different Combinations of Phosphoric Acid. - -2. On a particular Process, by means of which Phosphorus may be -converted into phosphoric Acid, without Combustion. - -The process here described consisted in throwing phosphorus, by a -few grains at a time, into warm nitric acid of the specific gravity -1·29895. It falls to the bottom like melted wax, and dissolves pretty -rapidly with effervescence: then another portion is thrown in, and the -process is continued till as much phosphorus has been employed as is -wanted; then the phosphoric acid may be obtained pure by distilling off -the remaining nitric acid with which it is still mixed. - -Hitherto Lavoisier had been unable to explain the anomalies respecting -hydrogen gas, or to answer the objections urged against his theory -in consequence of these anomalies. He had made several attempts to -discover what peculiar substance was formed during the combustion of -hydrogen, but always without success: at last, in 1783, he resolved to -make the experiment upon so large a scale, that whatever the product -might be, it should not escape him; but Sir Charles Blagden, who -had just gone to Paris, informed him that the experiment for which -he was preparing had already been made by Mr. Cavendish, who had -ascertained that the product of the combustion of hydrogen was _water_. -Lavoisier saw at a glance the vast importance of this discovery for -the establishment of the antiphlogistic theory, and with what ease it -would enable him to answer all the plausible objections which had been -brought forward against his opinions in consequence of the evolution -of hydrogen, when metals were calcined by solution in acids, and the -absorption of it when metals were reduced in an atmosphere of this -gas. He therefore resolved to repeat the experiment of Cavendish with -every possible care, and upon a scale sufficiently large to prevent -ambiguity. The experiment was made on the 24th of June, 1783, by -Lavoisier and Laplace, in the presence of M. Le Roi, M. Vandermonde, -and Sir Charles Blagden, who was at that time secretary of the Royal -Society. The quantity of water formed was considerable, and they found -that water was a compound of - - 1 volume oxygen - 1·91 volume hydrogen. - -Not satisfied with this, he soon after made another experiment along -with M. Meusnier to decompose water. For this purpose a porcelain tube, -filled with iron wire, was heated red-hot by being passed through a -furnace, and then the steam of water was made to traverse the red-hot -wire. To the further extremity of the porcelain tube a glass tube was -luted, which terminated in a water-trough under an inverted glass -receiver placed to collect the gas. The steam was decomposed by the -red-hot iron wire, its oxygen united to the wire, while the hydrogen -passed on and was collected in the water-cistern. - -Both of these experiments, though not made till 1783, and though the -latter of them was not read to the academy till 1784, were published in -the volume of the Memoirs for 1781. - -It is easy to see how this important discovery enabled Lavoisier to -obviate all the objections to his theory from hydrogen. He showed that -it was evolved when zinc or iron was dissolved in dilute sulphuric -acid, because the water underwent decomposition, its oxygen uniting to -the zinc or iron, and converting it into an oxide, while its hydrogen -made its escape in the state of gas. Oxide of iron was reduced when -heated in contact with hydrogen gas, because the hydrogen united to -the oxygen of the acid and formed water, and of course the iron was -reduced to the state of a metal. I consider it unnecessary to enter -into a minute detail of these experiments, because, in fact, they -added very little to what had been already established by Cavendish. -But it was this discovery that contributed more than any thing else -to establish the antiphlogistic theory. Accordingly, the great object -of Dr. Priestley, and other advocates of the phlogistic theory, was -to disprove the fact that water is a compound of oxygen and hydrogen. -Scheele admitted the fact that water is a compound of oxygen and -hydrogen; and doubtless, had he lived, would have become a convert -to the antiphlogistic theory, as Dr. Black actually did. In short, -it was the discovery of the compound nature of water that gave the -Lavoisierian theory the superiority over that of Stahl. Till the time -of this discovery every body opposed the doctrine of Lavoisier; but -within a very few years after it, hardly any supporters of phlogiston -remained. Nothing could be more fortunate for Lavoisier than this -discovery, or afford him greater reason for self-congratulation. - -We see the effect of this discovery upon his next paper, "On the -Formation of Carbonic Acid," which appeared in the Memoirs of the -Academy, for 1781. There, for the first time, he introduces new terms, -showing, by that, that he considered his opinions as fully established. -To the _dephlogisticated air_ of Priestley, or his own _pure air_, he -now gives the name of _oxygen_. The fixed air of Black he designates -_carbonic acid_, because he considered it as a compound of _carbon_ -(the pure part of charcoal) and oxygen. The object of this paper is to -determine the proportion of the constituents. He details a great many -experiments, and deduces from them all, that carbonic acid gas is a -compound of - - Carbon 0·75 - Oxygen 1·93 - -Now this is a tolerably near approximation to the truth. The true -constituents, as determined by modern chemists, being - - Carbon 0·75 - Oxygen 2·00 - -The next paper of M. Lavoisier, which appeared in the Memoirs of the -Academy, for 1782 (published in 1785), shows how well he appreciated -the importance of the discovery of the composition of water. It is -entitled, "General Considerations on the Solution of the Metals in -Acids." He shows that when metals are dissolved in acids, they are -converted into oxides, and that the acid does not combine with the -metal, but only with its oxide. When nitric acid is the solvent the -oxidizement takes place at the expense of the acid, which is resolved -into nitrous gas and oxygen. The nitrous gas makes its escape, and may -be collected; but the oxygen unites with the metal and renders it an -oxide. He shows this with respect to the solution of mercury in nitric -acid. He collected the nitrous gas given out during the solution of -the metal in the acid: then evaporated the solution to dryness, and -urged the fire till the mercury was converted into red oxide. The fire -being still further urged, the red oxide was reduced, and the oxygen -gas given off was collected and measured. He showed that the nitrous -gas and the oxygen gas thus obtained, added together, formed just the -quantity of nitric acid which had disappeared during the process. A -similar experiment was made by dissolving iron in nitric acid, and then -urging the fire till the iron was freed from every foreign body, and -obtained in the state of black oxide. - -It is well known that many metals held in solution by acids may be -precipitated in the metallic state, by inserting into the solution -a plate of some other metal. A portion of that new metal dissolves, -and takes the place of the metal originally in solution. Suppose, for -example, that we have a neutral solution of copper in sulphuric acid, -if we put into the solution a plate of iron, the copper is thrown down -in the metallic state, while a certain portion of the iron enters into -the solution, combining with the acid instead of the copper. But the -copper, while in solution, was in the state of an oxide, and it is -precipitated in the metallic state. The iron was in the metallic state; -but it enters into the solution in the state of an oxide. It is clear -from this that the oxygen, during these precipitations, shifts its -place, leaving the copper, and entering into combination with the iron. -If, therefore, in such a case we determine the exact quantity of copper -thrown down, and the exact quantity of iron dissolved at the same time, -it is clear that we shall have the relative weight of each combined -with the same weight of oxygen. If, for example, 4 of copper be thrown -down by the solution of 3·5 of iron; then it is clear that 3·5 of iron -requires just as much oxygen as 4 of copper, to turn both into the -oxide that exists in the solution, which is the black oxide of each. - -Bergman had made a set of experiments to determine the proportional -quantities of phlogiston contained in the different metals, by the -relative quantity of each necessary to precipitate a given weight -of another from its acid solution. It was the opinion at that time, -that metals were compounds of their respective calces and phlogiston. -When a metal dissolved in an acid, it was known to be in the state -of calx, and therefore had parted with its phlogiston: when another -metal was put into this solution it became a calx, and the dissolved -metal was precipitated in the metallic state. It had therefore united -with the phlogiston of the precipitating metal. It is obvious, that -by determining the quantities of the two metals precipitated and -dissolved, the relative proportion of phlogiston in each could be -determined. Lavoisier saw that these experiments of Bergman would serve -equally to determine the relative quantity of oxygen in the different -oxides. Accordingly, in a paper inserted in the Memoirs of the Academy, -for 1782, he enters into an elaborate examination of Bergman's -experiments, with a view to determine this point. But it is unnecessary -to state the deductions which he drew, because Bergman's experiments -were not sufficiently accurate for the object in view. Indeed, as -the mutual precipitation of the metals is a galvanic phenomenon, and -as the precipitated metal is seldom quite pure, but an alloy of the -precipitating and precipitated metal; and as it is very difficult -to dry the more oxidizable metals, as copper and tin, without their -absorbing oxygen when they are in a state of very minute division; -this mode of experimenting is not precise enough for the object which -Lavoisier had in view. Accordingly the table of the composition of the -metallic oxides which Lavoisier has drawn up is so very defective, that -it is not worth while to transcribe it. - -The same remark applies to the table of the affinities of oxygen which -Lavoisier drew up and inserted in the Memoirs of the Academy, for the -same year. His data were too imperfect, and his knowledge too limited, -to put it in his power to draw up any such table with any approach to -accuracy. I shall have occasion to resume the subject in a subsequent -chapter. - -In the same volume of the Memoirs of the Academy, this indefatigable -man inserted a paper in order to determine the quantity of oxygen -which combines with iron. His method of proceeding was, to burn a -given weight of iron in oxygen gas. It is well known that iron wire, -under such circumstances, burns with considerable splendour, and that -the oxide, by the heat, is fused into a black brittle matter, having -somewhat of the metallic lustre. He burnt 145·6 grains of iron in this -way, and found that, after combustion, the weight became 192 grains, -and 97 French cubic inches of oxygen gas had been absorbed. From this -experiment it follows, that the oxide of iron formed by burning iron in -oxygen gas is a compound of - - Iron 3·5 - Oxygen 1·11 - -This forms a tolerable approximation to the truth. It is now -known, that the quantity of oxygen in the oxide of iron formed by -the combustion of iron in oxygen gas is not quite uniform in its -composition; sometimes it is a compound of - - Iron 3½ - Oxygen 1⅓ - -While at other times it consists very nearly of - - Iron 3·5 - Oxygen 1 - -and probably it may exist in all the intermediate proportions between -these two extremes. The last of these compounds constitutes what is -now known by the name of _protoxide_, or _black oxide of iron_. The -first is the composition of the ore of iron so abundant, which is -distinguished by the name of _magnetic iron ore_. - -Lavoisier was aware that iron combines with more oxygen than exists -in the protoxide; indeed, his analysis of peroxide of iron forms a -tolerable approximation to the truth; but there is no reason for -believing that he was aware that iron is capable of forming only two -oxides, and that all intermediate degrees of oxidation are impossible. -This was first demonstrated by Proust. - -I think it unnecessary to enter into any details respecting two papers -of Lavoisier, that made their appearance in the Memoirs of the Academy, -for 1783, as they add very little to what he had already done. The -first of these describes the experiments which he made to determine the -quantity of oxygen which unites with sulphur and phosphorus when they -are burnt: it contains no fact which he had not stated in his former -papers, unless we are to consider his remark, that the heat given out -during the burning of these bodies has no sensible weight, as new. - -The other paper is "On Phlogiston;" it is very elaborate, but contains -nothing which had not been already advanced in his preceding memoirs. -Chemists were so wedded to the phlogistic theory, their prejudices -were so strong, and their understandings so fortified against every -thing that was likely to change their opinions, that Lavoisier found -it necessary to lay the same facts before them again and again, and to -place them in every point of view. In this paper he gives a statement -of his own theory of combustion, which he had previously done in -several preceding papers. He examines the phlogistic theory of Stahl at -great length, and refutes it. - -In the Memoirs of the Academy, for 1784, Lavoisier published a very -elaborate set of experiments on the combustion of alcohol, oil, and -different combustible bodies, which gave a beginning to the analysis -of vegetable substances, and served as a foundation upon which this -most difficult part of chemistry might be reared. He showed that during -the combustion of alcohol the oxygen of the air united to the vapour -of the alcohol, which underwent decomposition, and was converted -into water and carbonic acid. From these experiments he deduced as a -consequence, that the constituents of alcohol are carbon, hydrogen, -and oxygen, and nothing else; and he endeavoured from his experiments -to determine the relative proportions of these different constituents. -From these experiments he concluded, that the alcohol which he used in -his experiments was a compound of - - Carbon 2629·5 part. - Hydrogen 725·5 - Water 5861 - -It would serve no purpose to attempt to draw any consequences from -these experiments; as Lavoisier does not mention the specific gravity -of the alcohol, of course we cannot say how much of the water found -was merely united with the alcohol, and how much entered into -its composition. The proportion between the carbon and hydrogen, -constitutes an approximation to the truth, though not a very near one. - -Olive oil he showed to be a compound of hydrogen and carbon, and bees' -wax to be a compound of the same constituents, though in a different -proportion. - -This subject was continued, and his views further extended, in a -paper inserted in the Memoirs of the Academy, for 1786, entitled, -"Reflections on the Decomposition of Water by Vegetable and Animal -Substances." He begins by stating that when charcoal is exposed to -a strong heat, it gives out a little carbonic acid gas and a little -inflammable air, and after this nothing more can be driven off, however -high the temperature be to which it is exposed; but if the charcoal -be left for some time in contact with the atmosphere it will again -give out a little carbonic acid gas and inflammable gas when heated, -and this process may be repeated till the whole charcoal disappears. -This is owing to the presence of a little moisture which the charcoal -imbibes from the air. The water is decomposed when the charcoal is -heated and converted into carbonic acid and inflammable gas. When -vegetable substances are heated in a retort, the water which they -contain undergoes a similar decomposition, the carbon which forms one -of their constituents combines with the oxygen and produces carbonic -acid, while the hydrogen, the other constituent of the water, flies -off in the state of gas combined with a certain quantity of carbon. -Hence the substances obtained when vegetable or animal substances -are distilled did not exist ready formed in the body operated on; -but proceeded from the double decompositions which took place by the -mutual action of the constituents of the water, sugar, mucus, &c., -which the vegetable body contains. The oil, the acid, &c., extracted -by distilling vegetable bodies did not exist in them, but are formed -during the mutual action of the constituents upon each other, -promoted as their action is by the heat. These views were quite new -and perfectly just, and threw a new light on the nature of vegetable -substances and on the products obtained by distilling them. It showed -the futility of all the pretended analyses of vegetable substances, -which chemists had performed by simply subjecting them to distillation, -and the error of drawing any conclusions respecting the constituents -of vegetable substances from the results of their distillation, except -indeed with respect to their elementary constituents. Thus when by -distilling a vegetable substance we obtain water, oil, acetic acid, -carbonic acid, and carburetted hydrogen, we must not conclude that -these principles existed in the substance, but merely that it contained -carbon, hydrogen, and oxygen, in such proportions as to yield all these -principles by decompositions. - -As nitric acid acts upon metals in a very different way from sulphuric -and muriatic acids, and as it is a much better solvent of metals in -general than any other, it was an object of great importance towards -completing the antiphlogistic theory to obtain an accurate knowledge -of its constituents. Though Lavoisier did not succeed in this, yet he -made at least a certain progress, which enabled him to explain the -phenomena, at that time known, with considerable clearness, and to -answer all the objections to the antiphlogistic theory from the action -of nitric acid on metals. His first paper on the subject was published -in the Memoirs of the Academy, for 1776. He put a quantity of nitric -acid and mercury into a retort with a long beak, which he plunged into -the water-trough. An effervescence took place and gas passed over -in abundance, and was collected in a glass jar; the mercury being -dissolved the retort was still further heated, till every thing liquid -passed over into the receiver, and a dry yellow salt remained. The beak -of the retort was now again plunged into the water-trough, and the salt -heated till all the nitric acid which it contained was decomposed, -and nothing remained in the retort but red oxide of mercury. During -this last process much more gas was collected. All the gas obtained -during the solution of the mercury and the decomposition of the salt -was nitrous gas. The red oxide of mercury was now heated to redness, -oxygen gas was emitted in abundance, and the mercury was reduced to the -metallic state: its weight was found the very same as at first. It is -clear, therefore, that the nitrous gas and the oxygen gas were derived, -not from the mercury but from the nitric acid, and that the nitric acid -had been decomposed into nitrous gas and oxygen: the nitrous gas had -made its escape in the form of gas, and the oxygen had remained united -to the metal. - -From these experiments it follows clearly, that nitric acid is a -compound of nitrous gas and oxygen. The nature of nitrous gas itself -Lavoisier did not succeed in ascertaining. It passed with him for a -simple substance; but what he did ascertain enabled him to explain -the action of nitric acid on metals. When nitric acid is poured upon -a metal which it is capable of dissolving, copper for example, or -mercury, the oxygen of the acid unites to the metal, and converts into -an oxide, while the nitrous gas, the other constituent of the acid, -makes its escape in the gaseous form. The oxide combines with and is -dissolved by another portion of the acid which escapes decomposition. - -It was discovered by Dr. Priestley, that when nitrous gas and oxygen -gas are mixed together in certain proportions, they instantly unite, -and are converted into nitrous acid. If this mixture be made over -water, the volume of the gases is instantly diminished, because the -nitrous acid formed loses its elasticity, and is absorbed by the -water. When nitrous gas is mixed with air containing oxygen gas, the -diminution of volume after mixture is greater the more oxygen gas is -present in the air. This induced Dr. Priestley to employ nitrous gas as -a test of the purity of common air. He mixed together equal volumes of -the nitrous gas and air to be examined, and he judged of the purity -of the air by the degree of condensation: the greater the diminution -of bulk, the greater did he consider the proportion of oxygen in the -air under examination to be. This method of proceeding was immediately -adopted by chemists and physicians; but there was a want of uniformity -in the mode of proceeding, and a considerable diversity in the results. -M. Lavoisier endeavoured to improve the process, in a paper inserted -in the Memoirs of the Academy, for 1782; but his method did not answer -the purpose intended: it was Mr. Cavendish that first pointed out an -accurate mode of testing air by means of nitrous gas, and who showed -that the proportions of oxygen and azotic gas in common air are -invariable. - -Lavoisier, in the course of his investigations, had proved that -carbonic acid is a compound of carbon and oxygen; sulphuric acid, -of sulphur and oxygen; phosphoric acid, of phosphorus and oxygen; -and nitric acid, of nitrous gas and oxygen. Neither the carbon, the -sulphur, the phosphorus, nor the nitrous gas, possessed any acid -properties when uncombined; but they acquired these properties when -they were united to oxygen. He observed further, that all the acids -known in his time which had been decomposed were found to contain -oxygen, and when they were deprived of oxygen, they lost their acid -properties. These facts led him to conclude, that oxygen is an -essential constituent in all acids, and that it is the principle -which bestows acidity or the true acidifying principle. This was the -reason why he distinguished it by the name of oxygen.[5] These views -were fully developed by Lavoisier, in a paper inserted in the Memoirs -of the Academy, for 1778, entitled, "General Considerations on the -Nature of Acids, and on the Principles of which they are composed." -When this paper was published, Lavoisier's views were exceedingly -plausible. They were gradually adopted by chemists in general, and -for a number of years may be considered to have constituted a part of -the generally-received doctrines. But the discovery of the nature of -chlorine, and the subsequent facts brought to light respecting iodine, -bromine, and cyanogen, have demonstrated that it is inaccurate; that -many powerful acids exist which contain no oxygen, and that there is -no one substance to which the name of acidifying principle can with -justice be given. To this subject we shall again revert, when we come -to treat of the more modern discoveries. - - [5] From ὀξυς, sour, and γινομαι, which he defined the _producer of - acids_, the _acidifying principle_. - -Long as the account is which we have given of the labours of Lavoisier, -the subject is not yet exhausted. Two other papers of his remain to be -noticed, which throw considerable light on some important functions -of the living body: we allude to his experiments on _respiration_ and -_perspiration_. - -It was known, that if an animal was confined beyond a certain limited -time in a given volume of atmospherical air, it died of suffocation, -in consequence of the air becoming unfit for breathing; and that -if another animal was put into this air, thus rendered noxious by -breathing, its life was destroyed almost in an instant. Dr. Priestley -had thrown some light upon this subject by showing that air, in which -an animal had breathed for some time, possessed the property of -rendering lime-water turbid, and therefore contained carbonic acid gas. -He considered the process of breathing as exactly analogous to the -calcination of metals, or the combustion of burning bodies. Both, in -his opinion acted by giving out phlogiston; which, uniting with the -air of the atmosphere, converted it into phlogisticated air. Priestley -found, that if plants were made to vegetate for some time in air that -had been rendered unfit for supporting animal life by respiration, -it lost the property of extinguishing a candle, and animals could -breathe it again without injury. He concluded from this that animals, -by breathing, phlogisticated air, but that plants, by vegetating, -dephlogisticated air: the former communicated phlogiston to it, the -latter took phlogiston from it. - -After Lavoisier had satisfied himself that air is a mixture of oxygen -and azote, and that oxygen alone is concerned in the processes of -calcination and combustion, being absorbed and combined with the -substances undergoing calcination and combustion, it was impossible for -him to avoid drawing similar conclusions with respect to the breathing -of animals. Accordingly, he made experiments on the subject, and the -result was published in the Memoirs of the Academy, for 1777. From -these experiments he drew the following conclusions: - -1. The only portion of atmospherical air which is useful in breathing -is the oxygen. The azote is drawn into the lungs along with the oxygen, -but it is thrown out again unaltered. - -2. The oxygen gas, on the contrary, is gradually, by breathing, -converted into carbonic acid; and air becomes unfit for respiration -when a certain portion of its oxygen is converted into carbonic acid -gas. - -3. Respiration is therefore exactly analogous to calcination. When air -is rendered unfit for supporting life by respiration, if the carbonic -acid gas formed be withdrawn by means of lime-water, or caustic alkali, -the azote remaining is precisely the same, in its nature, as what -remains after air is exhausted of its oxygen by being employed for -calcining metals. - -In this first paper Lavoisier went no further than establishing these -general principles; but he afterwards made experiments to determine the -exact amount of the changes which were produced in air by breathing, -and endeavoured to establish an accurate theory of respiration. To this -subject we shall have occasion to revert again, when we give an account -of the attempts made to determine the phenomena of respiration by more -modern experimenters. - -Lavoisier's experiments on _perspiration_ were made during the frenzy -of the French revolution, when Robespierre had usurped the supreme -power, and when it was the object of those at the head of affairs -to destroy all the marks of civilization and science which remained -in the country. His experiments were scarcely completed when he was -thrown into prison, and though he requested a prolongation of his -life for a short time, till he could have the means of drawing up a -statement of their results, the request was barbarously refused. He has -therefore left no account of them whatever behind him. But Seguin, who -was associated with him in making these experiments, was fortunately -overlooked, and escaped the dreadful times of the reign of terror: he -afterwards drew up an account of the results, which has prevented them -from being wholly lost to chemists and physiologists. - -Seguin was usually the person experimented on. A varnished silk bag, -perfectly air-tight, was procured, within which he was enclosed, except -a slit over against the mouth, which was left open for breathing; and -the edges of the bag were accurately cemented round the mouth, by -means of a mixture of turpentine and pitch. Thus every thing emitted -by the body was retained in the bag, except what made its escape from -the lungs by respiration. By weighing himself in a delicate balance at -the commencement of the experiment, and again after he had continued -for some time in the bag, the quantity of matter carried off by -respiration was determined. By weighing himself without this varnished -covering, and repeating the operation after the same interval of time -had elapsed, as in the former experiment, he determined the loss of -weight occasioned by _perspiration_ and _respiration_ together. The -loss of weight indicated by the first experiment being subtracted from -that given by the second, the quantity of matter lost by _perspiration_ -through the pores of the skin was determined. The following facts were -ascertained by these experiments: - -1. The maximum of matter perspired in a minute amounted to 26·25 grains -troy; the minimum to nine grains; which gives 17·63 grains, at a -medium, in the minute, or 52·89 ounces in twenty-four hours. - -2. The amount of perspiration is increased by drink, but not by solid -food. - -3. Perspiration is at its minimum immediately after a repast; it -reaches its maximum during digestion. - -Such is an epitome of the chemical labours of M. Lavoisier. When we -consider that this prodigious number of experiments and memoirs were -all performed and drawn up within the short period of twenty years, -we shall be able to form some idea of the almost incredible activity -of this extraordinary man: the steadiness with which he kept his own -peculiar opinions in view, and the good temper which he knew how to -maintain in all his publications, though his opinions were not only -not supported, but actually opposed by the whole body of chemists in -existence, does him infinite credit, and was undoubtedly the wisest -line of conduct which he could possibly have adopted. The difficulties -connected with the evolution and absorption of hydrogen, constituted -the stronghold of the phlogistians. But Mr. Cavendish's discovery, that -water is a compound of oxygen and hydrogen, was a death-blow to the -doctrine of Stahl. Soon after this discovery was fully established, or -during the year 1785, M. Berthollet, a member of the academy, and fast -rising to the eminence which he afterwards acquired, declared himself -a convert to the Lavoisierian theory. His example was immediately -followed by M. Fourcroy, also a member of the academy, who had -succeeded Macquer as professor of chemistry in the Jardin du Roi. - -M. Fourcroy, who was perfectly aware of the strong feeling of -patriotism which, at that time, actuated almost every man of science -in France, hit upon a most infallible way of giving currency to the -new opinions. To the theory of Lavoisier he gave the name of _La -Chimie Française_ (French Chemistry). This name was not much relished -by Lavoisier, as, in his opinion, it deprived him of the credit which -was his due; but it certainly contributed, more than any thing else, -to give the new opinions currency, at least, in France; they became -at once a national concern, and those who still adhered to the old -opinions, were hooted and stigmatized as enemies to the glory of their -country. One of the most eminent of those who still adhered to the -phlogistic theory was M. Guyton de Morveau, a nobleman of Burgundy, who -had been educated as a lawyer, and who filled a conspicuous situation -in the Parliament of Dijon: he had cultivated chemistry with great -zeal, and was at that time the editor of the chemical part of the -Encyclopédie Méthodique. In the first half-volume of the chemical part -of this dictionary, which had just appeared, Morveau had supported the -doctrine of phlogiston, and opposed the opinions of Lavoisier with much -zeal and considerable skill: on this account, it became an object of -considerable consequence to satisfy Morveau that his opinions were -inaccurate, and to make him a convert to the antiphlogistic theory; for -the whole matter was managed as if it had been a political intrigue, -rather than a philosophical inquiry. - -Morveau was accordingly invited to Paris, and Lavoisier succeeded -without difficulty in bringing him over to his own opinions. We are -ignorant of the means which he took; no doubt friendly discussion -and the repetition of the requisite experiments, would be sufficient -to satisfy a man so well acquainted with the subject, and whose mode -of thinking was so liberal as Morveau. Into the middle of the second -half-volume of the chemical part of the Encyclopédie Méthodique -he introduced a long advertisement, announcing this change in his -opinions, and assigning his reasons for it. - -The chemical nomenclature at that time in use had originated with -the medical chemists, and contained a multiplicity of unwieldy and -unmeaning, and even absurd terms. It had answered the purposes of -chemists tolerably well while the science was in its infancy; but the -number of new substances brought into view had of late years become -so great, that the old names could not be applied to them without -the utmost straining: and the chemical terms in use were so little -systematic that it required a considerable stretch of memory to retain -them. These evils were generally acknowledged and lamented, and -various attempts had been made to correct them. Bergman, for instance, -had contrived a new nomenclature, confined chiefly to the salts and -adapted to the Latin language. Dr. Black had done the same thing: his -nomenclature possessed both elegance and neatness, and was, in several -respects, superior to the terms ultimately adopted; but with his usual -indolence and disregard of reputation, he satisfied himself merely with -drawing it up in the form of a table and exhibiting it to his class. -Morveau contrived a new nomenclature of the salts, and published it in -1783; and it appears to have been seen and approved of by Bergman. - -The old chemical phraseology as far as it had any meaning was entirely -conformable to the phlogistic theory. This was so much the case that -it was with difficulty that Lavoisier was able to render his opinions -intelligible by means of it. Indeed it would have been out of his power -to have conveyed his meaning to his readers, had he not invented and -employed a certain number of new terms. Lavoisier, aware of the defects -of the chemical nomenclature, and sensible of the advantage which his -own doctrine would acquire when dressed up in a language exactly suited -to his views, was easily prevailed upon by Morveau to join with him in -forming a new nomenclature to be henceforth employed exclusively by -the antiphlogistians, as they called themselves. For this purpose they -associated with themselves Berthollet, and Fourcroy. We do not know -what part each took in this important undertaking; but, if we are to -judge from appearances, the new nomenclature was almost exclusively -the work of Lavoisier and Morveau. Lavoisier undoubtedly contrived the -general phrases, and the names applied to the simple substances, so far -as they were new, because he had employed the greater number of them in -his writings before the new nomenclature was concocted. That the mode -of naming the salts originated with Morveau is obvious; for it differs -but little from the nomenclature of the salts published by him four -years before. - -The new nomenclature was published by Lavoisier and his associates in -1787, and it was ever after employed by them in all their writings. -Aware of the importance of having a periodical work in which they could -register and make known their opinions, they established the _Annales -de Chimie_, as a sort of counterpoise to the _Journal de Physique_, -the editor of which, M. Delametherie, continued a zealous votary of -phlogiston to the end of his life. This new nomenclature very soon made -its way into every part of Europe, and became the common language of -chemists, in spite of the prejudices entertained against it, and the -opposition which it every where met with. In the year 1796, or nine -years after the appearance of the new nomenclature, when I attended the -chemistry-class in the College of Edinburgh, it was not only in common -use among the students, but was employed by Dr. Black, the professor -of chemistry, himself; and I have no doubt that he had introduced it -into his lectures several years before. This extraordinary rapidity -with which the new chemical language came into use, was doubtless owing -to two circumstances. First, the very defective, vague, and barbarous -state of the old chemical nomenclature: for although, in consequence of -the prodigious progress which the science of chemistry has made since -the time of Lavoisier, his nomenclature is now nearly as inadequate -to express our ideas as that of Stahl was to express his; yet, at the -time of its appearance, its superiority over the old nomenclature was -so great, that it was immediately felt and acknowledged by all those -who were acquiring the science, who are the most likely to be free from -prejudices, and who, in the course of a few years, must constitute the -great body of those who are interested in the science. 2. The second -circumstance, to which the rapid triumph of the new nomenclature was -owing, is the superiority of Lavoisier's theory over that of Stahl. -The subsequent progress of the science has betrayed many weak points -in Lavoisier's opinions; yet its superiority over that of Stahl was -so obvious, and the mode of interrogating nature introduced by him -was so good, and so well calculated to advance the science, that no -unprejudiced person, who was at sufficient pains to examine both, could -hesitate about preferring that of Lavoisier. It was therefore generally -embraced by all the young chemists in every country; and they became, -at the same time, partial to the new nomenclature, by which only that -theory could be explained in an intelligible manner. - -When the new nomenclature was published, there were only three nations -in Europe who could be considered as holding a distinguished place -as cultivators of chemistry: France, Germany, and Great Britain. For -Sweden had just lost her two great chemists, Bergman and Scheele, and -had been obliged, in consequence, to descend from the high chemical -rank which she had formerly occupied. In France the fashion, and of -course almost the whole nation, were on the side of the new chemistry. -Macquer, who had been a stanch phlogistian to the last, was just -dead. Monnet was closing his laborious career. Baumé continued to -adhere to the old opinions; but he was old, and his chemical skill, -which had never been _accurate_, was totally eclipsed by the more -elaborate researches of Lavoisier and his friends. Delametherie was -a keen phlogistian, a man of some abilities, of remarkable honesty -and integrity, and editor of the Journal de Physique, at that time a -popular and widely-circulating scientific journal. But his habits, -disposition, and conduct, were by no means suited to the taste of his -countrymen, or conformable to the practice of his contemporaries. The -consequence was, that he was shut out of all the scientific coteries -of Paris; and that his opinions, however strongly, or rather violently -expressed, failed to produce the intended effect. Indeed, as his -views were generally inaccurate, and expressed without any regard to -the rules of good manners, they in all probability rather served to -promote than to injure the cause of his opponents. Lavoisier and his -friends appear to have considered the subject in this light: they never -answered any of his attacks, or indeed took any notice of them. France, -then, from the date of the publication of the new nomenclature, might -be considered as enlisted on the side of the antiphlogistic theory. - -The case was very different in Germany. The national prejudices of the -Germans were naturally enlisted on the side of Stahl, who was their -countryman, and whose reputation would be materially injured by the -refutation of his theory. The cause of phlogiston, accordingly, was -taken up by several German chemists, and supported with a good deal -of vigour; and a controversy was carried on for some years in Germany -between the old chemists who adhered to the doctrine of Stahl, and the -young chemists who had embraced the theory of Lavoisier. Gren, who was -at that time the editor of a chemical journal, deservedly held in high -estimation, and whose reputation as a chemist stood rather high in -Germany, finding it impossible to defend the Stahlian theory as it had -been originally laid down, introduced a new modification of phlogiston, -and attempted to maintain it against the antiphlogistians. The death -of Gren and of Wiegleb, who were the great champions of phlogiston, -left the field open to the antiphlogistians, who soon took possession -of all the universities and scientific journals in Germany. The most -eminent chemist in Germany, or perhaps in Europe at that time, was -Martin Henry Klaproth, professor of chemistry at Berlin, to whom -analytical chemistry lies under the greatest obligations. In the year -1792 he proposed to the Academy of Sciences of Berlin, of which he was -a member, to repeat all the requisite experiments before them, that -the members of the academy might be able to determine for themselves -which of the two theories deserved the preference. This proposal was -acceded to. All the fundamental experiments were repeated by Klaproth -with the most scrupulous attention to accuracy: the result was a -full conviction, on the part of Klaproth and the academy, that the -Lavoisierian theory was the true one. Thus the Berlin Academy became -antiphlogistians in 1792: and as Berlin has always been the focus of -chemistry in Germany, the determination of such a learned body must -have had a powerful effect in accelerating the propagation of the new -theory through that vast country. - -In Great Britain the investigation of gaseous bodies, to which -the new doctrines were owing, had originated. Dr. Black had begun -the inquiry--Mr. Cavendish had prosecuted it with unparalleled -accuracy--and Dr. Priestley had made known a great number of new -gaseous bodies, which had hitherto escaped the attention of chemists. -As the British chemists had contributed more than those of any other -nation to the production of the new facts on which Lavoisier's theory -was founded, it was natural to expect that they would have embraced -that theory more readily than the chemists of any other nation: but -the matter of fact was somewhat different. Dr. Black, indeed, with -his characteristic candour, speedily embraced the opinions, and even -adopted the new nomenclature: but Mr. Cavendish new modelled the -phlogistic theory, and published a defence of phlogiston, which it was -impossible at that time to refute. The French chemists had the good -sense not to attempt to overturn it. Mr. Cavendish after this laid -aside the cultivation of chemistry altogether, and never acknowledged -himself a convert to the new doctrines. - -Dr. Priestley continued a zealous advocate for phlogiston till the very -last, and published what he called a refutation of the antiphlogistic -theory about the beginning of the present century: but Dr. Priestley, -notwithstanding his merit as a discoverer and a man of genius, was -never, strictly speaking, entitled to the name of chemist; as he was -never able to make a chemical analysis. In his famous experiments, for -example, on the composition of water, he was obliged to procure the -assistance of Mr. Keir to determine the nature of the blue-coloured -liquid which he had obtained, and which Mr. Keir showed to be nitrate -of copper. Besides, Dr. Priestley, though perfectly honest and candid, -was so hasty in his decisions, and so apt to form his opinions without -duly considering the subject, that his chemical theories are almost all -erroneous and sometimes quite absurd. - -Mr. Kirwan, who had acquired a high reputation, partly by his -_mineralogy_, and partly by his experiments on the composition of -the salts, undertook the task of refuting the antiphlogistic theory, -and with that view published a work to which he gave the name of "An -Essay on Phlogiston and the Composition of Acids." In that book he -maintained an opinion which seems to have been pretty generally adopted -by the most eminent chemists of the time; namely, that phlogiston is -the same thing with what is at present called _hydrogen_, and which, -when Kirwan wrote, was called light _inflammable air_. Of course Mr. -Kirwan undertook to prove that every combustible substance and every -metal contains hydrogen as a constituent, and that hydrogen escapes -in every case of combustion and calcination. On the other hand, when -calces are reduced to the metallic state hydrogen is absorbed. The book -was divided into thirteen sections. In the first the specific gravity -of the gases was stated according to the best data then existing. The -second section treats of the composition of acids, and the composition -and decomposition of water. The third section treats of sulphuric acid; -the fourth, of nitric acid; the fifth, of muriatic acid; the sixth, -of aqua regia; the seventh, of phosphoric acid; the eighth, of oxalic -acid; the ninth, of the calcination and reduction of metals and the -formation of fixed air; the tenth, of the dissolution of metals; the -eleventh, of the precipitation of metals by each other; the twelfth, -of the properties of iron and steel; while the thirteenth sums up the -whole argument by way of conclusion. - -In this work Mr. Kirwan admitted the truth of M. Lavoisier's theory, -that during combustion and calcination, oxygen united with the burning -and calcining body. He admitted also that water is a compound of oxygen -and hydrogen. Now these admissions, which, however, it was scarcely -possible for a man of candour to refuse, rendered the whole of his -arguments in favour of the identity of hydrogen and phlogiston, and -of the existence of hydrogen in all combustible bodies, exceedingly -inconclusive. Kirwan's book was laid hold of by the French chemists, -as affording them an excellent opportunity of showing the superiority -of the new opinions over the old. Kirwan's view of the subject was -that which had been taken by Bergman and Scheele, and indeed by every -chemist of eminence who still adhered to the phlogistic system. A -satisfactory refutation of it, therefore, would be a death-blow to -phlogiston and would place the antiphlogistic theory upon a basis so -secure that it would be henceforth impossible to shake it. - -Kirwan's work on phlogiston was accordingly translated into French, -and published in Paris. At the end of each section was placed an -examination and refutation of the argument contained in it by some one -of the French chemists, who had now associated themselves in order to -support the antiphlogistic theory. The introduction, together with the -second, third, and eleventh sections were examined and refuted by M. -Lavoisier; the fourth, the fifth, and sixth sections fell to the share -of M. Berthollet; the seventh and thirteenth sections were undertaken -by M. de Morveau; the eighth, ninth, and tenth, by M. De Fourcroy; -while the twelfth section, on iron and steel was animadverted on by -M. Monge. These refutations were conducted with so much urbanity of -manner, and were at the same time so complete, that they produced all -the effects expected from them. Mr. Kirwan, with a degree of candour -and liberality of which, unfortunately, very few examples can be -produced, renounced his old opinions, abandoned phlogiston, and adopted -the antiphlogistic doctrines of his opponents. But his advanced age, -and a different mode of experimenting from what he had been accustomed -to, induced him to withdraw himself entirely from experimental science -and to devote the evening of his life to metaphysical and logical and -moral investigations. - -Thus, soon after the year 1790, a kind of interregnum took place in -British chemistry. Almost all the old British chemists had relinquished -the science, or been driven out of the field by the superior prowess -of their antagonists. Dr. Austin and Dr. Pearson will, perhaps, be -pointed out as exceptions. They undoubtedly contributed somewhat to -the progress of the science. But they were arranged on the side of -the antiphlogistians. Dr. Crawford, who had done so much for the -theory of heat, was about this time ruined in his circumstances by -the bankruptcy of a house to which he had intrusted his property. -This circumstance preyed upon a mind which had a natural tendency to -morbid sensibility, and induced this amiable and excellent man to put -an end to his existence. Dr. Higgins had acquired some celebrity as an -experimenter and teacher; but his disputes with Dr. Priestley, and his -laying claim to discoveries which certainly did not belong to him, had -injured his reputation, and led him to desert the field of science. Dr. -Black was an invalid, Mr. Cavendish had renounced the cultivation of -chemistry, and Dr. Priestley had been obliged to escape from the iron -hand of theological and political bigotry, by leaving the country. He -did little as an experimenter after he went to America; and, perhaps, -had he remained in England, his reputation would rather have diminished -than increased. He was an admirable pioneer, and as such, contributed -more than any one to the revolution which chemistry underwent; though -he was himself utterly unable to rear a permanent structure capable, -like the Newtonian theory, of withstanding all manner of attacks, -and becoming only the firmer and stronger the more it is examined. -Mr. Keir, of Birmingham, was a man of great eloquence, and possessed -of all the chemical knowledge which characterized the votaries of -phlogiston. In the year 1789 he attempted to stem the current of the -new opinions by publishing a dictionary of chemistry, in which all the -controversial points were to be fully discussed, and the antiphlogistic -theory examined and refuted. Of this dictionary only one part appeared, -constituting a very thin volume of two hundred and eight quarto pages, -and treating almost entirely of _acids_. Finding that the sale of -this work did not answer his expectations, and probably feeling, as -he proceeded, that the task of refuting the antiphlogistic opinions -was much more difficult, and much more hopeless than he expected, he -renounced the undertaking, and abandoned altogether the pursuit of -chemistry. - -It will be proper in this place to introduce some account of the most -eminent of those French chemists who embraced the theory of Lavoisier, -and assisted him in establishing his opinions. - -Claude-Louis Berthollet was born at Talloire, near Annecy, in Savoy, -on the 9th of December, 1748. He finished his school education at -Chambéry, and afterwards studied at the College of Turin, a celebrated -establishment, where many men of great scientific celebrity have been -educated. Here he attached himself to medicine, and after obtaining -a degree he repaired to Paris, which was destined to be the future -theatre of his speculations and pursuits. - -In Paris he had not a single acquaintance, nor did he bring with him -a single introductory letter; but understanding that M. Tronchin, -at that time a distinguished medical practitioner in Paris, was a -native of Geneva, he thought he might consider him as in some measure -a countryman. On this slender ground he waited on M. Tronchin, and -what is rather surprising, and reflects great credit on both, this -acquaintance, begun in so uncommon a way, soon ripened into friendship. -Tronchin interested himself for his young _protégée_, and soon got him -into the situation of physician in ordinary to the Duke of Orleans, -father of him who cut so conspicuous a figure in the French revolution, -under the name of M. Egalité. In this situation he devoted himself to -the study of chemistry, and soon made himself known by his publications -on the subject. - -In 1781 he was elected a member of the Academy of Sciences of Paris: -one of his competitors was M. Fourcroy. No doubt Berthollet owed his -election to the influence of the Duke of Orleans. In the year 1784 he -was again a competitor with M. de Fourcroy for the chemical chair at -the Jardin du Roi, left vacant by the death of Macquer. The chair was -in the gift of M. Buffon, whose vanity is said to have been piqued -because the Duke of Orleans, who supported Berthollet's interest, did -not pay him sufficient court. This induced him to give the chair to -Fourcroy; and the choice was a fortunate one, as his uncommon vivacity -and rapid elocution particularly fitted him for addressing a Parisian -audience. The chemistry-class at the Jardin du Roi immediately became -celebrated, and attracted immense crowds of admiring auditors. - -But the influence of the Duke of Orleans was sufficient to procure -for Berthollet another situation which Macquer had held. This was -government commissary and superintendent of the dyeing processes. -It was this situation which naturally turned his attention to the -phenomena of dyeing, and occasioned afterwards his book on dyeing; -which at the time of its publication was excellent, and exhibited a -much better theory of dyeing, and a better account of the practical -part of the art than any work which had previously appeared. The arts -of dyeing and calico-printing have been very much improved since the -time that Berthollet's book was written; yet if we except Bancroft's -work on the permanent colours, nothing very important has been -published on the subject since that period. We are at present almost as -much in want of a good work on dyeing as we were when Berthollet's book -appeared. - -In the year 1785 Berthollet, at a meeting of the Academy of Sciences, -informed that learned body that he had become a convert to the -antiphlogistic doctrines of Lavoisier. There was one point, however, -upon which he entertained a different opinion from Lavoisier, and -this difference of opinion continued to the last. Berthollet did not -consider oxygen as the acidifying principle. On the contrary, he was -of opinion that acids existed which contained no oxygen whatever. -As an example, he mentioned sulphuretted hydrogen, which possessed -the properties of an acid, reddening vegetable blues, and combining -with and neutralizing bases, and yet it was a compound of sulphur and -hydrogen, and contained no oxygen whatever. It is now admitted that -Berthollet was accurate in his opinion, and that oxygen is not of -itself an acidifying principle. - -Berthollet continued in the uninterrupted prosecution of his studies, -and had raised himself a very high reputation when the French -revolution burst upon the world in all its magnificence. It is not -our business here to enter into any historical details, but merely -to remind the reader that all the great powers of Europe combined -to attack France, assisted by a formidable army of French emigrants -assembled at Coblentz. The Austrian and Prussian armies hemmed her -in by land, while the British fleets surrounded her by sea, and thus -shut her out from all communication with other nations. Thus France -was thrown at once upon her own resources. She had been in the habit -of importing her saltpetre, and her iron, and many other necessary -implements of war: these supplies were suddenly withdrawn; and it was -expected that France, thus deprived of all her resources, would be -obliged to submit to any terms imposed upon her by her adversaries. -At this time she summoned her men of science to her assistance, and -the call was speedily answered. Berthollet and Monge were particularly -active, and saved the French nation from destruction by their activity, -intelligence, and zeal. Berthollet traversed France from one extremity -to the other; pointed out the mode of extracting saltpetre from the -soil, and of purifying it. Saltpetre-works were instantly established -in every part of France, and gunpowder made of it in prodigious -quantity, and with incredible activity. Berthollet even attempted to -manufacture a new species of gunpowder still more powerful than the -old, by substituting chlorate of potash for saltpetre: but it was found -too formidable a substance to be made with safety. - -The demand for cannon, muskets, sabres, &c., was equally urgent and -equally difficult to be supplied. A committee of men of science, of -which Berthollet and Monge were the leading members, was established, -and by them the mode of smelting iron, and of converting it into -steel, was instantly communicated, and numerous manufactories of these -indispensable articles rose like magic in every part of France. - -This was the most important period of the life of Berthollet. It -was in all probability his zeal, activity, sagacity, and honesty, -which saved France from being overrun by foreign troops. But perhaps -the moral conduct of Berthollet was not less conspicuous than his -other qualities. During the reign of terror, a short time before the -9th Thermidor, when it was the system to raise up pretended plots, -to give pretexts for putting to death those that were obnoxious to -Robespierre and his friends, a hasty notice was given at a sitting -of the Committee of Public Safety, that a conspiracy had just been -discovered to destroy the soldiers, by poisoning the brandy which was -just going to be served out to them previous to an engagement. It was -said that the sick in the hospitals who had tasted this brandy, all -perished in consequence of it. Immediate orders were issued to arrest -those previously marked for execution. A quantity of the brandy was -sent to Berthollet to be examined. He was informed, at the same time, -that Robespierre wanted a conspiracy to be established, and all knew -that opposition to his will was certain destruction. Having finished -his analysis, Berthollet drew up his results in a Report, which he -accompanied with a written explanation of his views; and he there -stated, in the plainest language, that nothing poisonous was mixed -with the brandy, but that it had been diluted with water holding small -particles of slate in suspension, an ingredient which filtration would -remove. This report deranged the plans of the Committee of Public -Safety. They sent for the author, to convince him of the inaccuracy of -his analysis, and to persuade him to alter its results. Finding that -he remained unshaken in his opinion, Robespierre exclaimed, "What, -Sir! darest thou affirm that the muddy brandy is free from poison?" -Berthollet immediately filtered a glass of it in his presence, and -drank it off. "Thou art daring, Sir, to drink that liquor," exclaimed -the ferocious president of the committee. "I dared much more," replied -Berthollet, "when I signed my name to that Report." There can be no -doubt that he would have paid the penalty of this undaunted honesty -with his life, but that fortunately the Committee of Public Safety -could not at that time dispense with his services. - -In the year 1792 Berthollet was named one of the commissioners of -the Mint, into the processes of which he introduced considerable -improvements. In 1794 he was appointed a member of the Commission -of Agriculture and the Arts: and in the course of the same year he -was chosen professor of chemistry at the Polytechnic School and -also in the Normal School. But his turn of mind did not fit him for -a public teacher. He expected too much information to be possessed -by his hearers, and did not, therefore, dwell sufficiently upon the -elementary details. His pupils were not able to follow his metaphysical -disquisitions on subjects totally new to them; hence, instead of -inspiring them with a love for chemistry, he filled them with langour -and disgust. - -In 1795, at the organization of the Institute, which was intended to -include all men of talent or celebrity in France, we find Berthollet -taking a most active lead; and the records of the Institute afford -abundant evidence of the perseverance and assiduity with which he -laboured for its interests. Of the committees to which all original -memoirs are in the first place referred, we find Berthollet, oftener -than any other person, a member, and his signature to the report of -each work stands generally first. - -In the year 1796, after the subjugation of Italy by Bonaparte, -Berthollet and Monge were selected by the Directory to proceed to -that country, in order to select those works of science and art with -which the Louvre was to be filled and adorned. While engaged in the -prosecution of that duty, they became acquainted with the victorious -general. He easily saw the importance of their friendship, and -therefore cultivated it with care; and was happy afterwards to possess -them, along with nearly a hundred other philosophers, as his companions -in his celebrated expedition to Egypt, expecting no doubt an eclat from -such a halo of surrounding science, as might favour the development of -his schemes of future greatness. On this expedition, which promised so -favourably for the French nation, and which was intended to inflict a -mortal stab upon the commercial greatness of Great Britain, Bonaparte -set out in the year 1798, accompanied by a crowd of the most eminent -men of science that France could boast of. That they might co-operate -more effectually in the cause of knowledge, these gentlemen formed -themselves into a society, named "The Institute of Egypt," which was -constituted on the same plan as the National Institute of France. Their -first meeting was on the 6th Fructidor (24th of August), 1798; and -after that they continued to assemble, at stated intervals. At these -meetings papers were read, by the respective members, on the climate, -the inhabitants, and the natural and artificial productions of the -country to which they had gone. These memoirs were published in 1800, -in Paris, in a single volume entitled, "Memoirs of the Institute of -Egypt." - -The history of the Institute of Egypt, as related by Cuvier, is not -a little singular, and deserves to be stated. Bonaparte, during -his occasional intercourse with Berthollet in Italy, was delighted -with the simplicity of his manners, joined to a force and depth of -thinking which he soon perceived to characterize our chemist. When -he returned to Paris, where he enjoyed some months of comparative -leisure, he resolved to employ his spare time in studying chemistry -under Berthollet. It was at this period that his illustrious pupil -imparted to our philosopher his intended expedition to Egypt, of which -no whisper was to be spread abroad till the blow was ready to fall; -and he begged of him not merely to accompany the army himself, but to -choose such men of talent and experience as he conceived fitted to -find there an employment worthy of the country which they visited, -and of that which sent them forth. To invite men to a hazardous -expedition, the nature and destination of which he was not permitted -to disclose, was rather a delicate task; yet Berthollet undertook it. -He could simply inform them that he would himself accompany them; -yet such was the universal esteem in which he was held, such was the -confidence universally placed in his honesty and integrity, that all -the men of science agreed at once, and without hesitation, to embark -on an unknown expedition, the dangers of which he was to share along -with them. Had it not been for the link which Berthollet supplied -between the commander-in-chief and the men of science, it would have -been impossible to have united, as was done on this occasion, the -advancement of knowledge with the progress of the French arms. - -During the whole of this expedition, Berthollet and Monge distinguished -themselves by their firm friendship, and by their mutually braving -every danger to which any of the common soldiers could be exposed. -Indeed, so intimate was their association that many of the army -conceived Berthollet and Monge to be one individual; and it is no small -proof of the intimacy of these philosophers with Bonaparte, that the -soldiers had a dislike at this double personage, from a persuasion -that it had been at his suggestion that they were led into a country -which they detested. It happened on one occasion that a boat, in which -Berthollet and some others were conveyed up the Nile, was assailed by a -troop of Mamelukes, who poured their small shot into it from the banks. -In the midst of this perilous voyage, M. Berthollet began very coolly -to pick up stones and stuff his pockets with them. When his motive for -this conduct was asked, "I am desirous," said he, "that in case of my -being shot, my body may sink at once to the bottom of this river, and -may escape the insults of these barbarians." - -In a conjuncture where a courage of a rarer kind was required, -Berthollet was not found wanting. The plague broke out in the French -army, and this, added to the many fatigues they had previously endured, -the diseases under which they were already labouring, would, it was -feared, lead to insurrection on the one hand, or totally sink the -spirits of the men on the other. Acre had been besieged for many weeks -in vain. Bonaparte and his army had been able to accomplish nothing -against it: he was anxious to conceal from his army this disastrous -intelligence. When the opinion of Berthollet was asked in council, -he spoke at once the plain, though unwelcome truth. He was instantly -assailed by the most violent reproaches. "In a week," said he, "my -opinion will be unfortunately but too well vindicated." It was as he -foretold: and when nothing but a hasty retreat could save the wretched -remains of the army of Egypt, the carriage of Berthollet was seized -for the convenience of some wounded officers. On this, he travelled on -foot, and without the smallest discomposure, across twenty leagues of -the desert. - -When Napoleon abandoned the army of Egypt, and traversed half the -Mediterranean in a single vessel, Berthollet was his companion. -After he had put himself at the head of the French government, and -had acquired an extent of power, which no modern European potentate -had ever before realized, he never forgot his associate. He was in -the habit of placing all chemical discoveries to his account, to the -frequent annoyance of our chemist; and when an unsatisfactory answer -was given him upon any scientific subject, he was in the habit of -saying, "Well; I shall ask this of Berthollet." But he did not limit -his affection to these proofs of regard. Having been informed that -Berthollet's earnest pursuits of science had led him into expenses -which had considerably deranged his fortune, he sent for him, and said, -in a tone of affectionate reproach, "M. Berthollet, I have always one -hundred thousand crowns at the service of my friends." And, in fact, -this sum was immediately presented to him. - -Upon his return from Egypt, Berthollet was nominated a senator by the -first consul; and afterwards received the distinction of grand officer -of the Legion of Honour; grand cross of the Order of Reunion; titulary -of the Senatory of Montpellier; and, under the emperor, he was created -a peer of France, receiving the title of Count. The advancement to -these offices produced no change in the manners of Berthollet. Of this -he gave a striking proof, by adopting, as his armorial bearing (at the -time that others eagerly blazoned some exploit), the plain unadorned -figure of his faithful and affectionate dog. He was no courtier -before he received these honours, and he remained equally simple and -unassuming, and not less devoted to science after they were conferred. - -As we advance towards the latter period of his life, we find the same -ardent zeal in the cause of science which had glowed in his early -youth, accompanied by the same generous warmth of heart that he ever -possessed, and which displayed itself in his many intimate friendships -still subsisting, though mellowed by the hand of time. At this period -La Place lived at Arcueil, a small village about three miles from -Paris. Between him and Berthollet there had long subsisted a warm -affection, founded on mutual esteem. To be near this illustrious -man Berthollet purchased a country-seat in the village: there he -established a very complete laboratory, fit for conducting all kinds of -experiments in every branch of natural philosophy. Here he collected -round him a number of distinguished young men, who knew that in his -house their ardour would at once receive fresh impulse and direction -from the example of Berthollet. These youthful philosophers were -organized by him into a society, to which the name of Société d'Arcueil -was given. M. Berthollet was himself the president, and the other -members were La Place, Biot, Gay-Lussac, Thenard, Collet-Descotils, -Decandolle, Humboldt, and A. B. Berthollet. This society published -three volumes of very valuable memoirs. The energy of this society was -unfortunately paralyzed by an untoward event, which imbittered the -latter days of this amiable man. His only son, M. A. B. Berthollet, in -whom his happiness was wrapped up, was unfortunately afflicted with a -lowness of spirits which rendered his life wholly insupportable to him. -Retiring to a small room, he locked the door, closed up every chink -and crevice which might admit the air, carried writing materials to -a table, on which he placed a second-watch, and then seated himself -before it. He now marked precisely the hour, and lighted a brasier of -charcoal beside him. He continued to note down the series of sensations -he then experienced in succession, detailing the approach and rapid -progress of delirium; until, as time went on, the writing became -confused and illegible, and the young victim dropped dead upon the -floor. - -After this event the spirits of the old man never again rose. -Occasionally some discovery, extending the limits of his favourite -science, engrossed his interest and attention for a short time: but -such intervals were rare, and shortlived. The restoration of the -Bourbons, and the downfall of his friend and patron Napoleon, added to -his sufferings by diminishing his income, and reducing him from a state -of affluence to comparative embarrassment. But he was now old, and the -end of his life was approaching. In 1822 he was attacked by a slight -fever, which left behind it a number of boils: these were soon followed -by a gangrenous ulcer of uncommon size. Under this he suffered for -several months with surprising fortitude. He himself, as a physician, -knew the extent of his danger, felt the inevitable progress of the -malady, and calmly regarded the slow approach of death. At length, -after a tedious period of suffering, in which his equanimity had never -once been shaken, he died on the 6th of November, when he had nearly -completed the seventy-fourth year of his age. - -His papers are exceedingly numerous, and of a very miscellaneous -nature, amounting to more than eighty. The earlier were chiefly -inserted into the various volumes of the Memoirs of the Academy. -He furnished many papers to the Annales de Chimie and the Journal -de Physique, and was also a frequent contributor to the Society of -Arcueil, in the different volumes of whose transactions several memoirs -of his are to be found. He was the author likewise of two separate -works, comprising each two octavo volumes. These were his Elements of -the Art of Dyeing, first published in 1791, in a single volume: but the -new and enlarged edition of 1814 was in two volumes; and his Essay on -Chemical Statics, published about the beginning of the present century. -I shall notice his most important papers. - -His earlier memoirs on sulphurous acid, on volatile alkali, and on -the decomposition of nitre, were encumbered by the phlogistic theory, -which at that time he defended with great zeal, though he afterwards -retracted these his first opinions upon all these subjects. Except his -paper on soaps, in which he shows that they are chemical compounds -of an oil (acting the part of an acid) and an alkaline base, and his -proof that phosphoric acid exists ready formed in the body (a fact long -before demonstrated by Gahn and Scheele), his papers published before -he became an antiphlogistian are of inferior merit. - -In 1785 he demonstrated the nature and proportion of the constituents -of ammonia, or volatile alkali. This substance had been collected in -the gaseous form by the indefatigable Priestley, who had shown also -that when electric sparks are made to pass for some time through a -given volume of this gas, its bulk is nearly doubled. Berthollet merely -repeated this experiment of Priestley, and analyzed the new gases -evolved by the action of electricity. This gas he found a mixture of -three volumes hydrogen and one volume azotic gas: hence it was evident -that ammoniacal gas is a compound of three volumes of hydrogen and one -volume of azotic gas united together, and condensed into two volumes. -The same discovery was made about the same time by Dr. Austin, and -published in the Philosophical Transactions. Both sets of experiments -were made without any knowledge of what was done by the other: but it -is admitted, on all hands, that Berthollet had the priority in point of -time. - -It was about this time, likewise, that he published his first paper on -chlorine. He observed, that when water, impregnated with chlorine, is -exposed to the light of the sun, the water loses its colour, while, at -the same time, a quantity of oxygen gas is given out. If we now examine -the water, we find that it contains no chlorine, but merely a little -muriatic acid. This fact, which is undoubted, led him to conclude -that chlorine is decomposed by the action of solar light, and that its -two elements are muriatic acid and oxygen. This led to the notion that -the basis of muriatic acid is capable of combining with various doses -of oxygen, and of forming various acids, one of which is chlorine: on -that account it was called _oxygenized muriatic acid_ by the French -chemists, which unwieldy appellation was afterwards shortened by Kirwan -into _oxymuriatic acid_. - -Berthollet observed that when a current of chlorine gas is passed -through a solution of carbonate of potash an effervescence takes place -owing to the disengagement of carbonic acid gas. By-and-by crystals -are deposited in fine silky scales, which possess the property of -detonating with combustible bodies still more violently than saltpetre. -Berthollet examined these crystals and showed that they were compounds -of potash with an acid containing much more oxygen than oxymuriatic -acid. He considered its basis as muriatic acid, and distinguished it by -the name of hyper-oxymuriatic acid. - -It was not till the year 1810, that the inaccuracy of these opinions -was established. Gay-Lussac and Thenard attempted in vain to -extract oxygen from chlorine. They showed that not a trace of that -principle could be detected. Next year Davy took up the subject and -concluded from his experiments that _chlorine_ is a simple substance, -that muriatic acid is a compound of chlorine and hydrogen, and -hyper-oxymuriatic acid of chlorine and oxygen. Gay-Lussac obtained this -acid in a separate state, and gave it the name of _chloric acid_, by -which it is now known. - -Scheele, in his original experiments on chlorine, had noticed the -property which it has of destroying vegetable colours. Berthollet -examined this property with care, and found it so remarkable that -he proposed it as a substitute for exposure to the sun in bleaching. -This suggestion alone would have immortalized Berthollet had he done -nothing else; since its effect upon some of the most important of -the manufactures of Great Britain has been scarcely inferior to that -of the steam-engine itself. Mr. Watt happened to be in Paris when -the idea suggested itself to Berthollet. He not only communicated it -to Mr. Watt, but showed him the process in all its simplicity. It -consisted in nothing else than in steeping the cloth to be bleached -in water impregnated with chlorine gas. Mr. Watt, on his return to -Great Britain, prepared a quantity of this liquor, and sent it to his -father-in-law, Mr. Macgregor, who was a bleacher in the neighbourhood -of Glasgow. He employed it successfully, and thus was the first -individual who tried the new process of bleaching in Great Britain. For -a number of years the bleachers in Lancashire and the neighbourhood -of Glasgow were occupied in bringing the process to perfection. The -disagreeable smell of the chlorine was a great annoyance. This was -attempted to be got rid of by dissolving potash in the water to be -impregnated with chlorine; but it was found to injure considerably the -bleaching powers of the gas. The next method tried was to mix the water -with quicklime, and then to pass a current of chlorine through it. The -quicklime was dissolved, and the liquor thus constituted was found to -answer very well. The last improvement was to combine the chlorine -with dry lime. At first two atoms of lime were united to one atom of -chlorine; but of late years it is a compound of one atom of lime, and -one of chlorine. This chloride is simply dissolved in water, and the -cloth to be bleached is steeped in it. For all these improvements, -which have brought the method of bleaching by means of chlorine to -great simplicity and perfection, the bleachers are indebted to Knox, -Tennant, and Mackintosh, of Glasgow; by whose indefatigable exertions -the mode of manufacturing chloride of lime has been brought to a state -of perfection. - -Berthollet's experiments on prussic acid and the prussiates deserve -also to be mentioned, as having a tendency to rectify some of the ideas -at that time entertained by chemists, and to advance their knowledge -of one of the most difficult departments of chemical investigation. -In consequence of his experiments on the nature and constituents of -sulphuretted hydrogen, he had already concluded that it was an acid, -and that it was destitute of oxygen: this had induced him to refuse his -assent to the hypothesis of Lavoisier, that _oxygen_ is the _acidifying -principle_. Scheele, in his celebrated experiments on prussic acid, -had succeeded in ascertaining that its constituents were carbon and -azote; but he had not been able to make a rigid analysis of that -acid, and consequently to demonstrate that oxygen did not enter into -it as a constituent. Berthollet took up the subject, and though his -analysis was also incomplete, he satisfied himself, and rendered it -exceedingly probable, that the only constituents of this acid were, -carbon, azote, and hydrogen, and that oxygen did not enter into it as -a constituent. This was another reason for rejecting the notion of -_oxygen_ as an acidifying principle. Here were two acids capable of -neutralizing bases, namely, sulphuretted hydrogen and prussic acid, and -yet neither of them contained oxygen. He found that when prussic acid -was treated with chlorine, its properties were altered; it acquired a -different smell and taste, and no longer precipitated iron blue, but -green. From his opinion respecting the nature of chlorine, that it was -a compound of muriatic acid and oxygen, he naturally concluded that by -this process he had formed a new prussic acid by adding oxygen to the -old constituents. He therefore called this new substance _oxyprussic -acid_. It has been proved by the more recent experiments of Gay-Lussac, -that the new acid of Berthollet is a compound of _cyanogen_ (the -prussic acid deprived of hydrogen) and _chlorine_: it is now called -_chloro-cyanic acid_, and is known to possess the characters assigned -it by Berthollet: it constitutes, therefore, a new example of an acid -destitute of oxygen. Berthollet was the first person who obtained -prussiate of potash in regular crystals; the salt was known long -before, but had been always used in a state of solution. - -Berthollet's discovery of fulminating silver, and his method of -obtaining pure hydrated potash and soda, by means of alcohol, deserve -to be mentioned. This last process was of considerable importance to -analytical chemistry. Before he published his process, these substances -in a state of purity were not known. - -I think it unnecessary to enter into any details respecting his -experiments on sulphuretted hydrogen, and the hydrosulphurets and -sulphurets. They contributed essentially to elucidate that obscure part -of chemistry. But his success was not perfect; nor did we understand -completely the nature of these compounds, till the nature of the -alkaline bases had been explained by the discoveries of Davy. - -The only other work of Berthollet, which I think it necessary to notice -here, is his book entitled "Chemical Statics," which he published -in 1803. He had previously drawn up some interesting papers on the -subject, which were published in the Memoirs of the Institute. Though -chemical affinity constitutes confessedly the basis of the science, -it had been almost completely overlooked by Lavoisier, who had done -nothing more on the subject than drawn up some tables of affinity, -founded on very imperfect data. Morveau had attempted a more profound -investigation of the subject in the article _Affinité_, inserted in -the chemical part of the Encyclopédie Méthodique. His object was, in -imitation of Buffon, who had preceded him in the same investigation, -to prove that chemical affinity is merely a case of the _attraction of -gravitation_. But it is beyond our reach, in the present state of our -knowledge, to determine the amount of attraction which the atoms of -bodies exert with respect to each other. This was seen by Newton, and -also by Bergman, who satisfied themselves with considering it as an -attraction, without attempting to determine its amount; though Newton, -with his usual sagacity, was inclined, from the phenomena of light, -to consider the attraction of affinity as much stronger than that -of gravitation, or at least as increasing much more rapidly, as the -distances between the attracting particles diminished. - -Bergman, who had paid great attention to the subject, considered -affinity as a certain determinate attraction, which the atoms of -different bodies exerted towards each other. This attraction varies -in intensity between every two bodies, though it is constant between -each pair. The consequence is, that these intensities may be denoted by -numbers. Thus, suppose a body _m_, and the atoms of six other bodies, -_a_, _b_, _c_, _d_, _e_, _f_, to have an affinity for _m_, the forces -by which they are attracted towards each other may be represented by -the numbers x, x+1, x+2, x+3, x+4, x+5. And the attractions may be -represented thus: - - Attraction between _m_ & _a_ = x - _m_ & _b_ = x+1 - _m_ & _c_ = x+2 - _m_ & _d_ = x+3 - _m_ & _e_ = x+4 - _m_ & _f_ = x+5 - -Suppose we have the compound _m a_, if we present _b_, it will unite -with _m_ and displace _a_, because the attraction between _m_ and _a_ -is only x, while that between _m_ & _b_ is x+1: _c_ will displace _b_; -_d_ will displace _c_, and so on, for the same reason. On this account -Bergman considered affinity as an _elective attraction_, and in his -opinion the intensity may always be estimated by decomposition. That -substance which displaces another from a third, has a greater affinity -than the body which is displaced. If _b_ displace _a_ from the compound -_a m_, then _b_ has a greater affinity for _m_ than _a_ has. - -The object of Berthollet in his Chemical Statics, was to combat this -opinion of Bergman, which had been embraced without examination -by chemists in general. If affinity be an attraction, Berthollet -considered it as evident that it never could occasion decomposition. -Suppose _a_ to have an affinity for _m_, and _b_ to have an affinity -for the same substances. Let the affinity between _b_ and _m_ be -greater than that between _a m_. Let _b_ be mixed with a solution of -the compound _a m_, then in that case _b_ would unite with _a m_, -and form the triple compound _a m b_. Both _a_ and _b_ would at once -unite with _m_. No reason can be assigned why _a_ should separate from -_m_, and _b_ take its place. Berthollet admitted that in fact such -decompositions often happened; but he accounted for them from other -causes, and not from the superior affinity of one body over another. -Suppose we have a solution of _sulphate of soda_ in water. This salt is -a compound of _sulphuric acid_ and _soda_; two substances between which -a strong affinity subsists, and which therefore always unites whenever -they come in contact. Suppose we have dissolved in another portion -of water, a quantity of barytes, just sufficient to saturate the -sulphuric acid in the sulphate of soda. If we mix these two solutions -together. The barytes will combine with the sulphuric acid and the -compound (_sulphate of barytes_) will fall to the bottom, leaving a -pure solution of soda in the water. In this case the barytes has seized -all the sulphuric acid, and displaced the soda. The reason of this, -according to Berthollet, is not that barytes has a stronger affinity -for sulphuric acid than soda has; but because sulphate of barytes -is insoluble in water. It therefore falls down, and of course the -sulphuric acid is withdrawn from the soda. But if we add to a solution -of sulphate of soda as much potash as will saturate all the sulphuric -acid, no such decomposition will take place; at least, we have no -evidence that it does. Both the alkalies, in this case, will unite to -the acid and form a triple compound, consisting of potash, sulphuric -acid, and soda. Let us now concentrate the solution by evaporation, -and crystals of sulphate of potash will fall down. The reason is, that -sulphate of potash is not nearly so soluble in water as sulphate of -soda. Hence it separates; not because sulphuric acid has a greater -affinity for potash than for soda, but because sulphate of potash is a -much less soluble salt than sulphate of soda. - -This mode of reasoning of Berthollet is plausible, but not convincing: -it is merely an _argumentum ad ignorantiam_. We can only prove the -decomposition by separating the salts from each other, and this can -only be done by their difference of solubility. But cases occur in -which we can judge that decomposition has taken place from some other -phenomena than precipitation. For example, _nitrate of copper_ is a -_blue_ salt, while _muriate of copper_ is _green_. If into a solution -of nitrate of copper we pour muriatic acid, no precipitation appears, -but the colour changes from blue to green. Is not this an evidence that -the muriatic acid has displaced the nitric, and that the salt held in -solution is not nitrate of copper, as it was at first, but muriate of -copper? - -Berthollet accounts for all decompositions which take place when a -third body is added, either by insolubility or by _elasticity_: as, for -example, when sulphuric acid is poured into a solution of carbonate -of ammonia, the carbonic acid all flies off, in consequence of its -elasticity, and the sulphuric acid combines with the ammonia in its -place. I confess that this explanation, of the reason why the carbonic -acid flies off, appears to me very defective. The ammonia and carbonic -acid are united by a force quite sufficient to overcome the elasticity -of the carbonic acid. Accordingly, it exhibits no tendency to escape. -Now, why should the elasticity of the acid cause it to escape when -sulphuric acid is added? It certainly could not do so, unless it has -weakened the affinity by which it is kept united to the ammonia. Now -this is the very point for which Bergman contends. The subject will -claim our attention afterwards, when we come to the electro-chemical -discoveries, which distinguished the first ten years of the present -century. - -Another opinion supported by Berthollet in his Chemical Statics is, -that quantity may be made to overcome force; or, in other words, that -it we mix a great quantity of a substance which has a weaker affinity -with a small quantity of a substance which has a stronger affinity, the -body having the weaker affinity will be able to overcome the other, and -combine with a third body in place of it. He gave a number of instances -of this; particularly, he showed that a large quantity of potash, -when mixed with a small quantity of sulphate of barytes, is able to -deprive the barytes of a portion of its sulphuric acid. In this way he -accounted for the decomposition of the common salt, by carbonate of -lime in the soda lakes in Egypt; and the decomposition of the same -salt by iron, as noticed by Scheele. - -I must acknowledge myself not quite satisfied with Berthollet's -reasoning on this subject. No doubt if two atoms of a body having a -weaker affinity, and one atom of a body having a stronger affinity, -were placed at equal distances from an atom of a third body, the -force of the two atoms might overcome that of the one atom. And it is -possible that such cases may occasionally occur: but such a balance -of distances must be rare and accidental. I cannot but think that all -the cases adduced by Berthollet are of a complicated nature, and admit -of an explanation independent of the efficacy of mass. And at any -rate, abundance of instances might be stated, in which mass appears to -have no preponderating effect whatever. Chemical decomposition is a -phenomenon of so complicated a nature, that it is more than doubtful -whether we are yet in possession of data sufficient to enable us to -analyze the process with accuracy. - -Another opinion brought forward by Berthollet in his work was of a -startling nature, and occasioned a controversy between him and Proust -which was carried on for some years with great spirit, but with perfect -decorum and good manners on both sides. Berthollet affirmed that bodies -were capable of uniting with each other in all possible proportions, -and that there is no such thing as a definite compound, unless it -has been produced by some accidental circumstances, as insolubility, -volatility, &c. Thus every metal is capable of uniting with all -possible doses of oxygen. So that instead of one or two oxides of -every metal, an infinite number of oxides of each metal exist. Proust -affirmed that all compounds are definite. Iron, says he, unites with -oxygen only in two proportions; we have either a compound of 3·5 iron -and 1 oxygen, or of 3·5 iron and 1·5 oxygen. The first constitutes -the _black_, and the second the _red_ oxide of iron; and beside these -there is no other. Every one is now satisfied that Proust's view of -the subject was correct, and Berthollet's erroneous. But a better -opportunity will occur hereafter to explain this subject, or at least -to give the information respecting it which we at present possess. - -Berthollet in this book points out the quantity of each base necessary -to neutralize a given weight of acid, and he considers the strength -of affinity as inversely that quantity. Now of all the bases known -when Berthollet wrote, ammonia is capable of saturating the greatest -quantity of acid. Hence he considered its affinity for acids as -stronger than that of any other base. Barytes, on the contrary, -saturates the smallest quantity of acid; therefore its affinity for -acids is smallest. Now ammonia is separated from acids by all the -other bases; while there is not one capable of separating barytes. It -is surprising that the notoriety of this fact did not induce him to -hesitate, before he came to so problematical a conclusion. Mr. Kirwan -had already considered the force of affinity as directly proportional -to the quantity of base necessary to saturate a given weight of acid. -When we consider the subject metaphysically, Berthollet's opinion is -most plausible; for it is surely natural to consider that body as the -strongest which produces the greatest effect. Now when we deprive an -acid of its properties, or neutralize it by adding a base, one would -be disposed to consider that base as acting with most energy, which -with the smallest quantity of matter is capable of producing a given -effect. This was the way that Berthollet reasoned. But if we attend -to the power which one base has of displacing another, we shall find -it very nearly proportional to the weight of it necessary to saturate -a given weight of acid; or, at least those bases act most powerfully -in displacing others of which the greatest quantity is necessary to -saturate a given weight of acid. Kirwan's opinion, therefore, was more -conformable to the order of decomposition. These two opposite views of -the subject show clearly that neither Kirwan nor Berthollet had the -smallest conception of the atomic theory; and, consequently, that the -allegation of Mr. Higgens, that he had explained the atomic theory -in his book on phlogiston, published in the year 1789, was not well -founded. Whether Berthollet had read that book I do not know, but there -can be no doubt that it was perused by Kirwan; who, however, did not -receive from it the smallest notions respecting the atomic theory. Had -he imbibed any such notions, he never would have considered chemical -affinity as capable of being measured by the weight of base capable of -neutralizing a given weight of acid. - -Berthollet was not only a man of great energy of character, but of -the most liberal feelings and benevolence. The only exception to this -is his treatment of M. Clement. This gentleman, in company with M. -Desormes, had examined the carbonic oxide of Priestley, and had shown -as Cruikshanks had done before them, that it is a compound of carbon -and oxygen, and that it contains no hydrogen whatever. Berthollet -examined the same gas, and he published a paper to prove that it was -a triple compound of oxygen, carbon, and hydrogen. This occasioned a -controversy, which chemists have finally determined in favour of the -opinion of Clement and Desormes. Berthollet, during this discussion, -did not on every occasion treat his opponents with his accustomed -temper and liberality; and ever after he opposed all attempts on the -part of Clement to be admitted a member of the Institute. Whether -there was any other reason for this conduct on the part of Berthollet, -besides difference of opinion respecting the composition of carbonic -oxide, I do not know: nor would it be right to condemn him without a -more exact knowledge of all the circumstances than I can pretend to. - -Antoine François de Fourcroy, was born at Paris on the 15th of June, -1755. His family had long resided in the capital, and several of his -ancestors had distinguished themselves at the bar. But the branch from -which he sprung had gradually sunk into poverty. His father exercised -in Paris the trade of an apothecary, in consequence of a charge -which he held in the house of the Duke of Orleans. The corporation -of apothecaries having obtained the general suppression of all such -charges, M. de Fourcroy, the father, was obliged to renounce his mode -of livelihood; and his son grew up in the midst of the poverty produced -by the monopoly of the privileged bodies in Paris. He felt this -situation the more keenly, because he possessed from nature an extreme -sensibility of temper. When he lost his mother, at the age of seven -years, he attempted to throw himself into her grave. The care of an -elder sister preserved him with difficulty till he reached the age at -which it was usual to be sent to college. There he was unlucky enough -to meet with a brutal master, who conceived an aversion for him and -treated him with cruelty: the consequence, was, a dislike to study; and -he quitted the college at the age of fourteen, somewhat less informed -than when he went to it. - -His poverty now was such that he was obliged to endeavour to support -himself by becoming writing-master. He had even some thoughts of going -on the stage; but was prevented by the hisses bestowed on a friend -of his who had unadvisedly entered upon that perilous career, and was -treated in consequence without mercy by the audience. While uncertain -what plan to follow, the advice of Viq. d'Azyr induced him to commence -the study of medicine. - -This great anatomist was an acquaintance of M. de Fourcroy, the father. -Struck with the appearance of his son, and the courage with which he -struggled with his bad fortune, he conceived an affection for him, and -promised to direct his studies, and even to assist him during their -progress. The study of medicine to a man in his situation was by no -means an easy task. He was obliged to lodge in a garret, so low in -the roof that he could only stand upright in the middle of the room. -Beside him lodged a water-carrier with twelve children. Fourcroy acted -as physician to this numerous family, and in recompence was always -supplied with abundance of water. He contrived to support himself by -giving lessons to other students, by facilitating the researches of -richer writers, and by some translations which he sold to a bookseller. -For these he was only half paid; but the conscientious bookseller -offered thirty years afterwards to make up the deficiency, when his -creditor was become director-general of public instruction. - -Fourcroy studied with so much zeal and ardour that he soon became well -acquainted with the subject of medicine. But this was not sufficient. -It was necessary to get a doctor's degree, and all the expenses at that -time amounted to 250_l._ An old physician, Dr. Diest, had left funds -to the faculty to give a gratuitous degree and licence, once every two -years, to the poor student who should best deserve them. Fourcroy was -the most conspicuous student at that time in Paris. He would therefore -have reaped the benefit of this benevolent institution had it not -been for the unlucky situation in which he was placed. There happened -to exist a quarrel between the faculty charged with the education of -medical men and the granting of degrees, and a society recently formed -by government for the improvement of the medical art. This dispute had -been carried to a great length, and had attracted the attention of all -the frivolous and idle inhabitants of Paris. Viq. d'Azyr was secretary -to the society, and of course one of its most active champions; and -was, in consequence, particularly obnoxious to the faculty of medicine -at Paris. Fourcroy was unluckily the acknowledged _protégée_ of this -eminent anatomist. This was sufficient to induce the faculty of -medicine to refuse him a gratuitous degree. He would have been excluded -in consequence of this from entering on the career of a practitioner, -had not the society, enraged at this treatment, and influenced by -a violent party spirit, formed a subscription, and contributed the -necessary expenses. - -It was no longer possible to refuse M. de Fourcroy the degree of -doctor, when he was thus enabled to pay for it. But above the simple -degree of doctor there was another, entitled _docteur regent_, which -depended entirely on the votes of the faculty. It was unanimously -refused to M. de Fourcroy. This refusal put it out of his power -afterwards to commence teacher in the medical school, and gave the -medical faculty the melancholy satisfaction of not being able to enroll -among their number the most celebrated professor in Paris. This violent -and unjust conduct of the faculty of medicine made a deep impression on -the mind of Fourcroy, and contributed not a little to the subsequent -downfall of that powerful body. - -Fourcroy being thus entitled to practise in Paris, his success depended -entirely on the reputation which he could contrive to establish. -For this purpose he devoted himself to the sciences connected with -medicine, as the shortest and most certain road by which he could -reach his object. His first writings showed no predilection for any -particular branch of science. He wrote upon _chemistry_, _anatomy_, -and _natural history_. He published an Abridgment of the History of -Insects, and a Description of the Bursæ Mucosæ of the Tendons. This -last piece seems to have given him the greatest celebrity; for in -1785 he was admitted, in consequence of it, into the academy as an -anatomist. But the reputation of Bucquet, at that time very high, -gradually drew his particular attention to chemistry, and he retained -this predilection during the rest of his life. - -Bucquet was at that time professor of chemistry in the Medical School -of Paris, and was greatly celebrated and followed on account of his -eloquence, and the elegance of his language. Fourcroy became in the -first place his pupil, and afterwards his particular friend. One -day, when a sudden attack of disease prevented him from lecturing as -usual, he entreated Fourcroy to supply his place. Our young chemist at -first declined, and alleged his ignorance of the method of addressing -a public audience. But, overcome by the persuasions of Bucquet, -he at last consented: and in this, his first essay, he spoke two -hours without disorder or hesitation, and acquitted himself to the -satisfaction of his whole audience. Bucquet soon after substituted him -in his place, and it was in his laboratory and in his class-room that -he first made himself acquainted with chemistry. He was enabled at the -death of Bucquet, in consequence of an advantageous marriage that he -had made, to purchase the apparatus and cabinet of his master; and -although the faculty of medicine would not allow him to succeed to the -chair of Bucquet, they could not prevent him from succeeding to his -reputation. - -There was a kind of college which had been established in the Jardin -du Roi, which at that time was under the superintendence of Buffon, -and Macquer was the professor of chemistry in this institution. On -the death of this chemist, in 1784, both Berthollet and Fourcroy -offered themselves as candidates for the vacant chair. The voice of -the public was so loud in favour of Fourcroy, that he was appointed -to the situation in spite of the high character of his antagonist and -the political influence which was exerted in his favour. He filled -this chair for twenty-five years, with a reputation for eloquence -continually on the increase. Such were the crowds, both of men and -women, who flocked to hear him, that it was twice necessary to enlarge -the size of the lecture room. - -After the revolution had made some progress, he was named a member of -the National Convention in the autumn of the memorable year 1793. It -was during the reign of terror, when the Convention itself, and with -it all France, was under the absolute dominion of one of the most -sanguinary monsters that ever existed: it was almost equally dangerous -for the members of the Convention to remain silent, or to take an -active part in the business of that assembly. Fourcroy never opened his -mouth in the Convention till after the death of Robespierre; at this -period he had influence enough to save the lives of some men of merit: -among others, of Darcet, who did not know the obligation under which he -lay to him till long after; at last his own life was threatened, and -his influence, of course, completely annihilated. - -It was during this unfortunate and disgraceful period, that many -eminent men lost their lives; among others, Lavoisier; and Fourcroy is -accused of having contributed to the death of this illustrious chemist: -but Cuvier entirely acquits him of this atrocious charge, and assures -us that it was urged against him merely out of envy at his subsequent -elevation. "If in the rigorous researches which we have made," says -Cuvier in his Eloge of Fourcroy, "we had found the smallest proof of -an atrocity so horrible, no human power could have induced us to sully -our mouths with his Eloge, or to have pronounced it within the walls of -this temple, which ought to be no less sacred to honour than to genius." - -Fourcroy began to acquire influence only after the 9th Thermidor, when -the nation was wearied with destruction, and when efforts were making -to restore those monuments of science, and those public institutions -for education, which during the wantonness and folly of the revolution -had been overturned and destroyed. Fourcroy was particularly active -in this renovation, and it was to him, chiefly, that the schools -established in France for the education of youth are to be ascribed. -The Convention had destroyed all the colleges, universities, and -academies throughout France. The effects of this absurd abolition soon -became visible; the army stood in need of surgeons and physicians, and -there were none educated to supply the vacant places: three new schools -were founded for educating medical men; they were nobly endowed. The -term _schools of medicine_ was proscribed as too aristocratical; -they were distinguished by the ridiculous appellation of _schools of -health_. The _Polytechnic School_ was next instituted, as a kind of -preparation for the exercise of the military profession, where young -men could be instructed in mathematics and natural philosophy, to make -them fit for entering the schools of the artillery, of engineers, -and of the marine. The _Central Schools_ was another institution for -which France was indebted to the efforts of Fourcroy. The idea was -good, though it was very imperfectly executed. It was to establish a -kind of university in every department, for which the young men were -to be prepared by a sufficient number of inferior schools scattered -through the department. But unfortunately these inferior schools were -never properly established or endowed; and even the central schools -themselves were never supplied with proper masters. Indeed, it was -found impossible to furnish such a number of masters at once. On that -account, an institution was established in Paris, called the _Normal -School_, for the express purpose of educating a sufficient number of -masters to supply the different central schools. - -Fourcroy, either as a member of the Convention or of the _Council of -the Ancients_, took an active part in all these institutions, as far -as regarded the plan and the establishment. He was equally concerned -in the establishment of the Institute and of the _Musée d'Histoire -Naturelle_. This last was endowed with the utmost liberality, and -Fourcroy was one of the first professors; as he was also in the School -of Medicine and the Polytechnic School. He was equally concerned in the -restoration of the university, which constituted one of the most useful -parts of Bonaparte's reign. - -The violent exertions which he made in the numerous situations which -he filled, and the prodigious activity which he displayed, gradually -undermined his constitution. He himself was sensible of his approaching -death, and announced it to his friends as an event which would -speedily take place. On the 16th of December, 1809, after signing some -despatches, he suddenly cried out, _Je suis mort_ (_I am dead_), and -dropped lifeless on the ground. - -He was twice married: first to Mademoiselle Bettinger, by whom he had -two children, a son and a daughter, who survived him. He was married -for the second time to Madame Belleville, the widow of Vailly, by whom -he had no family. He left but little fortune behind him; and two maiden -sisters, who lived with him, depended afterwards for their support on -his friend M. Vauquelin. - -Notwithstanding the vast quantity of papers which he published, it -will be admitted, without dispute, that the prodigious reputation -which he enjoyed during his lifetime was more owing to his eloquence -than to his eminence as a chemist--though even as a chemist he was -far above mediocrity. He must have possessed an uncommon facility -of writing. Five successive editions of his System of Chemistry -appeared, each of them gradually increasing in size and value: the -first being in two volumes and the last in ten. This last edition -he wrote in sixteen months: it contains much valuable information, -and doubtless contributed considerably to the general diffusion of -chemical knowledge. Its style is perhaps too diffuse, and the spirit -of generalizing from particular, and often ill-authenticated facts, is -carried to a vicious length. Perhaps the best of all his productions is -his Philosophy of Chemistry. It is remarkable for its conciseness, its -perspicuity, and the neatness of its arrangement. - -Besides these works, and the periodical publication entitled "Le -Médecin éclairé," of which he was the editor, there are above one -hundred and sixty papers on chemical subjects, with his name attached -to them, which appeared in the Memoirs of the Academy and of the -Institute; in the Annales de Chimie, or the Annales de Musée d'Histoire -Naturelle; of which last work he was the original projector. Many of -these papers contained analyses both animal, vegetable, and mineral, -of very considerable value. In most of them, the name of Vauquelin is -associated with his own as the author; and the general opinion is, -that the experiments were all made by Vauquelin; but that the papers -themselves were drawn up by Fourcroy. - -It would serve little purpose to go over this long list of papers; -because, though they contributed essentially to the progress of -chemistry, yet they exhibit but few of those striking discoveries, -which at once alter the face of the science, by throwing a flood of -light on every thing around them. I shall merely notice a few of what I -consider as his best papers. - -1. He ascertained that the most common biliary calculi are composed of -a substance similar to spermaceti. This substance, in consequence of -a subsequent discovery which he made during the removal of the dead -bodies from the burial-ground of the Innocents at Paris; namely, that -these bodies are converted into a fatty matter, he called _adipocire_. -It has since been distinguished by the name of _cholestine_; and has -been shown to possess properties different from those of adipocire and -spermaceti. - -2. It is to him that we are indebted for the first knowledge of the -fact, that the salts of magnesia and ammonia have the property of -uniting together, and forming double salts. - -3. His dissertation on the sulphate of mercury contains some good -observations. The same remark applies to his paper on the action of -ammonia on the sulphate, nitrate, and muriate of mercury. He first -described the double salts which are formed. - -4. The analysis of urine would have been valuable had not almost -all the facts contained in it been anticipated by a paper of Dr. -Wollaston, published in the Philosophical Transactions. It is to him -that we are indebted for almost all the additions to our knowledge -of calculi since the publication of Scheele's original paper on the -subject. - -5. I may mention the process of Fourcroy and Vauquelin for obtaining -pure barytes, by exposing nitrate of barytes to a red heat, as a -good one. They discovered the existence of phosphate of magnesia in -bones, of phosphorus in the brain and in the milts of fishes, and of a -considerable quantity of saccharine matter in the bulb of the common -onion; which, by undergoing a kind of spontaneous fermentation was -converted into _manna_. - -In these, and many other similar discoveries, which I think it -unnecessary to notice, we do not know what fell to the share of -Fourcroy and what to Vauquelin; but there is one merit at least to -which Fourcroy is certainly entitled, and it is no small one: he formed -and brought forward Vauquelin, and proved to him, ever after, a most -steady and indefatigable friend. This is bestowing no small panegyric -on his character; for it would have been impossible to have retained -such a friend through all the horrors of the French revolution, if his -own qualities had not been such as to merit so steady an attachment. - -Louis Bernard Guyton de Morveau was born at Dijon on the 4th of -January, 1737. His father, Anthony Guyton, was professor of civil -law in the University of Dijon, and descended from an ancient and -respectable family. At the age of seven he showed an uncommon -mechanical turn: being with his father at a small village near Dijon, -he there happened to meet a public officer returning from a sale, -whence he had brought back a clock that had remained unsold on account -of its very bad condition. Morveau supplicated his father to buy it. -The purchase was made for six francs. Young Morveau took it to pieces -and cleaned it, supplied some parts that were wanting, and put it up -again without any assistance. In 1799 this very clock was resold at a -higher price, together with the estate and house in which it had been -originally placed; having during the whole of that time continued to go -in the most satisfactory manner. When only eight years of age, he took -his mother's watch to pieces, cleaned it, and put it up again to the -satisfaction of all parties. - -After finishing his preliminary studies in his father's house, he went -to college, and terminated his attendance on it at the age of sixteen. -About this time he was instructed in botany by M. Michault, a friend -of his father, and a naturalist of some eminence. He now commenced law -student in the University of Dijon; and, after three years of intense -application, he went to Paris to acquire a knowledge of the practice of -the law. - -While in Paris, he not only attended to law, but cultivated at the same -time several branches of polite literature. In 1756 he paid a visit -to Voltaire, at Ferney. This seems to have inspired him with a love -of poetry, particularly of the descriptive and satiric kind. About a -year afterwards, when only twenty, he published a poem called "Le Rat -Iconoclaste, ou le Jesuite croquée." It was intended to throw ridicule -on a well-known anecdote of the day, and to assist in blowing the fire -that already threatened destruction to the obnoxious order of Jesuits. -The adventure alluded to was this: Some nuns, who felt a strong -predilection for a Jesuit, their spiritual director, were engaged in -their accustomed Christmas occupation of modelling a representation of -a religious mystery, decorated with several small statues representing -the holy personages connected with the subject, and among them that -of the ghostly father; but, to mark their favourite, his statue was -made of loaf sugar. The following day was destined for the triumph of -the Jesuit: but, meanwhile, a rat had devoured the valuable puppet. -The poem is written after the agreeable manner of the celebrated poem, -"Ververt." - -At the age of twenty-four he had already pleaded several important -causes at the bar, when the office of advocate-general, at the -parliament of Dijon, was advertised for sale. At that time all public -situations, however important, were sold to the best bidder. His father -having ascertained that this place would be acceptable to his son, -purchased it for forty thousand francs. The reputation of the young -advocate, and his engaging manners, facilitated the bargain. - -In 1764 he was admitted an honorary member of the Academy of Sciences, -Arts, and Belles Lettres, of Dijon. Two months after, he presented to -the assembled chamber of the parliament of Burgundy, a memoir on public -instruction, with a plan for a college, on the principles detailed in -his work. The encomiums which every public journal of the time passed -on this production, and the flattering letters which he received, were -unequivocal proofs of its value. In this memoir he endeavoured to -prove that man is _bad_ or _good_, according to the education which he -has received. This doctrine was contrary to the creed of Diderot, who -affirmed, in his Essay on the Life of Seneca, that nature makes wicked -persons, and that the best institutions cannot render them good. But -this mischievous opinion was successfully refuted by Morveau, in a -letter to an anonymous friend. - -The exact sciences were so ill taught, and lamely cultivated at Dijon, -during the time of his university education, that after his admission -into the academy his notions on mechanics and natural philosophy were -scanty and inaccurate. Dr. Chardenon was in the habit of reading -memoirs on chemical subjects; and on one occasion Morveau thought -it necessary to hazard some remarks which were ill received by the -doctor, who sneeringly told him that having obtained such success in -literature, he had better rest satisfied with the reputation so justly -acquired, and leave chemistry to those who knew more of the matter. - -Provoked at this violent remark, he resolved upon taking an honourable -revenge. He therefore applied himself to the study of Macquer's -Theoretical and Practical Chemistry, and of the Manual of Chemistry -which Beaumé had just published. To the last chemist he also sent an -extensive order for chemical preparations and utensils, with a view -of forming a small laboratory near his office. He began by repeating -many of Beaumé's experiments, and then trying his inexperienced hand -at original researches. He soon found himself strong enough to attack -the doctor. The latter had just been reading a memoir on the analysis -of different kinds of oil; and Morveau combated some of his opinions -with so much skill and sagacity, as astonished every one present. After -the meeting, Dr. Chardenon addressed him thus: "You are born to be an -honour to chemistry. So much knowledge could only have been gained by -genius united with perseverance. Follow your new pursuit, and confer -with me in your difficulties." - -But this new pursuit did not prevent Morveau from continuing to -cultivate literature with success. He wrote an _Eloge_ of Charles V. of -France, surnamed _the Wise_, which had been given out as the subject -of a prize, by the academy. A few months afterwards, at the opening of -the session of parliament, he delivered a discourse on the actual state -of jurisprudence; on which subject, three years after, he composed a -more extensive and complete work. No code of laws demanded reform more -urgently than those of France, and none saw more clearly the necessity -of such a reformation. - -About this time a young gentleman of Dijon had taken into his house an -adept, who offered, upon being furnished with the requisite materials, -to produce gold in abundance; but, after six months of expensive -and tedious operations (during which period the roguish pretender -had secretly distilled many oils, &c., which he disposed of for his -own profit), the gentleman beginning to doubt the sincerity of his -instructer, dismissed him from his service and sold the whole of his -apparatus and materials to Morveau for a trifling sum. - -Soon after he repaired to Paris, to visit the scientific establishments -of that metropolis, and to purchase preparations and apparatus which he -still wanted to enable him to pursue with effect his favourite study. -For this purpose he applied to Beaumé, then one of the most conspicuous -of the French chemists. Pleased with his ardour, Beaumé inquired what -courses of chemistry he had attended. "None," was the answer.--"How -then could you have learned to make experiments, and above all, how -could you have acquired the requisite dexterity?"--"Practice," replied -the young chemist, "has been my master; melted crucibles and broken -retorts my tutors."--"In that case," said Beaumé, "you have not -learned, you have invented." - -About this time Dr. Chardenon read a paper before the Dijon Academy -on the causes of the augmentation of weight which metals experience -when calcined. He combated the different explanations which had been -already advanced, and then proceeded to show that it might be accounted -for in a satisfactory manner by the _abstraction_ of phlogiston. -This drew the attention of Morveau to the subject: he made a set of -experiments a few months afterwards, and read a paper on the _phenomena -of the air during combustion_. It was soon after that he made a set of -experiments on the time taken by different substances to absorb or emit -a given quantity of heat. These experiments, if properly followed out, -would have led to the discovery of _specific heat_; but in his hands -they seem to have been unproductive. - -In the year 1772 he published a collection of scientific essays under -the title of "Digressions Académiques." The memoirs on _phlogiston_, -_crystallization_, and _solution_, found in this book deserve -particular attention, and show the superiority of Morveau over most of -the chemists of the time. - -About this time an event happened which deserves to be stated. It had -been customary in one of the churches of Dijon to bury considerable -numbers of dead bodies. From these an infectious exhalation had -proceeded, which had brought on a malignant disorder, and threatened -the inhabitants of Dijon with something like the plague. All attempts -to put an end to this infectious matter had failed, when Morveau tried -the following method with complete success: A mixture of common salt -and sulphuric acid in a wide-mouthed vessel was put upon chafing-dishes -in various parts of the church. The doors and windows were closed and -left in this state for twenty-four hours. They were then thrown open, -and the chafing-dishes with the mixtures removed. Every remains of the -bad smell was gone, and the church was rendered quite clean and free -from infection. The same process was tried soon after in the prisons -of Dijon, and with the same success. Afterwards chlorine gas was -substituted for muriatic acid gas, and found still more efficacious. -The present practice is to employ chloride of lime, or chloride of -soda, for the purpose of fumigating infected apartments, and the -process is found still more effectual than the muriatic acid gas, as -originally employed by Morveau. The nitric acid fumes, proposed by Dr. -Carmichael Smith, are also efficacious, but the application of them -is much more troublesome and more expensive than of chloride of lime, -which costs very little. - -In the year 1774 it occurred to Morveau, that a course of lectures on -chemistry, delivered in his native city, might be useful. Application -being made to the proper authorities, the permission was obtained, -and the necessary funds for supplying a laboratory granted. These -lectures were begun on the 29th of April, 1776, and seem to have been -of the very best kind. Every thing was stated with great clearness, -and illustrated by a sufficient number of experiments. His fame now -began to extend, and his name to be known to men of science in every -part of Europe; and, in consequence, he began to experience the fate of -almost all eminent men--to be exposed to the attacks of the malignant -and the envious. The experiments which he exhibited to determine the -properties of _carbonic acid gas_ drew upon him the animadversions of -several medical men, who affirmed that this gas was nothing else than a -peculiar state of sulphuric acid. Morveau answered these animadversions -in two pamphlets, and completely refuted them. - -About this time he got metallic conductors erected on the house of the -Academy at Dijon. On this account he was attacked violently for his -presumption in disarming the hand of the Supreme Being. A multitude of -fanatics assembled to pull down the conductors, and they would probably -have done much mischief, had it not been for the address of M. Maret, -the secretary, who assured them that the astonishing virtue of the -apparatus resided in the gilded point, which had purposely been sent -from Rome by the holy father! Will it excite any surprise, that within -less than twenty years after this the mass of the French people not -only renounced the Christian religion, and the spiritual dominion of -the pope, but declared themselves atheists! - -In 1777 Morveau published the first volume of a course of chemistry, -which was afterwards followed by three other volumes, and is known -by the name of "Elémens de Chimie de l'Académie de Dijon." This book -was received with universal approbation, and must have contributed -very much to increase the value of his lectures. Indeed, a text-book -is essential towards a successful course of lectures: it puts it in -the power of the students to understand the lecture if they be at -the requisite pains; and gives them a means of clearing up their -difficulties, when any such occur. I do not hesitate to say, that a -course of chemical lectures is twice as valuable when the students are -furnished with a good text-book, as when they are left to interpret the -lectures by their own unassisted exertions. - -Soon after he undertook the establishment of a manufacture of saltpetre -upon a large scale. For this he received the thanks of M. Necker, -who was at that time minister of finance, in the name of the King of -France. This manufactory he afterwards gave up to M. Courtois, whose -son still carries it on, and is advantageously known to the public as -the discoverer of _iodine_. - -His next object was to make a collection of minerals, and to make -himself acquainted with the science of mineralogy. All this was soon -accomplished. In 1777 he was charged to examine the slate-quarries -and the coal-mines of Burgundy, for which purpose he performed a -mineralogical tour through the province. In 1779 he discovered a -lead-mine in that country, and a few years afterwards, when the -attention of chemists had been drawn to sulphate of barytes and its -base, by the Swedish chemists, he sought for it in Burgundy, and found -it in considerable quantity at Thôte. This enabled him to draw up a -description of the mineral, and to determine the characters of the -base, to which he gave the name of _barote_; afterwards altered to -that of barytes. This paper was published in the third volume of the -Memoirs of the Dijon Academy. In this paper he describes his method of -decomposing sulphate of barytes, by heating it with charcoal--a method -now very frequently followed. - -In the year 1779 he was applied to by Pankouke, who meditated the great -project of the _Encyclopédie Méthodique_, to undertake the chemical -articles in that immense dictionary, and the demand was supported by a -letter from Buffon, whose request he did not think that he could with -propriety refuse. The engagement was signed between them in September, -1780. The first half-volume of the chemical part of this Encyclopédie -did not appear till 1786, and Morveau must have been employed during -the interval in the necessary study and researches. Indeed, it is -obvious, from many of the articles, that he had spent a good deal of -time in experiments of research. - -The state of the chemical nomenclature was at that period peculiarly -barbarous and defective. He found himself stopped at every corner for -want of words to express his meaning. This state of things he resolved -to correct, and accordingly in 1782 published his first essay on a -new chemical nomenclature. No sooner did this essay appear than it -was attacked by almost all the chemists of Paris, and by none more -zealously than by the chemical members of the academy. Undismayed by -the violence of his antagonists, and satisfied with the rectitude of -his views, and the necessity of the reform, he went directly to Paris -to answer the objections in person. He not only succeeded in convincing -his antagonists of the necessity of reform; but a few years afterwards -prevailed upon the most eminent chemical members of the academy, -Lavoisier, Berthollet, and Fourcroy, to unite with him in rendering -the reform still more complete and successful. He drew up a memoir, -exhibiting a plan of a methodical chemical nomenclature, which was read -at a meeting of the Academy of Sciences, in 1787. Morveau, then, was -in reality the author of the new chemical nomenclature, if we except -a few terms, which had been already employed by Lavoisier. Had he -done nothing more for the science than this, it would deservedly have -immortalized his name. For every one must be sensible how much the new -nomenclature contributed to the subsequent rapid extension of chemical -science. - -It was during the repeated conferences held with Lavoisier and the -other two associates that Morveau became satisfied of the truth of -Lavoisier's new doctrine, and that he was induced to abandon the -phlogistic theory. We do not know the methods employed to convert -him. Doubtless both reasoning and experiment were made use of for the -purpose. - -It was during this period that Morveau published a French translation -of the Opuscula of Bergman. A society of friends, under his -encouragement, translated the chemical memoirs of Scheele and many -other foreign books of importance, which by their means were made -known to the men of science in France. - -In 1783, in consequence of a favourable report by Macquer, Morveau -obtained permission to establish a manufactory of carbonate of soda, -the first of the kind ever attempted in France. It was during the -same year that he published his collection of pleadings at the bar, -among which we find his Discours sur la Bonhomie, delivered at the -opening of the sessions at Dijon, with which he took leave of his -fellow-magistrates, surrendering the insignia of office, as he had -determined to quit the profession of the law. - -On the 25th of April, 1784, Morveau, accompanied by President Virly, -ascended from Dijon in a balloon, which he had himself constructed, -and repeated the ascent on the 12th of June following, with a view of -ascertaining the possibility of directing these aerostatic machines, -by an apparatus of his own contrivance. The capacity of the balloon -was 10,498,074 French cubic feet. The effect produced by this bold -undertaking by two of the most distinguished characters in the town was -beyond description. Such ascents were then quite new, and looked upon -with a kind of reverential awe. Though Morveau failed in his attempts -to direct these aerial vessels, yet his method was ingenious and -exceedingly plausible. - -In 1786 Dr. Maret, secretary to the Dijon Academy, having fallen a -victim to an epidemic disease, which he had in vain attempted to -arrest, Morveau was appointed perpetual secretary and chancellor of -the institution. Soon after this the first half-volume of the chemical -part of the Encyclopédie Méthodique made its appearance, and drew the -attention of every person interested in the science of chemistry. No -chemical treatise had hitherto appeared worthy of being compared -to it. The article _Acid_, which occupies a considerable part, is -truely admirable; and whether we consider the historical details, the -completeness of the accounts, the accuracy of the description of the -experiments, or the elegance of the style, constitutes a complete model -of what such a work should be. I may, perhaps, be partial, as it was -from this book that I imbibed my own first notions in chemistry, but -I never perused any book with more delight, and when I compared it -with the best chemical books of the time, whether German, French, or -English, its superiority became still more striking. - -In the article _Acier_, Morveau had come to the very same conclusions, -with respect to the nature of _steel_, as had been come to by -Berthollet, Monge, and Vandermonde, in their celebrated paper on the -subject, just published in the Memoirs of the Academy. His own article -had been printed, though not published, before the appearance of the -Memoir of the Academicians. This induced him to send an explanation to -Berthollet, which was speedily published in the Journal de Physique. - -In September, 1787, he received a visit from Lavoisier, Berthollet, -Fourcroy, Monge, and Vandermonde. Dr. Beddoes, who was travelling -through France at the time, and happened to be in Dijon, joined the -party. The object of the meeting was to discuss several experiments -explanatory of the new doctrine. In 1789 an attempt was made to get -him admitted as a member of the Academy of Sciences; but it failed, -notwithstanding the strenuous exertions of Berthollet and his other -chemical friends. - -The French revolution had now broken out, occasioned by the wants of -the state on the one hand, and the resolute determination of the clergy -and the nobility on the other, not to submit to bear any share in the -public burdens. During the early part of this revolution Morveau took -no part whatever in politics. In 1790, when France was divided into -departments, he was named one of a commission by the National Assembly -for the formation of the department of the Côte d'Or. On the 25th of -August, 1791, he received from the Academy of Sciences the annual -prize of 2000 francs, for the most useful work published in the course -of the year. This was decreed him for his Dictionary of Chemistry, -in the Encyclopédie Méthodique. Aware of the pressing necessities of -the state, Morveau seized the opportunity of showing his desire of -contributing towards its relief, by making a patriotic offering of the -whole amount of his prize. - -When the election of the second Constitutional Assembly took place, -he was nominated a member by the electoral college of his department. -A few months before, his name had appeared among the list of members -proposed by the assembly, for the election of a governor to the -heir-apparent. All this, together with the dignity of solicitor-general -of the department to which he had recently been raised, not permitting -him to continue his chemical lectures at Dijon, of which he had already -delivered fifteen gratuitous courses, he resigned his chair in favour -of Dr. Chaussier, afterwards a distinguished professor at the Faculty -of Medicine of Paris; and, bidding adieu to his native city, proceeded -to Paris. - -On the ever memorable 16th of January, 1793, he voted with the majority -of deputies. He was therefore, in consequence of this vote, a regicide. -During the same year he resigned, in favour of the republic, his -pension of two thousand francs, together with the arrears of that -pension. - -In 1794 he received from government different commissions to act with -the French armies in the Low Countries. Charged with the direction -of a great aerostatic machine for warlike purposes, he superintended -that one in which the chief of the staff of General Jourdan and -himself ascended during the battle of Fleurus, and which so materially -contributed to the success of the French arms on that day. On his -return from his various missions, he received from the three committees -of the executive government an invitation to co-operate with several -learned men in the instruction of the _central schools_, and was named -professor of chemistry at the _Ecole Centrale des Travaux publiques_, -since better known under the name of the _Polytechnic School_. - -In 1795 he was re-elected member of the Council of Five Hundred, by -the electoral assemblies of Sarthe and Ile et Vilaine. The executive -government, at this time, decreed the formation of the National -Institute, and named him one of the forty-eight members chosen by -government to form the nucleus of that scientific body. - -In 1797 he resigned all his public situations, and once more attached -himself exclusively to science and to the establishments for public -instruction. In 1798 he was appointed a provisional director of the -Polytechnic School, to supply the place of Monge, who was then in -Egypt. He continued to exercise its duties during eighteen months, -to the complete satisfaction of every person connected with that -establishment. With much delicacy and disinterestedness, he declined -accepting the salary of 2000 francs attached to this situation, which -he thought belonged to the proper director, though absent from his -duties. - -In 1799 Bonaparte appointed him one of the administrators-general -of the Mint; and the year following he was made director of the -Polytechnic School. In 1803 he received the cross of the Legion of -Honour, then recently instituted; and in 1805 was made an officer -of the same order. These honours were intended as a reward for the -advantage which had accrued from the mineral acid fumigations which -he had first suggested. In 1811 he was created a baron of the French -empire. - -After having taught in the _Ecole Polytechnique_ for sixteen years, he -obtained leave, on applying to the proper authorities, to withdraw into -the retired station of private life, crowned with years and reputation, -and followed with the blessings of the numerous pupils whom he had -brought up in the career of science. In this situation he continued -about three years, during which he witnessed the downfall of Bonaparte, -and the restoration of the Bourbons. On the 21st of December, 1815, he -was seized with a total exhaustion of strength; and, after an illness -of three days only, expired in the arms of his disconsolate wife, and a -few trusty friends, having nearly completed the eightieth year of his -age. On the 3d of January, 1816, his remains were followed to the grave -by the members of the Institute, and many other distinguished men: and -Berthollet, one of his colleagues, pronounced a short but impressive -funeral oration on his departed friend. - -Morveau had married Madame Picardet, the widow of a Dijon academician, -who had distinguished himself by numerous scientific translations from -the Swedish, German, and English languages. The marriage took place -after they were both advanced in life, and he left no children behind -him. His publications on chemical subjects were exceedingly numerous, -and he contributed as much as any of his contemporaries to the -extension of the science; but as he was not the author of any striking -chemical discoveries, it would be tedious to give a catalogue of his -numerous productions which were scattered through the Dijon Memoirs, -the Journal de Physique, and the Annales de Chimie. - - - - -CHAPTER IV. - -PROGRESS OF ANALYTICAL CHEMISTRY. - - -Analysis, or the art of determining the constituents of which every -compound is composed, constitutes the essence of chemistry: it was -therefore attempted as soon as the science put on any thing like a -systematic form. At first, with very little success; but as knowledge -became more and more general, chemists became more expert, and -something like regular analysis began to appear. Thus, Brandt showed -that _white vitriol_ is a compound of sulphuric acid and oxide of -zinc; and Margraaf, that _selenite_ or _gypsum_ is a compound of -sulphuric acid and lime. Dr. Black made analyses of several of the -salts of magnesia, so far at least as to determine the nature of the -constituents. For hardly any attempt was made in that early period of -the art to determine the weight of the respective constituents. The -first person who attempted to lay down rules for the regular analysis -of minerals, and to reduce these rules to practice, was Bergman. -This he did in his papers "De Docimasia Minerarum Humida," "De Terra -Gemmarum," and "De Terra Tourmalini," published between the years 1777 -and 1780. - -To analyze a mineral, or to separate it into its constituent parts, it -is necessary in the first place, to be able to dissolve it in an acid. -Bergman showed that most minerals become soluble in muriatic acid if -they be reduced to a very fine powder, and then heated to redness, or -fused with an alkaline carbonate. After obtaining a solution in this -way he pointed out methods by which the different constituents may be -separated one after another, and their relative quantities determined. -The fusion with an alkaline carbonate required a strong red heat. -An earthenware crucible could not be employed, because at a fusing -temperature it would be corroded by the alkaline carbonate, and thus -the mineral under analysis would be contaminated by the addition of a -quantity of foreign matter. Bergman employed an iron crucible. This -effectually prevented the addition of any earthy matter. But at a red -heat the iron crucible itself is apt to be corroded by the action of -the alkali, and thus the mineral under analysis becomes contaminated -with a quantity of that metal. This iron might easily be separated -again by known methods, and would therefore be of comparatively small -consequence, provided we were sure that the mineral under examination -contained no iron; but when that happens (and it is a very frequent -occurrence), an error is occasioned which we cannot obviate. Klaproth -made a vast improvement in the art of analysis, by substituting -crucibles of fine silver for the iron crucibles of Bergman. The only -difficulty attending their use was, that they were apt to melt unless -great caution was used in heating them. Dr. Wollaston introduced -crucibles of platinum about the beginning of the present century. It -is from that period that we may date the commencement of accurate -analyzing. - -Bergman's processes, as might have been expected, were rude and -imperfect. It was Klaproth who first systematized chemical analysis and -brought the art to such a state, that the processes followed could -be imitated by others with nearly the same results, thus offering a -guarantee for the accuracy of the process. - -Martin Henry Klaproth, to whom chemistry lies under so many and such -deep obligations, was born at Wernigerode, on the 1st of December, -1743. His father had the misfortune to lose his whole goods by a great -fire, on the 30th of June, 1751, so that he was able to do little -or nothing for the education of his children. Martin was the second -of three brothers, the eldest of whom became a clergyman, and the -youngest private secretary at war, and keeper of the archives of the -cabinet of Berlin. Martin survived both his brothers. He procured such -meagre instruction in the Latin language as the school of Wernigerode -afforded, and he was obliged to procure his small school-fees by -singing as one of the church choir. It was at first his intention to -study theology; but the unmerited hard treatment which he met with -at school so disinclined him to study, that he determined, in his -sixteenth year, to learn the trade of an apothecary. Five years which -he was forced to spend as an apprentice, and two as an assistant in -the public laboratory in Quedlinburg, furnished him with but little -scientific information, and gave him little else than a certain -mechanical adroitness in the most common pharmaceutical preparations. - -He always regarded as the epoch of his scientific instruction, the -two years which he spent in the public laboratory at Hanover, from -Easter 1766, till the same time in 1768. It was there that he first -met with some chemical books of merit, especially those of Spielman, -and Cartheuser, in which a higher scientific spirit already breathed. -He was now anxious to go to Berlin, of which he had formed a high idea -from the works of Pott, Henkel, Rose, and Margraaf. An opportunity -presenting itself about Easter, 1768, he was placed as assistant in the -laboratory of Wendland, at the sign of the Golden Angel, in the Street -of the Moors. Here he employed all the time which a conscientious -discharge of the duties of his station left him, in completing his own -scientific education. And as he considered a profounder acquaintance -with the ancient languages, than he had been able to pick up at -the school of Wernigerode, indispensable for a complete scientific -education, he applied himself with great zeal to the study of the -Greek and Latin languages, and was assisted in his studies by Mr. -Poppelbourn, at that time a preacher. - -About Michaelmas, 1770, he went to Dantzig, as assistant in the public -laboratory: but in March of the following year he returned to Berlin, -as assistant in the office of the elder Valentine Rose, who was one -of the most distinguished chemists of his day. But this connexion did -not continue long; for Rose died in 1771. On his deathbed he requested -Klaproth to undertake the superintendence of his office. Klaproth not -only superintended this office for nine years with the most exemplary -fidelity and conscientiousness, but undertook the education of the -two sons of Rose, as if he had been their father. The younger died -before reaching the age of manhood: the elder became his intimate -friend, and the associate of all his scientific researches. For several -years before the death of Rose (which happened in 1808) they wrought -together, and Klaproth was seldom satisfied with the results of his -experiments till they had been repeated by Rose. - -In the year 1780 Klaproth went through his trials for the office of -apothecary with distinguished applause. His thesis, "On Phosphorus and -distilled Waters," was printed in the Berlin Miscellanies for 1782. -Soon after this, Klaproth bought what had formerly been the Flemming -laboratory in Spandau-street: and he married Sophia Christiana Lekman, -with whom he lived till 1803 (when she died) in a happy state. They had -three daughters and a son, who survived their parents. He continued -in possession of this laboratory, in which he had arranged a small -work-room of his own, till the year 1800, when he purchased the room -of the Academical Chemists, in which he was enabled, at the expense of -the academy, to furnish a better and more spacious apartment for his -labours, for his mineralogical and chemical collection, and for his -lectures. - -As soon as he had brought the first arrangements of his office to -perfection--an office which, under his inspection and management, -became the model of a laboratory, conducted upon the most excellent -principles, and governed with the most conscientious integrity, he -published in the various periodical works of Germany, such as "Crell's -Chemical Annals," the "Writings of the Society for the promotion of -Natural Knowledge," "Selle's Contributions to the Science of Nature -and of Medicine," "Köhler's Journal," &c.; a multitude of papers -which soon drew the attention of chemists; for example, his Essay on -Copal--on the Elastic Stone--on Proust's Sel perlée--on the Green Lead -Spar of Tschoppau--on the best Method of preparing Ammonia--on the -Carbonate of Barytes--on the Wolfram of Cornwall--on Wood Tin--on the -Violet Schorl--on the celebrated Aerial Gold--on Apatite, &c. All these -papers, which secured him a high reputation as a chemist, appeared -before 1788, when he was chosen an ordinary member of the physical -class of the Royal Berlin Academy of Sciences. The Royal Academy of -Arts had elected him a member a year earlier. From this time, every -volume of the Memoirs of the Academy, and many other periodical works -besides, contained numerous papers by this accomplished chemist; and -there is not one of them which does not furnish us with a more exact -knowledge of some one of the productions of nature or art. He has -either corrected false representations, or extended views that were -before partially known, or has revealed the composition and mixture -of the parts of bodies, and has made us acquainted with a variety of -new elementary substances. Amidst all these labours, it is difficult -to say whether we should most admire the fortunate genius, which, in -all cases, readily and easily divined the point where any thing of -importance lay concealed; or the acuteness which enabled him to find -the best means of accomplishing his object; or the unceasing labour -and incomparable exactness with which he developed it; or the pure -scientific feeling under which he acted, and which was removed at the -utmost possible distance from every selfish, every avaricious, and -every contentious purpose. - -In the year 1795 he began to collect his chemical works which lay -scattered among so many periodical publications, and gave them to -the world under the title of "Beitrage zur Chemischen Kenntniss der -Mineralkörper" (Contributions to the Chemical Knowledge of Mineral -Bodies). Of this work, which consists of six volumes, the last was -published in 1815, about a year before the author's death. It contains -no fewer than two hundred and seven treatises, the most valuable part -of all that Klaproth had done for chemistry and mineralogy. It is a -pity that the sale of this work did not permit the publication of a -seventh volume, which would have included the rest of his papers, which -he had not collected, and given us a good index to the whole work, -which would have been of great importance to the practical chemist. -There is, indeed, an index to the first five volumes; but it is meagre -and defective, containing little else than the names of the substances -on which his experiments were made. - -Besides his own works, the interest which he took in the labours of -others deserves to be noticed. He superintended a new edition of Gren's -Manual of Chemistry, remarkable not so much for what he added as for -what he took away and corrected. The part which he took in Wolff's -Chemical Dictionary was of great importance. The composition of every -particular treatise was by Professor Wolff; but Klaproth read over -every important article before it was printed, and assisted the editor -on all occasions with the treasures of his experience and knowledge. -Nor was he less useful to Fischer in his translation of Berthollet on -Affinity and on Chemical Statics. - -These meritorious services, and the lustre which his character and -discoveries conferred on his country were duly appreciated by his -sovereign. In 1782 he had been made assessor in the Supreme College of -Medicine and of Health, which then existed. At a more recent period -he enjoyed the same rank in the Supreme Council of Medicine and of -Health; and when this college was subverted, in 1810, he became a -member of the medical deputation attached to the ministry of the -interior. He was also a member of the perpetual court commission for -medicines. His lectures, too, procured for him several municipal -situations. As soon as the public became acquainted with his great -chemical acquirements he was permitted to give yearly two private -courses of lectures on chemistry; one for the officers of the royal -artillery corps, the other for officers not connected with the army, -who wished to accomplish themselves for some practical employment. -Both of these lectures assumed afterwards a municipal character. The -former led to his appointment as professor of the Artillery Academy -instituted at Tempelhoff; and, after its dissolution, to his situation -as professor in the Royal War School. The other lecture procured for -him the professorship of chemistry in the Royal Mining Institute. On -the establishment of the university, Klaproth's lectures became those -of the university, and he himself was appointed ordinary professor of -chemistry, and member of the academical senate. From 1797 to 1810 he -was an active member of a small scientific society, which met yearly -during a few weeks for the purpose of discussing the more recondite -mysteries of the science. In the year 1811, the King of Prussia added -to all his other honours the order of the Red Eagle of the third class. - -Klaproth spent the whole of a long life in the most active and -conscientious discharge of all the duties of his station, and in an -uninterrupted course of experimental investigations. He died at Berlin -on the 1st of January, 1817, in the 70th year of his age. - -Among the remarkable traits in his character was his incorruptible -regard for every thing that he believed to be true, honourable, -and good; his pure love of science, with no reference whatever to -any selfish, ambitious, and avaricious feeling; his rare modesty, -undebased by the slightest vainglory or boasting. He was benevolently -disposed towards all men, and never did a slighting or contemptuous -word respecting any person fall from him. When forced to blame, he did -it briefly, and without bitterness, for his blame always applied to -actions, not to persons. His friendship was never the result of selfish -calculation, but was founded on his opinion of the personal worth of -the individual. Amidst all the unpleasant accidents of his life, -which were far from few, he evinced the greatest firmness of mind. -In his common behaviour he was pleasant and composed, and was indeed -rather inclined to a joke. To all this may be added a true religious -feeling, so uncommon among men of science of his day. His religion -consisted not in words and forms, not in positive doctrines, nor in -ecclesiastical observances, which, however, he believed to be necessary -and honourable; but in a zealous and conscientious discharge of all -his duties, not only of those which are imposed by the laws of men, -but of those holy duties of love and charity, which no human law, but -only that of God can command, and without which the most enlightened of -men is but "as sounding brass, or a tinkling cymbal." He early showed -this religious feeling by the honourable care which he bestowed on the -education of the children of Valentine Rose. Nor did he show less care -at an after-period towards his assistants and apprentices, to whom he -refused no instruction, and in whose success he took the most active -concern. He took a pleasure in every thing that was good and excellent, -and felt a lively interest in every undertaking which he believed to -be of general utility. He was equally removed from the superstition -and infidelity of his age, and carried the principles of religion, not -on his lips, but in the inmost feelings of his heart, from whence they -emanated in actions which pervaded and ennobled his whole being and -conduct. - -When we take a view of the benefits which Klaproth conferred upon -chemistry, we must not look so much at the new elementary substances -which he discovered, though they must not be forgotten, as at the new -analytical methods which he introduced, the precision, and neatness, -and order, and regularity with which his analyses were conducted, and -the scrupulous fidelity with which every thing was faithfully stated as -he found it. - -1. When a mineral is subjected to analysis, whatever care we take -to collect all the constituents, and to weigh them without losing -any portion whatever, it is generally found that the sum of the -constituents obtained fall a little short of the weight of the mineral -employed in the analysis. Thus, if we take 100 grains of any mineral, -and analyze it, the weights of all the constituents obtained added -together will rarely make up 100 grains, but generally somewhat -less; perhaps only 99, or even 98 grains. But some cases occur, when -the analysis of 100 grains of a mineral gives us constituents that -weigh, when added together, more than 100 grains; perhaps 105, or, in -some rare cases, as much as 110. It was the custom with Bergman, and -other analysts of his time, to consider this deficiency or surplus as -owing to errors in the analysis, and therefore to slur it over in the -statement of the analysis, by bringing the weight of the constituents, -by calculation, to amount exactly to 100 grains. Klaproth introduced -the method of stating the results exactly as he got them. He gives the -weight of mineral employed in all his analyses, and the weight of each -constituent extracted. These weights, added together, generally show a -loss, varying from two per cent. to a half per cent. This improvement -may appear at first sight trifling; yet I am persuaded that to it -we are indebted for most of the subsequent improvements introduced -into analytical chemistry. If the loss sustained was too great, it -was obvious either that the analysis had been badly performed, or -that the mineral contains some constituent which had been overlooked, -and not obtained. This laid him under the necessity of repeating the -analysis; and if the loss continued, he naturally looked out for some -constituent which his analysis had not enabled him to obtain. It was -in this way that he discovered the presence of potash in minerals; and -Dr. Kennedy afterwards, by following out his processes, discovered -soda as a constituent. It was in this way that water, phosphoric acid, -arsenic acid, fluoric acid, boracic acid, &c., were also found to exist -as constituents in various mineral bodies, which, but for the accurate -mode of notation introduced by Klaproth, would have been overlooked and -neglected. - -2. When Klaproth first began to analyze mineral bodies, he found -it extremely difficult to bring them into a state capable of being -dissolved in acids, without which an accurate analysis was impossible. -Accordingly corundum, adamantine spar, and the zircon, or hyacinth, -baffled his attempts for a considerable time, and induced him to -consider the earth of corundum as of a peculiar nature. He obviated -this difficulty by reducing the mineral to an extremely fine powder, -and, after digesting it in caustic potash ley till all the water was -dissipated, raising the temperature, and bringing the whole into a -state of fusion. This fusion must be performed in a silver crucible. -Corundum, and every other mineral which had remained insoluble after -fusion with an alkaline carbonate, was found to yield to this new -process. This was an improvement of considerable importance. All -those stony minerals which contain a notable proportion of silica, in -general become soluble after having been kept for some time in a state -of ignition with twice their weight of carbonate of soda. At that -temperature the silica of the mineral unites with the soda, and the -carbonic acid is expelled. But when the quantity of silica is small, -or when it is totally absent, heating with carbonate of soda does not -answer so well. With such minerals, caustic potash or soda may be -substituted with advantage; and there are some of them that cannot -be analyzed without having recourse to that agent. I have succeeded -in analyzing corundum and chrysoberyl, neither of which, when pure, -contain any silica, by simply heating them in carbonate of soda; but -the process does not succeed unless the minerals be reduced to an -exceedingly minute powder. - -3. When Klaproth discovered potash in the idocrase, and in some other -minerals, it became obvious that the old mode of rendering minerals -soluble in acids by heating them with caustic potash, or an alkaline -carbonate, could answer only for determining the quantity of silica, -and of earths or oxides, which the mineral contained; but that it could -not be used when the object was to determine its potash. This led him -to substitute _carbonate of barytes_ instead of potash or soda, or -their carbonates. After having ascertained the quantity of silica, -and of earths, and metallic oxides, which the mineral contained, his -last process to determine the potash in it was conducted in this way: -A portion of the mineral reduced to a fine powder was mixed with four -or five times its weight of carbonate of barytes, and kept for some -time (in a platinum crucible) in a red heat. By this process, the whole -becomes soluble in muriatic acid. The muriatic acid solution is freed -from silica, and afterwards from barytes, and all the earths and oxides -which it contains, by means of carbonate of ammonia. The liquid, thus -freed from every thing but the alkali, which is held in solution by the -muriatic acid, and the ammonia, used as a precipitant, is evaporated -to dryness, and the dry mass, cautiously heated in a platinum crucible -till the ammoniacal salts are driven off. Nothing now remains but the -potash, or soda, in combination with muriatic acid. The addition of -muriate of platinum enables us to determine whether the alkali be -potash or soda: if it be potash, it occasions a yellow precipitate; but -nothing falls if the alkali be soda. - -This method of analyzing minerals containing potash or soda is commonly -ascribed to Rose. Fescher, in his Eloge of Klaproth, informs us that -Klaproth said to him, more than once, that he was not quite sure -whether he himself, or Rose, had the greatest share in bringing this -method to a state of perfection. From this, I think it not unlikely -that the original suggestion might have been owing to Rose, but that it -was Klaproth who first put it to the test of experiment. - -The objection to this mode of analyzing is the high price of the -carbonate of barytes. This is partly obviated by recovering the barytes -in the state of carbonate; and this, in general, may be done, without -much loss. Berthier has proposed to substitute oxide of lead for -carbonate of barytes. It answers very well, is sufficiently cheap, -and does not injure the crucible, provided the oxide of lead be mixed -previously with a little nitrate of lead, to oxidize any fragments -of metallic lead which it may happen to contain. Berthier's mode, -therefore, in point of cheapness, is preferable to that of Klaproth. -It is equally efficacious and equally accurate. There are some other -processes which I myself prefer to either of these, because I find them -equally easy, and still less expensive than either carbonate of barytes -or oxide of lead. Davy's method with boracic acid is exceptionable, on -account of the difficulty of separating the boracic acid completely -again. - -4. The mode of separating iron and manganese from each other employed -by Bergman was so defective, that no confidence whatever can be placed -in his results. Even the methods suggested by Vauquelin, though -better, are still defective. But the process followed by Klaproth is -susceptible of very great precision. He has (we shall suppose) the -mixture of iron and manganese to be separated from each other, in -solution, in muriatic acid. The first step of the process is to convert -the protoxide of iron (should it be in that state) into peroxide. -For this purpose, a little nitric acid is added to the solution, and -the whole heated for some time. The liquid is now to be rendered as -neutral as possible; first, by driving off as much of the excess of -acid as possible, by concentrating the liquid; and then by completing -the neutralization, by adding very dilute ammonia, till no more can be -added without occasioning a permanent precipitation. Into the liquid -thus neutralized, succinate or benzoate of ammonia is dropped, as long -as any precipitate appears. By this means, the whole peroxide of iron -is thrown down in combination with succinic, or benzoic acid, while -the whole manganese remains in solution. The liquid being filtered, to -separate the benzoate of iron, the manganese may now (if nothing else -be in the liquid) be thrown down by an alkaline carbonate; or, if the -liquid contain magnesia, or any other earthy matter, by hydrosulphuret -of ammonia, or chloride of lime. - -This process was the contrivance of Gehlen; but it was made known to -the public by Klaproth, who ever after employed it in his analyses. -Gehlen employed succinate of ammonia; but Hisinger afterwards showed -that benzoate of ammonia might be substituted without any diminution of -the accuracy of the separation. This last salt, being much cheaper than -succinate of ammonia, answers better in this country. In Germany, the -succinic acid is the cheaper of the two, and therefore the best. - -5. But it was not by new processes alone that Klaproth improved the -mode of analysis, though they were numerous and important; the -improvements in the apparatus contributed not less essentially to the -success of his experiments. When he had to do with very hard minerals, -he employed a mortar of flint, or rather of agate. This mortar he, -in the first place, analyzed, to determine exactly the nature of the -constituents. He then weighed it. When a very hard body is pounded in -such a mortar, a portion of the mortar is rubbed off, and mixed with -the pounded mineral. What the quantity thus abraded was, he determined -by weighing the mortar at the end of the process. The loss of weight -gave the portion of the mortar abraded; and this portion must be mixed -with the pounded mineral. - -When a hard stone is pounded in an agate mortar it is scarcely possible -to avoid losing a little of it. The best method of proceeding is to -mix the matter to be pounded (previously reduced to a coarse powder -in a diamond mortar) with a little water. This both facilitates the -trituration, and prevents any of the dust from flying away; and not -more than a couple of grains of the mineral should be pounded at once. -Still, owing to very obvious causes, a little of the mineral is sure -to be lost during the pounding. When the process is finished, the -whole powder is to be exposed to a red heat in a platinum crucible, -and weighed. Supposing no loss, the weight should be equal to the -quantity of the mineral pounded together with the portion abraded -from the mortar. But almost always the weight will be found less than -this. Suppose the original weight of the mineral before pounding was -_a_, and the quantity abraded from the mortar 1; then, if nothing were -lost, the weight should be _a_ + 1; but we actually find it only _b_, a -quantity less than _a_ + 1. To determine the weight of matter abraded -from the mortar contained in this powder, we say _a_ + 1: _b_:: 1: -_x_, the quantity from the mortar in our powder, and _x_ = _b_/_a_ -+ 1. In performing the analysis, Klaproth attended to this quantity, -which was silica, and subtracted it. Such minute attention may appear, -at first sight superfluous; but it is not so. In analyzing sapphire, -chrysoberyl, and some other very hard minerals, the quantity of silica -abraded from the mortar sometimes amounts to five per cent. of the -weight of the mineral; and if we were not to attend to the way in which -this silica has been introduced into the powder, we should give an -erroneous view of the constitution of the mineral under analysis. All -the analyses of chrysoberyl hitherto published, give a considerable -quantity of silica as a constituent of it. This silica, if really found -by the analysts, must have been introduced from the mortar, for pure -chrysoberyl contains no silica whatever, but is a definite compound of -glucina, alumina, and oxide of iron. - -When Klaproth operated with fire, he always selected his vessels, -whether of earthenware, glass, plumbago, iron, silver, or platinum, -upon fixed principles; and showed more distinctly than chemists had -previously been aware of, what an effect the vessel frequently has upon -the result. He also prepared his reagents with great care, to ensure -their purity; for obtaining several of which in their most perfect -state, he invented several efficient methods. It is to the extreme care -with which he selected his minerals for analysis, and to the purity -of his reagents, and the fitness of his vessels for the objects in -view, that the great accuracy of his analyses is to be, in a great -measure, ascribed. He must also have possessed considerable dexterity -in operating, for when he had in view to determine any particular point -with accuracy, his results came, in general, exceedingly near the -truth. I may notice, as an example of this, his analysis of sulphate -of barytes, which was within about one-and-a-half per cent. of absolute -correctness. When we consider the looseness of the data which chemists -were then obliged to use, we cannot but be surprised at the smallness -of the error. Berzelius, in possession of better data, and possessed of -much dexterity, and a good apparatus, when he analyzed this salt many -years afterwards, committed an error of a half per cent. - -Klaproth, during a very laborious life, wholly devoted to analytical -chemistry, entirely altered the face of mineralogy. When he began -his labours, chemists were not acquainted with the true composition -of a single mineral. He analyzed above 200 species, and the greater -number of them with so much accuracy, that his successors have, in -most cases, confirmed the results which he obtained. The analyses -least to be depended on, are of those minerals which contain both lime -and magnesia; for his process for separating lime and magnesia from -each other was not a good one; nor am I sure that he always succeeded -completely in separating silica and magnesia from each other. This -branch of analysis was first properly elucidated by Mr. Chenevix. - -6. Analytical chemistry was, in fact, systematized by Klaproth; and it -is by studying his numerous and varied analyses, that modern chemists -have learned this very essential, but somewhat difficult art; and have -been able, by means of still more accurate data than he possessed, -to bring it to a still greater degree of perfection. But it must not -be forgotten, that Klaproth was in reality the creator of this art, -and that on that account the greatest part of the credit due to the -progress that has been made in it belongs to him. - -It would be invidious to point out the particular analyses which are -least exact; perhaps they ought rather to be ascribed to an unfortunate -selection of specimens, than to any want of care or skill in the -operator. But, during his analytical processes, he discovered a variety -of new elementary substances which it may be proper to enumerate. - -In 1789 he examined a mineral called _pechblende_, and found in it -the oxide of a new metal, to which he gave the name of _uranium_. -He determined its characters, reduced it to the metallic state, and -described its properties. It was afterwards examined by Richter, -Bucholz, Arfvedson, and Berzelius. - -It was in the same year, 1789, that he published his analysis of the -zircon; he showed it to be a compound of silica and a new earth, to -which he gave the name of zirconia. He determined the properties of -this new earth, and showed how it might be separated from other bodies -and obtained in a state of purity. It has been since ascertained, -that it is a metallic oxide, and the metallic basis of it is now -distinguished by the name of _zirconium_. In 1795 he showed that the -_hyacinth_ is composed of the same ingredients as the zircon; and that -both, in fact, constitute only one species. This last analysis was -repeated by Morveau, and has been often confirmed by modern analytical -chemists. - -It was in 1795 that he analyzed what was at that time called _red -schorl_, and now _titanite_. He showed that it was the oxide of a new -metallic body, to which he gave the name of _titanium_. He described -the properties of this new body, and pointed out its distinctive -characters. It must not be omitted, however, that he did not succeed in -obtaining oxide of titanium, or _titanic acid_, as it is now called, in -a state of purity. He was not able to separate a quantity of oxide of -iron, with which it was united, and which gave it a reddish colour. It -was first obtained pure by H. Rose, the son of his friend and pupil, -who took so considerable a part in his scientific investigations. - -Titanium, in the metallic state, was some years ago discovered by Dr. -Wollaston, in the slag at the bottom of the iron furnace, at Merthyr -Tydvil, in Wales. It is a yellow-coloured, brittle, but very hard -metal, possessed of considerable beauty; but not yet applied to any -useful purpose. - -In 1797 he examined the menachanite, a black sand from Cornwall, which -had been subjected to a chemical analysis by Gregor, in 1791, who had -extracted from it a new metallic substance, which Kirwan distinguished -by the name of _menachine_. Klaproth ascertained that the new metal -of Gregor was the very same as his own titanium, and that menachanite -is a compound of titanic acid and oxide of iron. Thus Mr. Gregor had -anticipated him in the discovery of titanium, though he was not aware -of the circumstance till two years after his own experiments had been -published. - -In the year 1793 he published a comparative set of experiments on the -nature of carbonates of barytes and strontian; showing that their -bases are two different earths, and not the same, as had been hitherto -supposed in Germany. This was the first publication on strontian which -appeared on the continent; and Klaproth seems to have been ignorant of -what had been already done on it in Great Britain; at least, he takes -no notice of it in his paper, and it was not his character to slur over -the labours of other chemists, when they were known to him. Strontian -was first mentioned as a peculiar earth by Dr. Crawford, in his paper -on the medicinal properties of the muriate of barytes, published in -1790. The experiments on which he founded his opinions were made, he -informs us, by Mr. Cruikshanks. A paper on the same subject, by Dr. -Hope, was read to the Royal Society of Edinburgh, in 1793; but they had -been begun in 1791. In this paper Dr. Hope establishes the peculiar -characters of strontian, and describes its salts with much precision. - -Klaproth had been again anticipated in his experiments on strontian; -but he could not have become aware of this till afterwards. For his own -experiments were given to the public before those of Dr. Hope. - -On the 25th of January, 1798, his paper on the gold ores of -Transylvania was read at a meeting of the Academy of Sciences at -Berlin. During his analysis of these ores, he detected a new white -metal, to which he gave the name of _tellurium_. Of this metal he -describes the properties, and points out its distinguishing characters. - -These ores had been examined by Muller, of Reichenstein, in the year -1782; and he had extracted from them a metal which he considered as -differing from every other. Not putting full confidence in his own -skill, he sent a specimen of his new metal to Bergman, requesting him -to examine it and give his opinion respecting its nature. All that -Bergman did was to show that the metallic body which he had got was not -antimony, to which alone, of all known metals, it bore any resemblance. -It might be inferred from this, that Muller's metal was new. But -the subject was lost sight of, till the publication of Klaproth's -experiments, in 1802, recalled it to the recollection of chemists. -Indeed, Klaproth relates all that Muller had done, with the most -perfect fairness. - -In the year 1804 he published the analysis of a red-coloured mineral, -from Bastnäs in Sweden, which had been at one time confounded with -tungsten; but which the Elhuyarts had shown to contain none of that -metal. Klaproth showed that it contained a new substance, as one of -its constituents, which he considered as a new earth, and which he -called _ochroita_, because it forms coloured salts with acids. Two -years after, another analysis of the same mineral was published by -Berzelius and Hisinger. They considered the new substance which the -mineral contained as a metallic oxide, and to the unknown metallic base -they gave the name of _cerium_, which has been adopted by chemists -in preference to Klaproth's name. The characters of oxide of cerium -given by Berzelius and Hisinger, agree with those given by Klaproth -to ochroita, in all the essential circumstances. Of course Klaproth -must be considered as the discoverer of this new body. The distinction -between _earth_ and _metallic oxide_ is now known to be an imaginary -one. All the substances formerly called earths are, in fact, metallic -oxides. - -Besides these new substances, which he detected by his own labours, -he repeated the analyses of others, and confirmed and extended the -discoveries they had made. Thus, when Vauquelin discovered the new -earth _glucina_, in the emerald and beryl, he repeated the analysis -of these minerals, confirmed the discovery of Vauquelin, and gave a -detailed account of the characters and properties of glucina. Gadolin -had discovered another new earth in the mineral called gadolinite. This -discovery was confirmed by the analysis of Ekeberg, who distinguished -the new earth by the name of yttria. Klaproth immediately repeated -the analysis of the gadolinite, confirmed the results of Ekeberg's -analysis, and examined and described the properties of _yttria_. - -When Dr. Kennedy discovered soda in basalt, Klaproth repeated the -analysis of this mineral, and confirmed the results obtained by the -Edinburgh analyst. - -But it would occupy too much room, if I were to enumerate every example -of such conduct. Whoever will take the trouble to examine the different -volumes of the Beitrage, will find several others not less striking or -less useful. - -The service which Klaproth performed for mineralogy, in Germany, was -performed equally in France by the important labours of M. Vauquelin. -It was in France, in consequence of the exertions of Romé de Lisle, -and the mathematical investigations of the Abbé Hauy, respecting -the structure of crystals, which were gradually extended over the -whole mineral kingdom, that the reform in mineralogy, which has now -become in some measure general, originated. Hauy laid it down as a -first principle, that every mineral species is composed of the same -constituents united in the same proportion. He therefore considered -it as an object of great importance, to procure an exact chemical -analysis of every mineral species. Hitherto no exact analysis of -minerals had been performed by French chemists; for Sage, who was the -chemical mineralogist connected with the academy, satisfied himself -with ascertaining the nature of the constituents of minerals, without -determining their proportions. But Vauquelin soon displayed a knowledge -of the mode of analysis, and a dexterity in the use of the apparatus -which he employed, little less remarkable than that of Klaproth himself. - -Of Vauquelin's history I can give but a very imperfect account, as I -have not yet had an opportunity of seeing any particulars of his life. -He was a peasant-boy of Normandy, with whom Fourcroy accidentally met. -He was pleased with his quickness and parts, and delighted with the -honesty and integrity of his character. He took him with him to Paris, -and gave him the superintendence of his laboratory. His chemical -knowledge speedily became great, and his practice in experimenting -gave him skill and dexterity: he seems to have performed all the -analytical experiments which Fourcroy was in the habit of publishing. -He speedily became known by his publications and discoveries. When the -scientific institutions were restored or established, after the death -of Robespierre, Vauquelin became a member of the Institute and chemist -to the School of Mines. He was made also assay-master of the Mint. -He was a professor of chemistry in Paris, and delivered, likewise, -private lectures, and took in practical pupils into his laboratory. -His laboratory was of considerable size, and he was in the habit of -preparing both medicines and chemical reagents for sale. It was he -chiefly that supplied the French chemists with phosphorus, &c., which -cannot be conveniently prepared in a laboratory fitted up solely for -scientific purposes. - -Vauquelin was by far the most industrious of all the French chemists, -and has published more papers, consisting of mineral, vegetable, and -animal analyses, than any other chemist without exception. When he had -the charge of the laboratory of the School of Mines, Hauy was in the -habit of giving him specimens of all the different minerals which he -wished analyzed. The analyses were conducted with consummate skill, -and we owe to him a great number of improvements in the methods of -analysis. He is not entitled to the same credit as Klaproth, because he -had the advantage of many analyses of Klaproth to serve him as a guide. -But he had no model before him in France; and both the apparatus used -by him, and the reagents which he employed, were of his own contrivance -and preparation. I have sometimes suspected that his reagents were not -always very pure; but I believe the true reason of the unsatisfactory -nature of many of his analyses, is the bad choice made of the specimens -selected for analysis. It is obvious from his papers, that Vauquelin -was not a mineralogist; for he never attempts a description of the -mineral which he subjects to analysis, satisfying himself with the -specimen put into his hands by Hauy. Where that specimen was pure, as -was the case with emerald and beryl, his analysis is very good; but -when the specimen was impure or ill-chosen, then the result obtained -could not convey a just notion of the constituents of the mineral. -That Hauy would not be very difficult to please in his selection of -specimens, I think myself entitled to infer from the specimens of -minerals contained in his own cabinet, many of which were by no means -well selected. I think, therefore, that the numerous analyses published -by Vauquelin, in which the constituents assigned by him are not those, -or, at least, not in the same proportions, as have been found by -succeeding analysts, are to be ascribed, not to errors in the analysis, -which, on the contrary, he always performed carefully, and with the -requisite attention to precision, but to the bad selection of specimens -put into his hand by Hauy, or those other individuals who furnished him -with the specimens which he employed in his analyses. This circumstance -is very much to be deplored; because it puts it out of our power to -confide in an analysis of Vauquelin, till it has been repeated and -confirmed by somebody else. - -Vauquelin not only improved the analytical methods, and reduced the art -to a greater degree of simplicity and precision, but he discovered, -likewise, new elementary bodies. - -The red lead ore of Siberia had early drawn the attention of chemists, -on account of its beauty; and various attempts had been made to analyze -it. Among others, Vauquelin tried his skill upon it, in 1789, in -concert with M. Macquart, who had brought specimens of it from Siberia; -but at that time he did not succeed in determining the nature of the -acid with which the oxide of lead was combined in it. He examined -it again in 1797, and now succeeded in separating an acid to which, -from the beautiful coloured salts which it forms, he gave the name of -_chromic_. He determined the properties of this acid, and showed that -its basis was a new metal to which he gave the name of _chromium_. He -succeeded in obtaining this metal in a separate state, and showed that -its protoxide is an exceedingly beautiful green powder. This discovery -has been of very great importance to different branches of manufacture -in this country. The green oxide is used pretty extensively in painting -green on porcelain. It constitutes an exceedingly beautiful green -pigment, very permanent, and easily applied. The chromic acid, when -combined with oxide of lead, forms either a yellow or an orange colour -upon cotton cloth, both very fixed and exceedingly beautiful colours. -In that way it is extensively used by the calico-printers; and the -bichromate of potash is prepared, in a crystalline form, to a very -considerable amount, both in Glasgow and Lancashire, and doubtless in -other places. - -Vauquelin was requested by Hauy to analyze the _beryl_, a beautiful -light-green mineral, crystallized in six-sided prisms, which occurs -not unfrequently in granite rocks, especially in Siberia. He found it -to consist chiefly of silica, united to alumina, and to another earthy -body, very like alumina in many of its properties, but differing in -others. To this new earth he gave the name of _glucina_, on account -of the sweet taste of its salts; a name not very appropriate, as -alumina, yttria, lead, protoxide of chromium, and even protoxide of -iron, form salts which are distinguished by a sweet taste likewise. -This discovery of glucina confers honour on Vauquelin, as it shows -the care with which his analyses must have been conducted. A careless -experimenter might easily have confounded _glucina_ with _alumina_. -Vauquelin's mode of distinguishing them was, to add sulphate of potash -to their solution in sulphuric acid. If the earth in solution was -alumina, crystals of alum would form in the course of a short time; but -if the earth was glucina, no such crystals would make their appearance, -alumina being the basis of alum, and not glucina. He showed, too, that -glucina is easily dissolved in a solution of carbonate of ammonia, -while alumina is not sensibly taken up by that solution. - -Vauquelin died in 1829, after having reached a good old age. His -character was of the very best kind, and his conduct had always been -most exemplary. He never interfered with politics, and steered his way -through the bloody period of the revolution, uncontaminated by the -vices or violence of any party, and respected and esteemed by every -person. - -Mr. Chenevix deserves also to be mentioned as an improver of analytical -chemistry. He was an Irish gentleman, who happened to be in Paris -during the reign of terror, and was thrown into prison and put into the -same apartment with several French chemists, whose whole conversation -turned upon chemical subjects. He caught the infection, and, after -getting out of prison, began to study the subject with much energy and -success, and soon distinguished himself as an analytical chemist. - -His analysis of corundum and sapphire, and his observations on the -affinity between magnesia and silica, are valuable, and led to -considerable improvements in the method of analysis. His analyses of -the arseniates of copper, though he demonstrated that several different -species exist, are not so much to be depended on; because his method -of separating and estimating the quantity of arsenic acid is not -good. This difficult branch of analysis was not fully understood till -afterwards. - -Chenevix was for several years a most laborious and meritorious -chemical experimenter. It is much to be regretted that he should -have been induced, in consequence of the mistake into which he fell -respecting palladium, to abandon chemistry altogether. Palladium was -originally made known to the public by an anonymous handbill which was -circulated in London, announcing that _palladium_, or new silver, was -on sale at Mrs. Forster's, and describing its properties. Chenevix, in -consequence of the unusual way in which the discovery was announced, -naturally considered it as an imposition on the public. He went to -Mrs. Forster's, and purchased the whole palladium in her possession, -and set about examining it, prepossessed with the idea that it was an -alloy of some two known metals. After a laborious set of experiments, -he considered that he had ascertained it to be a compound of platinum -and mercury, or an amalgam of platinum made in a peculiar way, which -he describes. This paper was read at a meeting of the Royal Society by -Dr. Wollaston, who was secretary, and afterwards published in their -Transactions. Soon after this publication, another anonymous handbill -was circulated, offering a considerable price for every grain of -palladium _made_ by Mr. Chenevix's process, or by any other process -whatever. No person appearing to claim the money thus offered, Dr. -Wollaston, about a year after, in a paper read to the Royal Society, -acknowledged himself to have been the discoverer of palladium, and -related the process by which he had obtained it from the solution of -crude platina in aqua regia. There could be no doubt after this, that -palladium was a peculiar metal, and that Chenevix, in his experiments, -had fallen into some mistake, probably by inadvertently employing -a solution of palladium, instead of a solution of his amalgam of -platinum; and thus giving the properties of the one solution to the -other. It is very much to be regretted, that Dr. Wollaston allowed Mr. -Chenevix's paper to be printed, without informing him, in the first -place, of the true history of palladium: and I think that if he had -been aware of the bad consequences that were to follow, and that it -would ultimately occasion the loss of Mr. Chenevix to the science, he -would have acted in a different manner. I have more than once conversed -with Dr. Wollaston on the subject, and he assured me that he did every -thing that he could do, short of betraying his secret, to prevent -Mr. Chenevix from publishing his paper; that he had called upon, and -assured him, that he himself had attempted his process without being -able to succeed, and that he was satisfied that he had fallen into -some mistake. As Mr. Chenevix still persisted in his conviction of the -accuracy of his own experiments after repeated warnings, perhaps it -is not very surprising that Dr. Wollaston allowed him to publish his -paper, though; had he been aware of the consequences to their full -extent, I am persuaded that he would not have done so. It comes to be a -question whether, had Dr. Wollaston informed him of the whole secret, -Mr. Chenevix would have been convinced. - -Another chemist, to whom the art of analyzing minerals lies under -great obligations, is Dr. Frederick Stromeyer, professor of chemistry -and pharmacy, in the University of Gottingen. He was originally a -botanist, and only turned his attention to chemistry when he had the -offer of the chemical chair at Gottingen. He then went to Paris, and -studied practical chemistry for some years in Vauquelin's laboratory. -He has devoted most of his attention to the analysis of minerals; and -in the year 1821 published a volume of analyses under the title of -"Untersuchungen über die Mischung der Mineralkörper und anderer damit -verwandten Substanzen." It contains thirty analyses, which constitute -perfect models of analytical sagacity and accuracy. After Klaproth's -Beitrage, no book can be named more highly deserving the study of the -analytical chemist than Stromeyer's Untersuchungen. - -The first paper in this work contains the analysis of arragonite. -Chemists had not been able to discover any difference in the chemical -constitution of arragonite and calcareous spar, both being compounds of - - Lime 3·5 - Carbonic acid 2·75 - -Yet the minerals differ from each other in their hardness, specific -gravity, and in the shape of their crystals. Many attempts had been -made to account for this difference in characters between these two -minerals, but in vain. Mr. Holme showed that arragonite contained -about one per cent. of water, which is wanting in calcareous spar; -and that when arragonite is heated, it crumbles into powder, which is -not the case with calcareous spar. But it is not easy to conceive how -the addition of one per cent. of water should increase the specific -gravity and the hardness, and quite alter the shape of the crystals -of calcareous spar. Stromeyer made a vast number of experiments -upon arragonite, with very great care, and the result was, that the -arragonite from Bastenes, near Dax, in the department of Landes, and -likewise that from Molina, in Arragon, was a compound of - - 96 carbonate of lime - 4 carbonate of strontian. - -This amounts to about thirty-five atoms of carbonate of lime, and -one atom of carbonate of strontian. Now as the hardness and specific -gravity of carbonate of strontian is greater than that of carbonate of -lime, we can see a reason why arragonite should be heavier and harder -than calcareous spar. More late researches upon different varieties -of arragonite enabled him to ascertain that this mineral exists with -different proportions of carbonate of strontian. Some varieties contain -only 2 per cent., some only 1 per cent., and some only 0·75, or even -0·5 per cent.; but he found no specimen among the great number which -he analyzed totally destitute of carbonate of strontian. It is true -that Vauquelin afterwards examined several varieties in which he -could detect no strontian whatever; but as Vauquelin's mineralogical -knowledge was very deficient, it comes to be a question, whether the -minerals analyzed by him were really arragonites, or only varieties of -calcareous spar. - -To Professor Stromeyer we are likewise indebted for the discovery of -the new metal called _cadmium_; and the discovery does great credit -to his sagacity and analytical skill. He is inspector-general of the -apothecaries for the kingdom of Hanover. While discharging the duties -of his office at Hildesheim, in the year 1817, he found that the -carbonate of zinc had been substituted for the oxide of zinc, ordered -in the Hanoverian Pharmacopœia. This carbonate of zinc was manufactured -at Salzgitter. On inquiry he learned from Mr. Jost, who managed that -manufactory, that they had been obliged to substitute the carbonate -for the oxide of zinc, because the oxide had a yellow colour which -rendered it unsaleable. On examining this oxide, Stromeyer found -that it owed its yellow colour to the presence of a small quantity of -the oxide of a new metal, which he separated, reduced, and examined, -and to which he gave the name of _cadmium_, because it occurs usually -associated with zinc. The quantity of cadmium which he was able to -obtain from this oxide of zinc was but small. A fortunate circumstance, -however, supplied him with an additional quantity, and enabled him to -carry his examination of cadmium to a still greater length. During the -apothecaries' visitation in the state of Magdeburg, there was found, -in the possession of several apothecaries, a preparation of zinc -from Silesia, made in Hermann's laboratory at Schönebeck, which was -confiscated on the supposition that it contained arsenic, because its -solution gave a yellow precipitate with sulphuretted hydrogen, which -was considered as orpiment. This statement could not be indifferent -to Mr. Hermann, as it affected the credit of his manufactory; -especially as the medicinal counsellor, Roloff, who had assisted -at the visitation, had drawn up a statement of the circumstances -which occasioned the confiscation, and caused it to be published in -Hofeland's Medical Journal. He subjected the suspected oxide to a -careful examination; but he could not succeed in detecting any arsenic -in it. He then requested Roloff to repeat his experiments. This he -did; and now perceived that the precipitate, which he had taken for -orpiment, was not so in reality, but owed its existence to the presence -of another metallic oxide, different from arsenic and probably new. -Specimens of this oxide of zinc, and of the yellow precipitate, were -sent to Stromeyer for examination, who readily recognised the presence -of cadmium, and was able to extract from it a considerable quantity of -that metal. - -It is now nine years since the first volume of the Untersuchungen was -published. All those who are interested in analytical chemistry are -anxious for the continuance of that admirable work. By this time he -must have collected ample materials for an additional volume; and it -could not but add considerably to a reputation already deservedly high. - -There is no living chemist, to whom analytical chemistry lies under -greater obligations than to Berzelius, whether we consider the number -or the exactness of the analyses which he has made. - -Jacob Berzelius was educated at Upsala, when Professor Afzelius, -a nephew of Bergman, filled the chemical chair, and Ekeberg was -_magister docens_ in chemistry. Afzelius began his chemical career with -considerable _éclat_, his paper on sulphate of barytes being possessed -of very considerable merit. But he is said to have soon lost his -health, and to have sunk, in consequence, into listless inactivity. - -Andrew Gustavus Ekeberg was born in Stockholm, on the 16th of January, -1767. His father was a captain in the Swedish navy. He was educated at -Calmar; and in 1784 went to Upsala, where he devoted himself chiefly -to the study of mathematics. He took his degree in 1788, when he wrote -a thesis "De Oleis Seminum expressis." In 1789 he went to Berlin; and -on his return, in 1790, he gave a specimen of his poetical talents, -by publishing a poem entitled "Tal öfver Freden emellan Sverige och -Ryssland" (Discourse about the Peace between Sweden and Russia). After -this he turned his attention to chemistry; and in 1794 was made _chemiæ -docens_. In this situation he continued till 1813, when he died on -the 11th of February. He had been in such bad health for some time -before his death, as to be quite unable to discharge the duties of his -situation. He published but little, and that little consisted almost -entirely of chemical analyses. - -His first attempt was on phosphate of lime; then he wrote a paper -on the analysis of the topaz, the object of which was to explain -Klaproth's method of dissolving hard stony bodies. - -He made an analysis of gadolinite, and determined the chemical -properties of yttria. During these experiments he discovered the new -metal to which he gave the name of _tantalum_, and which Dr. Wollaston -afterwards showed to be the same with the _columbium_ of Mr. Hatchett. -He also published an analysis of the automalite, of an ore of titanium, -and of the mineral water of Medevi. In this last analysis he was -assisted by Berzelius, who was then quite unknown to the chemical world. - -Berzelius has been much more industrious than his chemical -contemporaries at Upsala. His first publication was a work in two -volumes on animal chemistry, chiefly a compilation, with the exception -of his experiments on the analysis of blood, which constitute an -introduction to the second volume. This book was published in 1806 -and 1808. In the year 1806 he and Hisinger began a periodical work, -entitled "Afhandlingar i Fysik, Kemi och Mineralogi," of which six -volumes in all were published, the last in 1818. In this work there -occur forty-seven papers by Berzelius, some of them of great length -and importance, which will be noticed afterwards; but by far the -greatest part of them consist of mineral analyses. We have the analysis -of cerium by Hisinger and Berzelius, together with an account of -the chemical characters of the two oxides of cerium. In the fourth -volume he gives us a new chemical arrangement of minerals, founded -on the supposition that they are all chemical compounds in definite -proportions. Mr. Smithson had thrown out the opinion that _silica_ -is an acid: which opinion was taken up by Berzelius, who showed, by -decisive experiments, that it enters into definite combinations -with most of the bases. This happy idea enabled him to show, that -most of the stony minerals are definite compounds of silica, with -certain earths or metallic oxides. This system has undergone several -modifications since he first gave it to the world; and I think it -more than doubtful whether his last co but he has taken care to have -translations of them inserted into Poggensdorf's Annalen, and the -Annales de Chimie et de Physique. - -In the Stockholm Memoirs, for 1819, we have his analysis of wavellite, -showing that this mineral is a hydrous phosphate of alumina. The -same analysis and discovery had been made by Fuchs, who published -his results in 1818; but probably Berzelius had not seen the paper; -at least he takes no notice of it. We have also in the same volume -his analysis of euclase, of silicate of zinc, and his paper on the -prussiates. - -In the Memoirs for 1820 we have, besides three others, his paper on -the mode of analyzing the ores of nickel. In the Memoirs for 1821 we -have his paper on the alkaline sulphurets, and his analysis of achmite. -The specimen selected for this analysis was probably impure; for two -successive analyses of it, made in my laboratory by Captain Lehunt, -gave a considerable difference in the proportion of the constituents, -and a different formula for the composition than that resulting from -the constituents found by Berzelius. - -In the Memoirs for 1822 we have his analysis of the mineral waters -of Carlsbad. In 1823 he published his experiments on uranium, which -were meant as a confirmation and extension of the examination of this -substance previously made by Arfvedson. In the same year appeared his -experiments on fluoric acid and its combinations, constituting one of -the most curious and important of all the numerous additions which -he has made to analytical chemistry. In 1824 we have his analysis of -phosphate of yttria, a mineral found in Norway; of polymignite, a -mineral from the neighbourhood of Christiania, where it occurs in the -zircon sienite, and remarkable for the great number of bases which it -contains united to titanic acid; namely, zirconia, oxide of iron, -lime, oxide of manganese, oxide of cerium, and yttria. We have also -his analysis of arseniate of iron, from Brazil and from Cornwall; and -of chabasite from Ferro. In this last analysis he mentions chabasites -from Scotland, containing soda instead of lime. The only chabasites in -Scotland, that I know of, occur in the neighbourhood of Glasgow; and -in none of these have I found any soda. But I have found soda instead -of lime in chabasites from the north of Ireland, always crystallized -in the form to which Hauy has given the name of _trirhomboidale_. I -think, therefore, that the chabasites analyzed by Arfvedson, to which -Berzelius refers, must have been from Ireland, and not from Scotland; -and I think it may be a question whether this form of crystal, if it -should always be found to contain soda instead of lime, ought not to -constitute a peculiar species. - -In 1826 we have his very elaborate and valuable paper on sulphur salts. -In this paper he shows that sulphur is capable of combining with -bodies, in the same way as oxygen, and of converting the acidifiable -bases into acids, and the alkalifiable bases into alkalies. These -sulphur acids and alkalies unite with each other, and form a new class -of saline bodies, which may be distinguished by the name of _sulphur -salts_. This subject has been since carried a good deal further by -M. H. Rose, who has by means of it thrown much light on some mineral -species hitherto quite inexplicable. Thus, what is called _nickel -glance_, is a sulphur salt of nickel. The acid is a compound of sulphur -and arsenic, the base a compound of sulphur and nickel. Its composition -may be represented thus: - - 1 atom disulphide of arsenic - 1 atom disulphide of nickel. - -In like manner glance cobalt is - - 1 atom disulphide of arsenic - 1 atom disulphide of nickel. - -Zinkenite is composed of - - 3 atoms sulphide of antimony - 1 atom sulphide of lead; - -and jamesonite of - - 2½ atoms sulphide of antimony - 1 atom sulphide of lead. - -Feather ore of antimony, hitherto confounded with sulphuret of -antimony, is a compound of - - 5 atoms sulphide of antimony - 3 atoms sulphide of lead. - -Gray copper ore, which has hitherto appeared so difficult to be reduced -to any thing like regularity, is composed of - - 1 atom sulphide of antimony or arsenic - 2 atoms sulphide of copper or silver. - -Dark red silver ore is composed of - - 1 atom sulphide of antimony - 1 atom sulphide of silver; - -and light red silver ore of - - 2 atoms sesquisulphide of arsenic - 3 atoms sulphide of silver. - -These specimens show how much light the doctrine of sulphur salts has -thrown on the mineral kingdom. - -In 1828 he published his experimental investigation of the characters -and compounds of palladium, rhodium, osmium, and iridium; and upon the -mode of analyzing the different ores of platinum. - -One of the greatest improvements which Berzelius has introduced into -analytical chemistry, is his mode of separating those bodies which -become acid when united to oxygen, as sulphur, selenium, arsenic, &c., -from those that become alkaline, as copper, lead, silver, &c. His -method is to put the alloy or ore to be analyzed into a glass tube, -and to pass over it a current of dry chlorine gas, while the powder in -the tube is heated by a lamp. The acidifiable bodies are volatile, and -pass over along the tube into a vessel of water placed to receive them, -while the alkalifiable bodies remain fixed in the tube. This mode of -analysis has been considerably improved by Rose, who availed himself of -it in his analysis of gray copper ore, and other similar compounds. - -Analytical chemistry lies under obligations to Berzelius, not merely -for what he has done himself, but for what has been done by those -pupils who were educated in his laboratory. Bonsdorf, Nordenskiöld, -C. G. Gmelin, Rose, Wöhler, Arfvedson, have given us some of the -finest examples of analytical investigations with which the science is -furnished. - -P. A. Von Bonsdorf was a professor of Abo, and after that university -was burnt down, he moved to the new locality in which it was planted by -the Russian government. His analysis of the minerals which crystallize -in the form of the amphibole, constitutes a model for the young -analysts to study, whether we consider the precision of the analyses, -or the methods by which the different constituents were separated and -estimated. His analysis of red silver ore first demonstrated that -the metals in it were not in the state of oxides. The nature of the -combination was first completely explained by Rose, after Berzelius's -paper on the sulphur salts had made its appearance. His paper on the -acid properties of several of the chlorides, has served considerably to -extend and to rectify the views first proposed by Berzelius respecting -the different classes of salts. - -Nils Nordenskiöld is superintendent of the mines in Finland: his -"Bidrag till närmare kännedom af Finland's Mineralier och Geognosie" -was published in 1820. It contains a description and analysis of -fourteen species of Lapland minerals, several of them new, and all -of them interesting. The analyses were conducted in Berzelius's -laboratory, and are excellent. In 1827 he published a tabular view -of the mineral species, arranged chemically, in which he gives the -crystalline form, hardness, and specific gravity, together with the -chemical formulas for the composition. - -C. G. Gmelin is professor of chemistry at Tubingen; he has devoted -the whole of his attention to chemical analysis, and has published a -great number of excellent ones, particularly in Schweigger's Journal. -His analysis of helvine, and of the tourmalin, may be specified as -particularly valuable. In this last mineral, he demonstrated the -presence of boracic acid. Leopold Gmelin, professor of chemistry at -Heidelberg, has also distinguished himself as an analytical chemist. -His System of Chemistry, which is at present publishing, promises to be -the best and most perfect which Germany has produced. - -Henry Rose, of Berlin, is the son of that M. Rose who was educated by -Klaproth, and afterwards became the intimate friend and fellow-labourer -of that illustrious chemist. He has devoted himself to analytical -chemistry with indefatigable zeal, and has favoured us with a -prodigious number of new and admirably-conducted analyses. His -analyses of pyroxenes, of the ores of titanium, of gray copper ore, -of silver glance, of red silver ore, miargyrite, polybasite, &c., may -be mentioned as examples. In 1829 he published a volume on analytical -chemistry, which is by far the most complete and valuable work of the -kind that has hitherto appeared; and ought to be carefully studied by -all those who wish to make themselves masters of the difficult, but -necessary art of analyzing compound bodies.[6] - - [6] An excellent English translation of this book with several - important additions by the author, has just been published by Mr. - Griffin. - -Wöhler is professor of chemistry in the Polytechnic School of Berlin; -he does not appear to have turned his attention to analytical -chemistry, but rather towards extending our knowledge of the compounds -which the different simple bodies are capable of forming with each -other. His discovery of cyanic acid may be mentioned as a specimen. He -is active and young; much, therefore, may be expected from him. - -Augustus Arfvedson has distinguished himself by the discovery of the -new fixed alkali, lithia, in petalite and spodumene. It has been lately -ascertained at Moscow, by M. R. Hermann, and the experiments have been -repeated and confirmed by Berzelius, that lithia is a much lighter -substance than it was found to be by Arfvedson, its atomic weight being -only 1·75. We have from Arfvedson an important set of experiments on -uranium and its oxides, and on the action of hydrogen on the metallic -sulphurets. He has likewise analyzed a considerable number of minerals -with great care; but of late years he seems to have lost his activity. -His analysis of chrysoberyl does not possess the accuracy of the rest: -by some inadvertence, he has taken a compound of glucina and alumina -for silica. - -I ought to have included Walmstedt and Trollé-Wachmeister among -the Swedish chemists who have contributed important papers towards -the progress of analytical chemistry, the memoir of the former on -chrysolite, and of the latter on the garnets, being peculiarly -valuable. But it would extend this work to an almost interminable -length, if I were to particularize every meritorious experimenter. This -must plead my excuse for having omitted the names of Bucholz, Gehlen, -Fuchs, Dumesnil, Dobereiner, Kupfer, and various other meritorious -chemists who have contributed so much to the perfecting of the -chemical analysis of the mineral kingdom. But it would be unpardonable -to leave out the name of M. Mitcherlich, professor of chemistry in -Berlin, and successor of Klaproth, who was also a pupil of Berzelius. -He has opened a new branch of chemistry to our consideration. His -papers on isomorphous bodies, on the crystalline forms of various sets -of salts, on the artificial formation of various minerals, do him -immortal honour, and will hand him down to posterity as a fit successor -of his illustrious predecessors in the chemical chair of Berlin--a city -in which an uninterrupted series of first-rate chemists have followed -each other for more than a century; and where, thanks to the fostering -care of the Prussian government, the number was never greater than at -the present moment. - -The most eminent analytical chemists at present in France are, Laugier, -a nephew and successor of Fourcroy, as professor of chemistry in the -Jardin du Roi, and Berthier, who has long had the superintendence of -the laboratory of the School of Mines. Laugier has not published many -analyses to the world, but those with which he has favoured us appear -to have been made with great care, and are in general very accurate. -Berthier is a much more active man; and has not merely given us many -analyses, but has made various important improvements in the analytical -processes. His mode of separating arsenic acid, and determining its -weight, is now generally followed; and I can state from experience -that his method of fusing minerals with oxide of lead, when the object -is to detect an alkali, is both accurate and easy. Berthier is young, -and active, and zealous; we may therefore expect a great deal from him -hereafter. - -The chemists in great Britain have never hitherto distinguished -themselves much in analytical chemistry. This I conceive is owing -to the mode of education which has been hitherto unhappily followed. -Till within these very few years, practical chemistry has been -nowhere taught. The consequence has been, that every chemist must -discover processes for himself; and a long time elapses before he -acquires the requisite dexterity and skill. About the beginning of the -present century, Dr. Kennedy, of Edinburgh, was an enthusiastic and -dexterous analyst; but unfortunately he was lost to the science by a -premature death, after giving a very few, but these masterly, analyses -to the public. About the same time, Charles Hatchett, Esq., was an -active chemist, and published not a few very excellent analyses; but -unfortunately this most amiable and accomplished man has been lost -to science for more than a quarter of a century; the baneful effects -of wealth, and the cares of a lucrative and extensive business, -having completely weaned him from scientific pursuits. Mr. Gregor, -of Cornwall, was an accurate man, and attended only to analytical -chemistry: his analyses were not numerous, but they were in general -excellent. Unfortunately the science was deprived of his services by -a premature death. The same observation applies equally to Mr. Edward -Howard, whose analyses of meteoric stones form an era in this branch of -chemistry. He was not only a skilful chemist, but was possessed of a -persevering industry which peculiarly fitted him for making a figure as -a practical chemist. Of modern British analytical chemists, undoubtedly -the first is Mr. Richard Philips; to whom we are indebted for not -a few analyses, conducted with great chemical skill, and performed -with great accuracy. Unfortunately, of late years he has done little, -having been withdrawn from science by the necessity of providing for -a large family, which can hardly be done, in this country, except -by turning one's attention to trade or manufactures. The same remark -applies to Dr. Henry, who has contributed so much to our knowledge of -gaseous bodies, and whose analytical skill, had it been wholly devoted -to scientific investigations, would have raised his reputation, as a -discoverer, much higher than it has attained; although the celebrity -of Dr. Henry, even under the disadvantages of being a manufacturing -chemist, is deservedly very high. Of the young chemists who have but -recently started in the path of analytical investigation, we expect the -most from Dr. Turner, of the London University. His analyses of the -ores of manganese are admirable specimens of skill and accuracy, and -have completely elucidated a branch of mineralogy which, before his -experiments, and the descriptions of Haidinger appeared, was buried in -impenetrable darkness. - -No man that Great Britain has produced was better fitted to have -figured as an analytical chemist, both by his uncommon chemical skill, -and the powers of his mind, which were of the highest order, than -Mr. Smithson Tennant, had he not been in some measure prevented by a -delicate frame of body, which produced in him a state of indolence -somewhat similar to that of Dr. Black. His discovery of osmium and -iridium, and his analysis of emery and magnesian limestone, may -be mentioned as proofs of what he could have accomplished had his -health allowed him a greater degree of exertion. His experiments on -the diamond first demonstrated that it was composed of pure carbon; -while his discovery of phosphuret of lime has furnished lecturers -on chemistry with one of the most brilliant and beautiful of those -exhibitions which they are in the habit of making to attract the -attention of their students. - -Smithson Tennant was the only child of the Rev. Calvert Tennant, -youngest son of a respectable family in Wensleydale, near Richmond, in -Yorkshire, and vicar of Selby in that county. He was born on the 30th -of November, 1761: he had the misfortune to lose his father when he was -only nine years of age; and before he attained the age of manhood he -was deprived likewise of his mother, by a very unfortunate accident: -she was thrown from her horse while riding with her son, and killed on -the spot. His education, after his father's death, was irregular, and -apparently neglected; he was sent successively to different schools in -Yorkshire, at Scorton, Tadcaster, and Beverley. He gave many proofs -while young of a particular turn for chemistry and natural philosophy, -both by reading all books of that description which fell in his way, -and by making various little experiments which the perusal of these -books suggested. His first experiment was made at nine years of age, -when he prepared a quantity of gunpowder for fireworks, according to -directions contained in some scientific book to which he had access. - -In the choice of a profession, his attention was naturally directed -towards medicine, as being more nearly allied to his philosophical -pursuits. He went accordingly to Edinburgh, about the year 1781, where -he laid the foundation of his chemical knowledge under Dr. Black. In -1782 he was entered a member of Christ's College, Cambridge, where he -began, from that time, to reside. He was first entered as a pensioner; -but disliking the ordinary discipline and routine of an academical -life, he obtained an exemption from those restraints, by becoming a -fellow commoner. During his residence at Cambridge his chief attention -was bestowed on chemistry and botany; though he made himself also -acquainted with the elementary parts of mathematics, and had mastered -the most important parts of Newton's Principia. - -In 1784 he travelled into Denmark and Sweden, chiefly with the view of -becoming personally acquainted with Scheele, for whom he had imbibed -a high admiration. He was much gratified by what he saw of this -extraordinary man, and was particularly struck with the simplicity of -the apparatus with which his great experiments had been performed. On -his return to England he took great pleasure in showing his friends at -Cambridge various mineralogical specimens, which had been presented to -him by Scheele, and in exhibiting several interesting experiments which -he had learned from that great chemist. A year or two afterwards he -went to France, to become personally acquainted with the most eminent -of the French chemists. Thence he went to Holland and the Netherlands, -at that time in a state of insurrection against Joseph II. - -In 1786 he left Christ's College along with Professor Hermann, and -removed with him to Emmanuel College. In 1788 he took his first degree -as bachelor of physic, and soon after quitted Cambridge and came to -reside in London. In 1791 he made his celebrated analysis of carbonic -acid, which fully confirmed the opinions previously stated by Lavoisier -respecting the constituents of this substance. His mode was to pass -phosphorus through red-hot carbonate of lime. The phosphorus was -acidified, and charcoal deposited. It was during these experiments that -he discovered phosphuret of lime. - -In 1792 he again visited Paris; but, from circumstances, being afraid -of a convulsion, he was fortunate enough to leave that city the day -before the memorable 10th of August. He travelled through Italy, and -then passed through part of Germany. On his return to Paris, in -the beginning of 1793, he was deeply impressed with the gloom and -desolation arising from the system of terror then beginning to prevail -in that capital. On calling at the house of M. Delametherie, of whose -simplicity and moderation he had a high opinion, he found the doors -and windows closed, as if the owner were absent. Being at length -admitted, he found his friend sitting in a back room, by candle-light, -with the shutters closed in the middle of the day. On his departure, -after a hurried and anxious conversation, his friend conjured him not -to come again, as the knowledge of his being there might be attended -with serious consequences to them both. To the honour of Delametherie, -it deserves to be stated, that through all the inquisitions of the -revolution, he preserved for his friend property of considerable value, -which Mr. Tennant had intrusted to his care. - -On his return from the continent, he took lodgings in the Temple, -where he continued to reside during the rest of his life. He still -continued the study of medicine, and attended the hospitals, but became -more indifferent about entering into practice. He took, however, a -doctor's degree at Cambridge in 1796; but resolved, as his fortune -was independent, to relinquish all idea of practice, as not likely -to contribute to his happiness. Exquisite sensibility was a striking -feature in his character, and it would, as he very properly conceived, -have made him peculiarly unfit for the exercise of the medical -profession. It may be worth while to relate an example of his practical -benevolence which happened about this time. - -He had a steward in the country, in whom he had long placed implicit -confidence, and who was considerably indebted to him. In consequence -of this man's becoming embarrassed in his circumstances, Mr. Tennant -went into the country to examine his accounts. A time and place were -appointed for him to produce his books, and show the extent of the -deficiency; but the unfortunate steward felt himself unequal to the -task of such an explanation, and in a fit of despair put an end to -his existence. Touched by this melancholy event, Mr. Tennant used his -utmost exertions for the relief and protection of the family whom -he had left, and not only forgave them the debt, but afforded them -pecuniary assistance, and continued ever afterwards to be their friend -and benefactor. - -During the year 1796 he made his experiments to prove that the diamond -is pure carbon. His method was to heat it in a gold tube, with -saltpetre. The diamond was converted into carbonic acid gas, which -combined with the potash from the saltpetre, and by the evolution of -which the quantity of carbon, in a given weight of diamond, might be -estimated. A characteristic trait of Mr. Tennant occurred during the -course of this experiment, which I relate on the authority of Dr. -Wollaston, who was present as an assistant, and who related the fact to -me. Mr. Tennant was in the habit of taking a ride on horseback every -day at a certain hour. The tube containing the diamond and saltpetre -were actually heating, and the experiment considerably advanced, when, -suddenly recollecting that his hour for riding was come, he left the -completion of the process to Dr. Wollaston, and went out as usual to -take his ride. - -In the year 1797, in consequence of a visit to a friend in -Lincolnshire, where he witnessed the activity with which improvements -in farming operations were at that time going on, he was induced to -purchase some land in that country, in order to commence farming -operations. In 1799 he bought a considerable tract of waste land in -Somersetshire, near the village of Cheddar, where he built a small -house, in which, during the remainder of his life, he was in the habit -of spending some months every summer, besides occasional visits at -other times of the year. These farming speculations, as might have -been anticipated from the indolent and careless habits of Mr. Tennant, -were not very successful. Yet it appears from the papers which he left -behind him, that he paid considerable attention to agriculture, that he -had read the best books on the subject, and collected many facts on it -during his different journeys through various parts of England. In the -course of these inquiries he had discovered that there were two kinds -of limestone known in the midland counties of England, one of which -yielded a lime injurious to vegetation. He showed, in 1799, that the -presence of carbonate of magnesia is the cause of the bad qualities of -this latter kind of limestone. He found that the magnesian limestone -forms an extensive stratum in the midland counties, and that it occurs -also in primitive districts under the name of dolomite. - -He infers from the slow solubility of this limestone in acids, that -it is a double salt composed of carbonate of lime and carbonate of -magnesia in chemical combination. He found that grain would scarcely -germinate, and that it soon perished in moistened carbonate of -magnesia: hence he concluded that magnesia is really injurious to -vegetation. Upon this principle he accounted for the injurious effects -of the magnesian limestone when employed as a manure. - -In 1802 he showed that emery is merely a variety of corundum, or of the -precious stone known by the name of sapphire. - -During the same year, while endeavouring to make an alloy of lead -with the powder which remains after treating crude platinum with -aqua regia, he observed remarkable properties in this powder, and -found that it contained a new metal. While he was engaged in the -investigation, Descotils had turned his attention to the same powder, -and had discovered that it contained a metal which gives a red colour -to the ammoniacal precipitate of platinum. Soon after, Vauquelin, -having treated the powder with alkali, obtained a volatile metallic -oxide, which he considered as the same metal that had been observed by -Descotils. In 1804 Mr. Tennant showed that this powder contains two new -metals, to which he gave the name of _osmium_ and _iridium_. - -Mr. Tennant's health, by this time, had become delicate, and he seldom -went to bed without a certain quantity of fever, which often obliged -him to get up during the night and expose himself to the cold air. To -keep himself in any degree in health, he found it necessary to take a -great deal of exercise on horseback. He was always an awkward and a bad -horseman, so that those rides were sometimes a little hazardous; and -I have more than once heard him say, that a fall from his horse would -some day prove fatal to him. In 1809 he was thrown from his horse near -Brighton, and had his collar-bone broken. - -In the year 1812 he was prevailed upon to deliver a few lectures on -the principles of mineralogy, to a number of his friends, among whom -were many ladies, and a considerable number of men of science and -information. These lectures were completely successful, and raised his -reputation very much among his friends as a lecturer. He particularly -excelled in the investigation of minerals by the blowpipe; and I have -heard him repeatedly say, that he was indebted for the first knowledge -of the mode of using that valuable instrument to Assessor Gahn Fahlun. - -In 1813, a vacancy occurring in the chemical professorship at -Cambridge, he was solicited to become a candidate. His friends exerted -themselves in his favour with unexampled energy; and all opposition -being withdrawn, he was elected professor in May, 1813. - -After the general pacification in 1814 he went to France, and repaired -to the southern provinces of that kingdom. He visited Lyons, Nismes, -Avignon, Marseilles, and Montpellier. He returned to Paris in November, -much gratified by his southern tour. He was to have returned to -England about the latter end of the year; but he continued to linger -on till the February following. On the 15th of that month he went to -Calais; but the wind blew directly into Calais harbour, and continued -unfavourable for several days. After waiting till the 20th he went to -Boulogne, in order to take the chance of a better passage from that -port. He embarked on board a vessel on the 22d, but the wind was still -adverse, and blew so violently that the vessel was obliged to put -back. When Mr. Tennant came ashore, he said that "it was in vain to -struggle with the elements, and that he was not yet tired of life." -It was determined, in case the wind should abate, to make another -trial in the evening. During the interval Mr. Tennant proposed to his -fellow-traveller, Baron Bulow, that they should hire horses and take -a ride. They rode at first along the sea-side; but, on Mr. Tennant's -suggestion, they went afterwards to Bonaparte's pillar, which stands on -an eminence about a league from the sea-shore, and which, having been -to see it the day before, he was desirous of showing to Baron Bulow. -On their return from thence they deviated a little from the road, in -order to look at a small fort near the pillar, the entrance to which -was over a fosse twenty feet deep. On the side towards them, there -was a standing bridge for some way, till it joined a drawbridge, which -turned on a pivot. The end next the fort rested on the ground. On the -side next to them it was usually fastened by a bolt; but the bolt had -been stolen about a fortnight before, and was not replaced. As the -bridge was too narrow for them to go abreast, the baron said he would -go first, and attempted to ride over it; but perceiving that it was -beginning to sink, he made an effort to pass the centre, and called out -to warn his companion of his danger; but it was too late: they were -both precipitated into the trench. The baron, though much stunned, -fortunately escaped without any serious hurt; but on recovering his -senses, and looking round for Mr. Tennant, he found him lying under his -horse nearly lifeless. He was taken, however, to the Civil Hospital, -as the nearest place ready to receive him. After a short interval, he -seemed in some slight degree to recover his senses, and made an effort -to speak, but without effect, and died within the hour. His remains -were interred a few days after in the public cemetery at Boulogne, -being attended to the grave by most of the English residents. - -There is another branch of investigation intimately connected with -analytical chemistry, the improvements in which have been attended -with great advantage, both to mineralogists and chemists. I mean the -use of the blowpipe, to make a kind of miniature analysis of minerals -in the dry way; so far, at least, as to determine the nature of the -constituents of the mineral under examination. This is attended with -many advantages, as a preliminary to a rigid analysis by solution. By -informing us of the nature of the constituents, it enables us to form -a plan of the analysis beforehand, which, in many cases, saves the -trouble and the tediousness of two separate analytical investigations; -for when we set about analyzing a mineral, of the nature of which we -are entirely ignorant, two separate sets of experiments are in most -cases indispensable. We must examine the mineral, in the first place, -to determine the nature of its constituents. These being known, we -can form a plan of an analysis, by means of which we can separate and -estimate in succession the amount of each constituent of the mineral. -Now a judicious use of the blowpipe often enables us to determine the -nature of the constituents in a few minutes, and thus saves the trouble -of the preliminary analysis. - -The blowpipe is a tube employed by goldsmiths in soldering. By means -of it, they force the flame of a candle or lamp against any particular -point which they wish to heat. This enables them to solder trinkets -of various kinds, without affecting any other part except the portion -which is required to be heated. Cronstedt and Engestroem first thought -of applying this little instrument to the examination of minerals. A -small fragment of the mineral to be examined, not nearly so large as -the head of a small pin, was put upon a piece of charcoal, and the -flame of a candle was made to play upon it by means of a blowpipe, so -as to raise it to a white heat. They observed whether it decrepitated, -or was dissipated, or melted; and whatever the effect produced was, -they were enabled from it to draw consequences respecting the nature of -the mineral under examination. - -The importance of this instrument struck Bergman, and induced him -to wish for a complete examination of the action of the heat of the -blowpipe upon all different minerals, either tried _per se_ upon -charcoal, or mixed with various fluxes; for three different substances -had been chosen as fluxes, namely, _carbonate of soda_, _borax_, and -_biphosphate of soda_; or, at least, what was in fact an equivalent -for this last substance, _ammonio-phosphate of soda_, or _microcosmic -salt_, at that time extracted from urine. This salt is a compound -of one integrant particle of phosphate of soda, and one integrant -particle of phosphate of ammonia. When heated before the blowpipe it -fuses, and the water of crystallization, together with the ammonia, are -gradually dissipated, so that at last nothing remains but biphosphate -of soda. These fluxes have been found to act with considerable energy -on most minerals. The carbonate of soda readily fuses with those that -contain much silica, while the borax and biphosphate of soda act most -powerfully on the bases, not sensibly affecting the silica, which -remains unaltered in the fused bead. A mixture of borax and carbonate -of soda upon charcoal in general enables us to reduce the metallic -oxides to the state of metals, provided we understand the way of -applying the flame properly. Bergman employed Gahn, who was at that -time his pupil, and whose skill he was well acquainted with, to make -the requisite experiments. The result of these experiments was drawn -up into a paper, which Bergman sent to Baron Born in 1777, and they -were published by him at Vienna in 1779. This valuable publication -threw a new light upon the application of the blowpipe to the assaying -of minerals; and for every thing new which it contained Bergman was -indebted to Gahn, who had made the experiments. - -John Gottlieb Gahn, the intimate friend of Bergman and of Scheele, -was one of the best-informed men, and one whose manners were the most -simple, unaffected, and pleasing, of all the men of science with whom I -ever came in contact. I spent a few days with him at Fahlun, in 1812, -and they were some of the most delightful days that I ever passed in my -life. His fund of information was inexhaustible, and was only excelled -by the charming simplicity of his manners, and by the benevolence and -goodness of heart which beamed in his countenance. He was born on the -17th of August, 1745, at the Woxna iron-works, in South Helsingland, -where his father, Hans Jacob Gahn, was treasurer to the government -of Stora Kopperberg. His grandfather, or great-grandfather, he told -me, had emigrated from Scotland; and he mentioned several families in -Scotland to which he was related. After completing his school education -at Westeräs, he went, in the year 1760, to the University of Upsala. -He had already shown a decided bias towards the study of chemistry, -mineralogy, and natural philosophy; and, like most men of science in -Sweden, where philosophical instrument-makers are scarcely to be found, -he had accustomed himself to handle the different tools, and to supply -himself in that manner with all the different pieces of apparatus which -he required for his investigations. He seems to have spent nearly -ten years at Upsala, during which time he acquired a very profound -knowledge in chemistry, and made various important discoveries, which -his modesty or his indifference to fame made him allow others to pass -as their own. The discovery of the rhomboidal nucleus of carbonate of -lime in a six-sided prism of that mineral, which he let fall, and which -was accidentally broken, constitutes the foundation of Hauy's system of -crystallization. He communicated the fact to Bergman, who published it -as his own in the second volume of his Opuscula, without any mention of -Gahn's name. - -The earth of bones had been considered as a peculiar simple earth; but -Gahn ascertained, by analysis, that it was a compound of phosphoric -acid and lime; and this discovery he communicated to Scheele, who, -in his paper on fluor spar, published in 1771, observed, in the -seventeenth section, in which he is describing the effect of phosphoric -acid on fluor spar, "It has lately been discovered that the earth of -bones, or of horns, is calcareous earth combined with phosphoric acid." -In consequence of this remark, in which the name of Gahn does not -appear, it was long supposed that Scheele, and not Gahn, was the author -of this important discovery. - -It was during this period that he demonstrated the metallic nature of -manganese, and examined the properties of the metal. This discovery was -announced as his, at the time, by Bergman, and was almost the only one -of the immense number of new facts which he had ascertained that was -publicly known to be his. - -On the death of his father he was left in rather narrow circumstances, -which obliged him to turn his immediate attention to mining and -metallurgy. To acquire a practical knowledge of mining he associated -with the common miners, and continued to work like them till he had -acquired all the practical dexterity and knowledge which actual labour -could give. In 1770 he was commissioned by the College of Mines to -institute a course of experiments, with a view to improve the method of -smelting copper, at Fahlun. The consequence of this investigation was a -complete regeneration of the whole system, so as to save a great deal -both of time and fuel. - -Sometime after, he became a partner in some extensive works at Stora -Kopperberg, where he settled as a superintendent. From 1770, when he -first settled at Fahlun, down to 1785, he took a deep interest in the -improvement of the chemical works in that place and neighbourhood. He -established manufactories of sulphur, sulphuric acid, and red ochre. - -In 1780 the Royal College of Mines, as a testimony of their sense of -the value of Gahn's improvements, presented him with a gold medal of -merit. In 1782 he received a royal patent as mining master. In 1784 he -was appointed assessor in the Royal College of Mines, in which capacity -he officiated as often as his other vocations permitted him to reside -in Stockholm. The same year he married Anna Maria Bergstrom, with whom -he enjoyed for thirty-one years a life of uninterrupted happiness. By -his wife he had a son and two daughters. - -In the year 1773 he had been elected chemical stipendiary to the Royal -College of Mines, and he continued to hold this appointment till the -year 1814. During the whole of this period the solution of almost -every difficult problem remitted to the college devolved upon him. In -1795 he was chosen a member of the committee for directing the general -affairs of the kingdom. In 1810 he was made one of the committee for -the general maintenance of the poor. In 1812 he was elected an active -associate of the Royal Academy for Agriculture; and in 1816 he became a -member of the committee for organizing the plan of a Mining Institute. -In 1818 he was chosen a member of the committee of the Mint; but from -this situation he was shortly after, at his own request, permitted to -withdraw. - -His wife died in 1815, and from that period his health, which had never -been robust, visibly declined. Nature occasionally made an effort to -shake off the disease; but it constantly returned with increasing -strength, until, in the autumn of 1818, the decay became more rapid in -its progress, and more decided in its character. He became gradually -weaker, and on the 8th of December, 1818, died without a struggle, and -seemingly without pain. - -Ever after the experiments on the blowpipe which Gahn performed at -the request of Bergman, his attention had been turned to that piece -of apparatus; and during the course of a long life he had introduced -so many improvements, that he was enabled, by means of the blowpipe, -to determine in a few minutes the constituents of almost any mineral. -He had gone over almost all the mineral kingdom, and determined the -behaviour of almost every mineral before the blowpipe, both by itself -and when mixed with the different fluxes and reagents which he had -invented for the purpose of detecting the different constituents; but, -from his characteristic unwillingness to commit his observations and -experiments to writing, or to draw them up into a regular memoir, had -not Berzelius offered himself as an assistant, they would probably -have been lost. By his means a short treatise on the blowpipe, with -minute directions how to use the different contrivances which he had -invented, was drawn up and inserted in the second volume of Berzelius's -Chemistry. Berzelius and he afterwards examined all the minerals -known, or at least which they could procure, before the blowpipe; -and the result of the whole constituted the materials of Berzelius's -treatise on the blowpipe, which has been translated into German, -French, and English. It may be considered as containing the sum of -all the improvements which Gahn had made on the use of the blowpipe, -together with all the facts that he had collected respecting the -phenomena exhibited by minerals before the blowpipe. It constitutes an -exceedingly useful and valuable book, and ought to make a part of the -library of every analytical chemist. - -Dr. Wollaston had paid as much attention to the blowpipe as Gahn, and -had introduced so many improvements into its use, that he was able, -by means of it, to determine the nature of the constituents of any -mineral in the course of a few minutes. He was fond of such analytical -experiments, and was generally applied to by every person who thought -himself possessed of a new mineral, in order to be enabled to state -what its constituents were. The London mineralogists if the race be not -extinct, must sorely feel the want of the man to whom they were in the -habit of applying on all occasions, and to whom they never applied in -vain. - -Dr. William Hyde Wollaston, was the son of the Reverend Dr. Wollaston, -a clergyman of some rank in the church of England, and possessed of a -competent fortune. He was a man of abilities, and rather eminent as an -astronomer. His grandfather was the celebrated author of the Religion -of Nature delineated. Dr. William Hyde Wollaston was born about the -year 1767, and was one of fifteen children, who all reached the age of -manhood. His constitution was naturally feeble; but by leading a life -of the strictest sobriety and abstemiousness he kept himself in a state -fit for mental exertion. He was educated at Cambridge, where he was at -one time a fellow. After studying medicine by attending the hospitals -and lectures in London, and taking his degree of doctor at Cambridge, -he settled at Bury St. Edmund's, where he practised as a physician -for some years. He then went to London, became a fellow of the Royal -College of Physicians, and commenced practitioner in the metropolis. A -vacancy occurring in St. George's Hospital, he offered himself for the -place of physician to that institution; but another individual, whom he -considered his inferior in knowledge and science, having been preferred -before him, he threw up the profession of medicine altogether, and -devoted the rest of his life to scientific pursuits. His income, in -consequence of the large family of his father, was of necessity small. -In order to improve it he turned his thoughts to the manufacture of -platinum, in which he succeeded so well, that he must have, by means -of it, realized considerable sums. It was he who first succeeded in -reducing it into ingots in a state of purity and fit for every kind of -use: it was employed, in consequence, for making vessels for chemical -purposes; and it is to its introduction that we are to ascribe the -present accuracy of chemical investigations. It has been gradually -introduced into the sulphuric acid manufactories, as a substitute for -glass retorts. - -Dr. Wollaston had a particular turn for contriving pieces of apparatus -for scientific purposes. His reflecting goniometer was a most valuable -present to mineralogists, and it is by its means that crystallography -has acquired the great degree of perfection which it has recently -exhibited. He contrived a very simple apparatus for ascertaining the -power of various bodies to refract light. His camera lucida furnished -those who were ignorant of drawing with a convenient method of -delineating natural objects. His periscopic glasses must have been -found useful, for they sold rather extensively: and his sliding rule -for chemical equivalents furnished a ready method for calculating the -proportions of one substance necessary to decompose a given weight of -another. - -Dr. Wollaston's knowledge was more varied, and his taste less exclusive -than any other philosopher of his time, except Mr. Cavendish: but -optics and chemistry are the two sciences which lie under the greatest -obligations to him. His first chemical paper on urinary calculi at once -added a vast deal to what had been previously known. He first pointed -out the constituents of the mulberry calculi, showing them to be -composed of oxalate of lime and animal matter. He first distinguished -the nature of the triple phosphates. It was he who first ascertained -the nature of the cystic oxides, and of the chalk-stones, which appear -occasionally in the joints of gouty patients. To him we owe the first -demonstration of the identity of galvanism and common electricity; -and the first explanation of the cause of the different phenomena -exhibited by galvanic and common electricity. To him we are indebted -for the discovery of palladium and rhodium, and the first account of -the properties and characters of these two metals. He first showed -that oxalic acid and potash unite in three different proportions, -constituting oxalate, binoxalate, and quadroxalate of potash. Many -other chemical facts, first ascertained by him, are to be found in the -numerous papers of his scattered over the last forty volumes of the -Philosophical Transactions: and perhaps not the least valuable of them -is his description of the mode of reducing platinum from the raw state, -and bringing it into the state of an ingot. - -Dr. Wollaston died in the month of January, 1829, in consequence of -a tumour formed in the brain, near, if I remember right, the thalami -nervorum opticorum. There is reason to suspect that this tumour had -been some time in forming. He had, without exception, the sharpest -eye that I have ever seen: he could write with a diamond upon glass -in a character so small, that nothing could be distinguished by the -naked eye but a ragged line; yet when the letters were viewed through -a microscope, they were beautifully regular and quite legible. He -retained his senses to almost the last moment of his life: when he lay -apparently senseless, and his friends were anxiously solicitous whether -he still retained his understanding, he informed them, by writing, that -his senses were still perfectly entire. Few individuals ever enjoyed a -greater share of general respect and confidence, or had fewer enemies, -than Dr. Wollaston. He was at first shy and distant, and remarkably -circumspect, but he grew insensibly more and more agreeable as you got -better acquainted with him, till at last you formed for him the most -sincere friendship, and your acquaintance ended in the warmest and -closest attachment. - - - - -CHAPTER V. - -OF ELECTRO-CHEMISTRY. - - -Electricity, like chemistry, is a modern science; for it can scarcely -claim an older origin than the termination of the first quarter of -the preceding century; and during the last half of that century, and -a small portion of the present, it participated with chemistry in the -zeal and activity with which it was cultivated by the philosophers -of Europe and America. For many years it was not suspected that any -connexion existed between chemistry and electricity; though some of the -meteorological phenomena, especially the production of clouds and the -formation of rain, which are obviously connected with chemistry, seem -likewise to claim some connexion with the agency of electricity. - -The discovery of the intimate relation between chemistry and -electricity was one of the consequences of a controversy carried -on about the year 1790 between Galvani and Volta, two Italian -philosophers, whose discoveries will render their names immortal. -Galvani, who was a professor of anatomy, was engaged in speculations -respecting muscular motion. He was of opinion that a peculiar fluid -was secreted in the brain, which was sent along the nerves to all -the different parts of the body. This nervous fluid possessed many -characters analogous to those of electricity: the muscles were capable -of being charged with it somewhat like a Leyden phial; and it was by -the discharge of this accumulation, by the voluntary power of the -nerves, that muscular motion was produced. He accidently discovered, -that if the crural nerve going into the muscles of a frog, and the -crural muscles, be laid bare immediately after death, and a piece of -zinc be placed in contact with the nerve, and a piece of silver or -copper with the muscle; when these two pieces of metal are made to -touch each other, violent convulsions are produced in the muscle, -which cause the limb to move. He conceived that these convulsions were -produced by the discharge of the nervous energy from the muscles, in -consequence of the conducting power of the metals. - -Volta, who repeated these experiments, explained them in a different -manner. According to him, the convulsions were produced by the passage -of a current of common electricity through the limb of the frog, -which was thrown into a state of convulsion merely in consequence of -its irritability. This irritability vanishes after the death of the -muscle; accordingly it is only while the principle of life remains that -the convulsions can be produced. Every metallic conductor, according -to him, possesses a certain electricity which is peculiar to it, -either positive or negative, though the quantity is so small, as to -be imperceptible, in the common state of the metal. But if a metal, -naturally positive, be placed in contact, while insulated, with a metal -naturally negative, the charge of electricity in both is increased by -induction, and becomes perceptible when the two metals are separated -and presented to a sufficiently delicate electrometer. Thus zinc is -naturally positive, and copper and silver naturally negative. If we -take two discs of copper and zinc, to the centre of each of which a -varnished glass handle is cemented, and after keeping them for a short -time in contact, separate them by the handles, and apply each to a -sufficiently delicate electrometer, we shall find that the zinc is -positive, and the silver or copper disc negative. When the silver and -copper are placed in contact while lying on the nerve and muscles of -the leg of a frog, the zinc becomes positive, and the silver negative, -by induction; but, as the animal substance is a conductor, this state -cannot continue: the two electricities pass through the conducting -muscles and nerve, and neutralize one another. And it is this current -which occasions the convulsions. - -Such was Volta's simple explanation of the convulsions produced in -galvanic experiments in the limb of a frog. Galvani was far from -allowing the accuracy of it; and, in order to obviate the objection to -his reasoning advanced by Volta from the necessity of employing two -metals, he showed that the convulsions might, in certain cases, be -produced by one metal. Volta showed that a very small quantity of one -metal, either alloyed with, or merely in contact with another, were -capable of inducing the two electricities. But in order to prove in the -most unanswerable manner that the two electricities were induced when -two different metals were placed in contact, he contrived the following -piece of apparatus: - -He procured a number (say 50) of pieces of zinc, about the size of -a crown-piece, and as many pieces of copper, and thirdly, the same -number of pieces of card of the same size. The cards were steeped in -a solution of salt, so as to be moist. He lays upon the table a piece -of zinc, places over it a piece of copper, and then a piece of moist -card. Over the card is placed a second piece of zinc, then a piece -of copper, then a piece of wet card. In this way all the pieces are -piled upon each other in exactly the same order, namely, zinc, copper, -card; zinc, copper, card; zinc, copper, card. So that the lowest plate -is zinc and the uppermost is copper (for the last wet card may be -omitted). In this way there are fifty pairs of zinc and copper plates -in contact, each separated by a piece of wet card, which is a conductor -of electricity. If you now moisten a finger of each hand with water, -and apply one wet finger to the lowest zinc plate, and the other to the -highest copper plate, the moment the fingers come in contact with the -plates an electric shock is felt, the intensity of which increases with -the number of pairs of plates in the pile. This is what is called the -Galvanic, or rather the Voltaic pile. It was made known to the public -in a paper by Volta, inserted in the Philosophical Transactions for -1800. This pile was gradually improved, by substituting troughs, first -of baked wood, and afterwards of porcelain, divided into as many cells -as there were pairs of plates. The size of the plates was increased; -they were made square, and instead of all being in contact, it was -found sufficient if they were soldered together by means of metallic -slips rising from one side of each square. The two plates thus soldered -were slipped over the diaphragm separating the contiguous cells, so -that the zinc plate was in one cell and the copper in the other. Care -was taken that the pairs were introduced all looking one way, so that -a copper plate had always a zinc plate immediately opposite to it. -The cells were filled with conducting liquid: brine, or a solution of -salt in vinegar, or dilute muriatic, sulphuric, or nitric acid, might -be employed; but dilute nitric acid was found to answer best, and the -energy of the battery is directly proportional to the strength of the -nitric acid employed. - -Messrs. Nicholson and Carlisle were the first persons who repeated -Volta's experiments with this apparatus, which speedily drew the -attention of all Europe. They ascertained that the zinc end of the -pile was positive and the copper end negative. Happening to put a drop -of water on the uppermost plate, and to put into it the extremity -of a gold wire connected with the undermost plate, they observed an -extrication of air-bubbles from the wire. This led them to suspect that -the water was decomposed. To determine the point, they collected a -little of the gas extricated and found it hydrogen. They then attached -a gold wire to the zinc end of the pile, and another gold wire to the -copper end, and plunged the two wires into a glass of water, taking -care not to allow them to touch each other. Gas was extricated from -both wires. On collecting that from the wire attached to the zinc end, -it was found to be _oxygen gas_, while that from the copper end was -hydrogen gas. The volume of hydrogen gas extricated was just double -that of the oxygen gas; and the two gases being mixed, and an electric -spark passed through them, they burnt with an explosion, and were -completely converted into water. Thus it was demonstrated that water -was decomposed by the action of the pile, and that the oxygen was -extricated from the positive pile and the hydrogen from the negative. -This held when the communicating wires were gold or platinum; but -if they were of copper, silver, iron, lead, tin, or zinc, then only -hydrogen gas was extricated from the negative wire. The positive wire -extricated little or no gas; but it was rapidly oxidized. Thus the -connexion between chemical decompositions and electrical currents was -first established. - -It was soon after observed by Henry, Haldane, Davy, and other -experimenters, that other chemical compounds were decomposed by the -electrical currents as well as water. Ammonia, for example, nitric -acid, and various salts, were decomposed by it. In the year 1803 an -important set of experiments was published by Berzelius and Hisinger. -They decomposed eleven different salts, by exposing them to the action -of a current of electricity. The salts were dissolved in water, and -iron or silver wires from the two poles of the pile were plunged into -the solution. In every one of these decompositions, the acid was -deposited round the positive wire, and the base of the salt round the -negative wire. When ammonia was decomposed by the action of galvanic -electricity, the azotic gas separated from the positive wire, and the -hydrogen gas from the negative. - -But it was Davy that first completely elucidated the chemical -decompositions produced by galvanic electricity, who first explained -the laws by which these decompositions were regulated, and who employed -galvanism as an instrument for decomposing various compounds, which had -hitherto resisted all the efforts of chemists to reduce them to their -elements. These discoveries threw a blaze of light upon the obscurest -parts of chemistry, and secured for the author of them an immortal -reputation. - -Humphry Davy, to whom these splendid discoveries were owing, was born -at Penzance, in Cornwall, in the year 1778. He displayed from his very -infancy a spirit of research, and a brilliancy of fancy, which augured, -even at that early period, what he was one day to be. When very -young, he was bound apprentice to an apothecary in his native town. -Even at that time, his scientific acquirements were so great, that -they drew the attention of Mr. Davis Gilbert, the late distinguished -president of the Royal Society. It was by his advice that he resolved -to devote himself to chemistry, as the pursuit best calculated to -procure him celebrity. About this time Mr. Gregory Watt, youngest son -of the celebrated improver of the steam-engine, happening to be at -Penzance, met with young Davy, and was delighted with the uncommon -knowledge which he displayed, at the brilliancy of his fancy, and -the great dexterity and ardour with which, under circumstances the -most unfavourable, he was prosecuting his scientific investigations. -These circumstances made an indelible impression on his mind, and led -him to recommend Davy as the best person to superintend the Bristol -Institution for trying the medicinal effects of the gases. - -After the discovery of the different gases, and the investigation of -their properties by Dr. Priestley, it occurred to various individuals, -nearly about the same time, that the employment of certain gases, or -at least of mixtures of certain gases, with common air in respiration, -instead of common air, might be powerful means of curing diseases. -Dr. Beddoes, at that time professor of chemistry at Oxford, was one -of the keenest supporters of these opinions. Mr. Watt, of Birmingham, -and Mr. Wedgewood, entertained similar sentiments. About the beginning -of the present century, a sum of money was raised by subscription, -to put these opinions to the test of experiment; and, as Dr. Beddoes -had settled as a physician in Bristol, it was agreed upon that the -experimental investigation should take place at Bristol. But Dr. -Beddoes was not qualified to superintend an institution of the kind: -it was necessary to procure a young man of zeal and genius, who would -take such an interest in the investigation as would compensate for -the badness of the apparatus and the defects of the arrangements. The -greatest part of the money had been subscribed by Mr. Wedgewood and -Mr. Watt: their influence of course would be greatest in recommending -a proper superintendent. Gregory Watt thought of Mr. Davy, whom he -had lately been so highly pleased with, and recommended him with -much zeal to superintend the undertaking. This recommendation being -seconded by that of Mr. Davis Gilbert, who was so well acquainted -with the scientific acquirements and genius of Davy, proved -successful, and Davy accordingly got the appointment. At Bristol he -was employed about a year in investigating the effects of the gases -when employed in respiration. But he did not by any means confine -himself to this, which was the primary object of the institution; -but investigated the properties and determined the composition of -nitric acid, ammonia, protoxide of azote and deutoxide of azote. -The fruit of his investigations was published in 1800, in a volume -entitled, "Researches, Chemical and Philosophical; chiefly concerning -Nitrous Oxide, or Dephlogisticated Nitrous Air, and its Respiration." -This work gave him at once a high reputation as a chemist, and was -really a wonderful performance, when the circumstances under which -it was produced are taken into consideration. He had discovered the -intoxicating effects which protoxide of azote (nitrous oxide) produces -when breathed, and had tried their effects upon a great number of -individuals. This fortunate discovery perhaps contributed more to his -celebrity, and to his subsequent success, than all the sterling merit -of the rest of his researches--so great is the effect of display upon -the greater part of mankind. - -A few years before, a philosophical institution had been established -in London, under the auspices of Count Rumford, which had received -the name of the Royal Institution. Lectures on chemistry and natural -philosophy were delivered in this institution; a laboratory was -provided, and a library established. The first professor appointed to -this institution, Dr. Garnet, had been induced, in consequence of some -disagreement between him and Count Rumford, to throw up his situation. -Many candidates started for it; but Davy, in consequence of the -celebrity which he had acquired by his researches, or perhaps by the -intoxicating effects of protoxide of azote, which he had discovered, -was, fortunately for the institution and for the reputation of England, -preferred to them all. He was appointed professor of chemistry, and Dr. -Thomas Young professor of natural philosophy, in the year 1801. Davy, -either from the more popular nature of his subject, or from his greater -oratorical powers, became at once a popular lecturer, and always -lectured to a crowded room; while Dr. Young, though both a profound and -clear lecturer, could scarcely command an audience of a dozen. It was -here that Davy laboured with unwearied industry during eleven years, -and acquired, by his discoveries the highest reputation of any chemist -in Europe. - -In 1811 he was knighted, and soon after married Mrs. Apreece, a widow -lady, daughter of Mr. Ker, who had been secretary to Lord Rodney, and -had made a fortune in the West Indies. He was soon after created a -baronet. About this time he resigned his situation as professor of -chemistry in the Royal Institution, and went to the continent. He -remained for some years in France and Italy. In the year 1821, when Sir -Joseph Banks died, a very considerable number of the fellows offered -their votes to Dr. Wollaston; but he declined standing as a candidate -for the president's chair. Sir Humphry Davy, on the other hand, was -anxious to obtain that honourable situation, and was accordingly -elected president by a very great majority of votes on the 30th of -November, 1821. This honourable situation he filled about seven years; -but his health declining, he was induced to resign in 1828, and to go -to Italy. Here he continued till 1829, when feeling himself getting -worse, and wishing to draw his last breath in his own country, he began -to turn his way homewards; but at Geneva he felt himself so ill, that -he was unable to proceed further: here he took to his bed, and here he -died on the 29th of May, 1829. - -It was his celebrated paper "On some chemical Agencies of Electricity," -inserted in the Philosophical Transactions for 1807, that laid the -foundation of the high reputation which he so deservedly acquired. I -consider this paper not merely as the best of all his own productions, -but as the finest and completest specimen of inductive reasoning -which appeared during the age in which he lived. It had been already -observed, that when two platinum wires from the two poles of a galvanic -pile are plunged each into a vessel of water, and the two vessels -united by means of wet asbestos, or any other conducting substance, -an _acid_ appeared round the positive wire and an _alkali_ round the -negative wire. The alkali was said by some to be _soda_, by others -to be _ammonia_. The acid was variously stated to be _nitric acid_, -_muriatic acid_, or even _chlorine_. Davy demonstrated, by decisive -experiments, that in all cases the acid and alkali are derived from -the decomposition of some salt contained either in the water or in -the vessel containing the water. Most commonly the salt decomposed -is common salt, because it exists in water and in agate, basalt, and -various other stony bodies, which he employed as vessels. When the same -agate cup was used in successive experiments, the quantity of acid -and alkali evolved diminished each time, and at last no appreciable -quantity could be perceived. When glass vessels were used, soda was -disengaged at the expense of the glass, which was sensibly corroded. -When the water into which the wires were dipped was perfectly pure, -and when the vessel containing it was free from every trace of saline -matter, no acid or alkali made its appearance, and nothing was evolved -except the constituents of water, namely, oxygen and hydrogen; the -oxygen appearing round the positive wire, and the hydrogen round the -negative wire. - -When a salt was put into the vessel in which the positive wire dipped, -the vessel into which the negative wire dipped being filled with -pure water, and the two vessels being united by means of a slip of -moistened asbestos, the acid of the salt made its appearance round the -positive wire, and the alkali round the negative wire, before it could -be detected in the intermediate space; but if an intermediate vessel, -containing a substance for which the alkali has a strong affinity, be -placed between these two vessels, the whole being united by means of -slips of asbestos, then great part, or even the whole of the alkali, -was stopped in this intermediate vessel. Thus, if the salt was nitrate -of barytes, and sulphuric acid was placed in the intermediate vessel, -much sulphate of barytes was deposited in the intermediate vessel, and -very little or even no barytes made its appearance round the negative -wire. Upon this subject a most minute, extensive, and satisfactory -series of experiments was made by Davy, leaving no doubt whatever of -the accuracy of the fact. - -The conclusions which he drew from these experiments are, that all -substances which have a chemical affinity for each other, are in -different states of electricity, and that the degree of affinity is -proportional to the intensity of these opposite states. When such -a compound body is placed in contact with the poles of a galvanic -battery, the positive pole attracts the constituent, which is -negative, and repels the positive. The negative acts in the opposite -way, attracting the positive constituent and repelling the negative. -The more powerful the battery, the greater is the force of these -attractions and repulsions. We may, therefore, by increasing the -energy of a battery sufficiently, enable it to decompose any compound -whatever, the negative constituent being attracted by the positive -pole, and the positive constituent by the negative pole. Oxygen, -chlorine, bromine, iodine, cyanogen, and acids, are _negative_ bodies; -for they always appear round the _positive_ pole of the battery, and -are therefore attracted to it: while hydrogen, azote, carbon, selenium, -metals, alkalies, earths, and oxide bases, are deposited round the -negative pole, and consequently are _positive_. - -According to this view of the subject, chemical affinity is merely -a case of the attractions exerted by bodies in different states of -electricity. Volta first broached the idea, that every body possesses -naturally a certain state of electricity. Davy went a step further, -and concluded, that the attractions which exist between the atoms of -different bodies are merely the consequence of these different states -of electricity. The proof of this opinion is founded on the fact, that -if we present to a compound, sufficiently strong electrical poles, it -will be separated into its constituents, and one of these constituents -will invariably make its way to the positive and the other to the -negative pole. Now bodies in a state of electrical excitement always -attract those that are in the opposite state. - -If electricity be considered as consisting of two distinct fluids, -which attract each other with a force inversely, as the square of the -distance, while the particles of each fluid repel each other with a -force varying according to the same law, then we must conclude that -the atoms of each body are covered externally with a coating of some -one electric fluid to a greater or smaller extent. Oxygen and the -other supporters of combustion are covered with a coating of negative -electricity; while hydrogen, carbon, and the metals, are covered with -a coating of positive electricity. What is the cause of the adherence -of the electricity to these atoms we cannot explain. It is not owing to -an attraction similar to gravitation; for electricity never penetrates -into the interior of bodies, but spreads itself only on the surface, -and the quantity of it which can accumulate is not proportional to -the quantity of matter but to the extent of surface. But whatever be -the cause, the adhesion is strong, and seemingly cannot be overcome. -If we were to suppose an atom of any body, of oxygen for example, to -remain uncombined with any other body, but surrounded by electricity, -it is obvious that the coating of negative electricity on its surface -would be gradually neutralized by its attracting and combining with -positive electricity. But let us suppose an atom of oxygen and an atom -of hydrogen to be united together, it is obvious that the positive -electricity of the one atom would powerfully attract the negative -electricity of the other, and _vice versâ_. And if these respective -electricities cannot leave the atoms, the two atoms will remain firmly -united, and the opposite electrical intensities will in some measure -neutralize each other, and thus prevent them from being neutralized -by electricity from any other quarter. But a current of the opposite -electricities passing through such a compound, might neutralize the -electricity in each, and thus putting an end to their attractions, -occasion decomposition. - -Such is a very imperfect outline of the electrical theory of affinity -first proposed by Davy to account for the decompositions produced by -electricity. It has been universally adopted by chemists; and some -progress has been made in explaining and accounting for the different -phenomena. It would be improper, in a work of this kind, to enter -further into the subject. Those who are interested in such discussions -will find a good deal of information in the first volume of Berzelius's -Treatise on Chemistry, in the introduction to the Traité de Chimie -appliqué aux Arts, by Dumas, or in the introduction to my System of -Chemistry, at present in the press. - -Davy having thus got possession of an engine, by means of which the -compounds, whose constituents adhered to each other might be separated, -immediately applied it to the decomposition of potash and soda; -bodies which were admitted to be compounds, though all attempts to -analyze them had hitherto failed. His attempt was successful. When -a platinum wire from the negative pole of a strong battery in full -action was applied to a lump of potash, slightly moistened, and lying -on a platinum tray attached to the positive pole of the battery, small -globules of a white metal soon appeared at its extremity. This white -metal he speedily proved to be the basis of potash. He gave it the name -of _potassium_, and very soon proved, that potash is a compound of five -parts by weight of this metal and one part of oxygen. Potash, then, -is a metallic oxide. He proved soon after that soda is a compound of -oxygen and another white metal, to which he gave the name of _sodium_. -Lime is a compound of _calcium_ and oxygen, magnesia of _magnesium_ and -oxygen, barytes of _barium_ and oxygen, and strontian of _strontium_ -and oxygen. In short, the fixed alkalies and alkaline earths, are -metallic oxides. When _lithia_ was afterwards discovered by Arfvedson, -Davy succeeded in decomposing it also by the galvanic battery, and -resolving it into oxygen and a white metal, to which the name of -_lithium_ was given. - -Davy did not succeed so well in decomposing alumina, glucina, yttria, -and zirconia, by the galvanic battery: they were not sufficiently good -conductors of electricity; but nobody entertained any doubt that they -also were metallic oxides. They have been all at length decomposed, and -their bases obtained by the joint action of chlorine and potassium, -and it has been demonstrated, that they also are metallic oxides. Thus -it has been ascertained, in consequence of Davy's original discovery -of the powers of the galvanic battery, that all the bases formerly -distinguished into the four classes of alkalies, alkaline earths, -earths proper, and metallic oxides, belong in fact only to one class, -and are all metallic oxides. - -Important as these discoveries are, and sufficient as they would -have been to immortalize the author of them, they are not the only -ones for which we are indebted to Sir Humphry Davy. His experiments -on _chlorine_ are not less interesting or less important in their -consequences. I have already mentioned in a former chapter, that -Berthollet made a set of experiments on chlorine, from which he had -drawn as a conclusion, that it is a compound of oxygen and muriatic -acid, in consequence of which it got the name of _oxymuriatic acid_. -This opinion of Berthollet had been universally adopted by chemists, -and admitted by them as a fundamental principle, till Gay-Lussac -and Thenard endeavoured, unsuccessfully, to decompose this gas, or -to resolve it into muriatic acid and chlorine. They showed, in the -clearest manner, that such a resolution was impossible, and that no -direct evidence could be adduced to prove that oxygen was one of its -constituents. The conclusion to which they came was, that muriatic acid -gas contained water as an essential constituent; and they succeeded by -this hypothesis in accounting for all the different phenomena which -they had observed. They even made an experiment to determine the -quantity of water thus combined. They passed muriatic acid through hot -litharge (protoxide of lead); muriate of lead was formed, and abundance -of water made its appearance and was collected. They did not attempt to -determine the proportions; but we can now easily calculate the quantity -of water which would be deposited when a given weight of muriatic acid -gas is absorbed by a given weight of litharge. Suppose we have fourteen -parts of oxide of lead: to convert it into muriate of lead, 4·625 -parts (by weight) of muriatic acid would be necessary, and during the -formation of the muriate of lead there would be deposited 1·125 parts -of water. So that from this experiment it might be concluded, that -about one-fourth of the weight of muriatic acid gas is water. - -The very curious and important facts respecting chlorine and muriatic -acid gas which they had ascertained, were made known by Gay-Lussac -and Thenard to the Institute, on the 27th of February, 1809, and an -abstract of them was published in the second volume of the Mémoires -d'Arcueil. There can be little doubt that it was in consequence of -these curious and important experiments of the French chemists that -Davy's attention was again turned to muriatic acid gas. He had already, -in 1808, shown that when potassium is heated in muriatic acid gas, -muriate of potash is formed, and a quantity of hydrogen gas evolved, -amounting to more than one-third of the muriatic acid gas employed, -and he had shown, that in no case can muriatic acid be obtained from -chlorine, unless water or its elements be present. This last conclusion -had been amply confirmed by the new investigations of Gay-Lussac and -Thenard. In 1810 Davy again resumed the examination of the subject, and -in July of that year read a paper to the Royal Society, to prove that -_chlorine_ is a simple substance, and that muriatic acid is a compound -of _chlorine_ and _hydrogen_. - -This was introducing an alteration in chemical theory of the same -kind, and nearly as important, as was introduced by Lavoisier, with -respect to the action of oxygen in the processes of combustion and -calcination. It had been previously supposed that sulphur, phosphorus, -charcoal, and metals, were compounds; one of the constituents of which -was phlogiston, and the other the acids or oxides which remained after -the combustion or calcination had taken place. Lavoisier showed that -the sulphur, phosphorus, charcoal, and metals, were simple substances; -and that the acids or calces formed were compounds of these simple -bodies and oxygen. In like manner, Davy showed that chlorine, instead -of being a compound of muriatic acid and oxygen, was, in fact, a simple -substance, and muriatic acid a compound of chlorine and hydrogen. -This new doctrine immediately overturned the Lavoisierian hypothesis -respecting oxygen as the acidifying principle, and altered all the -previously received notions respecting the muriates. What had been -called _muriates_ were, in fact, combinations of chlorine with the -combustible or metal, and were analogous to oxides. Thus, when muriatic -acid gas was made to act upon hot litharge, a double decomposition -took place, the chlorine united to the lead, while the hydrogen of the -muriatic acid united with the oxygen of the litharge, and formed water. -Hence the reason of the appearance of water in this case; and hence it -was obvious that what had been called muriate of lead, was, in reality, -a compound of chlorine and metallic lead. It ought, therefore, to be -called, not muriate of lead, but chloride of lead. - -It was not likely that this new opinion of Davy should be adopted by -chemists in general, without a struggle to support the old opinions. -But the feebleness of the controversy which ensued, affords a striking -proof how much chemistry had advanced since the days of Lavoisier, and -how free from prejudices chemists had become. One would have expected -that the French chemists would have made the greatest resistance to the -admission of these new opinions; because they had a direct tendency -to diminish the reputation of two of their most eminent chemists, -Lavoisier and Berthollet. But the fact was not so: the French chemists -showed a degree of candour and liberality which redounds highly to -their credit. Berthollet did not enter at all into the controversy. -Gay-Lussac and Thenard, in their Recherches Physico-chimiques, -published in 1811, state their reasons for preferring the old -hypothesis to the new, but with great modesty and fairness; and, -within less than a year after, they both adopted the opinion of Davy, -that chlorine is a simple substance, and muriatic acid a compound of -hydrogen and chlorine. - -The only opponents to the new doctrine who appeared against it, -were Dr. John Murray, of Edinburgh, and Professor Berzelius, of -Stockholm. Dr. Murray was a man of excellent abilities, and a very -zealous cultivator of chemistry; but his health had been always very -delicate, which had prevented him from dedicating so much of his -time to experimenting as he otherwise would have been inclined to -do. The only experimental investigations into which he entered was -the analysis of some mineral waters. His powers of elocution were -great. He was, in consequence, a popular and very useful lecturer. He -published animadversions upon the new doctrine respecting _chlorine_, -in Nicholson's Journal; and his observations were answered by Dr. John -Davy. - -Dr. John Davy was the brother of Sir Humphry, and had shown, by his -paper on fluoric acid and on the chlorides, that he possessed the same -dexterity and the same powers of inductive reasoning, which had given -so much celebrity to his brother. The controversy between him and Dr. -Murray was carried on for some time with much spirit and ingenuity -on both sides, and was productive of some advantage to the science -of chemistry, by the discovery of phosgene gas or chlorocarbonic -acid, which was made by Dr. Davy. It is needless to say to what -side the victory fell. The whole chemical world has for several -years unanimously adopted the theory of Davy; showing sufficiently -the opinion entertained respecting the arguments advanced by either -party. Berzelius supported the old opinion respecting the compound -nature of chlorine, in a paper which he published in the Annals of -Philosophy. No person thought it worth while to answer his arguments, -though Sir Humphry Davy made a few animadversions upon one or two of -his experiments. The discovery of iodine, which took place almost -immediately after, afforded so close an analogy with chlorine, and -the nature of the compounds which it forms was so obvious and so well -made out, that chemists were immediately satisfied; and they furnished -so satisfactory an answer to all the objections of Berzelius, that -I am not aware of any person, either in Great Britain or in France, -who adopted his opinions. I have not the same means of knowing the -impression which his paper made upon the chemists of Germany and -Sweden. Berzelius continued for several years a very zealous opponent -to the new doctrine, that chlorine is a simple substance. But he -became at last satisfied of the futility of his own objections, and -the inaccuracy of his reasoning. About the year 1820 he embraced the -opinion of Davy, and is now one of its most zealous defenders. Dr. -Murray has been dead for many years, and Berzelius has renounced his -notion, that muriatic acid is a compound of oxygen and an unknown -combustible basis. We may say then, I believe with justice, that at -present all the chemical world adopts the notion that chlorine is a -simple substance, and muriatic acid a compound of chlorine and hydrogen. - -The recent discovery of bromine, by Balard, has added another strong -analogy in favour of Davy's theory; as has likewise the discovery by -Gay-Lussac respecting prussic acid. At present, then, (not reckoning -sulphuretted and telluretted hydrogen gas), we are acquainted with -four acids which contain no oxygen, but are compounds of hydrogen with -another negative body. These are - - Muriatic acid, composed of chlorine and hydrogen - Hydriodic acid iodine and hydrogen - Hydrobromic acid bromine and hydrogen - Prussic acid cyanogen and hydrogen. - -So that even if we were to leave out of view the chlorine acids, the -sulphur acids, &c., no doubt can be entertained that many acids exist -which contain no oxygen. Acids are compounds of electro-negative bodies -and a base, and in them all the electro-negative electricity continues -to predominate. - -Next to Sir Humphry Davy, the two chemists who have most advanced -electro-chemistry are Gay-Lussac and Thenard. About the year 1808, -when the attention of men of science was particularly drawn towards -the galvanic battery, in consequence of the splendid discoveries of -Sir Humphry Davy, Bonaparte, who was at that time Emperor of France, -consigned a sufficient sum of money to Count Cessac, governor of the -Polytechnic School, to construct a powerful galvanic battery; and -Gay-Lussac and Thenard were appointed to make the requisite experiments -with this battery. It was impossible that a better choice could have -been made. These gentlemen undertook a most elaborate and extensive -set of experiments, the result of which was published in 1811, in two -octavo volumes, under the title of "Recherches Physico-chimiques, -faites sur la Pile; sur la Preparation chimique et les Propriétés du -Potassium et du Sodium; sur la Décomposition de l'Acide boracique; -sur les Acides fluorique, muriatique, et muriatique oxygené; sur -l'Action chimique de la Lumière; sur l'Analyse vegetale et animale, -&c." It would be difficult to name any chemical book that contains a -greater number of new facts, or which contains so great a collection of -important information, or which has contributed more to the advancement -of chemical science. - -The first part contains a very minute and interesting examination -of the galvanic battery, and upon what circumstances its energy -depends. They tried the effect of various liquid conductors, varied -the strength of the acids and of the saline solutions. This division -of their labours contains much valuable information for the practical -electro-chemist, though it would be inconsistent with the plan of this -work to enter into details. - -The next division of the work relates to potassium. Davy had hitherto -produced that metal only in minute quantities by the action of the -galvanic battery upon potash. But Gay-Lussac and Thenard contrived -a process by which it can be prepared on a large scale by chemical -decomposition. Their method was, to put into a bent gun-barrel, well -coated externally with clay, and passed through a furnace, a quantity -of clean iron-filings. To one extremity of this barrel was fitted a -tube containing a quantity of caustic potash. This tube was either shut -at one end by a stopper, or by a glass tube luted to it, and plunged -under the surface of mercury. To the other extremity of the gun-barrel -was also luted a tube, which plunged into a vessel containing mercury. -Heat was applied to the gun-barrel till it was heated to whiteness; -then, by means of a choffer, the caustic potash was melted and made to -trickle slowly into the white-hot iron-filings. At this temperature the -potash undergoes decomposition, the iron uniting with its oxygen. The -potassium is disengaged, and being volatile is deposited at a distance -from the hot part of the tube, where it is collected after the process -is finished. - -Being thus in possession, both of potassium and sodium in considerable -quantities, they were enabled to examine its properties more in detail -than Davy had done: but such was the care and industry with which -Davy's experiments had been made that very little remained to be -done. The specific gravity of the two metals was determined with more -precision than it was possible for Davy to do. They determined the -action of these metals on water, and measured the quantity of hydrogen -gas given out with more precision than Davy could. They discovered -also, by heating these metals in oxygen gas, that they were capable of -uniting with an additional dose of oxygen, and of forming peroxides of -potassium and sodium. These oxides have a yellow colour, and give out -the surplus oxygen, and are brought back to the state of potash and -soda when they are plunged into water. They exposed a great variety of -substances to the action of potassium, and brought to light a vast -number of curious and important facts, tending to throw new light on -the properties and characters of that curious metallic substance. - -By heating together anhydrous boracic acid and potassium in a copper -tube, they succeeded in decomposing the acid, and in showing it to -be a compound of oxygen, and a black matter like charcoal, to which -the name of _boron_ has been given. They examined the properties of -boron in detail, but did not succeed in determining with exactness -the proportions of the constituents of boracic acid. The subsequent -experiments of Davy, though not exact, come a good deal nearer the -truth. - -Their experiments on fluoric acid are exceedingly valuable. They -first obtained that acid in a state of purity, and ascertained its -properties. Their attempts to decompose it as well as those of Davy, -ended in disappointment. But Ampere conceived the idea that this -acid, like muriatic acid, is a compound of hydrogen with an unknown -supporter of combustion, to which the name _fluorine_ was given. -This opinion was adopted by Davy, and his experiments, though they -do not absolutely prove the truth of the opinion, give it at least -considerable probability, and have disposed chemists in general to -adopt it. The subsequent researches of Berzelius, while they have added -a great deal to our former knowledge respecting fluoric acid and its -compounds, have all tended to confirm and establish the doctrine that -it is a hydracid, and similar in its nature to the other hydracids. But -such is the tendency of fluorine to combine with every substance, that -hitherto it has been impossible to obtain it in an insulated state. We -want therefore, still, a decisive proof of the accuracy of the opinion. - -To the experiments of Gay-Lussac and Thenard on chlorine and muriatic -acid, I have already alluded in a former part of this chapter. It was -during their investigations connected with this subject, that they -discovered _fluoboric_ acid gas, which certainly adds considerably -to the probability of the theory of Ampere respecting the nature of -fluoric acid. - -I pass over a vast number of other new and important facts and -observations contained in this admirable work, which ought to be -studied with minute attention by every person who aspires at becoming a -chemist. - -Besides the numerous discoveries contained in the Recherches -Physico-chimique, Gay-Lussac is the author of two of so much importance -that it would be wrong to omit them. He showed that cyanogen is one -of the constituents of prussic acid; succeeded in determining the -composition of cyanogen, and showing it to be a compound of two -atoms of carbon and one atom of azote. Prussic acid is a compound of -one atom of hydrogen and one atom of cyanogen. Sulpho-cyanic acid, -discovered by Mr. Porrett, is a compound of one atom sulphuric, and -one atom cyanogen; chloro-cyanic acid, discovered by Berthollet, is -a compound of one atom chlorine and one atom cyanogen; while cyanic -acid, discovered by Wöhler, is a compound of one atom oxygen and -one atom cyanogen. I take no notice of the fulminic acid; because, -although Gay-Lussac's experiments are exceedingly ingenious, and his -reasoning very plausible, it is not quite convincing; especially as the -results obtained by Mr. Edmund Davy, and detailed by him in his late -interesting memoir on this subject, are somewhat different. - -The other discovery of Gay-Lussac is his demonstration of the peculiar -nature of iodine, his account of iodic and hydriodic acids, and of -many other compounds into which that curious substance enters as a -constituent. Sir H. Davy was occupied with iodine at the same time with -Gay-Lussac; and his sagacity and inventive powers were too great to -allow him to work upon such a substance without discovering many new -and interesting facts. - -To M. Thenard we are indebted for the discovery of the important fact, -that hydrogen is capable of combining with twice as much oxygen as -exists in water, and determining the properties of this curious liquid -which has been called deutoxide of hydrogen. It possesses bleaching -properties in perfection, and I think it likely that chlorine owes its -bleaching powers to the formation of a little deutoxide of hydrogen in -consequence of its action on water. - -The mantle of Davy seems in some measure to have descended on Mr. -Faraday, who occupies his old place at the Royal Institution. He has -shown equal industry, much sagacity, and great powers of invention. -The most important discovery connected with electro-magnetism, next -to the great fact, for which we are indebted to Professor Œrstedt -of Copenhagen, is due to Mr. Faraday; I mean the rotation of the -electric wires round the magnet. To him we owe the knowledge of the -fact, that several of the gases can be condensed into liquids by the -united action of pressure and cold, which has removed the barrier that -separated gaseous bodies from vapours, and shown us that all owe their -elasticity to the same cause. To him also we owe the knowledge of the -important fact, that chlorine is capable of combining with carbon. This -has considerably improved the history of chlorine and served still -further to throw new light on the analogy which exists between all the -supporters of combustion. They are doubtless all of them capable of -combining with every one of the other simple bodies, and of forming -compounds with them. For they are all negative bodies; while the other -simple substances without exception, when compared to them, possess -positive properties. We must therefore view the history of chemistry as -incomplete, till we have become acquainted with the compounds of every -supporter with every simple base. - - - - -CHAPTER VI. - -OF THE ATOMIC THEORY. - - -I come now to the last improvement which chemistry has received--an -improvement which has given a degree of accuracy to chemical -experimenting almost approaching to mathematical precision, which has -simplified prodigiously our views respecting chemical combinations; -which has enabled manufacturers to introduce theoretical improvements -into their processes, and to regulate with almost perfect precision the -relative quantities of the various constituents necessary to produce -the intended effects. The consequence of this is, that nothing is -wasted, nothing is thrown away. Chemical products have become not only -better in quality, but more abundant and much cheaper. I allude to the -atomic theory still only in its infancy, but already productive of -the most important benefits. It is destined one day to produce still -more wonderful effects, and to render chemistry not only the most -delightful, but the most useful and indispensable, of all the sciences. - -Like all other great improvements in science, the atomic theory -developed itself by degrees, and several of the older chemists -ascertained facts which might, had they been aware of their importance, -have led them to conclusions similar to those of the moderns. The -very attempt to analyze the salts was an acknowledgment that bodies -united with each other in definite proportions: and these definite -proportions, had they been followed out, would have led ultimately to -the doctrine of atoms. For how could it be, that six parts of potash -were always saturated by five parts of sulphuric acid and 6·75 parts -of nitric acid? How came it that five of sulphuric acid always went as -far in saturating potash as 6·75 of nitric acid? It was known, that -in chemical combinations it was the ultimate particles of matter that -combined. The simple explanation, therefore, would have been--that the -weight of an ultimate particle of sulphuric acid was only five, while -that of an ultimate particle of nitric acid was 6·75. Had such an -inference been drawn, it would have led directly to the atomic theory. - -The atomic theory in chemistry has many points of resemblance to -the fluxionary calculus in mathematics. Both give us the ratios -of quantities; both reduce investigations that would be otherwise -extremely difficult, or almost impossible, to the utmost simplicity; -and what is still more curious, both have been subjected to the same -kind of ridicule by those who have not put themselves to the trouble of -studying them with such attention as to understand them completely. The -minute philosopher of Berkeley, _mutatis mutandis_, might be applied to -the atomic theory with as much justice as to the fluxionary calculus; -and I have heard more than one individual attempt to throw ridicule -upon the atomic theory by nearly the same kind of arguments. - -The first chemists, then, who attempted to analyze the salts may be -considered as contributing towards laying the foundation of the atomic -theory, though they were not themselves aware of the importance of the -structure which might have been raised upon their experiments, had -they been made with the requisite precision. - -Bergman was the first chemist who attempted regular analyses of salts. -It was he that first tried to establish regular formulas for the -analyses of mineral waters, stones, and ores, by the means of solution -and precipitation. Hence a knowledge of the constituents of the salts -was necessary, before his formulas could be applied to practice. It was -to supply this requisite information that he set about analyzing the -salts, and his results were long considered by chemists as exact, and -employed by them to determine the results of their analyses. We now -know that these analytical results of Bergman are far from accurate; -they have accordingly been laid aside as useless: but this knowledge -has been derived from the progress of the atomic theory. - -The first accurate set of experiments to analyze the salts was made by -Wenzel, and published by him in 1777, in a small volume entitled "Lehre -von der Verwandschaft der Körper," or, "Theory of the Affinities of -Bodies." These analyses of Wenzel are infinitely more accurate than -those of Bergman, and indeed in many cases are equally precise with -the best which we have even at the present day. Yet the book fell -almost dead-born from the press; Wenzel's results never obtained the -confidence of chemists, nor is his name ever quoted as an authority. -Wenzel was struck with a phenomenon, which had indeed been noticed -by preceding chemists; but they had not drawn the advantages from it -which it was capable of affording. There are several saline solutions -which, when mixed with each other, completely decompose each other, so -that two new salts are produced. Thus, if we mix together solutions -of nitrate of lead and sulphate of soda in the requisite proportions, -the sulphuric acid of the latter salt will combine with the oxide of -lead of the former, and will form with it sulphate of lead, which will -precipitate to the bottom in the state of an insoluble powder, while -the nitric acid formerly united to the oxide of lead, will combine with -the soda formerly in union with the sulphuric acid, and form nitrate of -soda, which being soluble, will remain in solution in the liquid. Thus, -instead of the two old salts, - - Sulphate of soda - Nitrate of lead, - -we obtain the two new salts, - - Sulphate of lead - Nitrate of soda. - -If we mix the two salts in the requisite proportions, the decomposition -will be complete; but if there be an excess of one of the salts, that -excess will still remain in solution without affecting the result. If -we suppose the two salts anhydrous, then the proportions necessary for -complete decomposition are, - - Sulphate of soda 9 - Nitrate of lead 20·75 - ------ - 29·75 - -and the quantities of the new salts formed will be - - Sulphate of lead 19 - Nitrate of soda 10·75 - ----- - 29·75 - -We see that the absolute weights of the two sets of salts are the -same: all that has happened is, that both the acids and both the bases -have exchanged situations. Now if, instead of mixing these two salts -together in the preceding proportions, we employ - - Sulphate of soda 9 - Nitrate of lead 25·75 - -That is to say, if we employ 5 parts of nitrate of lead more than -is sufficient for the purpose; we shall have exactly the same -decompositions as before; but the 5 of excess of nitrate of lead will -remain in solution, mixed with the nitrate of soda. There will be -precipitated as before, - - Sulphate of lead 19 - -and there will remain in solution a mixture of - - Nitrate of soda 10·75 - Nitrate of lead 5 - -The phenomena are precisely the same as before; the additional 5 of -nitrate of lead have occasioned no alteration; the decomposition has -gone on just as if they had not been present. - -Now the phenomena which drew the particular attention of Wenzel is, -that if the salts were neutral before being mixed, the neutrality -was not affected by the decomposition which took place on their -mixture.[7] A salt is said to be neutral when it neither possesses the -characters of an acid or an alkali. Acids _redden_ vegetable _blues_, -while alkalies render them _green_. A neutral salt produces no effect -whatever upon vegetable blues. This observation of Wenzel is very -important: it is obvious that the salts, after their decomposition, -could not have remained neutral unless the elements of the two salts -had been such that the bases in each just saturated the acids in either -of the salts. - - [7] This observation is not without exception. It does not hold when - one of the salts is a phosphate or an arseniate, and this is the cause - of the difficulty attending the analysis of these genera of salts. - -The constituents of the two salts are as follows: - - { 5 sulphuric acid - 9 sulphate of soda { 4 soda, - - { 6·75 nitric acid - 20·75 nitrate of lead {14 oxide of lead. - -Now it is clear, that unless 5 sulphuric acid were just saturated by -4 soda and by 14 oxide of lead; and 6·75 of nitric acid by the same 4 -soda and 14 oxide of lead, the salts, after their decomposition, could -not have preserved their neutrality. Had 4 soda required only 5·75 of -nitric acid, or had 14 oxide of lead required only 4 sulphuric acid, to -saturate them, the liquid, after decomposition, would have contained -an excess of acid. As no such excess exists, it is clear that in -saturating an acid, 4 soda goes exactly as far as 14 oxide of lead; and -that, in saturating a base, 5 sulphuric acid goes just as far as 6·75 -nitric acid. - -Nothing can exhibit in a more striking point of view, the almost -despotic power of fashion and authority over the minds even of men -of science, and the small number of them that venture to think for -themselves, than the fact, that this most important and luminous -explanation of Wenzel, confirmed by much more accurate experiments than -any which chemistry had yet seen, is scarcely noticed by any of his -contemporaries, and seems not to have attracted the smallest attention. -In science, it is as unfortunate for a man to get before the age in -which he lives, as to continue behind it. The admirable explanation of -combustion by Hooke, and the important experiments on combustion and -respiration by Mayow, were lost upon their contemporaries, and procured -them little or no reputation whatever; while the same theory, and -the same experiments, advanced by Lavoisier and Priestley, a century -later, when the minds of men of science were prepared to receive them, -raised them to the very first rank among philosophers, and produced a -revolution in chemistry. So much concern has fortune, not merely in the -success of kings and conquerors, but in the reputation acquired by men -of science. - -In the year 1792 another labourer, in the same department of chemistry, -appeared: this was Jeremiah Benjamin Richter, a Prussian chemist, of -whose history I know nothing more than that his publications were -printed and published in Breslau, from which I infer that he was a -native of, or at least resided in, Silesia. He calls himself Assessor -of the Royal Prussian Mines and Smeltinghouses, and Arcanist of the -Commission of Berlin Porcelain Manufacture. He died in the prime of -life, on the 4th of May, 1807. In the year 1792 he published a work -entitled "Anfansgründe der Stochyometrie; oder, Messkunst Chymischer -Elemente" (Elements of Stochiometry; or, the Mathematics of the -Chemical Elements). A second and third volume of this work appeared in -1793, and a fourth volume in 1794. The object of this book was a rigid -analysis of the different salts, founded on the fact just mentioned, -that when two salts decompose each other, the salts newly formed -are neutral as well as those which have been decomposed. He took up -the subject nearly in the same way as Wenzel had done, but carried -the subject much further; and endeavoured to determine the capacity -of saturation of each acid and base, and to attach numbers to each, -indicating the weights which mutually saturate each other. He gave the -whole subject a mathematical dress, and endeavoured to show that the -same relation existed, between the numbers representing the capacity of -saturation of these bodies, as does between certain classes of figurate -numbers. When we strip the subject of the mystical form under which he -presented it, the labours of Richter may be exhibited under the two -following tables, which represent the capacity of saturation of the -acids and bases, according to his experiments. - - 1. ACIDS. - - Fluoric acid 427 - Carbonic 577 - Sebacic 706 - Muriatic 712 - Oxalic 755 - Phosphoric 979 - Formic 988 - Sulphuric 1000 - Succinic 1209 - Nitric 1405 - Acetic 1480 - Citric 1683 - Tartaric 1694 - - - 2. BASES. - - Alumina 525 - Magnesia 615 - Ammonia 672 - Lime 793 - Soda 859 - Strontian 1329 - Potash 1605 - Barytes 2222 - -To understand this table, it is only necessary to observe, that if we -take the quantity of any of the acids placed after it in the table, -that quantity will be exactly saturated by the weight of each base put -after it in the second column: thus, 1000 of sulphuric acid will be -just saturated by 525 alumina, 615 magnesia, 672 ammonia, 793 lime, and -so on. On the other hand, the quantity of any base placed after its -name in the second column, will be just saturated by the weight of each -acid placed after its name in the first column: thus, 793 parts of lime -will be just saturated by 427 of fluoric acid, 577 of carbonic acid, -706 of sebacic acid, and so on. - -This work of Richter was followed by a periodical work entitled "Ueber -die neuern Gegenstande der Chymie" (On the New Objects of Chemistry). -This work was begun in the year 1792, and continued in twelve different -numbers, or volumes, to the time of his death in 1807.[8] - - [8] I have only seen eleven parts of this work, the last of which - appeared in 1802; but I believe that a twelfth part was published - afterwards. - -Richter's labours in this important field produced as little attention -as those of Wenzel. Gehlen wrote a short panegyric upon him at his -death, praising his views and pointing out their importance; but I -am not aware of any individual, either in Germany or elsewhere, who -adopted Richter's opinions during his lifetime, or even seemed aware -of their importance, unless we are to except Berthollet, who mentions -them with approbation in his Chemical Statics. This inattention was -partly owing to the great want of accuracy which it is impossible -not be sensible of in Richter's experiments. He operated upon too -large quantities of matter, which indeed was the common defect of the -times, and was first checked by Dr. Wollaston. The dispute between the -phlogistians and the antiphlogistians, which was not fully settled in -Richter's time, drew the attention of chemists to another branch of -the subject. Richter in some measure went before the age in which he -lived, and had his labours not been recalled to our recollection by the -introduction of atomic theory, he would probably have been forgotten, -like Hooke and Mayow, and only brought again under review after the -new discoveries in the science had put it in the power of chemists in -general to appreciate the value of his labours. - -It is to Mr. Dalton that we are indebted for the happy and simple idea -from which the atomic theory originated. - -John Dalton, to whose lot it has fallen to produce such an alteration -and improvement in chemistry, was born in Westmorland, and belongs -to that small and virtuous sect known in this country by the name of -Quakers. When very young he lived with Mr. Gough of Kendal, a blind -philosopher, to whom he read, and whom he assisted in his philosophical -investigations. It was here, probably, that he acquired a considerable -part of his education, particularly his taste for mathematics. For -Mr. Gough was remarkably fond of mathematical investigations, and has -published several mathematical papers that do him credit. From Kendal -Mr. Dalton went to Manchester, about the beginning of the present -century, and commenced teaching elementary mathematics to such young -men as felt inclined to acquire some knowledge of that important -subject. In this way, together with a few courses of lectures on -chemistry, which he has occasionally given at the Royal Institution -in London, at the Institution in Birmingham, in Manchester, and once -in Edinburgh and in Glasgow, he has contrived to support himself for -more than thirty years, if not in affluence, at least in perfect -independence. And as his desires have always been of the most moderate -kind, his income has always been equal to his wants. In a country -like this, where so much wealth abounds, and where so handsome a -yearly income was subscribed to enable Dr. Priestley to prosecute -his investigations undisturbed and undistracted by the necessity of -providing for the daily wants of his family, there is little doubt -that Mr. Dalton, had he so chosen it, might, in point of pecuniary -circumstances, have exhibited a much more brilliant figure. But he has -displayed a much nobler mind by the career which he has chosen--equally -regardless of riches as the most celebrated sages of antiquity, and as -much respected and beloved by his friends, even in the rich commercial -town of Manchester, as if he were one of the greatest and most -influential men in the country. Towards the end of the last century, a -literary and scientific society had been established in Manchester, of -which Mr. Thomas Henry, the translator of Lavoisier's Essays, and who -distinguished himself so much in promoting the introduction of the new -mode of bleaching into Lancashire, was long president. Mr. Dalton, who -had already distinguished himself by his meteorological observations, -and particularly by his account of the Aurora Borealis, soon became a -member of the society; and in the fifth volume of their Memoirs, part -II., published in 1802, six papers of his were inserted, which laid the -foundation of his future celebrity. These papers were chiefly connected -with meteorological subjects; but by far the most important of them all -was the one entitled "Experimental Essays on the Constitution of mixed -Gases; on the Force of Steam or Vapour from water and other liquids in -different temperatures, both in a torricellian vacuum and in air; on -Evaporation; and on the Expansion of Gases by Heat." - -From a careful examination of all the circumstances, he considered -himself as entitled to infer, that when two elastic fluids or gases, -A and B, are mixed together, there is no mutual repulsion among their -particles; that is, the particles of A do not repel those of B, as they -do one another. Consequently, the pressure or whole weight upon any -one particle arises solely from those of its own kind. This doctrine -is of so startling a nature and so contrary to the opinions previously -received, that chemists have not been much disposed to admit it. But at -the same time it must be confessed, that no one has hitherto been able -completely to refute it. The consequences of admitting it are obvious: -we should be able to account for a fact which has been long known, -though no very satisfactory reason for it had been assigned; namely, -that if two gases be placed in two separate vessels, communicating -by a narrow orifice, and left at perfect rest in a place where the -temperature never varies, if we examine them after a certain interval -of time we shall find both equally diffused through both vessels. If we -fill a glass phial with hydrogen gas and another phial with common air -or carbonic acid gas and unite the two phials by a narrow glass tube -two feet long, filled with common air, and place the phial containing -the hydrogen gas uppermost, and the other perpendicularly below it, the -hydrogen, though lightest, will not remain in the upper phial, nor the -carbonic acid, though heaviest, in the undermost phial; but we shall -find both gases equally diffused through both phials. - -But the second of these essays is by far the most important. In it he -establishes, by the most unexceptionable evidence, that water, when -it evaporates, is always converted into an elastic fluid, similar in -its properties to air. But that the distance between the particles is -greater the lower the temperature is at which the water evaporates. -The elasticity of this vapour increases as the temperature increases. -At 32° it is capable of balancing a column of mercury about half an -inch in height, and at 212° it balances a column thirty inches high, -or it is then equal to the pressure of the atmosphere. He determined -the elasticity of vapour at all temperatures from 32° to 212°, pointed -out the method of determining the quantity of vapour that at any time -exists in the atmosphere, the effect which it has upon the volume of -air, and the mode of determining its quantity. Finally, he determined, -experimentally, the rate of evaporation from the surface of water at -all temperatures from 32° to 212°. These investigations have been of -infinite use to chemists in all their investigations respecting the -specific gravity of gases, and have enabled them to resolve various -interesting problems, both respecting specific gravity, evaporation, -rain and respiration, which, had it not been for the principles laid -down in this essay, would have eluded their grasp. - -In the last essay contained in this paper he has shown that all elastic -fluids expand the same quantity by the same addition of heat, and this -expansion is very nearly 1-480th part for every degree of Fahrenheit's -thermometer. In this last branch of the subject Mr. Dalton was followed -by Gay-Lussac, who, about half a year after the appearance of his -Essays, published a paper in the Annales de Chimie, showing that the -expansion of all elastic fluids, when equally heated, is the same. Mr. -Dalton concluded that the expansion of all elastic fluids by heat is -equable. And this opinion has been since confirmed by the important -experiments of Dulong and Petit, which have thrown much additional -light on the subject. - -In the year 1804, on the 26th of August, I spent a day or two at -Manchester, and was much with Mr. Dalton. At that time he explained to -me his notions respecting the composition of bodies. I wrote down at -the time the opinions which he offered, and the following account is -taken literally from my journal of that date: - -The ultimate particles of all simple bodies are _atoms_ incapable -of further division. These atoms (at least viewed along with their -atmospheres of heat) are all spheres, and are each of them possessed of -particular weights, which may be denoted by numbers. For the greater -clearness he represented the atoms of the simple bodies by symbols. The -following are his symbols for four simple bodies, together with the -numbers attached to them by him in 1804: - - Relative - weights. - [oxygen] Oxygen 6·5 - [hydrogen] Hydrogen 1 - [carbon] Carbon 5 - [azote] Azote 5 - -The following symbols represent the way in which he thought these atoms -were combined to form certain binary compounds, with the weight of an -integrant particle of each compound: - - Weights. - [oxygen][hydrogen] Water 7·5 - [oxygen][azote] Nitrous gas 11·5 - [carbon][hydrogen] Olefiant gas 6 - [azote][hydrogen] Ammonia 6 - [oxygen][carbon] Carbonic oxide 11·5 - -The following were the symbols by which he represented the composition -of certain tertiary compounds: - - Weights. - [oxygen][carbon][oxygen] Carbonic acid 18 - [oxygen][azote][oxygen] Nitrous oxide 16·5 - [carbon][hydrogen][carbon] Ether 11 - [hydrogen][carbon][hydrogen] Carburetted hydrogen 7 - [oxygen][azote][oxygen] Nitric acid 18 - -A quaternary compound: - - [oxygen][azote][oxygen] Oxynitric acid 24·5 - [oxygen] - -A quinquenary compound: - - [oxygen] - [azote] [azote][oxygen] Nitrous acid 29·5 - [oxygen] - -A sextenary compound: - - [carbon][oxygen][carbon] Alcohol 23·5 - [hydrogen][carbon][hydrogen] - -These symbols are sufficient to give the reader an idea of the notions -entertained by Dalton respecting the nature of compounds. Water is -a compound of one atom oxygen and one atom hydrogen as is obvious -from the symbol [oxygen][hydrogen]. Its weight 7·5 is that of an atom -of oxygen and an atom of hydrogen united together. In the same way -carbonic oxide is a compound of one atom oxygen and one atom carbon. -Its symbol is [oxygen][carbon], and its weight 11·5 is equal to an -atom of oxygen and an atom of carbon added together. Carbonic acid is -a tertiary compound, or it consists of three atoms united together; -namely, two atoms of oxygen and one atom of carbon. Its symbol is -[oxygen][carbon][oxygen], and its weight 18. A bare inspection of the -symbols and weights will make Mr. Dalton's notions respecting the -constitution of every body in the table evident to every reader. - -It was this happy idea of representing the atoms and constitution of -bodies by symbols that gave Mr. Dalton's opinions so much clearness. -I was delighted with the new light which immediately struck my -mind, and saw at a glance the immense importance of such a theory, -when fully developed. Mr. Dalton informed me that the atomic theory -first occurred to him during his investigations of olefiant gas and -carburetted hydrogen gases, at that time imperfectly understood, and -the constitution of which was first fully developed by Mr. Dalton -himself. It was obvious from the experiments which he made upon them, -that the constituents of both were carbon and hydrogen, and nothing -else. He found further, that if we reckon the carbon in each the same, -then carburetted hydrogen gas contains exactly twice as much hydrogen -as olefiant gas does. This determined him to state the ratios of these -constituents in numbers, and to consider the olefiant gas as a compound -of one atom of carbon and one atom of hydrogen; and carburetted -hydrogen of one atom of carbon and two atoms of hydrogen. The idea -thus conceived was applied to carbonic oxide, water ammonia, &c.; and -numbers representing the atomic weights of oxygen, azote, &c., deduced -from the best analytical experiments which chemistry then possessed. - -Let not the reader suppose that this was an easy task. Chemistry at -that time did not possess a single analysis which could be considered -as even approaching to accuracy. A vast number of facts had been -ascertained, and a fine foundation laid for future investigation; but -nothing, as far as weight and measure were concerned, deserving the -least confidence, existed. We need not be surprised, then, that Mr. -Dalton's first numbers were not exact. It required infinite sagacity, -and not a little labour, to come so near the truth as he did. How could -accurate analyses of gases be made when there was not a single gas -whose specific gravity was known, with even an approach to accuracy; -the preceding investigations of Dalton himself paved the way for -accuracy in this indispensable department; but still accurate results -had not yet been obtained. - -In the third edition of my System of Chemistry, published in 1807, I -introduced a short sketch of Mr. Dalton's theory, and thus made it -known to the chemical world. The same year a paper of mine on _oxalic -acid_ was published in the Philosophical Transactions, in which I -showed that oxalic acid unites in two proportions with strontian, -forming an _oxalate_ and _binoxalate_; and that, supposing the -strontian in both salts to be the same, the oxalic acid in the latter -is exactly twice as much as in the former. About the same time, Dr. -Wollaston showed that bicarbonate of potash contains just twice the -quantity of carbonic acid that exists in carbonate of potash; and that -there are three oxalates of potash; viz., _oxalate_, _binoxalate_, and -_quadroxalate_; the weight of acids in each of which are as the numbers -1, 2, 4. These facts gradually drew the attention of chemists to Mr. -Dalton's views. There were, however, some of our most eminent chemists -who were very hostile to the atomic theory. The most conspicuous -of these was Sir Humphry Davy. In the autumn of 1807 I had a long -conversation with him at the Royal Institution, but could not convince -him that there was any truth in the hypothesis. A few days after I -dined with him at the Royal Society Club, at the Crown and Anchor, -in the Strand. Dr. Wollaston was present at the dinner. After dinner -every member of the club left the tavern, except Dr. Wollaston, Mr. -Davy, and myself, who staid behind and had tea. We sat about an hour -and a half together, and our whole conversation was about the atomic -theory. Dr. Wollaston was a convert as well as myself; and we tried to -convince Davy of the inaccuracy of his opinions; but, so far from being -convinced, he went away, if possible, more prejudiced against it than -ever. Soon after, Davy met Mr. Davis Gilbert, the late distinguished -president of the Royal Society; and he amused him with a caricature -description of the atomic theory, which he exhibited in so ridiculous a -light, that Mr. Gilbert was astonished how any man of sense or science -could be taken in with such a tissue of absurdities. Mr. Gilbert -called on Dr. Wollaston (probably to discover what could have induced -a man of Dr. Wollaston's sagacity and caution to adopt such opinions), -and was not sparing in laying the absurdities of the theory, such as -they had been represented to him by Davy, in the broadest point of -view. Dr. Wollaston begged Mr. Gilbert to sit down, and listen to -a few facts which he would state to him. He then went over all the -principal facts at that time known respecting the salts; mentioned the -alkaline carbonates and bicarbonates, the oxalate, binoxalate, and -quadroxalate of potash, carbonic oxide and carbonic acid, olefiant gas, -and carburetted hydrogen; and doubtless many other similar compounds, -in which the proportion of one of the constituents increases in a -regular ratio. Mr. Gilbert went away a convert to the truth of the -atomic theory; and he had the merit of convincing Davy that his former -opinions on the subject were wrong. What arguments he employed I do -not know; but they must have been convincing ones, for Davy ever after -became a strenuous supporter of the atomic theory. The only alteration -which he made was to substitute _proportion_ for Dalton's word, _atom_. -Dr. Wollaston substituted for it the term _equivalent_. The object of -these substitutions was to avoid all theoretical annunciations. But, in -fact, these terms, _proportion_, _equivalent_, are neither of them so -convenient as the term _atom_: and, unless we adopt the hypothesis with -which Dalton set out, namely, that the ultimate particles of bodies are -_atoms_ incapable of further division, and that chemical combination -consists in the union of these atoms with each other, we lose all the -new light which the atomic theory throws upon chemistry, and bring our -notions back to the obscurity of the days of Bergman and of Berthollet. - -In the year 1808 Mr. Dalton published the first volume of his New -System of Chemical Philosophy. This volume consists chiefly of two -chapters: the first, on _heat_, occupies 140 pages. In it he treats of -all the effects of heat, and shows the same sagacity and originality -which characterize all his writings. Even when his opinions on a -subject are not correct, his reasoning is so ingenious and original, -and the new facts which he contrives to bring forward so important, -that we are always pleased and always instructed. The second chapter, -on the _constitution of bodies_, occupies 70 pages. The chief object -of it is to combat the peculiar notions respecting elastic fluids, -which had been advanced by Berthollet, and supported by Dr. Murray, -of Edinburgh. In the third chapter, on _chemical synthesis_, which -occupies only a few pages, he gives us the outlines of the atomic -theory, such as he had conceived it. In a plate at the end of the -volume he exhibits the symbols and atomic weights of thirty-seven -bodies, twenty of which were then considered as simple, and the other -seventeen as compound. The following table shows the atomic weight of -the simple bodies, as he at that time had determined them from the best -analytical experiments that had been made: - - Weight of - atom. - Hydrogen 1 - Azote 5 - Carbon 5 - Oxygen 7 - Phosphorus 9 - Sulphur 13 - Magnesia 20 - Lime 23 - Soda 28 - Potash 42 - Strontian 46 - Barytes 68 - Iron 38 - Zinc 56 - Copper 56 - Lead 95 - Silver 100 - Platinum 100 - Gold 140 - Mercury 167 - -He had made choice of hydrogen for unity, because it is the lightest -of all bodies. He was of opinion that the atomic weights of all other -bodies are multiples of hydrogen; and, accordingly, they are all -expressed in whole numbers. He had raised the atomic weight of oxygen -from 6·5 to 7, from a more careful examination of the experiments -on the component parts of water. Davy, from a more accurate set of -experiments, soon after raised the number for oxygen to 7·5: and -Dr. Prout, from a still more careful investigation of the relative -specific gravities of oxygen and hydrogen, showed that if the atom of -hydrogen be 1, that of oxygen must be 8. Every thing conspires to prove -that this is the true ratio between the atomic weights of oxygen and -hydrogen. - -In 1810 appeared the second volume of Mr. Dalton's New System of -Chemical Philosophy. In it he examines the elementary principles, -or simple bodies, namely, oxygen, hydrogen, azote, carbon, sulphur, -phosphorus, and the metals; and the compounds consisting of two -elements, namely, the compounds of oxygen with hydrogen, azote, -carbon, sulphur, phosphorus; of hydrogen with azote, carbon, sulphur, -phosphorus. Finally he treats of the fixed alkalies and earths. All -these combinations are treated of with infinite sagacity; and he -endeavours to determine the atomic weights of the different elementary -substances. Nothing can exceed the ingenuity of his reasoning. But -unfortunately at that time very few accurate chemical analyses existed; -and in chemistry no reasoning, however ingenious, can compensate for -this indispensable datum. Accordingly his table of atomic weights at -the end this second volume, though much more complete than that at the -end of the first volume, is still exceedingly defective; indeed no one -number can be considered as perfectly correct. - -The third volume of the New System of Chemical Philosophy was only -published in 1827; but the greatest part of it had been printed nearly -ten years before. It treats of the metallic oxides, the sulphurets, -phosphurets, carburets, and alloys. Doubtless many of the facts -contained in it were new when the sheets were put to the press; but -during the interval between the printing and publication, almost the -whole of them had not merely been anticipated, but the subject carried -much further. By far the most important part of the volume is the -Appendix, consisting of about ninety pages, in which he discusses, -with his usual sagacity, various important points connected with heat -and vapour. In page 352 he gives a new table of the atomic weights of -bodies, much more copious than those contained in the two preceding -volumes; and into which he has introduced the corrections necessary -from the numerous correct analyses which had been made in the interval. -He still adheres to the ratio 1:7 as the correct difference between the -weights of the atoms of hydrogen and oxygen. This shows very clearly -that he has not attended to the new facts which have been brought -forward on the subject. No person who has attended to the experiments -made on the specific gravity of these two gases during the last twelve -years, could admit that these specific gravities are to each other as 1 -to 14. If 1 to 16 be not the exact ratio, it will surely be admitted on -all hands that it is infinitely near it. - -Mr. Dalton represented the weight of an atom of hydrogen by 1, because -it is the lightest of bodies. In this he has been followed by the -chemists of the Royal Institution, by Mr. Philips, Dr. Henry, and -Dr. Turner, and perhaps some others whose names I do not at present -recollect. Dr. Wollaston, in his paper on Chemical Equivalents, -represented the atomic weight of oxygen by 1, because it enters into -a greater number of combinations than any other substance; and this -plan has been adopted by Berzelius, by myself, and by the greater -number, if not the whole, of the chemists on the continent. Perhaps the -advantage which Dr. Wollaston assigned for making the atom of oxygen -unity will ultimately disappear: for there is no reason for believing -that the other supporters of combustion are not capable of entering -into as many compounds as oxygen. But, from the constitution of the -atmosphere, it is obvious that the compounds into which oxygen enters -will always be of more importance to us than any others; and in this -point of view it may be attended with considerable convenience to have -oxygen represented by 1. In the present state of the atomic theory -there is another reason for making the atom of oxygen unity, which I -think of considerable importance. Chemists are not yet agreed about the -atom of hydrogen. Some consider water a compound of 1 atom of oxygen -and 2 atoms of hydrogen; others, of 1 atom of oxygen and 1 atom of -hydrogen. According to the first view, the atom of hydrogen is only -1-16th of the weight of an atom of oxygen; according to the second, it -is 1-8th. If, therefore, we were to represent the atom of hydrogen by -1, the consequence would be, that two tables of atomic weights would be -requisite--all the atoms in one being double the weight of the atoms in -the other: whereas, if we make the atom of oxygen unity, it will be the -atom of hydrogen only that will differ in the two tables. In the one -table it will be 0·125, in the other it will be 0·0625: or, reckoning -with Berzelius the atom of oxygen = 100, we have that of hydrogen = -12·5 or 6·25, according as we view water to be a compound of 1 atom of -oxygen with 1 or 2 atoms of hydrogen. - -In the year 1809 Gay-Lussac published in the second volume of the -Mémoires d'Arcueil a paper on the union of the gaseous substances with -each other. In this paper he shows that the proportions in which the -gases unite with each other are of the simplest kind. One volume of one -gas either combining with one volume of another, or with two volumes, -or with half a volume. The atomic theory of Dalton had been opposed -with considerable keenness by Berthollet in his Introduction to the -French translation of my System of Chemistry. Nor was this opposition -to be wondered at; because its admission would of course overturn all -the opinions which Berthollet had laboured to establish in his Chemical -Statics. The object of Gay-Lussac's paper was to confirm and establish -the new atomic theory, by exhibiting it in a new point of view. Nothing -can be more ingenious than his mode of treating the subject, or more -complete than the proofs which he brings forward in support of it. It -had been already established that water is formed by the union of one -volume of oxygen and two volumes of hydrogen gas. Gay-Lussac found by -experiment, that one volume of muriatic acid gas is just saturated by -one volume of ammoniacal gas: the product is sal ammoniac. Fluoboric -acid gas unites in two proportions with ammoniacal gas: the first -compound consists of one volume of fluoboric gas, and one volume of -ammoniacal; the second, of one volume of the acid gas, and two volumes -of the alkaline. The first forms a neutral salt, the second an alkaline -salt. He showed likewise, that carbonic acid and ammoniacal gas could -combine also in two proportions; namely, one volume of the acid gas -with one or two volumes of the alkaline gas. - -M. Amédée Berthollet had proved that ammonia is a compound of one -volume of azotic, and three volumes of hydrogen gas. Gay-Lussac himself -had shown that sulphuric acid is composed of one volume sulphurous -acid gas, and a half-volume of oxygen gas. He showed further, that the -compounds of azote and oxygen were composed as follows: - - Azote. Oxygen. - Protoxide of azote 1 volume + ½ volume - Deutoxide of azote 1 " + 1 - Nitrous acid 1 " + 2 - -He showed also, that when the two gases after combining remained in the -gaseous state, the diminution of volume was either 0, or ⅓, or ½. - -The constancy of these proportions left no doubt that the combinations -of all gaseous bodies were definite. The theory of Dalton applied to -them with great facility. We have only to consider a volume of gas -to represent an atom, and then we see that in gases one atom of one -gas combines either with one, two, or three atoms of another gas, and -never with more. There is, indeed, a difficulty occasioned by the way -in which we view the composition of water. If water be composed of -one atom of oxygen and one atom of hydrogen, then it follows that a -volume of oxygen contains twice as many atoms as a volume of hydrogen. -Consequently, if a volume of hydrogen gas represent an atom, half a -volume of oxygen gas must represent an atom. - -Dr. Prout soon after showed that there is an intimate connexion between -the atomic weight of a gas and its specific gravity. This indeed is -obvious at once. I afterwards showed that the specific gravity of a -gas is either equal to its atomic weight multiplied by 1·111[.1] (the -specific gravity of oxygen gas), or by 0·555[.5] (half the specific -gravity of oxygen gas), or by O·277[.7] (1-4th of the specific -gravity of oxygen gas), these differences depending upon the relative -condensation which the gases undergo when their elements unite. The -following table exhibits the atoms and specific gravity of these three -sets of gases: - - I. Sp. Gr. = Atomic Weight × 1·1111 - - Atomic Sp. - weight. gravity. - Oxygen gas 1 1·1111 - Fluosilicic acid 3·25 3·6111 - -II. Sp. Gr. = Atomic Weight × 0·555[.5]. - - Atomic weight. Sp. gravity. - Hydrogen 0·125 0·069[.4] - Azotic 1·75 0·072[.2] - Chlorine 4·5 2·5 - Carbon vapour 0·75 0·416[.6] - Phosphorus vapour 2 1·111[.1] - Sulphur vapour 2 1·111[.1] - Tellurium vapour 4 2·222[.2] - Arsenic vapour 4·75 2·638[.8] - Selenium vapour 5 2·777[.7] - Bromine vapour 10 5·555[.5] - Iodine vapour 15·75 8·75 - Steam 1·125 0·625 - Carbonic oxide gas 1·75 0·972[.2] - Carbonic acid 2·75 1·527[.7] - Protoxide of azote 2·75 1·527[.7] - Nitric acid vapour 6·75 3·75 - Sulphurous acid 4 2.222[.2] - Sulphuric acid vapour 5 2·777[.7] - Cyanogen 3·25 1·805[.5] - Fluoboric acid 4·25 2·361[.1] - Bisulphuret of carbon 4·75 2·638[.8] - Chloro-carbonic acid 6·25 3·472[.2] - - -III. Sp. Gr. = Atomic Weight × 0·277[.7]. - - Atomic weight. Sp. gravity. - Ammoniacal gas 2·125 0·5902[.7] - Hydrocyanic acid 3·375 0·9375 - Deutoxide of azote 3·75 1·041[.6] - Muriatic acid 4·625 1·2847[.2] - Hydrobromic acid 10·125 2·8125 - Hydriodic acid 15·875 4·40973 - - [Transcriber's Note: The numbers within [] thus [.2] represent numbers - with a dot above them in the original.] - -When Professor Berzelius, of Stockholm, thought of writing his -Elementary Treatise on Chemistry, the first volume of which was -published in the year 1808, he prepared himself for the task by reading -several chemical works which do not commonly fall under the eye of -those who compose elementary treatises. Among other books he read the -Stochiometry of Richter, and was much struck with the explanations -there given of the composition of salts, and the precipitation of -metals by each other. It followed from the researches of Richter, that -if we were in possession of good analyses of certain salts, we might -by means of them calculate with accuracy the composition of all the -rest. Berzelius formed immediately the project of analyzing a series -of salts with the most minute attention to accuracy. While employed in -putting this project in execution, Davy discovered the constituents -of the alkalies and earths, Mr. Dalton gave to the world his notions -respecting the atomic theory, and Gay-Lussac made known his theory of -volumes. This greatly enlarged his views as he proceeded, and induced -him to embrace a much wider field than he had originally contemplated. -His first analyses were unsatisfactory; but by repeating them and -varying the methods, he detected errors, improved his processes, and -finally obtained results, which agreed exceedingly well with the -theoretical calculations. These laborious investigations occupied him -several years. The first outline of his experiments appeared in the -77th volume of the Annales de Chimie, in 1811, in a letter addressed -by Berzelius to Berthollet. In this letter he gives an account of -his methods of analyses together with the composition of forty-seven -compound bodies. He shows that when a metallic protosulphuret is -converted into a sulphate, the sulphate is neutral; that an atom of -sulphur is twice as heavy as an atom of oxygen; and that when sulphite -of barytes is converted into sulphate, the sulphate is neutral, there -being no excess either of acid or base. From these and many other -important facts he finally draws this conclusion: "In a compound formed -by the union of two oxides, the one which (when decomposed by the -galvanic battery) attaches itself to the positive pole (the _acid_ for -example) contains two, three, four, five, &c., times as much oxygen, -as the one which attaches itself to the negative pole (the alkali, -earth, or metallic oxide)." Berzelius's essay itself appeared in the -third volume of the Afhandlingar, in 1810. It was almost immediately -translated into German, and published by Gilbert in his Annalen der -Physik. But no English translation has ever appeared, the editors of -our periodical works being in general unacquainted with the German -and other northern languages. In 1815 Berzelius applied the atomic -theory to the mineral kingdom, and showed with infinite ingenuity that -minerals are chemical compounds in definite or atomic proportions, and -by far the greater number of them combinations of acids and bases. He -applied the theory also to the vegetable kingdom by analyzing several -of the vegetable acids, and showing their atomic constitution. But -here a difficulty occurs, which in the present state of our knowledge, -we are unable to surmount. There are two acids, the _acetic_ and -_succinic_, that are composed of exactly the same number, and same kind -of atoms, and whose atomic weight is 6·25. The constituents of these -two acids are - - Atomic weight. - 2 atoms hydrogen 0·25 - 4 " carbon 3 - 3 " oxygen 3 - ---- - 6·25 - -So that they consist of _nine_ atoms. Now as these two acids are -composed of the same number and the same kind of atoms, one would -expect that their properties should be the same; but this is not the -case: acetic acid has a strong and aromatic smell, succinic acid has -no smell whatever. Acetic acid is so soluble in water that it is -difficult to obtain it in crystals, and it cannot be procured in a -separate state free from water; for the crystals of acetic acid are -composed of one atom of acid and one atom of water united together; but -succinic acid is not only easily obtained free from water, but it is -not even very soluble in that liquid. The nature of the salts formed -by these two acids is quite different; the action of heat upon each -is quite different; the specific gravity of each differs. In short -all their properties exhibit a striking contrast. Now how are we to -account for this? Undoubtedly by the different ways in which the atoms -are arranged in each. If the electro-chemical theory of combination be -correct, we can only view atoms as combining two by two. A substance -then, containing nine atoms, such as acetic acid, must be of a very -complex nature. And it is obvious enough that these nine atoms might -arrange themselves in a great variety of binary compounds, and the way -in which these binary compounds unite may, and doubtless does, produce -a considerable effect upon the nature of the compound formed. Thus, if -we make use of Mr. Dalton's symbols to represent the atoms of hydrogen, -carbon and oxygen, we may suppose the nine atoms constituting acetic -and succinic acid to be arranged thus: - - [hydrogen][carbon][hydrogen] - [oxygen][oxygen][oxygen] - [carbon][carbon][carbon] - -Or thus: - - [carbon][hydrogen][carbon] - [oxygen][oxygen][oxygen] - [carbon][hydrogen][carbon] - -Now, undoubtedly these two arrangements would produce a great change in -the nature of the compound. - -There is something in the vegetable acids quite different from the -acids of the inorganic kingdom, and which would lead to the suspicion -that the electro-chemical theory will not apply to them as it does to -the others. In the acids of carbon, sulphur, phosphorus, selenium, &c., -we find one atom of a positive substance united to one, two, or three -of a negative substance: we are not surprised, therefore, to find the -acid formed negative also. But in acetic and succinic acids we find -every atom of oxygen united with two electro-positive atoms: the wonder -then is, that the acid should not only retain its electro-negative -properties, but that it should possess considerable power as an acid. -In benzoic acid, for every atom of oxygen, there are present no fewer -than seven electro-positive atoms. - -Berzelius has returned to these analytical experiments repeatedly, so -that at last he has brought his results very near the truth indeed. -It is to his labours chiefly that the great progress which the atomic -theory has made is owing. - -In the year 1814 there appeared in the Philosophical Transactions a -description of a Synoptical Scale of Chemical Equivalents, by Dr. -Wollaston. In this paper we have the equivalents or atomic weights -of seventy-three different bodies, deduced chiefly from a sagacious -comparison of the previous analytical experiments of others, and almost -all of them very near the truth. These numbers are laid down upon -a sliding rule, by means of a table of logarithms, and over against -them the names of the substances. By means of this rule a great many -important questions respecting the substances contained on the scale -may be solved. Hence the scale is of great advantage to the practical -chemist. It gives, by bare inspection, the constituents of all the -salts contained on it, the quantity of any other ingredient necessary -to decompose any salt, and the weights of the new constituents that -will be formed. The contrivance of this scale, therefore, may be -considered as an important addition to the atomic theory. It rendered -that theory every where familiar to all those who employed it. To -it chiefly we owe, I believe, the currency of that theory in Great -Britain; and the prevalence of the mode which Dr. Wollaston introduced, -namely, of representing the atom of oxygen by unity, or at least by -ten, which comes nearly to the same thing. - -Perhaps the reader will excuse me if to the preceding historical -details I add a few words to make him acquainted with my own attempts -to render the atomic theory more accurate by new and careful analyses. -I shall not say any thing respecting the experiments which I undertook -to determine the specific gravity of the gases; though they were -performed with much care, and at a considerable expense, and though -I believe the results obtained approached accuracy as nearly as the -present state of chemical apparatus enables us to go. In the year -1819 I began a set of experiments to determine the exact composition -of the salts containing the different elementary bodies by means of -double decomposition, as was done by Wenzel, conceiving that in that -way the results would be very near the truth, while the experiments -would be more easily made. My mode was to dissolve, for example, a -certain weight of muriate of barytes in distilled water, and then to -ascertain by repeated trials what weight of sulphate of soda must be -added to precipitate the whole of the barytes without leaving any -surplus of sulphuric acid in the liquid. To determine this I put -into a watch-glass a few drops of the filtered liquor consisting of -the mixture of solutions of the two salts: to this I added a drop of -solution of sulphate of soda. If the liquid remained clear it was a -proof that it contained no sensible quantity of barytes. To another -portion of the liquid, also in a watch-glass, I added a drop of muriate -of barytes. If there was no precipitate it was a proof that the liquid -contained no sensible quantity of sulphuric acid. If there was a -precipitate, on the addition of either of these solutions, it showed -that there was an excess of one or other of the salts. I then mixed -the two salts in another proportion, and proceeded in this way till I -had found two quantities which when mixed exhibited no evidence of the -residual liquid containing any sulphuric acid or barytes. I considered -these two weights of the salts as the equivalent weights of the salt, -or as weights proportional to an integrant particle of each salt. I -made no attempt to collect the two new formed salts and to weigh them -separately. - -I published the result of my numerous experiments in 1825, in a work -entitled "An Attempt to establish the First Principles of Chemistry by -Experiment." The most valuable part of this book is the account of the -salts; about three hundred of which I subjected to actual analysis. Of -these the worst executed are the phosphates; for with respect to them -I was sometimes misled by my method of double decomposition. I was not -aware at first, that, in certain cases, the proportion of acid in -these salts varies, and the phosphate of soda which I employed gave me -a wrong number for the atomic weight of phosphoric acid. - - - - -CHAPTER VII. - -OF THE PRESENT STATE OF CHEMISTRY. - - -To finish this history it will be now proper to lay before the reader a -kind of map of the present state of chemistry, that he may be able to -judge how much of the science has been already explored, and how much -still remains untrodden ground. - -Leaving out of view light, heat, and electricity, respecting the nature -of which only conjectures can be formed, we are at present acquainted -with fifty-three simple bodies, which naturally divide themselves -into three classes; namely, _supporters_, _acidifiable bases_, and -_alkalifiable bases_. - -The supporters are oxygen, chlorine, bromine, iodine, and fluorine. -They are all in a state of negative electricity: for when compounds -containing them are decomposed by the voltaic battery they all attach -themselves to the positive pole. They have the property of uniting with -every individual belonging to the other two classes. When they combine -with the acidifiable bases in certain proportions they constitute -_acids_; when with the alkalifiable bases, _alkalies_. In certain -proportions they constitute _neutral_ bodies, which possess neither the -properties of acids nor alkalies. - -The acidifiable bases are seventeen in number; namely, hydrogen, azote, -carbon, boron, silicon, sulphur, selenium, tellurium, phosphorus, -arsenic, antimony, chromium, uranium, molybdenum, tungsten, titanium, -columbium. These bodies do not form acids with every supporter, or -in every proportion; but they constitute the bases of all the known -acids, which form a numerous set of bodies, many of which are still -very imperfectly investigated. And indeed there are a good many of -them that may be considered as unknown. These acidifiable bases are -all electro-positive; but they differ, in this respect, considerably -from each other; hydrogen and carbon being two of the most powerful, -while titanium and columbium have the least energy. Sulphur and -selenium, and probably some other bodies belonging to this class are -occasional electro-negative bodies, as well as the supporters. Hence, -when united to other acidifiable bases, they produce a new class of -acids, analogous to those formed by the supporters. These have got -the name of sulphur acids, selenium acids, &c. Sulphur forms acids -with arsenic, antimony, molybdenum, and tungsten, and doubtless with -several other bases. To distinguish such acids from alkaline bases, -I have of late made an alteration in the termination of the old word -_sulphuret_, employed to denote the combination of sulphur with a base. -Thus _sulphide_ of arsenic means an acid formed by the union of sulphur -and arsenic; _sulphuret_ of copper means an alkaline body formed by the -union of sulphur and copper. The term _sulphide_ implies an _acid_, the -term _sulphuret_ a _base_. This mode of naming has become necessary, -as without it many of these new salts could not be described in an -intelligible manner. The same mode will apply to the acid and alkaline -compounds of selenium. Thus a _selenide_ is an acid compound, and a -_seleniet_ an alkaline compound in which selenium acts the part of a -supporter or electro-negative body. The same mode of naming might and -doubtless will be extended to all the other similar compounds, as soon -as it becomes necessary. In order to form a systematic nomenclature it -will speedily be requisite to new-model all the old names which denote -acids and bases; because unless this is done the names will become too -numerous to be remembered. At present we denote the alkaline bodies -formed by the union of _manganese_ and oxygen by the name of _oxides -of manganese_, and the acid compound of oxygen and the same metal -by the name of _manganesic acid_. The word _oxide_ applies to every -compound of a base and oxygen, whether neutral or alkaline; but when -the compound has acid qualities this is denoted by adding the syllable -_ic_ to the name of the base. This mode of naming answered tolerably -well as long as the acids and alkalies were all combinations of oxygen -with a base; but now that we know the existence of eight or ten classes -of acids and alkalies, consisting of as many supporters, or acidifiable -bases united to bases, it is needless to remark how very defective -it has become. But this is not the place to dwell longer upon such a -subject. - -The alkalifiable bases are thirty-one in number; namely, potassium, -sodium, lithium, barium, strontium, calcium, magnesium, aluminum, -glucinum, yttrium, cerium, zirconium, thorium, iron, manganese, nickel, -cobalt, zinc, cadmium, lead, tin, bismuth, copper, mercury, silver, -gold, platinum, palladium, rhodium, iridium, osmium. The compounds -which these bodies form with oxygen, and the other supporters, -constitute all the alkaline bases or the substances capable of -neutralizing the acids. - -Some of the acidifiable bases, when united to a certain portion of -oxygen, constitute, not acids, but _bases_ or _alkalies_. Thus the -_green oxides of chromium and uranium_ are alkalies; while, on the -other hand, there is a compound of oxygen and manganese which possesses -acid properties. In such cases it is always the compound containing the -least oxygen which is an alkali, and that containing the most oxygen -that is an acid. - -The opinion at present universally adopted by chemists is, that the -ultimate particles of bodies consist of _atoms_, incapable of further -division; and these atoms are of a size almost infinitely small. It can -be demonstrated that the size of an atom of _lead_ does not amount to -so much as 1/888,492,000,000,000 of a cubic inch. - -But, notwithstanding this extreme minuteness, each of these atoms -possesses a peculiar weight and a peculiar bulk, which distinguish it -from the atoms of every other body. We cannot determine the absolute -weight of any of them, but merely the relative weights; and this is -done by ascertaining the relative proportions in which they unite. When -two bodies unite in only one proportion, it is reasonable to conclude -that the compound consists of 1 atom of the one body, united to 1 atom -of the other. Thus oxide of bismuth is a compound of 1 oxygen and 9 -bismuth; and, as the bodies unite in no other proportion, we conclude -that an atom of bismuth is nine times as heavy as an atom of oxygen. It -is in this way that the atomic weights of the simple bodies have been -attempted to be determined. The following table exhibits these weights -referred to oxygen as unity, and deduced from the best data at present -in our possession: - - Atomic weight. - Oxygen 1 - Fluorine 2·25 - Chlorine 4·5 - Bromine 10 - Calcium 2·5 - Magnesium 1·5 - Aluminum 1·25 - Glucinum 2·25 - Iodine 15·75 - Hydrogen 0·125 - Azote 1·75 - Carbon 0·75 - Boron 1 - Silicon 1 - Phosphorus 2 - Sulphur 2 - Selenium 5 - Tellurium 4 - Arsenic 4·75 - Antimony 8 - Chromium 4 - Uranium 26 - Molybdenum 6 - Tungsten 12·5 - Titanium 3·25 - Columbium 22·75 - Potassium 5 - Sodium 3 - Lithium 0·75 - Barium 8·5 - Strontium 5·5 - Yttrium 4·25 - Zirconium 5 - Thorinum 7·5 - Iron 3·5 - Manganese 3·5 - Nickel 3·25 - Cobalt 3·25 - Cerium 6·25 - Zinc 4·25 - Cadmium 7 - Lead 13 - Tin 7·25 - Bismuth 9 - Copper 4 - Mercury 12·5 - Silver 13·75 - Gold 12·5 - Platinum 12 - Palladium 6·75 - Rhodium 6·75 - Iridium 12·25 - Osmium 12·5 - -The atomic weights of these bodies, divided by their specific gravity, -ought to give us the comparative size of the atoms. The following -table, constructed in this way, exhibits the relative bulks of these -atoms which belong to bodies whose specific gravity is known: - - Volume. - - Carbon 1 - Nickel } 1·75 - Cobalt } - Manganese } - Copper } 2 - Iron } - Platinum } 2·6 - Palladium } - Zinc 2·75 - Rhodium } - Tellurium } 3 - Chromium } - Molybdenum 3·25 - Silica } 3·5 - Titanium } - Cadmium 3·75 - Arsenic } - Phosphorus } 4 - Antimony } - Tungsten } - Bismuth } 4·25 - Mercury } - Tin } 4·66 - Sulphur } - Selenium } 5·4 - Lead } - Gold } - Silver } 6 - Osmium } - Oxygen } - Hydrogen } 9·33 - Azote } - Chlorine } - Uranium 13·5 - Columbium } 14 - Sodium } - Bromine 15·75 - Iodine 24 - Potassium 27 - - -We have no data to enable us to determine the shape of these atoms. The -most generally received opinion is, that they are spheres or spheroids; -though there are difficulties in the way of admitting such an opinion, -in the present state of our knowledge, nearly insurmountable. - -The probability is, that all the supporters have the property of -uniting with all the bases, in at least three proportions. But by -far the greater number of these compounds still remain unknown. The -greatest progress has been made in our knowledge of the compounds of -oxygen; but even there much remains to be investigated; owing, in a -great measure, to the scarcity of several of the bases which prevent -chemists from subjecting them to the requisite number of experiments. -The compounds of chlorine have also been a good deal investigated; but -bromine and iodine have been known for so short a time, that chemists -have not yet had leisure to contrive the requisite processes for -causing them to unite with bases. - -The acids at present known amount to a very great number. The oxygen -acids have been most investigated. They consist of two sets: those -consisting of oxygen united to a single base, and those in which -it is united to two or more bases. The last set are derived from -the animal and vegetable kingdoms: it does not seem likely that the -electro-chemical theory of Davy applies to them. They must derive -their acid qualities from some electric principle not yet adverted to; -for, from Davy's experiments, there can be little doubt that they are -electro-negative, as well as the other acids. The acid compounds of -oxygen and a single base are about thirty-two in number. Their names are - - Hyponitrous acid - Nitrous acid? - Nitric acid - Carbonic acid - Oxalic acid - Boracic acid - Silicic acid - Hypophosphorous acid - Phosphorous acid - Phosphoric acid - Hyposulphurous acid - Subsulphurous acid - Sulphurous acid - Sulphuric acid - Hyposulphuric acid - Selenious acid - Selenic acid - Arsenious acid - Arsenic acid - Antimonious acid - Antimonic acid - Oxide of tellurium - Chromic acid - Uranic acid - Molybdic acid - Tungstic acid - Titanic acid - Columbic acid - Manganesic acid - Chloric acid - Bromic acid - Iodic acid. - -The acids from the vegetable and animal kingdoms (not reckoning a -considerable number which consist of combinations of sulphuric acid -with a vegetable or animal body), amount to about forty-three: so -that at present we are acquainted with very nearly eighty acids which -contain oxygen as an essential constituent. - -The other classes of acids have been but imperfectly investigated. -Hydrogen enters into combination and forms powerful acids with all the -supporters except oxygen. These have been called hydracids. They are - - Muriatic acid, or hydrochloric acid - Hydrobromic acid - Hydriodic acid - Hydrofluoric acid, or fluoric acid - Hydrosulphuric acid - Hydroselenic acid - Hydrotelluric acid - -These constitute (such of them as can be procured) some of the most -useful and most powerful chemical reagents in use. There is also -another compound body, _cyanogen_, similar in its characters to a -supporter: it also forms various acids, by uniting to hydrogen, -chlorine, oxygen, sulphur, &c. Thus we have - - Hydrocyanic acid - Chlorocyanic acid - Cyanic acid - Sulpho-cyanic acid, &c. - -We know, also, fluosilicic acid and fluoboric acids. If to these we -add fulminic acid, and the various sulphur acids already investigated, -we may state, without risk of any excess, that the number of acids at -present known to chemists, and capable of uniting to bases, exceeds a -hundred. - -The number of alkaline bases is not, perhaps, so great; but it must -even at present exceed seventy; and it will certainly be much augmented -when chemists turn their attention to the subject. Now every base is -capable of uniting with almost every acid,[9] in all probability in at -least three different proportions: so that the number of _salts_ which -they are capable of forming cannot be fewer than 21,000. Now scarcely -1000 of these are at present known, or have been investigated with -tolerable precision. What a prodigious field of investigation remains -to be traversed must be obvious to the most careless reader. In such -a number of salts, how many remain unknown that might be applied to -useful purposes, either in medicine, or as mordants, or dyes, &c. How -much, in all probability, will be added to the resources of mankind by -such investigations need not be observed. - - [9] Acids and bases of the same class all unite. Thus sulphur acids - unite with sulphur bases; oxygen acids with oxygen bases, &c. - -The animal and vegetable kingdoms present a still more tempting field -of investigation. Animal and vegetable substances may be arranged -under three classes, acids, alkalies, and neutrals. The class of acids -presents many substances of great utility, either in the arts, or for -seasoning food. The alkalies contain almost all the powerful medicines -that are drawn from the vegetable kingdom. The neutral bodies are -important as articles of food, and are applied, too, to many other -purposes of first-rate utility. All these bodies are composed (chiefly, -at least) of hydrogen, carbon, oxygen, and azote; substances easily -procured abundantly at a cheap rate. Should chemists, in consequence -of the knowledge acquired by future investigations, ever arrive at the -knowledge of the mode of forming these principles from their elements -at a cheap rate, the prodigious change which such a discovery would -make upon the state of society must be at once evident. Mankind would -be, in some measure, independent of climate and situation; every thing -could be produced at pleasure in every part of the earth; and the -inhabitants of the warmer regions would no longer be the exclusive -possessors of comforts and conveniences to which those in less favoured -regions of the earth are strangers. Let the science advance for -another century with the same rapidity that it has done during the -last fifty years, and it will produce effects upon society of which -the present race can form no adequate idea. Even already some of -these effects are beginning to develop themselves;--our streets are -now illuminated with gas drawn from the bowels of the earth; and the -failure of the Greenland fishery during an unfortunate season like the -last, no longer fills us with dismay. What a change has been produced -in the country by the introduction of steam-boats! and what a still -greater improvement is at present in progress, when steam-carriages -and railroads are gradually taking the place of horses and common -roads. Distances will soon be reduced to one-half of what they are at -present; while the diminished force and increased rate of conveyance -will contribute essentially to lower the rest of our manufactures, and -enable us to enter into a successful competition with other nations. - -I must say a few words upon the application of chemistry to physiology -before concluding this imperfect sketch of the present state of the -science. The only functions of the living body upon which chemistry -is calculated to throw light, are the processes of digestion, -assimilation, and secretion. The nervous system is regulated by laws -seemingly quite unconnected with chemistry and mechanics, and, in -the present state of our knowledge, perfectly inscrutable. Even in -the processes of digestion, assimilation, and secretion, the nervous -influence is important and essential. Hence even of these functions -our notions are necessarily very imperfect; but the application of -chemistry supplies us with some data at least, which are too important -to be altogether neglected. - -The food of man consists of solids and liquids, and the quantity of -each taken by different individuals is so various, that no general -average can be struck. I think that the drink will, in most cases, -exceed the solid food in nearly the proportion of 4 to 3; but the solid -food itself contains not less than 7-10ths of its weight of water. In -reality, then, the quantity of liquid taken into the stomach is to that -of solid matter as 10 to 1. The food is introduced into the mouth, -comminuted by the teeth, and mixed up with the saliva into a kind of -pulp. - -The saliva is a liquid expressly secreted for this purpose, and the -quantity certainly does not fall short of ten ounces in the twenty-four -hours: indeed I believe it exceeds that amount: it is a liquid almost -as colourless as water, slightly viscid, and without taste or smell: -it contains about 3/1000 of its weight of a peculiar matter, which is -transparent and soluble in water: it has suspended in it about 1·4/1000 -of its weight of mucus; and in solution, about 2·8/1000 of common salt -and soda: the rest is water. - -From the mouth the food passes into the stomach, where it is changed -to a kind of pap called chyme. The nature of the food can readily be -distinguished after mastication; but when converted into _chyme_, it -loses its characteristic properties. This conversion is produced by -the action of the eighth pair of nerves, which are partly distributed -on the stomach; for when they are cut, the process is stopped: but -if a current of electricity, by means of a small voltaic battery, be -made to pass through the stomach, the process goes on as usual. Hence -the process is obviously connected with the action of electricity. A -current of electricity, by means of the nerves, seems to pass through -the food in the stomach, and to decompose the common salt which is -always mixed with the food. The muriatic acid is set at liberty, and -dissolves the food; for _chyme_ seems to be simply a solution of the -food in muriatic acid. - -The chyme passes through the pyloric orifice of the stomach into the -duodenum, the first of the small intestines, where it is mixed with two -liquids, the bile, secreted by the liver, and the pancreatic juice, -secreted by the pancreas, and both discharged into the duodenum to -assist in the further digestion of the food. The chyme is always acid; -but after it has been mixed with the bile, the acidity disappears. The -characteristic constituent of the bile is a bitter-tasted substance -called _picromel_, which has the property of combining with muriatic -acid, and forming with it an insoluble compound. The pancreatic juice -also contains a peculiar matter, to which chlorine communicates a red -colour. The use of the pancreatic juice is not understood. - -During the passage of the chyme through the small intestines it is -gradually separated into two substances; the _chyle_, which is absorbed -by the lacteals, and the excrementitious matter, which is gradually -protruded along the great intestines, and at last evacuated. The chyle, -in animals that live on vegetable food, is semitransparent, colourless, -and without smell; but in those that use animal food it is white, -slightly similar to milk, with a tint of pink. When left exposed to -the air it coagulates as blood does. The coagulum is _fibrin_. The -liquid portion contains _albumen_, and the usual salts that exist in -the blood. Thus the chyle contains two of the constituents of blood; -namely, _albumen_, which perhaps may be formed in the stomach, and -_fibrin_, which is formed in the small intestines. It still wants the -third constituent of blood, namely, the _red_ globules. - -From the lacteals the chyle passes into the thoracic duct; thence into -the left subclavian vein, by which it is conveyed to the heart. From -the heart it passes into the lungs, during its circulation through -which the _red globules_ are supposed to be formed, though of this we -have no direct evidence. - -The lungs are the organs of _breathing_, a function so necessary -to hot-blooded animals, that it cannot be suspended, even for a -few minutes, without occasioning death. In general, about twenty -inspirations, and as many expirations, are made in a minute. The -quantity of air which the lungs of an ordinary sized man can contain, -when fully distended, is about 300 cubic inches. But the quantity -actually drawn in and thrown out, during ordinary inspirations and -expirations, amounts to about sixteen cubic inches each time. - -In ordinary cases the volume of air is not sensibly altered by -respiration; but it undergoes two remarkable changes. A portion of its -oxygen is converted into carbonic acid gas, and the air expired is -saturated with humidity at the temperature of 98°. The moisture thus -given out amounts to about seven ounces troy, or very little short -of half an avoirdupois pound. The quantity of carbonic acid formed -varies much in different individuals, and also at different times in -the day; being a maximum at twelve o'clock at noon, and a minimum at -midnight. Perhaps four of carbonic acid, in every 100 cubic inches of -air breathed, may be a tolerable approach to the truth; that is to say, -that every six respirations produce four cubic inches of carbonic acid. -This would amount to 19,200 cubic inches in twenty-four hours. Now -the weight of 19,200 cubic inches of carbonic acid gas is 18·98 troy -ounces, which contain rather more than five troy ounces of carbon. - -These alterations in the air are doubtless connected with -corresponding alterations in the blood, though with respect to the -specific nature of these alterations we are ignorant. But there -are two purposes which respiration answers, the nature of which we -can understand, and which seem to afford a reason why it cannot be -interrupted without death. It serves to develop the _animal heat_, -which is so essential to the continuance of life; and it gives the -blood the property of stimulating the heart; without which it would -cease to contract, and put an end to the circulation of the blood. -This stimulating property is connected with the scarlet colour which -the blood acquires during respiration; for when the scarlet colour -disappears the blood ceases to stimulate the heart. - -The temperature of the human body in a state of health is about 98° -in this country; but in the torrid zone it is a little higher. Now as -we are almost always surrounded by a medium colder than 98°, it is -obvious that the human body is constantly giving out heat; so that -if it did not possess the power of generating heat, it is clear that -its temperature would soon sink as low as that of the surrounding -atmosphere. - -It is now generally understood that common combustion is nothing else -than the union of oxygen gas with the burning body. The substances -commonly employed as combustibles are composed chiefly of carbon and -hydrogen. The heat evolved is proportional to the oxygen gas which -unites with these bodies. And it has been ascertained that every 3¾ -cub¾ic inches of oxygen which combine with carbon or hydrogen occasion -the evolution of 1° of heat. - -There are reasons for believing that not only carbon but also hydrogen -unite with oxygen in the lungs, and that therefore both carbonic acid -and water are formed in that organ. And from the late experiments -of M. Dupretz it is clear that the heat evolved in a given time, by -a hot-blooded animal, is very little short of the heat that would be -evolved by the combustion of the same weight of carbon and hydrogen -consumed during that time in the lungs. Hence it follows that the heat -evolved in the lungs is the consequence of the union of the oxygen of -the air with the carbon and hydrogen of the blood, and that the process -is perfectly analogous to combustion. - -The specific heat of arterial blood is somewhat greater than that of -venous blood. Hence the reason why the temperature of the lungs does -not become higher by breathing, and why the temperature of the other -parts of the body are kept up by the circulation. - -The blood seems to be completed in the kidneys. It consists essentially -of albumen, fibrin, and the red globules, with a considerable quantity -of water, holding in solution certain salts which are found equally -in all the animal fluids. It is employed during the circulation in -supplying the waste of the system, and in being manufactured into all -the different secretions necessary for the various functions of the -living body. By these different applications of it we cannot doubt that -its nature undergoes very great changes, and that it would soon become -unfit for the purposes of the living body were there not an organ -expressly destined to withdraw the redundant and useless portions of -that liquid, and to restore it to the same state that it was in when -it left the lungs. These organs are the _kidneys_; through which all -the blood passes, and during its circulation through which the urine is -separated from it and withdrawn altogether from the body. These organs -are as necessary for the continuance of life as the lungs themselves; -accordingly, when they are diseased or destroyed, death very speedily -ensues. - -The quantity of urine voided daily is very various; though, doubtless, -it bears a close relation to that of the drink. It is nearly but not -quite equal to the amount of the drink; and is seldom, in persons who -enjoy health, less than 2 lbs. avoirdupois in twenty-four hours. Urine -is one of the most complex substances in the animal kingdom, containing -a much greater number of ingredients than are to be found in the blood -from which it is secreted. - -The water in urine voided daily amounts to about 1·866lbs. The blood -contains no acid except a little muriatic. But in urine we find -sulphuric, phosphoric, and uric acids, and sometimes oxalic and nitric -acids, and perhaps also some others. The quantity of sulphuric acid -may be about forty-eight grains daily, containing nineteen grains of -sulphur. The phosphoric acid about thirty-three grains, containing -about fourteen grains of phosphorus. The uric acid may amount to -fourteen grains. These acids are in combination with potash, or soda, -or ammonia, and also with a very little lime and magnesia. The common -salt evacuated daily in the urine amounts to about sixty-two grains. -The urea, a peculiar substance found only in the urine, amounts perhaps -to as much as 420 grains. - -It would appear from these facts that the kidneys possess the property -of converting the sulphur and phosphorus, which are known to exist in -the blood, into acids, and likewise of forming other acids and urea. - -The quantity of water thrown out of the system by the urine and lungs -is scarcely equal to the amount of liquid daily consumed along with the -food. But there is another organ which has been ascertained to throw -out likewise a considerable quantity of moisture, this organ is the -skin; and the process is called _perspiration_. From the experiments of -Lavoisier and Seguin it appears that the quantity of moisture given out -daily by the skin amounts to 54·89 ounces: this added to the quantity -evolved from the lungs and the urine considerably exceeds the weight of -liquid taken with the food, and leaves no doubt that water as well as -carbonic acid must be formed in the lungs during respiration. - -Such is an imperfect sketch of the present state of that department of -physiology which is most intimately connected with Chemistry. It is -amply sufficient, short as it is, to satisfy the most careless observer -how little progress has hitherto been made in these investigations; and -what an extensive field remains yet to be traversed by future observers. - - - THE END. - - - C. 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They have -been replaced by the name of the element within [] thus - [hydrogen]. - -In chapter VI the final numeral in several of the decimal numbers is -surmounted by a point. 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