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+The Project Gutenberg Etext of Getting Gold, by J. C. F. Johnson
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+Title: Getting Gold
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+Author: J. C. F. Johnson
+
+Release Date: January, 2003  [Etext #3679]
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+The Project Gutenberg Etext of Getting Gold, by J. C. F. Johnson
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+Etext prepared by Dagny, dagnyj@hotmail.com
+and John Bickers, jbickers@ihug.co.nz
+
+
+
+
+
+GETTING GOLD:
+
+A PRACTICAL TREATISE
+FOR
+PROSPECTORS, MINERS, AND STUDENTS.
+
+BY
+
+J. C. F. JOHNSON, F. G. S.,
+MEMBER OF THE AUST. INST. OF MINING ENGINEERS;
+
+AUTHOR OF
+"PRACTICAL MINING," "THE GENESIOLOGY OF GOLD," ETC.
+
+
+
+PREPARER'S NOTE
+
+  This text was prepared from a 1898 edition, published by Charles
+  Griffin & Company, Limited; Exeter Street, Strand, London. It is
+  the second edition, revised. Numerous drawings and diagrams have
+  been omitted.
+
+
+
+PREFACE
+
+  Some six years ago the author published a small book entitled
+  "Practical Mining," designed specially for the use of those
+  engaged in the always fascinating, though not as invariably
+  profitable, pursuit of "Getting Gold." Of this ten thousand copies
+  were sold, nearly all in Australasia, and the work is now out of
+  print. The London /Mining Journal/ of September 9th, 1891, said of
+  it: "We have seldom seen a book in which so much interesting
+  matter combined with useful information is given in so small a
+  space."
+
+  The gold-mining industry has grown considerably since 1891, and it
+  appeared to the writer that the present would be a propitious time
+  to bring out a similar work, but with a considerably enlarged
+  scope. What has been aimed at is to make "Getting Gold" a
+  compendium, in specially concrete form, of useful information
+  respecting the processes of winning from the soil and the after-
+  treatment of gold and gold ores, including some original practical
+  discoveries by the author. Practical information, original and
+  selected, is given to mining company directors, mine managers,
+  quartz mill operators, and prospectors. In "Rules of Thumb,"
+  chapters XI. and XII., will be found a large number of useful
+  hints on subjects directly and indirectly connected with gold-
+  mining.
+
+  The author's mining experience extends back thirty years and he
+  therefore ventures to believe with some degree of confidence that
+  the information, original or compiled, which the book contains,
+  will be found both useful and profitable to those who are in any
+  capacity interested in the gold-mining industry.
+
+J. C. F. J.
+
+  LONDON, November, 1896.
+
+
+
+
+
+GETTING GOLD
+
+
+
+CHAPTER I
+
+INTRODUCTORY
+
+GOLD is a name to charm by. It is desired by all nations, and is the
+one metal the supply of which never exceeds the demand. Some one has
+aptly said, "Gold is the most potent substance on the surface of our
+planet." Tom Hood sings:
+
+  Gold, gold, gold, gold!
+  Bright and yellow, hard and cold;
+  Molten, graven, hammered, rolled,
+  Heavy to get, and light to hold;
+  Stolen, borrowed, squandered, doled.
+
+That this much appreciated metal is heavy to get is proved by the high
+value which has been placed on it from times remote to date, and that
+it is light to hold most of us know to our cost.
+
+We read no farther than the second chapter in the Bible when we find
+mention of gold. There Moses speaks of "the land of Havilah, where
+there is gold"; and in Genesis, chapter xxiv., we read that Abraham's
+servant gave Rebekah an earring of half a shekel weight, say 5 dwt. 13
+grs., and "two bracelets of ten shekels weight," or about 4 1/2 ozs.
+Then throughout the Scriptures, and, indeed, in all historic writings,
+we find frequent mention of the king of metals, and always it is
+spoken of as a commodity highly prized.
+
+I have sometimes thought, however, that either we are mistaken in the
+weights used by the Hebrew nation in early days, or that the
+arithmetic of those times was not quite "according to Cocker." We
+read, I. Kings x. and xli., that Solomon in one year received no less
+than six hundred and three score and six talents of gold. If a talent
+of gold was, as has been assumed, 3000 shekels of 219 grains each, the
+value of the golden treasure accumulated in this one year by the
+Hebrew king would have been 3,646,350 pounds sterling. Considering
+that the only means of "getting gold" in those days was a most
+primitive mode of washing it from river sands, or a still more
+difficult and laborious process of breaking the quartz from the lode
+without proper tools or explosives, and then slowly grinding it by
+hand labour between two stones, the amount mentioned is truly
+enormous.
+
+Of this treasure the Queen of Sheba, who came to visit the Hebrew
+monarch, contributed a hundred and twenty talents, or, say, 600,000
+pounds worth. Where the Land of Ophir, whence this golden lady came,
+was really situated has evoked much controversy, but there is now a
+general opinion that Ophir was on the east coast of Africa, somewhere
+near Delagoa Bay, in the neighbourhood of the Limpopo and Sabia
+rivers. It should be mentioned that the name of the "black but comely"
+queen was Sabia, which may or may not be a coincidence, but it is
+certainly true that the rivers of this district have produced gold
+from prehistoric times till now.
+
+The discovery of remarkable ruins in the newly acquired province of
+Mashonaland, which evince a high state of civilisation in the
+builders, may throw some light on this interesting subject.
+
+The principal value of gold is as a medium of exchange, and its high
+appreciation is due, first, to the fact that it is in almost universal
+request; and, secondly, to its comparative scarcity; yet, oddly
+enough, with the exception of that humble but serviceable metal iron,
+gold is the most widely distributed metal known. Few, if any,
+countries do not possess it, and in most parts of the world, civilised
+and uncivilised, it is mined for and brought to market. The torrid,
+temperate, and frigid zones are almost equally auriferous. Siberia,
+mid-Asia, most parts of Europe, down to equatorial and southern Africa
+in the Old World, and north, central, and southern America, with
+Australasia, in what may be termed the New World, are all producers of
+gold in payable quantities.
+
+In the earlier ages, the principal source of the precious metal was
+probably Africa, which has always been prolific in gold. To this day
+there are to be seen in the southern provinces of Egypt excavations
+and the remains of old mine buildings and appliances left by the
+ancient gold-miners, who were mostly State prisoners. Some of these
+mines were worked by the Pharaohs of, and before, the time of Moses;
+and in these dreadful places thousands of Israelites were driven to
+death by the taskmaster's whip. Amongst the old appliances is one
+which approximated very closely to the amalgamating, or blanket table,
+of a modern quartz mill.
+
+The grinding was done between two stones, and possibly by means of
+such primitive mechanism as is used to-day by the natives of Korea.
+
+The Korean Mill is simply a large hard stone to which a rocking motion
+is given by manual power by means of the bamboo handles while the ore
+is crushed between the upper and basement stone.
+
+Solomon says "there is no new thing under the sun"; certainly there is
+much that is not absolutely new in appliances for gold extraction. I
+lately learned that the principle of one of our newest concentrating
+machines, the Frue vanner, was known in India and the East centuries
+ago; and we have it on good authority--that of Pliny--that gold saving
+by amalgamation with mercury was practised before the Christian era.
+It will not be surprising then if, ere long, some one claims to have
+invented the Korean Mill, with improvements.
+
+Few subjects in mineralogical science have evoked more controversy
+than the origin of gold. In the Middle Ages, and, indeed, down to the
+time of that great philosopher, Sir Isaac Newton, who was himself
+bitten with the craze, it was widely believed that, by what was known
+as transmutation, the baser metals might be changed to gold; and much
+time and trouble were expended in attempts to make gold--needless to
+say without the desired result. Doubtless, however, many valuable
+additions to chemical science, and also some useful metallic alloys,
+were thus discovered.
+
+The latest startling statement on this subject comes from, of course,
+the wonderland of the world, America. In a recently published journal
+it is said that a scientific metallurgist there has succeeded in
+producing absolutely pure gold, which stands all tests, from silver.
+Needless to say, if this were true, at all events the much vexed hi-
+metallic question would be solved at once and for all time.
+
+It is now admitted by all specialists that the royal metal, though
+differing in material respects in its mode of occurrence from its
+useful but more plebeian brethren of the mineral kingdom, has yet been
+deposited under similar conditions from mineral salts held in
+solution.
+
+The first mode of obtaining this much desired metal was doubtless by
+washing the sand of rivers which flowed through auriferous strata.
+Some of these, such as the Lydian stream, Pactolus, were supposed to
+renew their golden stores miraculously each year. What really happened
+was that the winter floods detached portions of auriferous drift from
+the banks, which, being disintegrated by the rush and flow of the
+water, would naturally deposit in the still reaches and eddies any
+gold that might be contained therein.
+
+The mode of washing was exactly that carried on by the natives in some
+districts of Africa to-day. A wooden bowl was partly filled with
+auriferous sand and mud, and, standing knee-deep in the stream, the
+operator added a little water, and caused the contents of the bowl to
+take a circular motion, somewhat as the modern digger does with his
+tin dish, with this difference, that his ancient prototype allowed the
+water and lighter particles to escape over the rim as he swirled the
+stuff round and round. I presume, in finishing the operation, he
+collected the golden grains by gently lapping the water over the
+reduced material, much as we do now.
+
+I have already spoken of the mode in which auriferous lode-stuff was
+treated in early times--i.e., by grinding between stones. This is also
+practised in Africa to-day, and we have seen that the Koreans, with
+Mongolian acuteness, have gone a step farther, and pulverise the
+quartz by rocking one stone on another. In South America the arrastra
+is still used, which is simply the application of horse or mule power
+to the stone-grinding process, with use of mercury.
+
+The principal sources of the gold supply of the modern world have
+been, first, South America, Transylvania in Europe, Siberia in Asia,
+California in North America, and Australia. Africa has always produced
+gold from time immemorial.
+
+The later development in the Johannesburg district, Transvaal, which
+has absorbed during the last few years so many millions of English
+capital, is now, after much difficulty and disappointment--thanks to
+British pluck and skill--producing splendidly. The yield for 1896 was
+2,281,874 ounces--a yield never before equalled by lode-mining from
+one field.
+
+In the year 1847 gold was discovered in California, at Sutor's
+sawmill, Sacramento Valley, where, on the water being cut off, yellow
+specks and small nuggets were found in the tail race. The enormous
+"rush" which followed is a matter of history and the subject of many
+romances, though the truth has, in this instance, been stranger than
+fiction.
+
+The yield of the precious metal in California since that date up to
+1888 amounts to 256,000,000 pounds.
+
+Following close on the American discovery came that of Australia, the
+credit of which has usually been accorded to Hargraves, a returned
+Californian digger, who washed out payable gold at Lewis Ponds Creek,
+near Bathurst, in 1851. But there is now no reason to doubt that gold
+had previously been discovered in several parts of that great island
+continent. It may be news to many that the first gold mine worked in
+Australia was opened about twelve miles from Adelaide city, S.A., in
+the year 1848. This mine was called the Victoria; several of the
+Company's scrip are preserved in the Public Library; but some two
+years previous to this a man named Edward Proven had found gold in the
+same neighbourhood.
+
+Most Governments nowadays encourage in every possible way the
+discovery of gold-fields, and rewards ranging from hundreds to
+thousands of pounds are given to successful prospectors of new
+auriferous districts. The reward the New South Wales authorities meted
+out to a wretched convict, who early in this century had dared to find
+gold, was a hundred lashes vigorously laid on to his already
+excoriated back. The man then very naturally admitted that the alleged
+discovery was a fraud, and that the nugget produced was a melted down
+brass candlestick. One would have imagined that even in those
+unenlightened days it would not have been difficult to have found a
+scientist sufficiently well informed to put a little nitric acid on
+the supposed nugget, and so determine whether it was the genuine
+article, without skinning a live man first to ascertain. My belief is
+that the unfortunate fellow really found gold, but, as Mr. Deas
+Thompson, the then Colonial Secretary, afterwards told Hargraves in
+discouraging his reported discovery, "You must remember that as soon
+as Australia becomes known as a gold-producing country it is utterly
+spoiled as a receptacle for convicts."
+
+This, then, was the secret of the unwillingness of the authorities to
+encourage the search for gold, and it is after all due to the fact
+that the search was ultimately successful beyond all precedent, that
+Australia has been for so many years relieved of the curse of
+convictism, and has ceased once and for all to be a depot for the
+scoundrelism of Britain--"Hurrah for the bright red gold!"
+
+Since the year 1851 to date the value of the gold raised in the
+Australasian colonies has realised the enormous amount of nearly
+550,000,000 pounds. One cannot help wondering where it all goes.
+
+Mulhall gives the existing money of the world at 2437 million pounds,
+of which 846 millions are paper, 801 millions silver, and 790 millions
+gold. From 1830 to 1880 the world consumed by melting down plate,
+etc., 4230 tons of silver more than it mined. From 1800 to 1870 the
+value of gold was about 15 1/2 times that of silver. From 1870 to 1880
+it was 167 times the value of silver and now exceeds it over twenty
+times. In 1700 the world had 301 million pounds of money; in 1800, 568
+million pounds; and in 1860, 1180 million pounds sterling.
+
+The gold first worked for in Australia, as in other places, was of
+course alluvial, by which is usually understood loose gold in nuggets,
+specks, and dust, lying in drifts which were once the beds of long
+extinct streams and rivers, or possibly the moraines of glaciers, as
+in New Zealand.
+
+Further on the differences will be mentioned between "alluvial" and
+"reef" or lode gold, for that there is a difference in origin in many
+occurrences, is, I think, provable. I hold, and hold strongly, that
+true alluvial gold is not always derived from the disintegration of
+lodes or reefs. For instance, the "Welcome Nugget" certainly never
+came from a reef. No such mass of gold, or anything approaching it,
+has ever yet been taken from a quartz matrix. It was found at Bakery
+Hill, Ballarat, in 1858, weight 2195 ozs., and sold for 10,500 pounds.
+This was above its actual value.
+
+The "Welcome Stranger," a still larger mass of gold, was found amongst
+the roots of a tree at Dunolly, Victoria, in 1869, by two starved out
+"fossickers" named Deeson and Oates. The weight of this, the largest
+authenticated nugget ever found was 2268 1/2 ozs., and it was sold for
+10,000 pounds, but it was rendered useless as a specimen by the
+finders, who spent a night burning it to remove the adhering quartz.
+
+But the ordinary digger neither hopes nor expects to unearth such
+treasures as these. He is content to gather together by means of
+puddling machine, cradle, long tom, or even puddling tub and tin dish,
+the scales, specks, dust, and occasional small nuggets ordinarily met
+with in alluvial "washes."
+
+Having sunk to the "wash," or "drift," the digger, by means of one or
+more of the appliances mentioned above, proceeds to separate the gold
+from the clay and gravel in which it is found. Of course in large
+alluvial claims, where capital is employed, such appliances are
+superseded by steam puddles, buddles, and other machinery, and
+sometimes mercury is used to amalgamate the gold when very fine.
+Hydraulicing is the cheapest form of alluvial mining, but can only be
+profitably carried out where extensive drifts, which can be worked as
+quarry faces, and unlimited water exist in the same neighbourhood.
+When such conditions obtain a few grains of gold to the yard or ton
+will pay handsomely.
+
+Lode or reef mining, is a more expensive and complicated process,
+requiring much skill and capital. First, let me explain what a lode
+really is. The American term is "ledge," and it is not inappropriate
+or inexpressive. Imagine then a ledge, or kerbstone, continuing to
+unknown depths in the earth at any angle varying from perpendicular to
+nearly horizontal. This kerbstone is totally distinct from the rocks
+which enclose it; those on one side may be slate, on the other,
+sandstone; but the lode, separated usually by a small band of soft
+material known to miners as "casing," or fluccan," preserves always an
+independent existence, and in many instances is practically bottomless
+so far as human exploration is concerned.
+
+There are, however, reefs or lodes which are not persistent in depth.
+Sometimes the lode formation is found only in the upper and newer
+strata, and cuts out when, say, the basic rocks (such as granite,
+etc.) are reached. Again, there is a form of lode known among miners
+as a "gash" vein. It is sometimes met with in the older crystalline
+slates, particularly when the lode runs conformably with the cleavage
+of the rock.
+
+Much ignorance is displayed on the subject of lode formation and the
+deposition of metals therein, even by mining men of long experience.
+Many still insist that lodes, particularly those containing gold, are
+of igneous origin, and point to the black and brown ferro-manganic
+outcrops in confirmation. It must be admitted that often the upper
+portions of a lode present a strong appearance of fire agency, but
+exactly the same appearance can be caused by oxidation of iron and
+manganese in water.
+
+It may now be accepted as a proven fact that no true lode has been
+formed, or its metals deposited except by aqueous action. That is to
+say, the bulk of the lode and all its metalliferous contents were once
+held in solution in subterranean waters, which were ejected by geysers
+or simply filtered into fissures formed either by the shrinkage of the
+earth's crust in process of cooling or by volcanic force.
+
+It is not contended that the effect of the internal fires had no
+influence on the formation of metalliferous veins, indeed, it is
+certain that they had, but the action was what is termed hydrothermal
+(hot water); and such action we may see in progress to-day in New
+Zealand, where hot springs stream or spout above the surface, when the
+silica and lime impregnated water, reduced in heat and released from
+pressure, begins forthwith to deposit the minerals previously held in
+solution. Hence the formation of the wondrous Pink and White Terrace,
+destroyed by volcanic action some eight years since, which grew almost
+while you watched; so rapidly was the silica deposited that a dead
+beetle or ti-tree twig left in the translucent blue water for a few
+days became completely coated and petrified.
+
+Gold differs in its mode of occurrence from other metals in many
+respects; but there is no doubt that it was once held in aqueous
+solution and deposited in its metallic form by electro-chemical
+action. It is true we do not find oxides, carbonates, or bromides of
+gold in Nature, nor can we feel quite sure that gold now exists
+naturally as a sulphide, chloride, or silicate, though the presumption
+is strongly that it does. If so, the deposition of the gold may be
+ceaselessly progressing.
+
+Generally reef gold is finer as to size of the particles, and, as a
+rule, inferior in quality to alluvial. Thus, in addition to the extra
+labor entailed in breaking into one of the hardest of rocks, quartz,
+the /madre de oro/ ("mother of gold") of the Spaniards, there is the
+additional labour required to pulverise the rock so as to set free the
+tiniest particles of the noble metal it so jealously guards. There is
+also the additional difficult operation of saving and gathering
+together these small specks, and so producing the massive cakes and
+bars of gold in their marketable state.
+
+Having found payable gold in quartz on the surface, the would-be miner
+has next to ascertain two things. First, the strike or course of the
+lode; and secondly, its underlie, or dip. The strike, or course, is
+the direction which the lode takes lengthwise.
+
+In Australia the term "underlie" is used to designate the angle from
+the perpendicular at which the lode lies in its enclosing rocks, and
+by "dip" the angle at which it dips or inclines lengthwise on its
+course. Thus, at one point the cap of a lode may appear on the
+surface, and some distance further the cap may be hundreds of feet
+below. Usually a shaft is sunk in the reef to prove the underlie, and
+a level, or levels, driven on the course to ascertain its direction
+underground, also if the gold extends, and if so, how far. This being
+proved, next a vertical shaft is sunk on the hanging or upper wall
+side, and the reef is either tapped thereby, or a cross-cut driven to
+intersect it.
+
+We will now assume that our miners have found their lode payable, and
+have some hundreds of tons of good gold-bearing stone in sight or at
+the surface. They must next provide a reducing plant. Of means for
+crushing or triturating quartz there is no lack, and every year gives
+us fresh inventions for the purpose, each one better than that which
+preceded it, according to its inventor. Most practical men, however,
+prefer to continue the use of the stamper battery, which is virtually
+a pestle and mortar on a large scale. Why we adhere to this form of
+pulverising machine is that, though somewhat wasteful of power, it is
+easily understood, its wearing parts are cheaply and expeditiously
+replaced, and it is so strong that even the most perversely stupid
+workman cannot easily break it or put it out of order.
+
+The stone, being pounded into sand of such degree of fineness as the
+gold requires, passes through a perforated iron plate called a
+"grating," or "screen," on to an inclined surface of copper plates
+faced with mercury, having small troughs, or "riffles," containing
+mercury, placed at certain distances apart.
+
+The crushed quartz is carried over these copper "tables," as they are
+termed, thence over the blanket tables--that is, inclined planes
+covered with coarse serge, blankets, or other flocculent material--so
+that the heavy particles may be caught in the hairs, or is passed over
+vanners or concentrating machines. The resulting "concentrates" are
+washed off from time to time and reserved for secondary treatment.
+
+To begin with, they are roasted to get rid of the sulphur, arsenic,
+etc., which would interfere with the amalgamation or lixiviation, and
+then either ground to impalpable fineness in one of the many
+triturating pans with mercury, or treated by chlorine or potassium
+cyanide.
+
+If, however, we are merely amalgamating, then at stated periods the
+battery and pans are cleaned out, the amalgam rubbed or scraped from
+the copper plates and raised from the troughs and riffles. It is then
+squeezed through chamois leather, or good calico will do as well, and
+retorted in a large iron retort, the nozzle of which is kept in water
+so as to convert the mercury vapour again to the metallic form. The
+result is a spongy cake of gold, which is either sold as "retorted"
+gold or smelted into bars.
+
+The other and more scientific methods of extracting the precious metal
+from its matrices, such as lixiviation or leaching, by means of
+solvents (chlorine, cyanogen, hyposulphite of soda, etc.), will be
+more fully described later on.
+
+
+
+CHAPTER II
+
+GOLD PROSPECTING--ALLUVIAL AND GENERAL
+
+It is purposed in this chapter to deal specially with the operation of
+searching for valuable mineral by individuals or small working
+parties.
+
+It is well known that much disappointment and loss accrue through lack
+of knowledge by prospectors, who with all their enterprise and energy
+are often very ignorant, not only of the probable locality, mode of
+occurrence, and widely differing appearance of the various valuable
+minerals, but also of the best means of locating and testing the ores
+when found. It is for the information of such as these that this
+chapter is mainly intended, not for scientists or miners of large
+experience.
+
+All of us who have had much to do with mining know that the majority
+of the best mineral finds have been made by the purest accident; often
+by men who had no mining knowledge whatever; and that many valuable
+discoveries have been delayed, or, when made, abandoned as not
+payable, from the same cause--ignorance of the rudiments of mineralogy
+and mining. I have frequently been asked by prospectors, when
+inspecting new mineral fields, what rudimentary knowledge will be most
+useful to them and how it can be best obtained.
+
+If a man can spare the time a course of lessons at some accredited
+school of mines will be, undoubtedly, the best possible training; but
+if he asks what books he should read in order to obtain some primary
+technical instruction, I reply: First, an introductory text-book of
+geology, which will tell him in the simplest and plainest language all
+he absolutely requires to know on this important subject. Every
+prospector should understand elementary geology so far as general
+knowledge of the history of the structure of the earth's crust and of
+the several actions that have taken place in the past, or are now in
+operation, modifying its conditions. He may with advantage go a few
+steps further and learn to classify the various formations into
+systems, groups, and series: but he can acquire all that he need
+absolutely know from this useful little 2s. 6d. book. Next, it is
+advisable to learn something about the occurrence and appearance of
+the valuable minerals and the formations in which they are found. For
+all practical purposes I can recommend Cox and Ratte's "Mines and
+Minerals," one of the Technical Education series of New South Wales,
+which deals largely with the subject from an Australian standpoint,
+and is therefore particularly valuable to the Australian miner, but
+which will be found applicable to most other gold-bearing countries. I
+must not, however, omit to mention an admirably compiled /multum in
+parvo/ volume prepared by Mr. G. Goyder, jun., Government Assayer and
+Assay Instructor at the School of Mines, Adelaide. It is called the
+"Prospectors' Pocketbook," costs only one shilling, is well bound, and
+of handy size to carry. In brief, plain language it describes how a
+man, having learned a little of assaying, may cheaply provide himself
+with a portable assay plant, and fluxes, and also gives considerable
+general information on the subject of minerals, their occurrence and
+treatment.[*]
+
+[*] Another excellent and really practical book is Prof. Cole's
+    "Practical Aids in Geology" (second edition), 10s. 6d.
+
+It may here be stated that some twelve years ago I did a large amount
+of practical silver assaying on the Barrier (Broken Hill), which was
+not then so accessible a place as it is now, and got closely correct
+results from a number of different mines, with an extemporised plant
+almost amusing in its simplicity. All I took from Adelaide were a
+small set of scales capable of determining the weight of a button down
+to 20 ozs. to the ton, a piece of cheese cloth to make a screen or
+sieve, a tin ring 1 l/2 in. diameter, by 1/2 in. high, a small brass
+door knob to use as a cupel mould, and some powdered borax, carbonate
+of soda, and argol for fluxes; while for reducing lead I had recourse
+to the lining of a tea-chest, which lead contains no silver--John
+Chinaman takes good care of that. My mortar was a jam tin, without top
+or bottom, placed on an anvil; the pestle a short steel drill. The
+blacksmith at Mundi Mundi Station made me a small wrought iron
+crucible, also a pair of bent tongs from a piece of fencing-wire. The
+manager gave me a small common red flower pot for a muffle, and with
+the smith's forge (the fire built round with a few blocks of talcose
+schist) for a furnace, my plant was complete. I burned and crushed
+bones to make my bone-dust for cupelling, and thus provided made
+nearly forty assays, some of which were afterwards checked in
+Adelaide, in each instance coming as close as check assays generally
+do. Nowadays one can purchase cheaply a very effective portable plant,
+or after a few lessons a man may by practice make himself so
+proficient with the blowpipe as to obtain assay results sufficiently
+accurate for most practical purposes.
+
+Coming then to the actual work of prospecting. What the prospector
+requires to know is, first, the usual locality of occurrence of the
+more valuable minerals; secondly, their appearance; thirdly, a simple
+mode of testing. With respect to occurrence, the older sandy and clay
+slates, chlorite slates, micaceous, and hornblendic schists,
+particularly at or near their junction with the intrusive granite and
+diorite, generally form the most likely geological country for the
+finding of mineral lodes, particularly gold, silver and tin. But those
+who have been engaged in practical mining for long, finding by
+experience that no two mineral fields are exactly alike in all their
+characteristics, have come to the conclusion that it is unwise to form
+theories as to why metals should or should not be found in certain
+enclosing rocks or matrices. Some of the best reef gold got in
+Victoria has been obtained in dead white, milky-looking quartz almost
+destitute of base metal. In South Australia reef gold is almost
+invariably associated with iron, either as oxide, as "gossan;" or
+ferruginous calcite, "limonite;" or granular silica, conglomerated by
+iron, the "ironstone" which forms the capping or outcrop of many of
+our reefs, and which is often rich in gold.
+
+But to show that it is unsafe to decide off-hand in what class of
+matrix metals will or will not be found, I may say that in my own
+experience I have seen payable gold in the following materials:--
+
+Quartz, dense and milky, also in quartz of nearly every colour and
+appearance, saccharoidal, crystalline, nay, even in clear glass-like
+six-sided prismatic crystals, and associated with silver, copper,
+lead, arsenic, iron as sulphide, oxide, carbonate, and tungstate,
+antimony, bismuth, nickel, zinc, lead, and other metals in one form or
+another; in slate, quartzite, mica schist, granite, diorite, porphyry,
+felsite, calcite, dolomite, common carbonate of iron, siliceous sinter
+from a hot spring, as at Mount Morgan; as alluvial gold in drifts
+formed of almost all these materials; and once, perhaps the most
+curious matrix of all, a small piece of apparently alluvial gold,
+naturally imbedded in a shaly piece of coal. This specimen, I think,
+is in the Sydney Museum. One thing, however, the prospector may make
+sure of: he will always find gold more or less intimately associated
+with silica (Quartz) in one or other of its many forms, just as he
+will always find cassiterite (oxide of tin) in the neighbourhood of
+granite containing muscovite (white mica), which so many people will
+persist in terming talc. It is stated to be a fact that tin has never
+been found more than about two miles from such granite.
+
+From what has been said of its widely divergent occurrences it will be
+admitted that the Cornish miners' saying with regard to metals
+generally applies with great force to gold: "Where it is, there it
+is": and "Cousin Jack" adds, with pathetic emphasis, "and where it is
+generally, there I ain't."
+
+I have already spoken of the geological "country rock" in which red
+gold is most likely to be discovered--i.e., the junction of the slates
+and schists with the igneous or metamorphic (altered) rocks, or in
+this vicinity. Old river beds formed of gravelly drifts in the same
+neighbourhood may probably contain alluvial gold, or shallow deposits
+of "wash" on hillsides and in valleys will often carry good surface
+gold. This is sometimes due to the denudation, or wearing away, of the
+hills containing quartz-veins--that is, where the alluvial gold really
+was derived from such veins, which, popular opinion to the contrary,
+is not always the case.
+
+Much disappointment and loss of time and money may sometimes be
+prevented if prospectors will realise that /all/ alluvial gold does
+not come from the quartz veins or reefs; and that following up an
+alluvial lead, no matter how rich, will not inevitably develop a
+payable gold lode. Sometimes gold, evidently of reef origin, is found
+in the alluvial; but in that case it is generally fine as regards the
+size of the particles, more or less sharp-edged, or crystalline in
+form if recently shed; while such gold is often of poorer quality than
+the true alluvial which occurs in mammillary (breast-like) nuggets,
+and is of a higher degree of purity as gold.
+
+The ordinary non-scientific digger will do well to give credence to
+this view of the case, and will often thereby save himself much
+useless trouble. Sometimes also the alluvial gold, coarser in size
+than true reef-born alluvial, is derived almost /in situ/ from small
+quartz "leaders," or veins, which the grinding down of the face of the
+slates has exposed; these leaders in time being also broken and worn,
+set free the gold they have contained, which does not, as a rule,
+travel far, but sometimes becomes water-worn by the rubbing over it of
+the disintegrated fragments of rock.
+
+But the heavy, true alluvial gold, in great pure masses, mammillary,
+or botryoidal (like a bunch of grapes) in shape, have assuredly been
+formed by accretion on some metallic base, from gold salts in
+solution, probably chloride, but possibly sulphide.
+
+Nuggets, properly so-called, are never found in quartz lodes; but, as
+will be shown later, a true nugget having all the characteristics of
+so-called water-worn alluvial may be artificially formed on a small
+piece of galena, or pyrites, by simply suspending the base metal by a
+thread in a vessel containing a weak solution of chloride of gold in
+which a few hard-wood chips are thrown.
+
+Prospecting for alluvial gold at shallow depths is a comparatively
+easy process, requiring no great amount of technical knowledge.
+Usually the first gold is got at or near the surface and then traced
+to deep leads, if such exist.
+
+At Mount Brown Goldfield, N.S.W., in 1881, I saw claimholders turning
+out to work equipped only with a small broom made of twigs and a tin
+dish. With the broom they carefully swept out the crevices of the
+decomposed slate as it was exposed on the surface, and putting the
+resulting dust and fragments into the tin dish proceeded to dry blow
+it.
+
+The /modus operandi/ is as follows: The operator takes the dish about
+half full of dirt, and standing with his back or side to the wind, if
+there be any, begins throwing the stuff up and catching it, or
+sometimes slowly pouring it from one dish to another, the wind in
+either case carrying away the finer particles. He then proceeds to
+reduce the quantity by carefully extracting the larger fragments of
+rock, till eventually he has only a handful or so of moderately fine
+"dirt" which contains any gold there may be. If in good sized nuggets
+it is picked out, if in smaller pieces or fine grains the digger
+slowly blows the sand and dust aside with his breath, leaving the gold
+exposed. This process is both tedious and unhealthy, and of course can
+only be carried out with very dry surface dirt. The stuff in which the
+gold occurred at Mount Brown was composed of broken slate with a few
+angular fragments of quartz. Yet, strange to say, the gold was
+invariably waterworn in appearance.
+
+Dry blowing is now much in vogue on the West Australian fields owing
+to the scarcity of water; but the great objection is first, the large
+amount of dust the unfortunate dry blower has to carry about his
+person, and secondly, that the peck of dirt which is supposed to last
+most men a life time has to be made a continuous meal of every day.
+
+For wet alluvial prospecting the appliances, besides pick and shovel,
+are puddling tub, tin dish, and cradle; the latter, a man handy with
+tools can easily make for himself.
+
+In sinking, the digger should be careful to avoid making his shaft
+inconveniently small, and not to waste his energy by sinking a large
+"new chum" hole, which usually starts by being about three times too
+large for the requirements at the surface, but narrows in like a
+funnel at 10 feet or less. A shaft, say 4 feet by 2 feet 6 inches and
+sunk plumb, the ends being half rounded, is large enough for all
+requirements to a considerable depth, though I have seen smart men,
+when they were in a hurry to reach the drift, get down in a shaft even
+less in size.
+
+The novice who is trying to follow or to find a deep lead must fully
+understand that the present bed of the surface river may not, in fact
+seldom does, indicate the ancient watercourses long since buried
+either by volcanic or diluvial action, which contain the rich
+auriferous deposits for which he is seeking; and much judgment and
+considerable underground exploration are often required to decide on
+the true course of leads. Only by a careful consideration of all the
+geological surroundings can an approximate idea be obtained from
+surface inspection alone; and the whole probable conditions which led
+to the present contour of the country must be carefully taken into
+account.
+
+How am I to know the true bottom when I see it? asks the inexperienced
+digger. Well, nothing but long experience and intelligent observation
+will prevent mistakes at times, particularly in deep ground; but as a
+general rule, though it may sound paradoxical, you may know the bottom
+by the top.
+
+That is, we will assume you are sinking in, say, 10 to 12 feet ground
+in a gully on the bank of which the country rock is exposed, and is,
+say, for instance, a clay slate or sandy slate set at a certain angle;
+then, in all probability, unless there be a distinct fault or change
+in the country rock between the slate outcrop and your shaft, the
+bottom will be a similar slate, standing at the same angle; and this
+will very probably be overlaid by a deposit of pipeclay, formed by the
+decomposition of the slates.
+
+From the crevices of these slates, sometimes penetrating to a
+considerable distance, you may get gold, but it is useless attempting
+to sink through them. If the outcropping strata be a soft calcareous
+(limy) sandstone or soft felspathic rock, and that be also the true
+bottom, great care should be exercised or one is apt to sink through
+the bottom, which may be very loose and decomposed. I have known
+mistakes made in this way when many feet have been sunk, and driven
+through what was actually bed rock, though so soft as to deceive even
+men of experience. The formation, however, must be the guide, and
+except in some specially difficult cases, a man can soon tell when he
+is really on bed rock or "bottom."
+
+On an alluvial lead the object of every one is to "get on the gutter,"
+that is, to reach the lowest part of the old underground watercourse,
+through which for centuries the gold may have been accretionising from
+the percolation of the mineral-impregnated water; or, when derived
+from reefs or broken down leaders, the flow of water has acted as a
+natural sluice wherein the gold is therefore most thickly collected.
+Sometimes the lead runs for miles and is of considerable width, at
+others it is irregular, and the gold-bearing "gutter" small and hard
+to find. In many instances, for reasons not readily apparent, the best
+gold is not found exactly at the lowest portion of these narrow
+gutters, but a little way up the sides. This fact should be taken into
+consideration in prospecting new ground, for many times a claim has
+been deserted after cleaning up the "bottom," and another man has got
+far better gold considerably higher up on the sides of the gutter. For
+shallow alluvial deposits, where a man quickly works out his 30 by 30
+feet claim, it may be cheaper at times to "paddock" the whole ground--
+that is, take all away from surface to bottom, but if he is in wet
+ground and he has to drive, great care should be taken to properly
+secure the roof by means of timber. How this may best be done the
+local circumstances only can decide.
+
+
+
+CHAPTER III
+
+LODE OR REEF PROSPECTING
+
+The preceding chapter dealt more especially with prospecting as
+carried on in alluvial fields. I shall now treat of preliminary mining
+on lodes or "reefs."
+
+As has already been stated, the likeliest localities for the
+occurrence of metalliferous deposits are at or near the junction of
+the older sedimentary formations with the igneous or intrusive rocks,
+such as granites, diorites, etc. In searching for payable lodes,
+whether of gold, silver, copper, or even tin in some forms of
+occurrence, the indications are often very similar. The first
+prospecting is usually done on the hilltops or ridges, because, owing
+to denudation by ice or water which have bared the bedrock, the
+outcrops are there more exposed, and thence the lodes are followed
+down through the alluvial covered plains, partly by their "strike" or
+"trend," and sometimes by other indicating evidences, which the
+practical miner has learned to know.
+
+For instance, a lesson in tracing the lode in a grass covered country
+was taught me many years ago by an old prospector who had struck good
+gold in the reef at a point some distance to the east of what had been
+considered the true course. I asked him why he had opened the ground
+in that particular place. Said he, "Some folks don't use their eyes.
+You stand here and look towards that claim on the rise where the reef
+was last struck. Now, don't you see there is almost a track betwixt
+here and there where the grass and herbage is more withered than on
+either side? Why? Well, because the hard quartz lode is close to the
+surface all the way, and there is no great depth of soil to hold the
+moisture and make the grass grow."
+
+I have found this simple lesson in practical prospecting of use since.
+But the strike or course of a quartz reef is more often indicated by
+outcrops, either of the silica itself or ironstone "blows," as the
+miners call them, but the term is a misnomer, as it argues the easily
+disproved igneous theory of veins of ejection, meaning thereby that
+the quartz with its metalliferous contents was thrown out in a molten
+state from the interior of the earth. This has in no case occurred,
+and the theory is an impossible one. True lodes are veins of injection
+formed by the infiltration of silicated waters carrying the metals
+also in solution. This water filled the fissures caused either by the
+cooling of the earth's crust, or formed by sudden upheavals of the
+igneous rocks.
+
+Sometimes in alluvial ground the trend of the reef will be revealed by
+a track of quartz fragments, more or less thickly distributed on the
+surface and through the superincumbent soil. Follow these along, and
+at some point, if the lode be continuous, a portion of its solid mass
+will generally be found to protrude and can then again be prospected.
+
+There is no rule as to the trend or strike of lodes, except that a
+greater number are found taking a northerly and southerly course than
+one which is easterly and westerly. At all events, such is the case in
+Australia, but it cannot be said that either has the advantage in
+being more productive. Some of the richest mines in Australasia have
+been in lodes running easterly and westerly, while gold, tin, and
+copper, in great quantity and of high percentage to the ton, have been
+got in such mines as Mount Morgan, Mount Bischoff, and the Burra,
+where there are no lodes properly so-called at all.
+
+Mount Morgan is the richest and most productive gold mine in
+Australasia and amongst the best in the world.
+
+Its yield for 1895 was 128,699 oz. of gold, valued at 528,700 pounds.
+Dividends paid in 1895, 300,000 pounds.
+
+This mine was opened in 1886. Up to May 31, 1897, the total yield was
+1,631,981 ozs. of gold, sold at 6,712,187 pounds, from which 4,400,000
+pounds have been paid in dividends. (See /Mining Journal/, for Oct. 9,
+1897.)
+
+Mount Morgan shareholders have, in other words, divided over 43 1/2
+tons of standard gold.
+
+The Burra Burra Mine, about 100 miles from Adelaide, in a direction a
+little to the east of north, was found in 1845 by a shepherd named
+Pickett. It is singularly situated on bald hills standing 130 feet
+above the surrounding country. The ores obtained from this copper mine
+had been chiefly red oxides, very rich blue and green carbonates,
+including malachite, and also native copper. The discovery of this
+mine, supporting, as it did at one time, a large population, marked a
+new era in the history of the colony. The capital invested in it was
+12,320 pounds in 5 pound shares, and no subsequent call was ever made
+upon the shareholders. The total amount paid in dividends was 800,000
+pounds. After being worked by the original owners for some years the
+mine was sold to a new company, but during the last few years it has
+not been worked, owing in some degree to the low price of copper and
+also to the fact that the deposit then being worked apparently became
+exhausted. For many years the average yield was from 10,000 to 13,000
+tons of ore, averaging 22 to 23 per cent of copper. It is stated that,
+during the twenty-nine and a half years in which the mine was worked,
+the company expended 2,241,167 in general expenses. The output of ore
+during the same period amounted to 234,648 tons, equal to 51,622 tons
+of copper. This, at the average price of copper, amounted to a money
+value of 4,749,224 pounds. The mine stopped working in 1877.
+
+Mount Bischoff, Tasmania, has produced, since the formation of the
+Company to December 1895, 47,263 tons of tin ore. It is still in full
+work and likely to be for years to come.
+
+Each of these immense metalliferous deposits was found outcropping on
+the summit of a hill of comparatively low altitude. There are no true
+walls nor can the ore be traced away from the hill in lode form. These
+occurrences are generally held to be due to hydrothermal or geyser
+action.
+
+Then again lodes are often very erratic in their course. Slides and
+faults throw them far from their true line, and sometimes the lode is
+represented by a number of lenticular (double-pointed in section)
+masses of quartz of greater or less length, either continuing point to
+point or overlapping, "splicing," as the miners call it. Such
+formations are very common in West Australia. All this has to be
+considered and taken into account when tracing the run of stone.
+
+This tyro also must carefully remember that in rough country where the
+lode strikes across hills and valleys, the line of the cap or outcrop
+will apparently be very sinuous owing to the rises and depressions of
+the surface. Many people even now do not understand that true lodes or
+reefs are portions of rock or material differing from the surrounding
+and enclosing strata, and continuing down to unknown depths at varying
+angles. Therefore, if you have a north and south lode outcropping on a
+hill and crossing an east and west valley, the said lode, underlying
+east, when you have traced its outcrop to the lowest point in the
+valley, between the two hills, will be found to be a greater or less
+distance, according to the angle of its dip or underlie, to the east
+of the outcrop on the hill where it was first seen. If it be followed
+up the next hill it will come again to the west, the amount of
+apparent deviation being regulated by the height of the hills and
+depth of the valley.
+
+A simple demonstration will make this plain. Take a piece of half-inch
+pine board, 2 ft. long and 9 in. wide, and imagine this to be a lode;
+now cut a half circle out of it from the upper edge with a fret saw
+and lean the board say at an angle of 45 degrees to the left, look
+along the top edge, which you are to consider as the outcrop on the
+high ground, the bottom of the cut being the outcrop in the valley,
+and it will be seen that the lowest portion of the cut is some inches
+to the right; so it is with the lode, and in rough country very nice
+judgment is required to trace the true course.
+
+For indications, never pass an ironstone "blow" without examination.
+Remember the pregnant Cornish saying with regard to mining and the
+current aphorism, "The iron hat covers the golden head." "Cousin
+Jack," put it "Iron rides a good horse." The ironstone outcrop may
+cover a gold, silver, copper or tin lode.
+
+If you are searching for gold, the presence of the royal metal should
+be apparent on trial with the pestle and mortar; if silver, either by
+sight in one of its various forms or by assay, blowpipe or otherwise;
+copper will reveal itself by its peculiar colour, green or blue
+carbonates, red oxides, or metallic copper. It is an easy metal to
+prospect for, and its percentage is not difficult to determine
+approximately. Tin is more difficult to identify, as it varies so
+greatly in appearance.
+
+Having found your lode and ascertained its course, you want next to
+ascertain its value. As a rule (and one which it will be well to
+remember) if you cannot find payable metal, particularly in gold
+"reef" prospecting, at or near the surface, it is not worth while to
+sink, unless, of course, you design to strike a shoot of metal which
+some one has prospected before you. The idea is exploded that
+auriferous lodes necessarily improve in value with depth. The fact is
+that the metal in any lode is not, as a rule, equally continuous in
+any direction, but occurs in shoots dipping at various angles in the
+length of the lode, in bunches or sometimes in horizontal layers.
+Nothing but actual exploiting with pick, powder, and brains,
+particularly brains, will determine this point.
+
+Where there are several parallel lodes and a rich shoot has been found
+in one and the length of the payable ore ascertained, the neighbouring
+lodes should be carefully prospected opposite to the rich spot, as
+often similar valuable deposits will thus be found. Having ascertained
+that you have, say, a gold reef payable at surface and for a
+reasonable distance along its course, you next want to ascertain its
+underlie or dip, and how far the payable gold goes down.
+
+As a general rule in many parts of Australia--though by no means an
+inflexible rule--a reef running east of north and west of south will
+underlie east; if west of north and east of south it will go down to
+the westward and so round the points of the compass till you come to
+east and west; when if the strike of the lodes in the neighbourhood
+has come round from north-east to east and west the underlie will be
+to the south; if the contrary was the case, to the north. It is
+surprising how often this mode of occurrence will be found to obtain.
+But I cannot too strongly caution the prospector not to trust to
+theory but to prove his lode and his metal by following it down on the
+underlie. "Stick to your gold" is an excellent motto. As a general
+thing it is only when the lode has been proved by an underlie shaft to
+water level and explored by driving on its course for a reasonable
+distance that one need begin to think of vertical shafts and the
+scientific laying out of the mine.
+
+A first prospecting shaft need not usually be more than 5 ft. by 3 ft.
+or even 5 ft. by 2 ft. 6 in., particularly in dry country. One may
+often see in hard country stupid fellows wasting time, labour, and
+explosives in sinking huge excavations as much as 10 ft. by 8 ft. in
+solid rock, sometimes following down 6 inches of quartz.
+
+When your shaft is sunk a few feet, you should begin to log up the top
+for at least 3 ft. or 4 ft., so as to get a tip for your "mullock" and
+lode stuff. This is done by getting a number of logs, say 6 inches
+diameter, lay one 7 ft. log on each side of your shaft, cut two
+notches in it 6 ft. apart opposite the ends of the shaft, lay across
+it a 5 ft. log similarly notched, so making a frame like a large
+Oxford picture frame. Continue this by piling one set above another
+till the desired height is attained, and on the top construct a rough
+platform and erect your windlass. If you have an iron handle and axle
+I need not tell you how to set up a windlass, but where timber is
+scarce you may put together the winding appliance described in the
+chapter headed "Rules of Thumb."
+
+If you have "struck it rich" you will have the pleasure of seeing your
+primitive windlass grow to a "whip, a "whim," and eventually to a big
+powerful engine, with its huge drum and Eiffel tower-like "poppet
+heads," or "derrick," with their great spindle pulley wheels revolving
+at dizzy speed high in air.
+
+"How shall I know if I have payable gold so as to save time and
+trouble in sinking?" says the novice. Truly it is a most important
+part of the prospector's art, whether he be searching for alluvial or
+reef gold, stream or lode tin, copper, or other valuable metal.
+
+I presume you know gold when you see it?
+
+If you don't, and the doubtful particle is coarse enough, take a
+needle and stick the point into the questionable specimen. If gold the
+steel point will readily prick it; if pyrites or yellow mica the point
+will glance off or only scratch it.
+
+The great importance of the first prospect from the reef is well shown
+by the breathless intensity with which the two bearded, bronzed
+pioneer prospectors in some trackless Australian wild bend over the
+pan in which the senior "mate" is slowly reducing the sample of
+powdered lode stuff. How eagerly they examine the last pinch of "black
+sand" in the corner of the dish. Prosperity and easy times, or poverty
+and more "hard graft" shall shortly be revealed in the last dexterous
+turn of the pan. Let us hope it is a "pay prospect."
+
+The learner, if he be far afield and without appliances of any kind,
+can only guess his prospect. An old prospector will judge from six
+ounces of stuff within a few pennyweights what will be the yield of a
+ton. I have seen many a good prospect broken with the head of a pick
+and panned in a shovel, but for reef prospecting you should have a
+pestle and mortar. The handiest for travelling is a mortar made from a
+mercury bottle cut in half, and a not too heavy wrought iron pestle
+with a hardened face. To be particular you require a fine screen in
+order to get your stuff to regulated fineness. The best for the
+prospector, who is often on the move, is made from a piece of
+cheesecloth stretched over a small hoop.
+
+If you would be more particular take a small spring balance or an
+improvised scale, such as is described in Mr. Goyder's excellent
+little book, p. 14, which will enable you to weigh down to one-
+thousandth of a grain. It is often desirable to burn your stone before
+crushing, as it is thus more easily triturated and will reveal all its
+gold; but remember, that if it originally contained much pyrites,
+unless a similar course is adopted when treated in the battery, some
+of the gold will be lost in the pyrites.
+
+Having crushed your gangue to a fine powder you proceed to pan it off
+in a similar manner to that of washing out alluvial earth, except that
+in prospecting quartz one has to be much more particular, as the gold
+is usually finer. The pan is taken in both hands, and enough water to
+cover the prospect by a few inches is admitted. The whole is then
+swirled round, and the dirty water poured off from time to time till
+the residue is clean quartz sand and heavy metal. Then the pan is
+gently tipped, and a side to side motion is given to it, thus causing
+the heavier contents to settle down in the corner. Next the water is
+carefully lapped in over the side, the pan being now tilted at a
+greater angle until the lighter particles are all washed away. The pan
+is then once more righted, and very little water is passed over the
+pinch of heavy mineral a few times, when the gold will be revealed in
+a streak along the bottom. In this operation, as in all others, only
+practice will make perfect, and a few practical lessons are worth
+whole pages of written instruction.
+
+To make an amalgamating assay that will prove the amount of gold which
+can be got from a ton of your lode, take a number of samples from
+different parts, both length and breadth. The drillings from the
+blasting bore-holes collected make the best test. When finely
+triturated weigh off one or two pounds, place in a black iron pan (it
+must not be tinned), with 4 ozs. of mercury, 4 ozs. salt, 4 ozs. soda,
+and about half a gallon of boiling water; then, with a stick, stir the
+pulp constantly, occasionally swirling the dish as in panning off,
+till you feel certain that every particle of the gangue has come in
+contact with the mercury; then carefully pan off into another dish so
+as to lose no mercury. Having got your amalgam clean squeeze it
+through a piece of chamois leather, though a good quality of new
+calico previously wetted will do as well. The resulting pill of hard
+amalgam can then be wrapped in a piece of brown paper, placed on an
+old shovel, and the mercury driven off over a hot fire; or a clay
+tobacco pipe, the mouth being stopped with clay, makes a good retort
+(see "Rules of Thumb," pipe and potato retorting). The residue will be
+retorted gold, which, on being weighed and the result multiplied by
+2240 for a 1 lb. assay, or by 1120 for 2 lb., will give the amount of
+gold per ton which an ordinary battery might be expected to save. Thus
+1 grain to the pound, 2240 lbs. to the ton, would show that the stuff
+contained 4 oz. 13 dwt. 8 gr. per ton.
+
+If there should be much base metal in your sample such as say stibnite
+(sulphide of antimony), a most troublesome combination to the
+amalgamator--instead of the formula mentioned above add to your
+mercury about one dwt. of zinc shavings or clippings, and to your
+water sufficient sulphuric acid to bring it to about the strength of
+vinegar (weaker, if anything, not stronger), place your material
+preferably in an earthenware or enamelled basin if procurable, but
+iron will do, and intimately mix by stirring and shaking till all
+particles have had an opportunity to combine with the mercury. Retort
+as before described. This device is my own invention.
+
+The only genuine test after all is the battery, and that, owing to
+various causes, is often by no means satisfactory. First, there is a
+strong, almost unconquerable temptation to select the stone, thus
+making the testing of a few tons give an unduly high average; but more
+often the trouble is the other way. The stuff is sent to be treated at
+some inefficient battery with worn-out boxes, shaky foundations, and
+uneven tables, sometimes with the plates not half amalgamated, or
+coated with impurities, the whole concern superintended by a man who
+knows as little about the treatment of auriferous quartz by the
+amalgamating or any other processes as a dingo does of the
+differential calculus. Result: 3 dwt. to the ton in the retort, 30
+dwt. in the tailings, and a payable claim declared a "duffer."
+
+When the lode is really rich, particularly if it be carrying coarse
+gold, and owing to rough country, or distance, a good battery is not
+available, excellent results in a small way may be obtained by the
+somewhat laborious, but simple, process of "dollying." A dolly is a
+one man power single stamp battery, or rather an extra sized pestle
+and mortar (see "Rules of Thumb").
+
+Silver lodes and lodes which frequently carry more or less gold, are
+often found beneath the dark ironstone "blows," composed of
+conglomerates held together by ferric and manganic oxides; or, where
+the ore is galena, the surface indications will frequently be a
+whitish limey track sometimes extending for miles, and nodules or
+"slugs" of that ore will generally be found on the surface from place
+to place. Most silver ores are easily recognisable, and readily tested
+by means of the blowpipe or simple fire assay. Sometimes the silver on
+being tested is found to contain a considerable percentage of gold as
+in the great Comstock lode in Nevada. Ore from the big Broken Hill
+silver load, New South Wales, also contains an appreciable quantity of
+the more precious metal. A natural alloy of gold containing 20 per
+cent silver, termed electrum, is the lowest grade of the noble metal.
+
+Tin, lode, and stream, or alluvial, occurs only as an oxide, termed
+cassiterite, and yet you can well appreciate the compliment one
+Cornish miner pays to another whose cleverness he wishes to commend,
+when he says of him, "Aw, he do know tin," when you look at a
+representative collection of tin ores. In various shapes, from sharp-
+edged crystals to mammillary-shaped nuggets of wood-tin; from masses
+of 30 lbs. weight to a fine sand, like gunpowder, in colour black,
+brown, grey, yellow, red, ruby, white, and sometimes a mingling of
+several colours, it does require much judgment to know tin.
+
+Stream tin is generally associated with alluvial gold. When such is
+the case there is no difficulty in saving the gold if you save the
+tin, for the yellow metal is of much greater specific gravity. As the
+natural tin is an oxide, and therefore not susceptible to
+amalgamation, the gold can be readily separated by means of mercury.
+
+Lode tin sometimes occurs in similar quartz veins to those in which
+gold is got, and is occasionally associated with gold. Tin is also
+found, as at Eurieowie, in dykes, composed of quartz crystals and
+large scales of white mica, traversing the older slates. A similar
+occurrence takes place at Mount Shoobridge and at Bynoe Harbour, in
+the Northern Territory of South Australia; indeed, one could not
+readily separate the stone from these three places if it were mixed.
+As before stated tin will never be found far from granite, and that
+granite must have white mica as one of its constituents. It is seldom
+found in the darker coloured rocks, or in limestone country, but it
+sometimes occurs in gneiss, mica schist, and chlorite schist. Numerous
+other minerals are at times mistaken for tin, the most common of which
+are tourmaline or schorl, garnet, wolfram (which is a tungstate of
+iron with manganese), rutile or titanic acid, blackjack or zinc
+blende, together with magnetic, titanic, and specular iron in fine
+grains.
+
+This rough and ready mode of determining whether the ore is tin is by
+weight and by scratching or crushing, when, what is called the
+"streak" is obtained. The colour of the tin streak is whitey-grey,
+which, when once known, is not easily mistaken. The specific gravity
+is about 7.0. Wolfram, which is most like it, is a little heavier,
+from 7.0 to 7.5, but its streak is red, brown, or blackish-brown.
+Rutile is much lighter, 4.2, and the streak light-brown; tourmaline is
+only 3.2. Blackjack is 4.3, and its streak yellowish-white.
+
+I have seen several pounds weight to the dish got in some of the New
+South Wales shallow sinking tin-fields, and, as a rule, payable gold
+was also present. Fourteen years ago I told Western Australian people,
+when on a visit to that colony, that the neighbourhood of the Darling
+range would produce rich tin. Lately this had been proved to be the
+case, and I look forward to a great development of the tin mining
+industry in the south-western portion of Westralia.
+
+The tin "wash" in question may also contain gold, as the country rock
+of the neighbourhood is such as gold is usually found in.[*]
+
+[*] Since this book was in the printers' hands, the discovery of
+    payable gold has been reported from this district. A detailed
+    discussion of methods of prospecting will be found in chapter ii.
+    Of Le Neve Foster's "Ore and Stone Mining," and Mr. S. Herbert
+    Cox's "Handbook for Prospectors."
+
+
+
+CHAPTER IV
+
+THE GENESIOLOGY OF GOLD--AURIFEROUS LODES
+
+Up to a comparatively recent time it was considered heretical for any
+one to advance the theory that gold had been deposited where found by
+any other agency than that of fire. As late as 1860 Mr. Henry Rosales
+convinced himself, and apparently the Victorian Government also, that
+quartz veins with their enclosed metal had been ejected from the
+interior of the earth in a molten state. His essay, which is very
+ingenious and cleverly written, obtained a prize which the Government
+had offered, but probably Mr. Rosales himself would not adduce the
+same arguments in support of the volcanic or igneous theory to-day.
+His phraseology is very technical; so much so that the ordinary
+inquirer will find it somewhat difficult to follow his reasoning or
+understand his arguments, which have apparently been founded only on
+the occurrence of gold in some of the earlier discovered quartz lodes,
+and the conclusions at which he arrived are not borne out by later
+experience. He says:--"While, however, there are not apparent signs of
+mechanical disturbances, during the long period that elapsed from the
+cooling of the earth's surface to the deposition of the Silurian and
+Cambrian systems, it is to be presumed that the internal igneous
+activity of the earth's crust was in full force, so that on the inner
+side of it, in obedience to the laws of specific gravity, chemical
+attraction, and centrifugal force, a great segregation of silica in a
+molten state took place. This molten silica continually accumulating,
+spreading, and pressing against the horizontal Cambro-Silurian beds
+during a long period at length forced its way through the
+superincumbent strata in all directions; and it is abundantly evident,
+under the conditions of this force and the resistance offered to its
+action, that the line it would and must choose would be along any
+continuous and slightly inclined diagonal, at times crossing the
+strata of the schists, though generally preferring to develop itself
+and egress between the cleavage planes and dividing seams of the
+different schistose beds."
+
+He goes on to say, "Another argument to the same end (i.e., the
+igneous origin) may be shown from the fact that the auriferous quartz
+lodes have exercised a manifest metamorphic action on the adjacent
+walls or casing; they have done so partly in a mineralogical sense,
+but generally there has been a metamorphic alteration of the rock."
+Mr. Rosales then tells his readers, what we all know must be the case,
+that the gold would be volatilised by the heat, as would be also the
+other metals, which he says, were in the form of arseniurets and
+sulphurets; but he fails to explain how the sublimated metals
+afterwards reassumed their metallic form. Seeing that, in most cases,
+they would be hermetically enclosed in molten and quickly solidifying
+silica they could not be acted on to any great extent by aqueous
+agency. Neither does Mr. Rosales's theory account at all for
+auriferous lodes; which below water level are composed of a solid mass
+of sulphide of iron with traces of other sulphides, gold, calcspar,
+and a comparatively small percentage of silica. Nor will it
+satisfactorily explain the auriferous antimonial silica veins of the
+New England district, New South Wales, in which quantities of angular
+and unaltered fragments of slate from the enclosing rocks are found
+imbedded in the quartz.
+
+With respect to the metamorphism of the enclosing rocks to a greater
+degree of hardness, which Mr. Rosales considered was due to heat, it
+should be remembered that these rocks in their original state were
+much softer and more readily fusible than the quartz, consequently all
+would have been molten and mingled together instead of showing as a
+rule clearly defined walls. It is much more rational to suppose that
+the increased hardness imparted to the slates and schists at or near
+their contact with the lode is due to an infiltration of silica from
+the silicated solution which at one time filled the fissure. Few
+scientists can now be found to advance the purely igneous theory of
+lode formation, though it must be admitted that volcanic action has
+probably had much influence not only in the formation of mineral
+veins, but also on the occurrence of the minerals therein. But the
+action was hydrothermal, just such as was seen in course of operation
+in New Zealand a few years ago when, in the Rotomahana district, one
+could actually see the growing of the marvellous White and Pink
+Terraces formed by the release of silica from the boiling water
+exuding from the hot springs, which water, so soon as the heat and
+pressure were removed, began to deposit its silica very rapidly; while
+at the Thames Gold-field, in the same country hot, silicated water
+continuously boiled out of the walls of some of the lodes after the
+quartz had been removed and re-deposited a siliceous sinter thereon.
+
+On this subject I note the recently published opinions of Professor
+Lobley, a gentleman whose scientific reputation entitles his
+utterances to respect, but who, when he contends that gold is not
+found in the products of volcanic action is, I venture to think,
+arguing from insufficient premises. Certainly his theories do not hold
+good either in Australasia or America where gold is often, nay, more
+usually, found at, or near, either present or past regions of volcanic
+action.
+
+It is always gratifying to have one's theories confirmed by men whose
+opinions carry weight in the scientific world. About seventeen years
+ago I first published certain theories on gold deposition, which, even
+then, were held by many practical men, and some scientists, to be open
+to question. Of late years, however, the theory of gold occurrence by
+deposition from mineral salts has been accepted by all but the "mining
+experts" who infest and afflict the gold mining camps of the world.
+These opine that gold ought to occur in "pockets" only (meaning
+thereby their own).
+
+Recently Professor Joseph Le Conte, at a meeting of the American
+Institute of Mining Engineers, criticised a notable essay on the
+"Genesis of Ore Deposits," by Bergrath F. Posepny. The Professor's
+general conclusions are:
+
+1. "Ore deposits, using the term in its widest sense, may take place
+from any kinds of waters, but especially from alkaline solutions, for
+these are the natural solvents of metallic sulphides, and metallic
+sulphides are usually the original form of such deposits."
+
+2. "They may take place from waters at any temperature and any
+pressure, but mainly from those at high temperature and under heavy
+pressure, because, on account of their great solvent power, such
+waters are heavily freighted with metals."
+
+3. "The depositing waters may be moving in any direction, up-coming,
+horizontally moving, or even sometimes down-going, but mainly up-
+coming; because by losing heat and pressure at every step such waters
+are sure to deposit abundantly."
+
+4. "Deposits may take place in any kind of waterways--in open
+fissures, in incipient fissures, joints, cracks, and even in porous
+sandstone, but especially in great open fissures, because these are
+the main highways of ascending waters from the greatest depths."
+
+5. "Deposits may be found in many regions and in many kinds of rocks,
+but mainly in mountain regions, and in metamorphic and igneous rocks,
+because the thermosphere is nearer the surface, and ready access
+thereto through great fissures is found mostly in these regions and in
+these rocks."
+
+These views are in accordance with nearly all modern research into
+this interesting and fruitful subject.
+
+Among the theories which they discredit is that ore bodies may usually
+be assumed to become richer in depth. As applied to gold lodes the
+teaching of experience does not bear out this view.
+
+If it be taken into account that the time in which most of our
+auriferous siliceous lodes were formed was probably that indicated in
+Genesis as before the first day or period when "the earth was without
+form and void, and darkness was upon the face of the deep," it will be
+realised that the action we behold now taking place in a small way in
+volcanic regions, was probably then almost universal. The crust of the
+earth had cooled sufficiently to permit water to lie on its surface,
+probably in hot shallow seas, like the late Lake Rotomahana. Plutonic
+action would be very general, and volcanic mud, ash, and sand would be
+ejected and spread far and wide, which, sinking to the bottom of the
+water, may possibly be the origin of what we now designate the azoic
+or metamorphic slates and schists, as also the early Cambrian and
+Silurian strata. These, from the superincumbent weight and internal
+heat, became compacted, and, in some cases, crystallised, while at the
+same time, from the ingress of the surface waters to the heated
+regions below, probably millions of geysers were spouting their
+mineral impregnated waters in all directions; and in places where the
+crust was thin, explosions of super-heated steam caused huge
+upheavals, rifts, and chasms, into which these waters returned, to be
+again ejected, or to be the cause of further explosions. Later, as the
+cooling-process continued, there would be shrinkages of the earth's
+crust causing other fissures; intrusive granites further dislocated
+and upheaved the slates. About this age, probably, when really dry
+land began to appear, came the first formation of mineral lodes, and
+the waters, heavily charged with silicates, carbonates of lime,
+sulphides, etc., in solution, commenced to deposit their contents in
+solid form when the heat and pressure were removed.
+
+I am aware that part of the theory here propounded as to the probable
+mode of formation of the immense sedimentary beds of the Archaic or
+Azoic period is not altogether orthodox--i.e., that the origin of
+these beds is largely due to the ejection of mud, sand, and ashes from
+subterraneous sources, which, settling in shallow seas, were
+afterwards altered to their present form. It is difficult, however, to
+believe that at this very early period of geologic history so vast a
+time had elapsed as would be required to account for these enormous
+depositions of sediment, if they were the result only of the
+degradation of previously elevated portions of the earth's surface by
+water agency. Glacial action at that time would be out of the
+question.
+
+But what about the metals? Whence came the metallic gold of our reefs
+and drifts? What was it originally--a metal or a metallic salt, and if
+the latter, what was its nature?--chloride, sulphide, or silicate,
+one, or all three? I incline to the latter hypothesis. All three are
+known, and the chemical conditions of the period were favorable for
+their natural production. Assuming that they did exist, the task of
+accounting for the mode of occurrence of our auriferous quartz lodes
+is comparatively simple. Chloride of gold is at present day contained
+in sea water and in some mineral waters, and would have been likely to
+be more abundant during the Azoic and early Paleozoic period.
+
+Sulphide of gold would have been produced by the action of
+sulphuretted hydrogen; hence probably our auriferous pyrites lodes,
+while silicate of gold might have resulted from a combination of gold
+chlorides with silicic acid, and thus the frequent presence of gold in
+quartz is accounted for.
+
+A highly interesting and instructive experiment, showing how gold
+might be, and probably was, deposited in quartz veins, was carried out
+by Professor Bischof some years ago. He, having prepared a solution of
+chloride of gold, added thereto a solution of silicate of potash,
+whereupon, as he states, the yellow colour of the chloride
+disappeared, and in half an hour the fluid turned blue, and a
+gelatinous dark-blue precipitate appeared and adhered to the sides of
+the vessel. In a few days moss-like forms were seen on the surface of
+the precipitate, presumably approximating to what we know as
+dendroidal gold--that is, having the appearance of moss, fern, or
+twigs. After allowing the precipitate to remain undisturbed under
+water for a month or two a decomposition took place, and in the
+silicate of gold specks of metallic gold appeared. From this, the
+Professor argues, and with good show of reason, that as we know now
+that the origin of our quartz lodes was the silicates contained in
+certain rocks, it is probable that a natural silicate of gold may be
+combined with these silicates. If this can be demonstrated, the reason
+for the almost universal occurrence of gold in quartz is made clear.
+
+About 1870, Mr. Skey, analyst to the New Zealand Geological Survey
+Department, made a number of experiments of importance in respect to
+the occurrence of gold. These experiments were summarised by Sir James
+Hector in an address to the Wellington Philosophical Society in 1872.
+Mr. Skey's experiments disproved the view generally held that gold is
+unaffected by sulphur or sulphuretted hydrogen gas, and showed that
+these elements combined with avidity, and that the gold thus treated
+resisted amalgamation with mercury. Mr. Skey proved the act of
+absorption of sulphur by gold to be a chemical act, and that
+electricity was generated in sufficient quantity and intensity during
+the process to decompose metallic solutions. Sulphur in certain forms
+had long been known to exercise a prejudicial effect upon the
+amalgamation of gold, but this had always been attributed to the
+combination of the sulphur with the quicksilver used. Now, however, it
+is certain that the sulphurising of the gold must be taken into
+account. We must remember that the particles of gold in the stone may
+be enveloped with a film of auriferous sulphide, by which they are
+protected from the solvent actions of the mercury. The sulphurisation
+of the gold gives no ocular manifestation by change of colour or
+perceptible increase of weight, as in the case of the formation of
+sulphides of silver, lead and other metals, on account of the
+extremely superficial action of the sulphur, and hence probably the
+existence of the gold sulphide escaped detection by chemists.
+
+Closely allied to this subject is the investigation of the mode in
+which certain metals are reduced from their solutions by metallic
+sulphides, or, in common language, the influence which the presence of
+such substances as mundic and galena may exercise in effecting the
+deposit of pure metals, such as gold, in mineral lodes. The close
+relation which the richness of gold veins bears to the prevalence of
+pyrites has been long familiar both to scientific observers and to
+practical miners. The gold is an after deposit to the pyrites, and, as
+Mr. Skey was the first to explain, due to its direct reducing
+influences. By a series of experiments Mr. Skey proved that the
+reduction of the metal was due to the direct action of the sulphide,
+and showed that each grain of iron pyrites, when thoroughly oxidised,
+will reduce 12 1/4 grains of gold from its solution as chloride. He
+also included salts of platina and silver in this general law, and
+demonstrated that solutions of any of these metals traversing a vein
+rock containing certain sulphides would be decomposed, and the pure
+metal deposited. We are thus enabled to comprehend the constant
+association of gold, or native alloys of gold and silver, in veins
+which traverse rocks containing an abundance of pyrites, whether they
+have been formed as the result of either sub-aqueous volcanic outburst
+or by the metamorphism of the deeper-seated strata which compose the
+superficial crust of the earth.
+
+Mr. Skey also showed by very carefully conducted experiments that the
+metallic sulphides are not only better conductors of electricity than
+has hitherto been supposed, but that when paired they were capable of
+exhibiting strong electro-motive power. Thus, if galena and zinc
+blende in acid solutions be connected in the usual manner by a voltaic
+pair, sulphuretted hydrogen is evolved from the surface of the former,
+and a current generated which is sufficient to reduce gold, silver or
+copper from their solutions in coherent electro-plate films. The
+attributing of this property of generating voltaic currents, hitherto
+supposed to be almost peculiar to metals, to such sulphides as are
+commonly found in metalliferous veins, further led Mr. Skey to
+speculate how far the currents discovered to exist in such veins by
+Mr. E. F. Fox might be produced by the gradual oxidation of mixed
+sulphides, and that veins containing bands of different metallic
+sulphides, bounded by continuing walls, and saturated with mineral
+waters, may constitute under some circumstances a large voltaic
+battery competent to produce electro-deposition of metals, and that
+the order of the deposit of these mineral lodes will be found to bear
+a definite relation to the order in which the sulphides rank in the
+table of their electro-motive power. These researches may lead to some
+clearer comprehension of the law which regulates the distribution of
+auriferous veins, and may explain why in some cases the metal should
+be nearly pure, while in others it is so largely alloyed with silver.
+
+The following extract was lately clipped from a mining paper. If true,
+the experiment is interesting:--
+
+"An American scientist has just concluded a very interesting and
+suggestive experiment. He took a crushed sample of rich ore from
+Cripple Creek, which carried 1100 ozs. of gold per ton, and digested
+it in a very weak solution of sodium chloride and sulphate of iron,
+making the solution correspond as near as practicable to the waters
+found in Nature. The ore was kept in a place having a temperature
+little less than boiling water for six weeks, when all the gold,
+except one ounce per ton, was found to have gone into solution. A few
+small crystals of pyrite were then placed in the bottle of solution,
+and the gold began immediately to precipitate on them. It was
+noticeable, however, that the pyrite crystals which were free from
+zinc, galena, or other extraneous matter received no gold precipitate.
+Those which had such foreign associations were beautifully covered
+with fine gold crystals."
+
+Experimenting in a somewhat similar direction abut twelve months
+since, I found that the West Australian mine water, with the addition
+of an acid, was a solvent of gold. The idea of boiling it did not
+occur to me, as the action was rapid in cold water.
+
+Assuming, then, that gold originally existed as a mineral salt, when
+and how did it take metallic form? Doubtless, just in the same manner
+as we now (by means of well-known reagents which are common in nature)
+precipitate it in the laboratory. With regard to that found in quartz
+lodes finely disseminated through the gangue, the change was brought
+about by the same agency which caused the silicic acid to solidify and
+take the form in which we now see it in the quartz veins. Silica is
+soluble in solutions of alkaline carbonates, as shown in New Zealand
+geysers; the solvent action being increased by heat and pressure, so
+also would be the silicate or sulphide of gold. When, however, the
+waters with their contents were released from internal pressure and
+began to lose their heat the gold would be precipitated together with
+the salts of some other metals, and would, where the waters could
+percolate, begin to accretionise, thus forming the heavy or specimen
+gold of some reefs. On this class of deposition I shall have more to
+say when treating of the origin of alluvial gold in the form of
+nuggets.
+
+Mr. G. F. Becker, of the United States Geological Survey, writing of
+the geology of the Comstock lode, says:--"Baron Von Richthofen was of
+opinion that fluorine and chlorine had played a large part of the ore
+deposition in the Comstock, and this the writer is not disposed to
+deny; but, on the other hand, it is plain that most of the phenomena
+are sufficiently accounted for on the supposition that the agents have
+been merely solutions of carbonic and hydro-sulphuric acids. These
+reagents will attack the bisilicates and felspars. The result would be
+carbonates and sulphides of metals, earth, alkalies, and free quartz,
+but quartz and sulphides of the metals are soluble in solutions of
+carbonates and sulphides of the earths and alkalies, and the essential
+constituents of the ore might, therefore, readily be conveyed to
+openings in the vein where they would have been deposited on relief of
+pressure and diminution of temperature. An advance boring on the 3000
+ft. level of the Yellow Jacket struck a powerful stream of water at
+3065 ft. (in the west country), which was heavily charged with
+hydrogen sulphide, and had a temperature of 170 degrees F., and there
+is equal evidence of the presence of carbonic acid in the water of the
+lower levels. A spring on the 2700 ft. level of the Yellow Jacket
+which showed a temperature of about 150 degrees F., was found to be
+depositing a sinter largely composed of carbonates."
+
+It may be worth while here to speak of the probable reason why gold,
+and indeed almost all the metals generally occur in shutes in the
+lodes; and why, as is often the case, these shutes are found to be
+more or less in a line with each other in parallel lodes, and why also
+the junction of two lodes is frequently specially productive. The
+theory with respect to these phenomena which appears most feasible is,
+that at these points certain chemical action has taken place, by which
+the deposition of the metals has been specially induced. Generally a
+careful examination of the enclosing rocks where the shute is found
+will reveal some points of difference from the enclosing rocks at
+other parts of the course of the lode, and when ore shutes are found
+parallel in reefs running on the same course, bands or belts of
+similar country rock will be found at the productive points. From this
+we may fairly reason that at these points the slow stream filling the
+lode cavity met with a reagent percolating from this particular band
+of rock, which caused the deposition of its metals; and, indeed, I am
+strongly disposed to believe that the deposition of metals,
+particularly in some loose lodes, may even now be proceeding. But as
+in Nature's laboratory the processes, if certain, are slow, this
+theory may be difficult to prove.
+
+Why the junction of lodes is often found to be more richly
+metalliferous than neighbouring parts is probably because there the
+depositing reagents met. This theory is well put by Mr. S. Herbert
+Cox, late of Sydney, in his useful book, "Mines and Minerals." He
+says:--"It is a well-known fact in all mining districts that the
+junctions of lodes are generally the richest points, always supposing
+that this junction takes place in 'kindly country,' and the
+explanation of this we think is simple on the aqueous theory of
+filling of lodes. The water which is traversing two different channels
+of necessity passes through different belts of country, and will thus
+have different minerals in solution. As a case in point, let us
+suppose that the water in one lode contained in solution carbonates of
+lime, and the alkalies and silica derived form a decomposition of
+felspars; and that the other, charged with hydro-sulphuric acid,
+brought with it sulphide of gold dissolved in sulphide of lime. The
+result of these two waters meeting would be that carbonate of lime
+would be formed, hydro-sulphuric acid would be set free, and sulphide
+of gold would be deposited, as well as silica, which was formerly held
+in solution by the carbonic acid."
+
+Most practical men who have given the subject attention will, I think,
+be disposed to coincide with this view, though there are some who hold
+that the occurrence of these parallel ore shutes and rich deposits at
+the junctions of lodes is due to extraneous electrical agency. Of
+this, however I have failed to find any satisfactory evidence.
+
+There is, however, proof that lodes are actually re-forming and the
+action observed is very interesting as showing how the stratification
+in some lodes has come about. Instances are not wanting of the growth
+of silica on the sides of the drives in mines. This was so in some of
+the mines on the Thames, New Zealand, previously mentioned, where in
+some cases the deposition was so rapid as to be noticeable from day to
+day, whilst the big pump was actually choked by siliceous deposits. In
+old auriferous workings which have been under water for years, in many
+parts of the world, formations of iron and silica have been found on
+the walls and roof, while in mining tunnels which have been long
+unused stalactites composed of silica and calcite have formed. Then,
+again, experiments made by the late Professor Cosmo Newbery, in
+Victoria, showed that a distinctly appreciable amount of gold, iron,
+and silica (the latter in granular form) could be extracted from solid
+mine timber; which had been submerged for a considerable time.
+
+This reaction then must be in progress at the present time, and
+doubtless under certain conditions pyrites would eventually take the
+place of the timber, as is the case with some of the long buried
+driftwood found in Victorian deep leads. Again, we know that the water
+from some copper mines is so charged with copper sulphate that if
+scrap iron be thrown into it, the iron will be taken up by the
+sulphuric acid, and metallic copper deposited in its place. All this
+tends to prove that the deposition of metals from their salts, though
+probably not now as rapid as formerly, is still ceaselessly going on
+in some place or another where the necessary conditions are
+favourable.
+
+With regard to auriferous pyritic lodes, it does not appear even now
+to be clear, as some scientists assert, that their gold is never found
+in chemical combination with the sulphides of the base metals. On the
+contrary, I think much of the evidence points in the other direction.
+
+I have long been of opinion that it is really so held in many of the
+ferro-sulphides and arsenio-ferro sulphides. On this subject Mr. T.
+Atherton contributed a short article in 1891 to the /Australian Mining
+Standard/ which is worthy of notice. He says, referring to an
+occurrence of a Natural Sulphide of Gold: "The existence of gold, in
+the form of a natural sulphide in conjunction with pyrites, has often
+been advanced theoretically, as a possible occurrence; but up to the
+present time has, I believe, never been established as an actual fact.
+During my investigation on the ore of the Deep Creek mines, Nambucca,
+New South Wales, I have found in them what I believe to be gold
+existing as a natural sulphide. The lode is a large irregular one of
+pure arsenical pyrites carrying, in addition to gold and silver,
+nickel and cobalt. It exists in a felsite dyke immediately on the
+coast. Surrounding it on all sides are micaceous schists, and in the
+neighbourhood about half a mile distant is a large granite hill about
+800 feet high. In the lode and its walls are large quantities of pyro-
+phyllite, and in some parts of the mine there are deposits of pure
+white translucent mica, but in the ore itself it is a yellow or pale
+olive green, and is never absent from the pyrites.
+
+"From the first I was much struck with the exceedingly fine state of
+division in which the gold existed in the ore. After roasting and very
+carefully grinding down in an agate mortar, I have never been able to
+get any pieces of gold exceeding one-thousandth of an inch in
+diameter, and the greater quantity is very much finer than this.
+Careful dissolving of the pyrites and gangue so as to leave the gold
+intact failed to find it in any larger diameter. As this was a very
+unusual experience in investigations on many other kinds of pyrites, I
+was led further into the matter.
+
+"Ultimately, after a number of experiments, there was nothing left but
+to test for gold existing as a natural sulphide. Taking 200 gr. of ore
+from a sample assaying 17 oz. fine gold per ton, grinding it finely
+and heating for some hours with yellow sodium sulphide--on decomposing
+the filtrate and treating for gold I got a result at the rate of 12
+oz. per ton. This was repeated several times with the same result.
+
+"This sample came from the lode at the 140 ft. level, whilst samples
+from the higher levels where the ore is more oxidised, although
+carrying the gold in exactly the same degree of fineness, do not give
+as high a percentage of auric sulphide.
+
+"It would appear that all the gold in the pyrites (and I have never
+found any gold existing apart from the pyrites) has originally taken
+its place there as a sulphide."
+
+Professor Newbery, who made many valuable suggestions on the subject,
+says, speaking of gold in pyritous lodes:
+
+"As it (the gold salt) may have been in the same solution that
+deposited the pyrites, which probably contained its iron in the form
+of proto-carbonate with sulphates, it was not easy at first to imagine
+any ordinary salt of gold; but this I find can be accomplished with
+very dilute solutions in the presence of an alkaline carbonate and a
+large excess of carbonic acid, both of which are common constituents
+of mineral waters, especially in Victoria. This is true of chloride of
+gold, and if the sulphide is required in solution, it is only
+necessary to charge the solution with an excess of sulphuretted
+hydrogen. In this matter both sulphides may be retained in the same
+solution, depositing gradually with the escape of the carbonic acid."
+
+Pyritic lodes usually contain a considerable proportion of calcareous
+matter, mostly carbonates, and consequently it appears not improbable
+that the gold may remain in some instances as a sulphide, particularly
+in samples of pyrites, in which it cannot be detected even by the
+microscope until by calcination the iron sulphide is changed to an
+oxide, wherein the gold may be seen in minute metallic specks. The
+whole subject is full of interest, and careful scientific
+investigation may lead to astonishing results.
+
+
+
+CHAPTER V
+
+THE GENESIOLOGY OF GOLD--AURIFEROUS DRIFTS
+
+Having considered the origin of auriferous lodes, and the mode by
+which in all probability the gold was conveyed to them and deposited
+as a metal, it is necessary also to inquire into the derivation of the
+gold of our auriferous drifts, and the reasons for its occurrence
+therein.
+
+When quite a lad on the Victorian alluvial fields, I frequently heard
+old diggers assert that gold grew in the drifts where found. At the
+time we understood this to mean that it grew like potatoes; and,
+although not prepared with a scientific argument to prove that such
+was not so, the idea was generally laughed at. I have lived to learn
+that these old hard-heads were nearer the truth than possibly they
+clearly realised, and that gold does actually grow or agglomerate;
+and, indeed, is probably even now thus growing, though it is likely
+that the chemical and electric action in the mineral waters flowing
+through the drifts is not in this age nearly so active as formerly.
+
+Most boys have tried the experiment of dipping a clean-bladed knife
+into sulphate of copper, and so depositing on the steel a film of
+copper, which adheres closely until worn away. This is a simple
+demonstration of a hydro-metallurgical process, though probably young
+hopeful is not aware of the fact; and it is really by an enlargement
+of this process that our beautiful and artistic gold- and silver-
+plated ware is produced.
+
+In the great laboratory of Nature similar chemical depositions have
+taken place in the past, and may still be in progress; indeed, there
+is sound scientific reason to suppose that in certain localities this
+is even now the case, and that in this way much of our so-called
+alluvial gold has been formed, that is, by the deposition on metallic
+bases of the gold held in solution.
+
+We will, however, take, to begin with, the generally accepted theory
+as to the occurrence of alluvial gold. First, let it be said, that
+certain alluvial gold is unquestionably derived from the denudation of
+quartz lodes. Such is the gold dust found in many Asiatic and African
+rivers, in the great placer mines of California, as also the gold dust
+gained from the beach sand on the west coast of New Zealand, or in the
+enormous alluvial drifts of the Shoalhaven Valley, New South Wales. Of
+the first, many fabulous tales are told to account for its being found
+in particular spots each summer after the winter floods, and
+miraculous agency was asserted, while the early beachcombers of the
+Hokitika district found an equally ridiculous derivation for their
+gold, which was always more plentiful after heavy weather. They
+imagined that the breakers were disintegrating some abnormally rich
+auriferous reefs out at sea, and that the resultant gold was washed up
+on the beach.
+
+The facts are simply, with regard to the rivers, that the winter
+floods break down the drifts in the banks and agitate the auriferous
+detritus, thus acting as natural sluices, and cause the metal to
+accumulate in favourable spots; whilst on the New Zealand coast the
+heavy seas breaking on the shingly beach, carry off the lighter
+particles, leaving behind the gold, which is so much heavier. These
+beaches are composed, as also are the "terraces" behind, of enormous
+glacial and fluvial deposits, all containing more or less gold, and
+extend inland to the foot of the mountains.
+
+It is almost certain that the usually fine gold got by hydraulicing in
+Californian canyons, in the gullies of the New Zealand Alps, and the
+great New South Wales drifts, is largely the result of the attrition
+of the boulders and gravel of moraines, which has thus freed, to a
+certain extent, the auriferous particles. But when we find large
+nuggety masses of high carat gold in the beds of dead rivers, another
+origin has to be sought.
+
+As previously stated, there is fair reason to assume that at least
+three salts of gold have existed, and, possibly, may still be found in
+Nature--silicate, sulphide, and chloride. All of these are soluble and
+in the presence of certain reagents, also existing naturally, can be
+deposited in metallic form. Therefore, if, as is contended, reef gold
+was formed with the reefs from solutions in mineral waters, by
+inferential reasoning it can be shown that much of our alluvial gold
+was similarly derived.
+
+The commonly accepted theory, however, is that the alluvial matter of
+our drifts has been ground out of the solid siliceous lodes by glacial
+and fluvial action, and that the auriferous leads have been formed by
+the natural sluicing operations of former streams. To this, however,
+there are several insuperable objections.
+
+First, how comes it that alluvial gold is usually superior in purity
+to the "reef" gold immediately adjacent? Second, why is it that masses
+of gold, such as the huge nuggets found in Victoria and New South
+Wales, have never been discovered in lodes? Third, how is it that
+these heavy masses which, from their specific gravity, should be found
+only at the very bottom of the drifts, if placed by water action, are
+sometimes found in all positions from the surface to the bottom of the
+"wash"? And, lastly, why is it that when an alluvial lead is traced up
+to, or down from, an auriferous reef, that the light, angular gold
+lies close to the roof, while the heavy masses are often placed much
+farther away? Any one who has worked a ground sluice knows how
+extremely difficult it is with a strong head of water to shift from
+its position an ounce of solid gold. What, then, would be the force
+required to remove the Welcome Nugget? Under certain circumstances,
+Niagara would not be equal to the task.
+
+The generally smooth appearance of alleged alluvial gold is adduced as
+an argument in favour of its having been carried by water from its
+original place of deposit, and thus in transit become waterworn; while
+some go so far as to say that it was shot out of the reefs in a molten
+state. The latter idea has been already disposed of, but if not, it
+may be dismissed with the statement that the heat which would melt
+silica in the masses met with in lodes would sublimate any gold
+contained, and dissipate it, not in nuggets but in fumes. With regard
+to the assumed waterworn appearance of alluvial gold, I have examined
+with the microscope the smooth surface of more than one apparently
+waterworn nugget, and found that it was not scratched and abraded, as
+would have been the case had it been really waterworn, but that it
+presented the same appearance, though infinitely finer in grain, as
+the surface of a piece of metal fresh from the electrical plating-
+bath.
+
+Mr. Daintree, of the Victorian Geological Survey, many years ago
+discovered accidentally that gold chloride would deposit its metal on
+a metallic base in the presence of any organic substance. Mr. Daintree
+found that a piece of undissolved gold in a bottle containing chloride
+of gold in solution had, owing to a portion of the cork having fallen
+into the liquid, grown or accretionised so much that it could not be
+extracted through the neck. This lead Mr. Charles Wilkinson, who has
+contributed much to our scientific knowledge of metallurgy, to
+experiment further in the same direction. He says: "Using the most
+convenient salt of gold, the terchloride, and employing wood as the
+decomposing agent, in order to imitate as closely as possible the
+organic matter supposed to decompose the solution circulating through
+the drifts, I first immersed a piece of cubic iron pyrites taken from
+the coal formation of Cape Otway, far distant from any of our gold
+rocks, and therefore less likely to contain gold than other pyrites.
+The specimen (No. 1) was kept in dilute solution for about three
+weeks, and is completely covered with a bright film of gold. I
+afterwards filed off the gold from one side of a cube crystal to show
+the pyrites itself and the thickness of the surrounding coating, which
+is thicker than ordinary notepaper. If the conditions had continued
+favourable for a very lengthened period, this specimen would doubtless
+have formed the nucleus of a large nugget. Iron, copper, and arsenical
+pyrites, antimony, galena, molybdenite, zinc blende, and wolfram were
+treated in the above manner with similar results. In the above
+experiments a small chip of wood was employed as the decomposing
+agent. In one instance I used a piece of leather. All through the wood
+and leather gold was disseminated in fine particles, and when cut
+through the characteristic metallic lustre was brightly reflected. The
+first six of these sulphides were also operated upon simply in the
+solution without organic matter; but they remained unaltered."
+
+Wilkinson found that when the solution of gold chloride was as strong
+as, say, four grains to the ounce of water, that the pyrites or other
+base began to decompose, and the iron sulphide changed to yellow
+oxide, the "gossan" of our lodes, and that though the gold was
+deposited, this occurred in an irregular way, and it was coated with a
+dark brown powdery film something like the "black gold," often found
+in drifts containing much ferruginous matter. Such were the curious
+Victorian nuggets Spondulix and Lothair.
+
+Professor Newbery also made a number of similar experiments, and
+arrived at like results. He states as follows: "I placed a cube of
+galena in a solution of chloride of gold, with free access of air, and
+put in organic matter; gold was deposited as usual, in a bright
+metallic film, apparently completely coating the cube. After a few
+months the film burst along the edges of the cube, and remained in
+that state with the cracks open without any further alteration in size
+or form being apparent. Upon removing it a few days ago and breaking
+it open, I found that a large portion of the galena had been
+decomposed, forming chloride and sulphate of lead and free sulphur,
+which were mixed together, encasing a small nucleus of undecomposed
+sulphate of lead. The formation of these salts had exerted sufficient
+force to burst open the gold coating, which upon the outside had the
+mammillary form noticed by Wilkinson, while the inside was rough and
+irregular with crystals forcing their way into the lead salts. Had
+this action continued undisturbed, the result would have been a nugget
+with a nucleus of lead salts, or if there had been a current to remove
+the results of decomposition, a nugget without a nucleus of foreign
+matter."
+
+But Newbery also made another discovery which still further
+establishes the probability of the accretionary growth of gold in
+drifts. In the first experiments both investigators used organic
+substances as the reagent to cause the deposit of gold on its base,
+and in each case these substances whether woodchips, leather, or even
+dead flies, were found to be so absolutely impregnated with gold as to
+leave a golden skeleton when afterwards burned. Timber found in the
+Ballarat deep leads has been proved to be similarly impregnated.
+
+Newbery found that gold could also be deposited on sulphurets without
+any other reagent. He says: "In our mineral sulphurets, however, we
+have agents which are not only capable of reducing gold and silver
+from solution, but besides are capable of locating them when so
+reduced in coherent and bulky masses. Thus the aggregation of the
+nuggety forms of gold from solution becomes a still more simple
+matter, only one reagent being necessary, so that there is a greater
+probability of such depositions obtaining than were a double process
+necessary. Knowing the action of sulphides, the manner or the mode of
+formation of a portion at least of these nuggets seems apparent.
+Conceive a stream or river fed by springs rising in a country
+intersected by auriferous reefs, and consequently in this case
+carrying gold in solution; the drift of such a country must be to a
+greater or lesser extent pyritous, so that the /debris/ forming the
+beds of these streams or rivers will certainly contain nodules of such
+matters disseminated or even stopping them in actual contact with the
+flow of water. It follows, then, from what has been previously
+affirmed, that there will be a reduction of gold by these nodules, and
+that the metal thus reduced will be firmly attached to them, at first
+in minute spangles isolated from each other, but afterwards
+accumulating and connecting in a gradual manner at that point of the
+pyritous mass most subject to the current until a continuous film of
+some size appears. This being formed the pyrites and gold are to a
+certain extent polarised, the film or irregular but connected mass of
+gold forming the negative, and the pyrites the positive end of a
+voltaic pair; and so according as the polarisation is advanced to
+completion the further deposition of gold is changed in its manner
+from an indiscriminate to an orderly and selective deposition
+concentrated upon the negative or gold plate. The deposition of gold
+being thus controlled, its loss by dispersion or from the crumbling
+away of the sustaining pyrites is nearly or quite prevented, a
+conservative effect which we could scarcely expect to obtain if
+organic matter were the reducing agent. Meanwhile there is a gradual
+wasting away of the pyrites or positive pole, its sulphur being
+oxidised to sulphuric acid and its iron to sesquioxide of iron, or
+hematite, a substance very generally associated with gold nuggets.
+According to the original size of the pyritous mass, the protection it
+receives from the action of oxidising substances other than gold, the
+strength of the gold solution, length of exposure to it, the rate of
+supply and velocity of stream, will be the size of the gold nugget. As
+to the size of a pyritous mass necessary to produce in this manner a
+large nugget, it is by no means considerable. A mass of common pyrites
+(bisulphide of iron) weighing only 12 lbs. is competent for the
+construction of the famous 'Welcome Nugget,' an Australian find having
+weight equal to 152 lbs. avoirdupois. Such masses of pyrites are by no
+means uncommon in our drifts or the beds of our mountain streams. Thus
+we find that no straining of the imagination is required to conceive
+of this mode of formation for the huge masses of gold found in
+Australia in particular, such as the Welcome Nugget, 184 lbs. 9 oz.;
+the Welcome Stranger, a surface nugget, 190 lbs. after smelting; the
+Braidwood specimen nugget, 350 lbs., two-thirds gold; besides many
+other large masses of almost virgin gold which have been obtained from
+time to time in the alluvial diggings."
+
+The author has made a number of experiments in the same direction, but
+more with the idea of demonstrating how possibly gold may in certain
+cases have been deposited in siliceous formations after such
+formations had solidified. Some of the results were remarkable and
+indeed unexpected. I found that I could produce artificial specimens
+of auriferous quartz from stone which had previously contained no gold
+whatever, also that it was not absolutely necessary that the stone so
+treated should contain any metallic sulphides.
+
+The following was contributed by the author and is from the
+"Transactions" of the Australasian Institute of Mining Engineers for
+1893:--
+
+"THE DEPOSITION OF GOLD.
+
+"The question as to how gold was originally deposited in our
+auriferous lodes is one to which a large amount of attention has been
+given, both by mineralogists and practical miners, and which has been
+hotly argued by those who held the igneous theory and those who
+pronounced for the aqueous theory. It was held by the former that as
+gold was not probably existent in nature in any but its metallic form,
+therefore it had been deposited in its siliceous matrix while in a
+molten state, and many ingenious arguments were adduced in support of
+this contention. Of late, however, most scientific men, and indeed
+many purely empirical inquirers (using the word empirical in its
+strict sense) have come to the conclusion that though the mode in
+which they were composed was not always identical, all lodes,
+including auriferous formations, were primarily derived from mineral-
+impregnated waters which deposited their contents in fissures caused
+either by the cooling of the earth's crust or by volcanic agency.
+
+"The subject is one which has long had a special attraction for the
+writer, who has published several articles thereon, wherein it was
+contended that not only was gold deposited in the lodes from aqueous
+solution, but that some gold found in form of nuggets had not been
+derived from lodes but was nascent in its alluvial bed; and for this
+proof was afforded by the fact that certain nuggets have been
+unearthed having the shape of an adjacent pebble or angular fragment
+of stone indented in them. Moreover, no true nugget of any great size
+has ever been found in a lode such as the Welcome, 2159 oz., or the
+Welcome Stranger, 2280 oz.; while it was accidentally discovered some
+years ago that gold could be induced to deposit itself from its
+mineral salt to the metallic state on any suitable base, such as iron
+sulphide.
+
+"Following out this fact, I have experimented with various salts of
+gold, and have obtained some very remarkable results. I have found it
+practicable to produce most natural looking specimens of auriferous
+quartz from stone which previously, as proved by assay, contained no
+gold whatever. Moreover, the gold, which penetrates the stone in a
+thorough manner, assumes some of the more natural forms. It is always
+more or less mammillary, but at times, owing to causes which I have
+not yet quite satisfied myself upon, is decidedly dendroidal, as may
+be seen in one of the specimens which I have submitted to members.
+Moreover, I find it possible to moderate the colour and to produce a
+specimen in which the gold shall be as ruddy yellow as in the ferro-
+oxide gangue of Mount Morgan, or to tone it to the pale primrose hue
+of the product of the Croydon mines.
+
+"I note that the action of the bath in which the stone is treated has
+a particularly disintegrating effect on many of the specimens. Some,
+which before immersion were of a particularly flinty texture, became
+in a few weeks so friable that they could be broken up by the fingers.
+So far as my experiments have extended they have proved this, that it
+was not essential that the silica and gold should have been deposited
+at the one time in auriferous lodes. A non-auriferous siliceous
+solution may have filled a fissure, and, after solidifying, some
+volcanic disturbance may have forced water impregnated with a gold
+salt through the interstices of the lode formation, when, if the
+conditions were favourable, the gold would be deposited in metallic
+forms. I prefer, for reasons which will probably be understood, not to
+say exactly by what process my results are obtained, but submit
+specimens for examination.
+
+"(1) Piece of previously non-gold bearing stone. Locality near
+Adelaide, now showing gold freely in mammillary and dendroidal form.
+
+"(2) Stone from New South Wales, showing gold artificially introduced
+in interstices and on face.
+
+"(3) Stone from West Australia, very glassy looking, now thoroughly
+impregnated with gold; the mammillary formation being particularly
+noticeable.
+
+"(4) Somewhat laminated quartz from Victoria, containing a little
+antimony sulphide. In this specimen the gold not only shows on the
+surface but penetrates each of the laminations, as is proved by
+breaking.
+
+"(5) Consists of fragments of crystallised carbonate of lime from
+Tarrawingee, in which the gold is deposited in spots, in appearance
+like ferrous oxide, until submitted to the magnifying glass.
+
+"The whole subject is worthy of much more time than I can possibly
+give it. The importance lies in this: That having found how the much
+desired metal may have been deposited in its matrix, the knowledge
+should help to suggest how it may be economically extracted
+therefrom."
+
+A very remarkable nugget weighing 16 3/4 oz. was sluiced from near the
+surface in one of my own mining properties at Woodside, South
+Australia, some years ago, which illustrated the nuclear theory very
+beautifully. This nugget is very irregular in shape, fretted and
+chased as though with a jeweller's graving tool, showing plainly the
+shape of the pyritous crystals on which it was formed while the
+interstices were filled with red hematite iron just as found in
+artificially formed nuggets on a sulphide of iron base. The author has
+a nugget from the same locality weighing about 1 1/2 oz. which
+exhibits in a marked degree the same characteristics, as indeed does
+most of the alluvial gold found in the Mount Lofty Ranges; also a
+nugget from near the centre of Australia weighing four ounces, in
+which the original crystals of pyrites are reproduced in gold just as
+an iron horse-shoe, placed in a launder through which cupriferously
+impregnated water flows, will in time be changed to nearly pure copper
+and yet retain its shape.
+
+Now with regard to the four points I have put as to the apparent
+anomalies of occurrence of alluvial gold. The reason why alluvial gold
+is of finer quality as a rule than reef is probably because while gold
+and silver, which have a considerable affinity for each other, were
+presumably dissolved from their salts and held in solution in the same
+mineral water, they would in many cases not be deposited together, for
+the reason that silver is most readily deposited in the presence of
+alkalies, which would be found in excess in mineral waters coming
+direct from the basic rocks, while gold is induced to precipitate more
+quickly in acid solutions, which would be the character of the waters
+after they had been exposed to atmospheric action and to contact with
+organic matters.
+
+This, then, may explain not only the comparatively greater purity of
+the alluvial gold, but also why big nuggets are found so far from
+auriferous reefs, and also why heavy masses of gold have been
+frequently unearthed from among the roots even of living trees, but
+more particularly in drifts containing organic matter, such as ancient
+timber.
+
+All, then, that has been adduced goes to establish the belief that the
+birthplace of our gold is in certain of the earlier rocks comprising
+the earth's crust, and that its appearance as the metal we value so
+highly is the result of electro-chemical action, such as we can
+demonstrate in the laboratory.
+
+
+
+CHAPTER VI
+
+GOLD EXTRACTION
+
+We now come to a highly important part of our subject, the practical
+treatment of ores and matrixes for the extraction of the metals
+contained. The methods employed are multitudinous, but may be divided
+into four classes, namely, washing, amalgamating with mercury,
+chlorinating, cyaniding and other leaching processes, and smelting.
+The first is used in alluvial gold and tin workings and in preparing
+some silver, copper, and other ores for smelting, and consists merely
+in separating the heavier metals and minerals from their gangues by
+their greater specific gravity in water. The second includes the
+trituration of the gangue and the extraction of its gold or silver by
+means of mercury. Chlorinating and leaching generally is a process
+whereby metals are first changed by chemical action into their mineral
+salts, as chloride of gold, nitrate of silver, sulphate of copper, and
+being dissolved in water are afterwards redeposited in the metallic
+form by means of well-known re-agents.
+
+In really successful mining it is in the last degree important that
+the mode of extraction of metals in the most scientific manner should
+be thoroughly understood, but as a general rule the science of
+metallurgy is but very superficially grasped even by those whose
+special business it is to treat ore bodies in order to extract their
+metalliferous contents, and whether in quartz crushing mill,
+lixiviating, or smelting works there is much left to be desired in the
+method of treating our ores.
+
+My attention was recently attracted to an article written by Mr. F. A.
+H. Rauft, M.E., from which I make the following extract:
+
+He says, speaking of the German treatment of ores and the mode of
+procedure in Australia, "It is high time that Government stepped in
+and endeavoured by prompt and decisive action to bring the mining
+industry upon a sound and legitimate basis. Though our ranges abound
+in all kinds of minerals that might give employment to hundreds of
+thousands of people, mining is carried on in a desultory, haphazard
+fashion. There is no system, and the treatment of ores is of necessity
+handed over to the tender mercies of men who have not even an idea of
+what an intricate science metallurgy has become in older countries.
+During many years of practical experience I have never known a single
+instance where a lode, on being worked, gave a return according to
+assay, and I have never known any mine where some of the precious
+metals could not be found in the tailings or slag. The Germans employ
+hundreds of men in working for zinc which produces some two or three
+per cent to the ton; here the same percentage of tin could hardly be
+made payable, and this, mark you, is owing not to cheaper labour
+alone, but chiefly to the labour-saving appliances and the results of
+the researches of such gigantic intellects as Professor Kerl and many
+others, of whom we in this country never even hear. Go into any of the
+great mining works of central Germany, and you may see acres covered
+by machinery ingeniously constructed to clean, break, and sort, and
+ultimately deliver the ores into trucks or direct into the furnace,
+and the whole under the supervision of a youngster or two. When a
+parcel of ore arrives at any of the works, say Freiberg or Clausthal,
+it is carefully assayed by three or four different persons and then
+handed over to practical experts, who are expected to produce the full
+amount of previous metal according to assay; and if by any chance they
+do not, a fixed percentage of the loss is deducted from their salary;
+or, if the result is in excess of this assay which is more frequently
+the case, a small bonus is added to their pay. Compare this system
+with our own wasteful, reckless method of dealing with our precious
+metals, and we may hide our heads in very shame."
+
+All really practical men will, I think, endorse Mr. Rauft's opinion.
+Well organised and conducted schools of mines will gradually
+ameliorate this unsatisfactory state of things, and I hope before long
+that we shall have none but qualified certificated men in our mines.
+In the meantime a few practical hints, particularly on that very
+difficult branch of the subject, the saving of gold, will, it is
+hoped, be found of service.
+
+The extraction of gold from the soil is an industry so old that its
+first introduction is lost in the mist of ages. As before stated, gold
+is one of the most widely disseminated of the metals, and man, so soon
+as he had risen from the lowest forms of savagery, began to be
+attracted by the kingly metal, which he found to be easily fashioned
+into articles of ornament and use, and to be practically non-
+corrodable.
+
+What we now term the dish or pan, then, doubtless generally a wooden
+bowl, was the appliance first used; but they had also an arrangement,
+somewhat like our modern blanket tables, over which the auriferous
+sand was passed by means of a stream of water. The sands of some of
+the rivers from which portions of the gold supply of the old world was
+derived are still washed over year after year in exactly the same
+manner as was employed, probably, thousands of years ago, the labour,
+very arduous, being often carried on by women, who, standing knee deep
+in water, pan off the sand in wooden bowls much as the digger in
+modern alluvial fields does with his tin dish. The resulting gold
+often consists of but a grain or two of fine dust-gold, which is
+carefully collected in quills, and so exported or traded for goods.
+
+The digger of to-day having discovered payable alluvial dirt at such a
+depth as to permit of its being profitably worked by small parties of
+men with limited or no capital, procures first a half hogshead for a
+puddling tub, a "cradle," or "long tom," and tin dish. The "wash
+dirt," as the auriferous drift is usually termed, contains a
+considerable admixture of clay of a more or less tenacious character,
+and the bulk of this has to be puddled and so disintegrated before the
+actual separation of the gold is attempted in the cradle or dish. This
+is done in the tub by constantly stirring with a shovel, and changing
+the water as it becomes charged with the floating argillaceous, or
+clayey, particles. The gravel is then placed in the hopper of the
+cradle which separates the larger stones and pebbles, the remainder
+passing down over inclined ledges as the cradle is slowly rocked and
+supplied with water. At the bottom of each ledge is a riffle to arrest
+the particles of gold. Sometimes, when the gold is very fine,
+amalgamated copper plates are introduced and the lower ledges are
+covered with green baize to act as blanket tables and catch gold which
+might otherwise be lost.
+
+A long tom is a trough some 12 feet in length by 20 inches in width at
+the upper end, widening to 30 inches at the lower end; it is about 9
+inches deep and has a fall of 1 inch to a foot. An iron screen is
+placed at the lower end where large stones are caught, and below this
+screen is the riffle box, 12 feet long, 3 feet wide, and having the
+same inclination as the upper trough. It is fitted with several
+riffles in which mercury is sometimes placed.
+
+Much more work can be done with this appliance than with the cradle,
+which it superseded. Of course, the gold must be coarse and water
+plentiful.
+
+When, however, the claim is paying, and the diggings show signs of
+some permanency, a puddling machine is constructed. This is described
+in the chapter called "Rules of Thumb."
+
+Hydraulicing and ground sluicing is a very cheap and effective method
+of treating large quantities of auriferous drift, and, given
+favourable circumstances, such as a plentiful supply of water with
+good fall and extensive loose auriferous deposits, a very few grains
+to the ton or load can be made to give payable returns. The water is
+conveyed in flumes, or pipes to a point near where it is required,
+thence in wrought iron pipes gradually reduced in size and ending in a
+great nozzle somewhat like that of a fireman's hose. The "Monitor," as
+it is sometimes called, is generally fixed on a movable stand, so
+arranged that the strong jet of water can be directed to any point by
+a simple adjustment. A "face" is formed in the drift, and the water
+played against the lower portion of the ledge, which is quickly
+undermined, and falls only to be washed away in the stream of water,
+which is conducted through sluices with riffles, and sometimes over
+considerable lengths of amalgamated copper plates. This class of
+mining has been most extensively carried out in California and New
+Zealand, and some districts of Victoria, but the truly enormous drifts
+of the Shoalhaven district in New South Wales must in the near future
+add largely to the world's gold supply. These drifts which are
+auriferous from grass roots to bed rock extend for nearly fifty miles,
+and are in places over 200 feet deep. Want of capital and want of
+knowledge has hitherto prevented their being profitably worked on a
+large scale.
+
+The extraction of reef gold from its matrix is a much more complicated
+process, and the problem how most effectively to obtain that great
+desideratum--a complete separating and saving operation--is one which
+taxes the skill and evokes the ingenuity of scientific men all over
+the world. The difficulty is that as scarcely any two gangues, or
+matrixes, are exactly alike, the treatment which is found most
+effective on one mine will often not answer in another. Much also
+depends on the proportion of gold to the ton of rock under treatment,
+as the most scientific and perfect processes of lixiviation hitherto
+adopted will not pay, even when all other conditions are favourable,
+if the amount of gold is much under half an ounce to the ton and even
+then will leave but a very small profit. If, however, the gold is
+"free," and the lode large, a very few pennyweights (or "dollars," as
+the Americans say) to the ton will pay handsomely. The mode of
+extraction longest in vogue, and after all the cheapest and most
+effective, for free milling ores where the gold is not too fine, is
+amalgamation with mercury, which metal has a strong affinity for gold,
+silver, and copper.
+
+As to crushing appliances, I shall not say much. "Their name is legion
+for they are many," and the same may be said of concentrators. It may
+be old-fashioned, but I admit my predilection is still in favour of
+the stamper-battery, for the reason that though it may be slower in
+proportion to the power employed, it is simple and not liable to get
+out of order, a great advantage when one has so often to depend on men
+who bring to their work a supply principally of main strength and
+stupidity. For the same reason I prefer the old draw and lift, and
+plunger pumps to newer but more complicated water-lifters.
+
+On both these points, however, I am constrained to admit that my
+opinion has recently been somewhat shaken.
+
+I have lately seen two appliances which appear to mark a new era in
+the scientific progress of mining. One is the "Griffin Mill," the
+other the "Lemichel Siphon Elevateur."
+
+The first is in some respects on the principle of the Huntingdon Mill.
+The latter, if the inventor may be believed and the results seem to
+show he can be, will be a wonderful factor in developing not only
+mining properties where a preponderance of water is the trouble, but
+also in providing an automatic, and therefore extremely cheap, mode of
+water-raising and supply, which in simplicity is thus far unexampled.
+Atmospheric pressure alone is relied on. The well-known process of the
+syphon is the basis, but with this essential difference, that a large
+proportion of the water drawn up to the apex of the syphon is super-
+elevated to heights regulated by the fall obtained in the outlet leg.
+This elevation can be repeated almost indefinitely by returning the
+waste water to the reservoirs.
+
+The Lemichel Syphon is a wonderful, yet most simple application of
+natural force. The inlet leg of the syphon is larger in diameter than
+the outlet leg, and is provided at the bottom with a valve or "clack."
+The outlet leg has a tap at its base. At the apex are two chambers,
+with an intermediary valve, regulated by a counterpoise weighted
+lever. The first chamber has also a vertical valve and pipe.
+
+When the tap of the outlet leg is turned, the water flows as in an
+ordinary syphon, but owing to the rapid automatic opening and shutting
+of the valve in the first chamber about 45 per cent of the water is
+diverted, and may be raised to a height of many feet above the top of
+the syphon.
+
+It need not be impressed on practical men that if this invention will
+perform anything like what is claimed for it, its value can hardly be
+calculated. After a careful inspection of the appliance in operation,
+I believe it will do all that is stated.
+
+Another invention is combined with this which, by a very small
+expenditure of fuel, will enable the first point of atmospheric
+pressure to be attained. In this way the unwatering of mines may be
+very inexpensively effected, or water for irrigation purposes may be
+raised from an almost level stream.
+
+The Griffin Mill is a centrifugal motion crusher with one roller only,
+which, by an ingenious application of motive force, revolves in an
+opposite direction to its initial momentum, and which evolves a force
+of 6000 lb. against the tire, which is only 30 inches in diameter. For
+hard quartz the size should be increased by at least 6 inches. It is
+claimed for this mill that it will pulverise to a gauge of 900 holes
+to the square inch from 1 1/2 to 2 1/2 tons per hour, or, say roughly,
+150 tons per week.
+
+The Huntingdon mill is a good crusher and amalgamator where the
+material to be operated on is comparatively soft, but does not do such
+good work when the stone is of a hard flinty nature.
+
+A No. 4 Dodge stone-breaker working about 8 hours will keep a five-
+foot Huntingdon mill going 24 hours, and an automatic feeder is
+essential. For that matter both are almost essential for an ordinary
+stamper battery, and will certainly increase the crushing capacity and
+do better work from the greater regularity of the feed.
+
+A 10 h.-p. (nominal) engine of good type is sufficient for Huntingdon
+mill, rock breaker, self-feeder and steam pump. A five-foot mill under
+favourable circumstances will crush about as much as eight head of
+medium weight stamps.
+
+The Grusonwek Ball Mills, made by Krupp of Germany, also that made by
+the Austral Otis Company, Melbourne, are fast and excellent crushing
+triturating appliances for either wet or dry working, but are
+specially suited only for ores when the gold is fine and evenly
+distributed in the stone. The trituration is effected by revolving the
+stone in a large cylinder together with a number of steel balls of
+various sizes, the attrition of which with the rock quickly grinds it
+to powder of any required degree of fineness.
+
+More mines have been ruined by bad mill management probably than by
+bad mining, though every experienced man must have seen in his time
+many most flagrant instances of bungling in the latter respect. Shafts
+are often sunk on the wrong side of the lode or too near or too far
+away therefrom, while instances have not been wanting where the (mis)
+manager has, after sinking his shaft, driven in the opposite direction
+to that where the lode should be found.
+
+A common error is that of erecting machinery before there is
+sufficient ore in sight to make it certain that enough can be provided
+to keep the plant going. In mines at a distance from the centre of
+direction it is almost impossible to check mistakes of this
+description, caused by the ignorance or over sanguineness of the mine
+superintendent, and they are often as disastrous as they are
+indefensible. Another fertile source of failure is the craze for
+experimenting with untried inventions, alleged to be improvements on
+well-known methods.
+
+A rule in the most scientific of card games, whist, is "when in doubt
+lead trumps." It might be paraphrased for mining thus: "When in doubt
+about machinery use that which has been proved." Let some one else do
+the experimenting.
+
+The success of a quartz mine depends as much on favourable working
+conditions as on its richness in gold. Thus it may be that a mine
+carrying 5 or 6 oz. of gold to the ton but badly circumstanced as to
+distance, mountainous roads, lack of wood and water, in some cases a
+plethora of the latter, or irregularly faulted country, may be less
+profitable than another showing only 5 or 6 dwt., but favourably
+situated.
+
+It is usually desirable to choose for the battery site, when possible,
+the slope of a hill which consists of rock that will give a good
+foundation for your battery.
+
+The economical working depends greatly on the situation, which is
+generally fixed more or less, in the proximity of the water. The
+advantages of having ample water for battery purposes, or of using
+water as a motive power, are so great that it is very often desirable
+to construct a tramway of considerable length, when, by so doing, that
+power can be utilised; hence most quartz mills are placed near
+streams, or in valleys where catchment dams can be effectively
+constructed, except, of course, in districts where much water has to
+be pumped from the mine.
+
+If water-power can be used, the water-motor will necessarily be placed
+as low as possible, in order to obtain the fullest available power.
+One point is essential. Special care must be taken to keep the
+appliances above the flood-level. If the water in the stream is not
+sufficient to carry off the tailings, the battery should be placed at
+such a height as to leave sufficient slope for tailings' dumps. This
+is more important when treating ore of such value that the tailings
+are worth saving for secondary treatment. In this case provision
+should be made for tailings, dams, or slime pits.
+
+Whether the battery is worked by water, steam, or gas power, an ample
+supply of water is absolutely necessary, at least until some
+thoroughly effective mode of dry treatment is established. If it can
+be possibly arranged the water should be brought in by gravitation,
+and first cost is often least cost; but where this is impossible,
+pumps of sufficient capacity, not only to provide the absolute
+quantity used, but to meet any emergency, should be erected.
+
+The purer the water the better it will be for amalgamating purposes,
+and in cold climates it is desirable to make provision for heating the
+water supplied to the battery. This can be done by means of steam from
+the boiler led through the feed tanks; but where the boiler power is
+not more than required, waste steam from the engine may be employed,
+but care must be taken that no greasy matter comes in contact with the
+plates. The exhaust steam from the engine may be utilised by carrying
+it through tubes fitted in an ordinary 400 gallon tank.
+
+Reducing appliances have often to be placed in districts where the
+water supply is insufficient for the battery. When this is so every
+available means must be adopted for saving the precious liquid, such
+as condensing the exhaust steam from the engine. This may be done by
+conducting it through a considerable length of ordinary zinc piping,
+such as is used for carrying the water from house roofs. Also tailings
+pits should be made, in which the tailings and slimes are allowed to
+settle, and the cleared water is pumped back to be again used. These
+pits should, where practicable, be cemented. It is usual, also, to
+have one or two tailings dams at different levels; the tailings are
+run into the upper dam, and are allowed to settle; the slimes overflow
+from it into the lower dam, and are there deposited, while the cleared
+water is pumped back to the battery. Arrangements are made by which
+all these reservoirs can be sluiced out when they are filled with
+accumulated tailings. It is well not to leave the sluicing for too
+long a period, as when the slimes and tailings are set hard they are
+difficult to remove.
+
+Where a permanent reducing plant is to be erected, whatever form of
+mill may be adopted, it is better for many reasons to use automatic
+ore feeders. Of these the best two I have met are the "Tulloch" and
+"Challenge" either of which can be adapted to any mill and both do
+good work.
+
+By their use the reducing capacity of the mill is increased, and the
+feeding being regular the wear and tear is decreased, while by the
+regulated feeding of the "pulp" in the battery box or mortar can be
+maintained at any degree of consistency which may be found desirable,
+and thus the process of amalgamation will be greatly facilitated. The
+only objection which can be urged against the automatic feeder is that
+the steel points of picks, gads, drills, and other tools may be
+allowed to pass into the mortar or mill, and thus cause considerable
+wear and tear. This, I think, can be avoided by the adoption of the
+magnet device, described in "Rules of Thumb."
+
+There are many mines where 3 to 4 dwt. of gold cover all the cost, the
+excess being clear profit. In fact there are mines which with a yield
+of 1 1/2 to 2 dwt. a ton, and crushing with water power, have actually
+yielded large profits. On the other hand, mines which have given
+extraordinary trial crushings have not paid working expenses.
+Everything depends on favourable local conditions and proper
+management.
+
+Having decided what class of crushing machinery you will adopt, the
+first point is to fix on the best possible site for its erection. This
+requires much judgment, as success or failure may largely depend on
+the position of your machinery. One good rule is to get your crusher
+as reasonably high as possible, as it is cheaper to pump your feed
+water a few feet higher so as to get a good clear run for your
+tailings, and also to give you room to erect secondary treatment
+appliances, such as concentrators and amalgamators below your copper
+plates and blanket strakes.
+
+Next, and this is most important, see that your foundations are solid
+and strong. A very large number of the failures of quartz milling
+plants is due to neglect of this rule.
+
+I once knew a genius who erected a 10-Lead mill in a new district, and
+who adopted the novel idea of placing a "bed log" laterally beneath
+his stampers. The log was laid in a little cement bed which, when the
+battery started, was not quite dry. The effect was comical to every
+one but the unfortunate owners. It was certainly the liveliest, but at
+the same time one of the most ineffective batteries I have seen.
+
+In a stamp mill the foundations are usually made of hard wood logs
+about 5 to 6 feet long, set on end, the bottom end resting on rock and
+set round with cement concrete. These are bolted together, and the
+"box" or mortar is bolted to them. The horizontal logs to carry the
+"horses" or supports for the battery frame should also be of good
+size, and solidly and securely bolted. The same applies to your
+engine-bed, but whether it be of timber, or mason work, above all
+things provide that the whole of your work is set out square and true
+to save after-wear and friction.
+
+Considerable difference of opinion exists as to the most effective
+weight for stamps. My experience has been that this largely depends on
+the nature of your rock, as does also the height for the drop. I have
+usually found that with medium stamps, say 7 to 7 1/2 cwt. with fair
+drop and lively action, about 80 falls per minute, the best results
+were obtained, but the tendency of modern mill men is towards the
+heavier stamps, 9 cwt. and even heavier.
+
+To find the horse-power required to drive a battery, multiply the
+weight of one stamp by the number of stamps in the battery; the height
+of lift in feet by the number of lifts per minute; add one-third of
+the product for friction, and the result will be the number of feet-
+lbs. per minute; divide this by 33,000 which is the number of feet-
+lbs. per minute equal to 1 h.-p. and the result will be the h.-p.
+required. Thus if a stamp weighs 800 lb. and you have five in the box,
+and each stamp has a lift of 9 in. = 0.75 ft. and strikes 80 blows per
+minute, then 800 x 5 x 0.75 x 80 = 240,000; one-third of 240,000 =
+80,000 which added to 240,000 = 320,000; and 320,000 divided by 33,000
+= 9.7 h.-p. or 1.9 h.-p. each stamp.
+
+The total weight of a battery, including stamper box, stampers, etc.,
+may be roughly estimated at about 1 ton per stamp. Medium weight
+stampers, including shank cam, disc, head, and shoe, weigh from 600 to
+700 lb., and need about 3/4 h.-p. to work them.
+
+The quantity of water required for the effective treatment of gold-
+bearing rock in a stamper battery varies according to the composition
+of the material to be operated upon, but generally it is more than the
+inexperienced believe. For instance, "mullocky" lode stuff, containing
+much clayey matter or material carrying a large percentage of heavy
+metal, such as titanic iron or metallic sulphides, will need a larger
+quantity of water per stamp than clean quartz. A fair average quantity
+would be 750 to 1000 gallons per hour for each box of five stamps. In
+general practice I have seldom found 1000 gallons per hour more than
+sufficient.
+
+As to the most effective mesh for the screen or grating no definite
+rule can be given, as that depends so largely on the size of the gold
+particles contained in the gangue. The finer the particles the closer
+must be the mesh, and nothing but careful experiment will enable the
+battery manager to decide this most important point. The American
+slotted screens are best; they wear better than the punched gratings
+and can be used of finer gauge. Woven steel wire gauze is employed
+with good effect in some mills where especially fine trituration is
+required. This class of screen requires special care as it is somewhat
+fragile, but with intelligent treatment does good work.
+
+The fall or inclination of the tables, both copper and blanket
+strakes, is also regulated by the class of ore. If it should be heavy
+then the fall must be steeper. A fair average drop is 3/4 inch to the
+foot. Be careful that your copper tables are thoroughly water-tight,
+for remember you are dealing with a very volatile metal, quicksilver;
+and where water will percolate mercury will penetrate.
+
+The blanket tables are simply a continuation of the mercury tables,
+but covered with strips of coarse blanket, green baize, or other
+flocculent material, intended to arrest the heavier metallic particles
+which, owing to their refractory nature, have not been amalgamated.
+
+The blanket table is, however, a very unsatisfactory concentrator at
+best, and is giving place to mechanical concentrators of various
+descriptions.
+
+An ancient Egyptian gold washing table was used by the Egyptians in
+treating the gold ores of Lower Egypt. The ore was first ground, it is
+likely by means of some description of stone arrasts and then passed
+over the sloping table with water, the gold being retained in the
+riffles. In these the material would probably be mechanically
+agitated. Although for its era ingenious it will be plain to practical
+men that if the gold were fine the process would be very ineffective.
+Possibly, but of this I have no evidence, mercury was used to retain
+the gold on the riffles, as previously stated. This method of saving
+the precious metal was known to the ancients.
+
+At a mine of which I was managing director the lode was almost
+entirely composed of sulphide of iron, carbonate of lime or calcspar,
+with a little silica. In this case it has been found best to crush
+without mercury, then run the pulp into pans, where it is
+concentrated. The concentrates are calcined in a common reverberatory
+furnace, and afterwards amalgamated with mercury in a special pan, the
+results as to the proportion of gold extracted being very
+satisfactory; but it does not therefore follow that this process would
+be the most suitable in another mine where the lode stuff, though in
+some respects similar, yet had points of difference.
+
+I was lately consulted with respect to the treatment of a pyritic ore
+in a very promising mine, but could not recommend the above treatment,
+because though the pyrites in the gangue was similar, the bulk of the
+lode consisted of silica, consequently there would be a great waste of
+power in triturating the whole of the stuff to what, with regard to
+much of it, would be an unnecessary degree of fineness. I am of
+opinion that in cases such as this, where it is not intended to adopt
+the chlorination or cyanogen process, it will be found most economical
+to crush to a coarse gauge, concentrate, calcine the concentrates, and
+finally amalgamate in some suitable amalgamator.
+
+Probably for this mode of treatment Krom rolls would be found more
+effective reducing agents than stampers, as with them the bulk of the
+ore can be broken to any required gauge and there would consequently
+be less loss in "slimes."
+
+The great art in effective battery work is to crush your stuff to the
+required fineness only, and then to provide that each particle is
+brought into contact with the mercury either in box, trough, plate, or
+pan. To do this the flow of water must be carefully regulated; neither
+so much must be used as to carry the stuff off too quickly nor so
+little as to cause the troughs and plates to choke. In cold weather
+the water may be warmed by passing the feed-pipe through a tank into
+which the steam from the engine exhausts, and this will be found to
+keep the mercury bright and lively. But be careful no engine oil or
+grease mingles with the water, as grease on the copper tables will
+absolutely prevent amalgamation.
+
+The first point, then, is to crush the gangue effectively, the degree
+of fineness being regulated by the fineness of the gold itself. This
+being done, then comes the question of saving the gold. If the quartz
+be clean, and the gold unmixed with base metal, the difficulty is
+small. All that is required is to ensure that each particle of the
+Royal metal shall be brought into contact with the mercury. The main
+object is to arrest the gold at the earliest possible stage;
+therefore, if you are treating clean stone containing free gold,
+either coarse or fine, I advise the use of mercury in the boxes, for
+the reason that a considerable proportion of the gold will be caught
+thereby, and settling to the bottom, or adhering to amalgamated plates
+in the boxes, where such are used, will not be afterwards affected by
+the crushing action, which might otherwise break up, or "flour," the
+mercury. On the whole, I rather favour the use of mercury in the box
+at any time, unless the ore is very refractory--that is, contains too
+great a proportion of base metals, particularly sulphides of iron,
+arsenic, etc., when the result will not be satisfactory, but may
+entail great loss by the escape of floured mercury carrying with it
+particles of gold. Here only educated intelligence, with experience,
+will assist the battery manager to adopt the right system.
+
+The crushed stuff--generally termed the "pulp"--passes from the boxes
+through the "screens" or "gratings," and so on to the "tables"--i.e.,
+sheets of copper amalgamated on the upper surface with mercury, and
+sometimes electroplated with silver and afterwards treated with
+mercury. Unless the quartz is very clean, and, consequently light, I
+am opposed to the form of stamper box with mercury troughs cast in the
+"lip," nor do I think that a trough under the lip is a good
+arrangement, as it usually gets so choked and covered with the heavy
+clinging base metals as to make it almost impossible for the gold to
+come in contact with the mercury. It will be found better where the
+gold is fine, or the gangue contains much base metal, to run the pulp
+from the lip of the battery into a "distributor."
+
+The distributor is a wooden box the full width of the "mortar," having
+a perforated iron bottom set some three to four inches above the first
+copper plate, which should come up under the lip. The effect of this
+arrangement is that the pulp is dashed on the plate by the falling
+water, and the gold at once coming in contact with the mercury begins
+to accumulate and attract that which follows, till the amalgam becomes
+piled in little crater-shaped mounds, and thus 75 per cent of the gold
+is saved on the top plate.
+
+I have tried a further adaptation of this process when treating ores
+containing a large percentage of iron oxide, where the bulk of the
+gold is impalpably fine, and contained in the "gossan." At the end of
+the blanket table, or at any point where the crushed stuff last passes
+before going to the "tailings heap," or "sludge pit," a "saver" is
+placed. The saver is a strong box about 15 in. square by 3 ft. high,
+one side of which is removable, but must fit tight. Nine slots are cut
+inside at 4 in. apart, and into these are fitted nine square
+perforated copper plates, having about eighty to a hundred 1/4 in.
+holes in each; the perforations should not come opposite each other.
+These plates are to be amalgamated on both sides with mercury, in
+which a very little sodium has been placed (if acid ores are being
+treated, zinc should be employed in place of sodium, and to prevent
+the plates becoming bare, if the stuff is very poor, thick zinc
+amalgam may be used with good effect; but in that case discontinue the
+sodium, and occasionally, if required, say once or twice in the day,
+mix an ounce of sulphuric acid in a quart of water and slowly pour it
+into the launder above the saver). Underneath the "saver" you require
+a few riffles, or troughs, to catch any waste mercury, but if not
+overfed there should be no waste. This simple appliance, which is
+automatic and requires little attention, will sometimes arrest a
+considerable quantity of gold.
+
+We now come to the subsidiary processes of battery work, the
+"cleaning" of plates, and "scaling" same when it is desired to get all
+the gold off them, the cleaning and retorting of amalgam, and of the
+mercury, smelting gold, etc.
+
+Plates should be tenderly treated, kept as smooth as possible, and
+when cleaning up after crushing, in your own battery, the amalgam--
+except, say, at half-yearly intervals--should be removed with a rubber
+only; the rubber is simply a square of black indiarubber or soft pine
+wood.
+
+When crushing rich ore, and you want to get nearly all the gold off
+your plates, the scraper may be resorted to. This is usually made by
+the mine blacksmith from an old flat file which is cut in half, the
+top turned over, beaten out to a sharp blade, and kept sharp by
+touching it up on the grinding-stone. This, if carefully used, will
+remove the bulk of the amalgam without injury to the plate.
+
+Various methods of "scaling" plates will be found among "Rules of
+Thumb."
+
+Where base metals are present in the lode stuff frequent retortings of
+the mercury, say not less than once a month, will be found to have a
+good effect in keeping it pure and active. For this purpose, and in
+order to prevent stoppage of the machinery, a double quantity is
+necessary, so that half may be used alternately. Less care is required
+in retorting the mercury than in treating the amalgam, as the object
+in the one case is more to cleanse the metal of impurities than to
+save gold, which will for the most part have been extracted by
+squeezing through the chamois leather or calico. A good strong heat
+may therefore at once be applied to the retort and continued, the
+effect being to oxidise the arsenic, antimony, lead, etc., which, in
+the form of oxides, will not again amalgamate with the mercury, but
+will either lie on its surface under the water, into which the nozzle
+of the retort is inserted, or will float away on the surface of the
+water. I have also found that covering the top of the mercury with a
+few inches of broken charcoal when retorting has an excellent
+purifying effect.
+
+In retorting amalgam, much care and attention is required.
+
+First, never fill the retort too full, give plenty of room for
+expansion; for, when the heat is applied, the amalgam will rise like
+dough in an oven, and may be forced into the discharge pipe, the
+consequence being a loss of amalgam or the possible bursting of the
+retort. Next, be careful in applying the heat, which should be done
+gradually, commencing at the top. This is essential to prevent waste
+and to turn out a good-looking cake of gold, which all battery
+managers like to do, even if they purpose smelting into bars.
+
+Sometimes special difficulties crop up in the process of separating
+the gold from the amalgam. At the first "cleaning up" on the Frasers
+Mine at Southern Cross, West Australia, great consternation was
+excited by the appearance of the retorted gold, which, as an old miner
+graphically put it, was "as black as the hind leg of a crow," and
+utterly unfit for smelting, owing to the presence of base metals. Some
+time after this I was largely interested in the Blackborne mine in the
+same district when a similar trouble arose. This I succeeded in
+surmounting, but a still more serious one was too much for me--i.e.,
+the absence of payable gold in the stone. I give here an extract from
+the /Australian Mining Standard/, of December 9th, 1893, with
+reference to the mode of cleaning the amalgam which I adopted.
+
+NEW METHOD OF SEPARATING GOLD FROM IMPURE AMALGAM.
+
+I had submitted to me lately a sample of amalgam from a mine in West
+Australia which amalgam had proved a complete puzzle to the manager
+and amalgamator. The Mint returns showed a very large proportion of
+impurity, even in the smelted gold. When retorted only, the Mint
+authorities refused to take it after they had treated two cakes, one
+of 119 oz., which yielded only 35 oz. 5 dwt. standard gold, and one of
+140 oz., which gave 41 oz. 10 dwt. The gold smelted on the mine was
+nearly as bad proportionately. Thus, 128 oz. smelted down at the Mint
+to 87 oz. 8 dwt. and 109 oz. to 55 oz. 10 dwt. The impurity was
+principally iron, a most unusual thing in my experience, and was due
+to two causes revealed by assay of the ore and analysis of the mine
+water, viz., an excess of arsenate of iron in the stone, and the
+presence in large proportions of mineral salts, principally chloride
+of Calcium CaCl., sodium NaCl, and magnesium MgCl2, in the mine water
+used in the battery. The exact analysis of the water was as follows:--
+
+  Carbonate of Iron         FeCO3        2.76 grains per gallon
+  Carbonate of Calcium      CaCO3        7.61 grains per gallon
+  Sulphate of Calcium       CaSO4       81.71 grains per gallon
+  Chloride of Calcium       CaCl2     2797.84 grains per gallon
+  Chloride of Magnesium     MgCl2      610.13 grains per gallon
+  Chloride of Sodium or
+     Common Salt            NaCl      5072.65 grains per gallon
+
+          Total solid matter         8572.70 = 19.5 oz. to the gallon.
+
+It will be seen, then, that this water is nearly four times more salt
+that that of the sea. The effect of using a water of this character,
+as I have previously found, is to cause the amalgamation of
+considerable quantities of iron with the gold as in this case.
+
+I received 10 oz. of amalgam, and having found what constituted its
+impurities proceeded to experiment as to its treatment. When retorted
+on the mine it was turned out in a black cake so impure as almost to
+make it impossible to smelt properly. I found the same result on first
+retorting, and after a number of experiments which need not be
+recapitulated though some were fairly effective, I hit on the
+following method, which was found to be most successful and will
+probably be so found in other localities where similarly unfavourable
+conditions prevail.
+
+I took a small ball of amalgam, placed it in a double fold of new fine
+grained calico, and after soaking in hot water put it under a powerful
+press. The weight of the ball before pressing was 1583 gr. From this
+383 gr. of mercury was expressed and five-eighths of a grain of gold
+was retorted from this expressed mercury. The residue, in the form of
+a dark, grey, and very friable cake, was powdered up between the
+fingers and retorted, when it became a brown powder; it was afterwards
+calcined on a flat sheet in the open air; result, 510 gr. of russet-
+coloured powder. Smelted with borax, the iron oxide readily separated
+with the slag; result, 311 gr. gold 871-1000 fine; a second smelting
+brought this up to 914-1000 fine. Proportion of smelted gold to
+amalgam, one-fifth.
+
+The principal point about this mode of treatment is the squeezing out
+of the mercury, whereby the amalgam goes into the retort in the form
+of powder, thus preventing the slagging of the iron and enclosure of
+the gold. The second point of importance is thorough calcining before
+smelting.
+
+Of course it would be practicable, if desired, to treat the powder
+with hydrochloric acid, and thus remove all the iron, but in a large
+way this would be too expensive, and my laboratory treatment, though
+necessarily on a small scale, was intended to be on a practical basis.
+
+The amalgam at this mine was in this way afterwards treated with great
+success.
+
+For the information of readers who do not understand the chemical
+symbols it may be said that
+
+  FeCO3 is carbonate of iron;
+  CaCO3 is carbonate of calcium;
+  CaSO4 is sulphate of calcium;
+  CaCl2 is chloride of calcium;
+  MgCl2 is chloride of magnesium;
+  NaCl is chloride of sodium, or common salt.
+
+
+
+CHAPTER VII
+
+GOLD EXTRACTION--SECONDARY PROCESSES AND LIXIVIATION
+
+Before any plan is adopted for treating the ore in a new mine the
+management should very seriously and carefully consider the whole
+circumstances of the case, taking into account the quantity and
+quality of the lode stuff to be operated on, and ascertain by analysis
+what are its component parts, for, as before stated, the treatment
+which will yield most satisfactory results with a certain class of
+gangue on one mine will sometimes, even when the material is
+apparently similar, prove a disastrous failure in another. Some time
+since I was glad to note that the manager of a prominent mine strongly
+discountenanced the purchase of any extracting plant until he was
+fully satisfied as to the character of the bulk of the ore he would
+have to treat. It would be well for the pockets of shareholders and
+the reputation of managers, if more of our mine superintendents
+followed this prudent and sensible course.
+
+Having treated on gold extraction with mercury by amalgamated plates
+and their accessories, something must be said about secondary modes of
+saving in connection with the amalgamation process. The operations
+described hitherto have been the disintegration of the gold-bearing
+material and the extraction therefrom of the coarser free gold. But it
+must be understood that most auriferous lode stuff contains a
+proportion of sulphides of various metals, wherein a part of the gold,
+usually in a very finely divided state, is enclosed, and on this gold
+the mercury has no influence. Also many lodes contain hard heavy
+ferric ores, such as titanic iron, tungstate of iron, and hematite, in
+which gold is held. In others, again, are found considerable
+quantities of soft powdery iron oxide or "gossan," and compounds such
+as limonite, aluminous clay, etc., which, under the action of the
+crushing mill become finely divided and float off in water as
+"slimes," carrying with them atoms of gold, often microscopically
+small. To save the gold in such matrixes as these is an operation
+which even the best of our mechanical appliances have not yet fully
+accomplished.
+
+Where there is not too great a proportion of base metals on which the
+solvent will act, and when the material is rich enough in gold to pay
+for the extra cost of treatment, chlorination or cyanisation are the
+best modes of extraction yet practically adopted.
+
+Presuming, however, that we are working by the amalgamation process,
+and have crushed our stone and obtained the free gold, the next
+requirement is an effective concentrator. Of these there are many
+before the public, and some do excellent work, but do not act equally
+well in all circumstances. The first and most primitive is the blanket
+table, previously mentioned; but it can hardly be said to be very
+effective, and requires constant attention and frequent changing and
+washing of the strips of blanket.
+
+Instead of blanket tables percussion tables are sometimes used, to
+which a jerking motion is given against the flow of the water and
+pulp, and by this means the heavier minerals are gathered towards the
+upper part of the table, and are from thence removed from time to time
+as they become concentrated.
+
+I have seen this appliance doing fairly good work, but it is by no
+means a perfect concentrator.
+
+Another form of "shaking table" is one in which the motion is given
+sideways, and this, whether amalgamated, or provided with small
+riffles, or covered with blanket, keeps the pulp lively and encourages
+the retention of the heavier particles, whether of gold or base metals
+containing gold. There has also been devised a rocking table the
+action of which is analogous to that of the ordinary miner's cradle.
+This appliance, working somewhat slowly, swings on rockers from side
+to side, and is usually employed in mills where, owing to the
+complexity of the ore, difficulties have been met with in amalgamating
+the gold. Riffles are provided and even very fine gold is sometimes
+effectively recovered by their aid.
+
+The Frue vanner will, as a rule, act well when the pulp is
+sufficiently fine. It is really a adaptation of an old and simple
+apparatus used in China and India for washing gold dust from the sands
+of rivers. The original consisted of an endless band of strong cloth
+or closely woven matting, run on two horizontal rollers placed about
+seven feet apart, one being some inches lower than the other. The
+upper is caused to revolve by means of a handle. The cloth is thus
+dragged upwards against a small stream of water and sand fed to it by
+a second man, the first man not only turning the handle but giving a
+lateral motion to the band by means of a rope tied to one side.
+
+Chinamen were working these forerunners of the Frue vanner forty years
+ago in Australia, and getting fair returns.
+
+The Frue vanner is an endless indiarubber band drawn over an inclined
+table, to which a revolving and side motion is given by ingenious
+automatic mechanism, the pulp being automatically fed from the upper
+end, and the concentrates collected in a trough containing water in
+which the band is immersed in its passage under the table; the lighter
+particles wash over the lower end. The only faults with the vanner are
+--first, it is rather slow; and secondly, though so ingenious it is
+just a little complicated in construction for the average non-
+scientific operative.
+
+Of pan concentrators there is an enormous selection, the principle in
+most being similar--i.e., a revolving muller, which triturates the
+sand, so freeing the tiny golden particles and admitting of their
+contact with the mercury. The mistake with respect to most of these
+machines is the attempt to grind and amalgamate in one operation. Even
+when the stone under treatment contains no deleterious compounds the
+simple action of grinding the hard siliceous particles has a bad
+effect on the quicksilver, causing it to separate into small globules,
+which either oxidising or becoming coated with the impurities
+contained in the ore will not reunite, but wash away in the slimes and
+take with them a percentage of the gold. As a grinder and
+concentrator, and in some cases as an amalgamator, when used
+exclusively for either purpose, the Watson and Denny pan is effective;
+but although successfully used at one mine I know, the mode there
+adopted would, for reasons previously given, be very wasteful in many
+other mines.
+
+There is considerable misconception, even among men with some
+practical knowledge, as to the proper function of these secondary
+saving appliances; and sometimes good machines are condemned because
+they will not perform work for which they were never intended. It
+cannot be too clearly realized that the correct order of procedure for
+extracting the gold held in combination with base metals is--first,
+reduction of the particles to a uniform gauge and careful
+concentration only; next, the dissipation, usually by simple
+calcination, of substances in the concentrates inimical to the
+thorough absorption of the gold by the mercury; and lastly, the
+amalgamation of the gold and mercury.
+
+For general purposes, where the gangue has not been crushed too fine,
+I think the Duncan pan will usually be found effective in saving the
+concentrates. In theory it is an enlargement of the alluvial miner's
+tin dish, and the motion imparted to it is similar to the eccentric
+motion of that simple separator.
+
+The calcining may be effectively carried out in an ordinary
+reverberatory furnace, the only skill required being to prevent over
+roasting and so slagging the concentrates; or not sufficiently
+calcining so as to remove all deleterious constituents; the subject,
+however, is fully treated in Chapter VIII.
+
+For amalgamating I prefer some form of settler to any further grinding
+appliance, but I note also improvements in the rotary amalgamating
+barrel, which, though slow, is, under favourable conditions, an
+effective amalgamator. The introduction of steam under pressure into
+an iron cylinder containing a charge of concentrates with mercury is
+said to have produced good results, and I am quite prepared to believe
+such would be the case, as we have long known that the application of
+steam to ores in course of amalgamation facilitates the process
+considerably.
+
+Some seventeen years since I was engaged on the construction of a dry
+amalgamator in which sublimated mercury was passed from a retort
+through the descending gangue in a vertical cylinder, the material
+thence falling through an aperture into a revolving settler, the
+object being to save water on mines in dry country. The model, about
+quarter size, was completed when my attention was called to an
+American invention, in which the same result was stated to be attained
+more effectively by blowing the mercury spray through the triturated
+material by means of a steam jet. I had already encountered a
+difficulty, since found so obstructive by experimentalists in the same
+direction, that is, the getting of the mercury back into its liquid
+metallic form. This difficulty I am now convinced can be largely
+obviated by my own device of using a very weak solution of sulphuric
+acid (it can hardly be too weak) and adding a small quantity of zinc
+to the mercury. It is perfectly marvellous how some samples of mercury
+"sickened" or "floured" by bad treatment, may be brought back to the
+bright limpid metal by a judicious use of these inexpensive materials.
+
+Thus it will probably be found practicable to crush dry and amalgamate
+semi-dry by passing the material in the form of a thin pasty mass to a
+settler, as in the old South American arrastra, and, by slowly
+stirring, recover the mercury, and with it the bulk of the gold.
+
+The following is from the /Australian Mining Standard/, and was headed
+"Amalgamation Without Overflow":
+
+"Recent experiments at the Ballarat School of Mines have proved that a
+deliverance from difficulties is at hand from an unexpected quarter.
+The despised Chilian mill and Wheeler pan, discarded at many mines,
+will solve the problem, but the keynote of success is amalgamation
+without overflow. Dispense with the overflow and the gold is saved.
+
+"Two typical mines--the Great Mercury Proprietary Gold Mine, of
+Kuaotunu, N.Z., the other, the Pambula, N.S.W.--have lately been
+conducting a series of experiments with the object of saving their
+fine gold in an economical manner. The last and best trials made by
+these companies were at the Ballarat School of Mines, where
+amalgamation without overflow was put to a crucial test, in each case
+with the gratifying result that ninety-six per cent of the precious
+metal was secured. What this means to the Great Mercury Mine, for
+instance, can easily be imagined when it is understood that
+notwithstanding all the latest gold-saving adjuncts during the last
+six months 1260 tons of ore, worth 4l. 17s. 10 2/3d. a ton, have been
+put through for a saving of 1l. 9s. 1 2/3d. only; or in other words
+over two-thirds of the gold has gone to waste (for the time being) in
+the tailings, and in the tailings at the present moment lie the
+dividends that should have cheered shareholders' hearts.
+
+"And now for the /modus operandi/, which, it must be remembered, is
+not hedged in by big royalties to any one, rights, patent or
+otherwise. The ore to be treated is first calcined, then put through a
+rock-breaker or stamper battery in a perfectly dry state. If the
+battery is used, ordinary precautions, of course, must be taken to
+prevent waste, or the dust becoming obnoxious to the workmen. The ore
+is then transferred to the Chilian mill and made to the consistency of
+porridge, the quicksilver being added. When the principal work of
+amalgamation is done (experience soon teaching the amount of grinding
+necessary), from the Chilian mill the paste (so to say) is passed to a
+Wheeler or any other good pan of a similar type, when the gold-saving
+operation is completed."
+
+This being an experiment in the same direction as my own, I tried it
+on a small scale. I calcined some very troublesome ore till it was
+fairly "sweet," triturated it, and having reduced it with water to
+about the consistency of invalid's gruel, put it into a little berdan
+pan made from a "camp oven," which I had used for treating small
+quantities of concentrates, and from time to time drove a spray of
+mercury, wherein a small amount of zinc had been dissolved, into the
+pasty mass by means of a steam jet, added about half an ounce of
+sulphuric acid and kept the pan revolving for several hours. The
+result was an unusually successful amalgamation and consequent
+extraction--over ninety per cent.
+
+Steam--or to use the scientific term, hydro-thermal action--has played
+such an important part in the deposition of metals that I cannot but
+think that under educated intelligence it will prove a powerful agent
+in their extraction. About fourteen years ago I obtained some rather
+remarkable results from simply boiling auriferous ferro-sulphides in
+water. There is in this alone an interesting, useful, and profitable
+field for investigation and experiment.
+
+The most scientific and perfect mode of gold extraction (when the
+conditions are favourable) is lixiviation by means of chlorine,
+potassium cyanide, or other aurous solvent, for by this means as much
+as 98 per cent of the gold contained in suitable ores can be converted
+into its mineral salt, and being dissolved in water, re-deposited in
+metallic form for smelting; but lode stuff containing much lime would
+not be suitable for chlorination, or the presence of a considerable
+proportion of such a metal as copper, particularly in metallic form,
+would be fatal to success, while cyanide of potassium will also attack
+metals other than gold, and hence discount the effect of this solvent.
+
+The earlier practical applications of chlorine to gold extraction were
+known as Mears' and Plattner's processes, and consisted in placing the
+material to be operated on in vats with water, and introducing
+chlorine gas at the bottom, the mixture being allowed to stand for a
+number of hours, the minimum about twelve, the maximum forty-eight.
+The chlorinated water was then drawn off containing the gold in
+solution which was deposited as a brown powder by the addition of
+sulphate of iron.
+
+Great improvements on this slow and imperfect method have been made of
+late years, among the earlier of which was that of Messrs. Newbery and
+Vautin. They placed the pulp with water in a gaslight revolving
+cylinder, into which the chlorine was introduced, and atmospheric air
+to a pressure of 60 lb. to the square inch was pumped in. The cylinder
+with its contents was revolved for two hours, then the charge was
+withdrawn and drained nearly dry by suction, the resultant liquid
+being slowly filtered through broken charcoal on which the chloride
+crystals were deposited, in appearance much like the bromo-chlorides
+of silver ore seen on some of the black manganic oxides of the Barrier
+silver mines. The charcoal, with its adhering chlorides, was conveyed
+to the smelting-house and the gold smelted into bars of extremely pure
+metal. Messrs. Newbery and Vautin claimed for their process decreased
+time for the operation with increased efficiency.
+
+At Mount Morgan, when I visited that celebrated mine, they were using
+what might be termed a composite adaptation process. Their
+chlorination works, the largest in the world, were putting through
+1500 tons per week. The ore as it came from the mine was fed
+automatically into Krom roller mills, and after being crushed and
+sifted to regulation gauge was delivered into trucks and conveyed to
+the roasting furnaces, and thence to cooling floors, from which it was
+conveyed to the chlorinating shed. Here were long rows of revolving
+barrels, on the Newbery-Vautin principle, but with this marked
+difference, that the pressure in the barrel was obtained from an
+excess of the gas itself, generated from a charge of chloride of lime
+and sulphuric acid. On leaving the barrels the pulp ran into settling
+vats, somewhat on the Plattner plan, and the clear liquid having been
+drained off was passed through a charcoal filter, as adopted by
+Newbery and Vautin. The manager, Mr. Wesley Hall, stated that he
+estimated cost per ton was not more than 30s., and he expected shortly
+to reduce that when he began making his own sulphuric acid. As he was
+obtaining over 4 oz. to the ton the process was paying very well, but
+it will be seen that the price would be prohibitive for poor ores
+unless they could be concentrated before calcination.
+
+The Pollok process is a newer, and stated to be a cheaper mode of
+lixiviation by chlorine. It is the invention of Mr. J. H. Pollok, of
+Glasgow University, and a strong Company was formed to work it. With
+him the gas is produced by the admixture of bisulphate of sodium
+(instead of sulphuric acid, which is a very costly chemical to
+transport) and chloride of lime. Water is then pumped into a strong
+receptacle containing the material for treatment and powerful
+hydraulic pressure is applied. The effect is stated to be the rapid
+change of the metal into its salt, which is dissolved in the water and
+afterwards treated with sulphate of iron, and so made to resume its
+metallic form.
+
+It appears, however, to me that there is no essential difference in
+the pressure brought to bear for the quickening of the process. In
+each case it is an air cushion, induced in the one process by the
+pumping in of air to a cylinder partly filled with water, and in the
+other by pumping in water to a cylinder partly filled with air.
+
+The process of extracting gold from lode stuff and tailings by means
+of cyanide of potassium is now largely used and may be thus briefly
+described:--It is chiefly applied to tailings, that is, crushed ore
+that has already passed over the amalgamating and blanket tables. The
+tailings are placed in vats, and subjected to the action of solutions
+of cyanide of potassium of varying strengths down to 0.2 per cent.
+These dissolve the gold, which is leached from the tailings, passed
+through boxes in which it is precipitated either by means of zinc
+shavings, electricity, or to the precipitant. The solution is made up
+to its former strength and passed again through fresh tailings. When
+the tailings contain a quantity of decomposed pyrites, partly
+oxidised, the acidity caused by the freed sulphuric acid requires to
+be neutralised by an alkali, caustic soda being usually employed.
+
+When "cleaning up," the cyanide solution in the zinc precipitating
+boxes is replaced by clean water. After careful washing in the box, to
+cause all pure gold and zinc to fall to the bottom, the zinc shavings
+are taken out. The precipitates are then collected, and after
+calcination in a special furnace for the purpose of oxidising the
+zinc, are smelted in the usual manner.
+
+The following description of an electrolytic method of gold deposition
+from a cyanide solution was given by Mr. A. L. Eltonhead before the
+Engineers' Club of Philadelphia.
+
+A description of the process is as follows:--"The ore is crushed to a
+certain fineness, depending on the character of the gangue. It is then
+placed in leaching vats, with false bottoms for filtration, similar to
+other leaching plants. A solution of cyanide of potassium and other
+chemicals of known percentage is run over the pulp and left to stand a
+certain number of hours, depending on the amount of metal to be
+extracted. It is then drained off and another charge of the same
+solution is used, but of less strength, which is also drained. The
+pulp is now washed with clean water, which leaches all the gold and
+silver out, and leaves the tailings ready for discharge, either in
+cars or sluiced away by water, if it is plentiful.
+
+"The chemical reaction of cyanide of potassium with gold is as
+follows, according to Elsner:--
+
+  2Au + 4KCy + O + H2O = 2KAuCy2 + 2KHO.
+
+That is, a double cyanide of gold and potassium is formed.
+
+"All filtered solutions and washings from the leaching vats are saved
+and passed through a precipitating 'box' of novel construction, which
+may consist either of glass, iron or wood, and be made in any shape,
+either oval, round, or rectangular--if the latter, it will be about 10
+ft. long, 4 ft. wide and 1 ft. high--and is partitioned off lengthwise
+into five compartments. Under each partition, on the inside or bottom
+of the 'box,' grooves may be cut a quarter- to a half-inch deep,
+extending parallel with the partitions to serve as a reservoir for the
+amalgam, and give a rolling motion to the solution as it passes along
+and through the four compartments. The centre compartment is used to
+hold the lead or other suitable anode and electrolyte.
+
+"The anode is supported on a movable frame or bracket, so it may be
+moved either up or down as desired, it being worked by thumb-screws at
+each end.
+
+"The electrolyte may consist of saturated solutions of soluble
+alkaline metals and earth. The sides or partitions of each compartment
+dip into the mercury, which must cover the 'box' evenly on the bottom
+to the depth of about a half-inch.
+
+"Amalgamated copper strips or discs are placed in contact with the
+mercury and extended above it, to allow the gold and silver solution
+of cyanide to come in contact.
+
+"The electrodes are connected with the dynamo; the anode of lead being
+positive and the cathode of mercury being negative. The dynamo is
+started, and a current of high amperage and low voltage is generated,
+generally 100 to 125 amperes, and with sufficient pressure to
+decompose the electrolyte between the anode and the cathode.
+
+"As the gas is generated at the anode, a commotion is created in the
+liquid, which brings a fresh and saturated solution of electrolyte
+between the electrodes for electrolysis, and makes it continuous in
+its action.
+
+"The solution of double cyanide of gold, silver, and potassium, which
+has been drained from the leaching vats, is passed over the mercury in
+the precipitating 'box' when the decomposition of the electrolyte by
+the electric current is being accomplished, the gold and silver are
+set free and unite with the mercury, and are also deposited on the
+plates or discs of copper, forming amalgam, which is collected and
+made marketable by the well known and tried methods. The above
+solution is regenerated with cyanide of potassium by the setting free
+of the metals in the passage over the 'box.'
+
+"In using this solution again for a fresh charge of pulp, it is
+reinforced to the desired percentage, or strengthened with cyanide of
+potassium and other chemicals, and is always in good condition for
+continuing the operation of dissolving.
+
+"The potassium acting on the water of the solution creates nascent
+hydrogen and potassium hydrate; the nascent hydrogen sets free the
+metals (gold and silver), which are precipitated into the mercury and
+form amalgam, leaving hydrocyanic acid; this latter combines with the
+potassium hydrate of the former reaction, thus forming cyanide of
+potassium. There are other reactions for which I have not at present
+the chemical formulas.
+
+"As the solution passes over the mercury, the centre compartment of
+the 'box' is moved slowly longitudinally, which spreads the mercury,
+the solution is agitated and comes in perfect contact with the
+mercury, as well as the amalgamated plates or discs of copper,
+ensuring a perfect precipitation.
+
+"It is not always necessary to precipitate all the gold and silver
+from the solution, for it is used over and over again indefinitely;
+but when it is required, it can be done perfectly and cheaply in a
+very short time.
+
+"No solution leached from the pulp, containing cyanide of potassium,
+gold and silver, need be run to waste, which is in itself an enormous
+saving over the use of zinc shavings when handling large quantities of
+pulp and solution.
+
+"Some of the advantages the electro-chemical process has over other
+cyanide processes are: Its cleanliness, quickness of action,
+cheapness, and large saving of cyanide of potassium by regeneration;
+not wasting the solutions, larger recovery of the gold and silver from
+the solutions; the cost of recovery less; the loss of gold, silver,
+and cyanide of potassium reduced to a minimum; the use of caustic
+alkali in such quantity as may be desired to keep the cyanide solution
+from being destroyed by the solidity of the pulp, and also sometimes
+to give warmth, as a warm cyanide solution will dissolve gold and
+silver quicker than a cold one. These caustic alkalies do not
+interfere with or prevent the perfect precipitation of the metals. The
+bullion recovered in this process is very fine, while the zinc-
+precipitated bullion is only about 700 fine.
+
+"The gold and silver is dissolved, and then precipitated in one
+operation, which we know cannot be done in the 'chlorination process';
+besides, the cost of plant and treatment is much less in the above-
+described process.
+
+"The electro-chemical process, which I have hastily sketched will, I
+think, be the future cheap method of recovering fine or flour gold
+from our mines and waste tailings or ore dumps.
+
+"Without going into details of cost of treatment, I will state that
+with a plant of a capacity of handling 10,000 tons of pulp per month,
+the cost should not exceed 8s. per ton, but that may be cheapened by
+labour-saving devices. There being no expensive machinery, a plant
+could be very cheaply erected wherever necessary."
+
+
+
+CHAPTER VIII
+
+CALCINATION OR ROASTING OF ORES
+
+The object of calcining or roasting certain ores before treatment is
+to dissipate the sulphur or sulphides of arsenic, antimony, lead,
+etc., which are inimical to treatment, whether by ordinary mercuric
+amalgamation or lixiviation. The effect of the roasting is first to
+sublimate and drive off as fumes the sulphur and a proportion of the
+objectionable metals. What is left is either iron oxide, "gossan," or
+the oxides of the other metals. Even lead can thus be oxidised, but
+requires more care as it melts nearly as readily as antimony and is
+much less volatile. The oxides in the thoroughly roasted ore will not
+amalgamate with mercury, and are not acted on by chlorine or cyanogen.
+
+To effect the oxidation of sulphur, it is necessary not only to bring
+every particle of sulphur into contact with the oxygen of the air, but
+also to provide adequate heat to the particles sufficient to raise
+them to the temperature that will induce oxidation. No appreciable
+effect follows the mere contact of air with sulphur particles at
+atmospheric temperature; but if the particles be raised to a
+temperature of 500 degrees Fahr., the sulphur is oxidised to the
+gaseous sulphur dioxide. The same action effects the elimination of
+the arsenic and antimony associated with gold and silver ores, as when
+heated to a certain constant temperature these metals readily oxidise.
+
+The science of calcination consists of the method by which the
+sulphide ores, having been crushed to a proper degree of fineness, are
+raised to a sufficient temperature and brought into intimate contact
+with atmospheric air.
+
+It will be obvious then that the most effective method of roasting
+will be one that enables the particles to be thoroughly oxidised at
+the lowest cost in fuel and in the most rapid manner.
+
+The roasting processes in practical use may be divided into three
+categories:
+
+/First or A Process./--Roasting on a horizontal and stationary hearth,
+the flame passing over a mass of ore resting on such hearth. In order
+to expose the upper surface of the ore to contact with air the
+material is turned over by manual labour. This furnace of the
+reverberatory type is provided with side openings by which the turning
+over of the ore can be manually effected, and the new ore can be
+charged and afterwards withdrawn.
+
+/Second or B Process./--Roasting in a revolving hearth placed at a
+slight incline angle from the horizontal. The furnace is of
+cylindrical form and is internally lined with refractory material. It
+has projections that cause the powdered ore to be lifted above the
+flame, and, at a certain height, to fall through the flame and so be
+rapidly raised to the temperature required to effect the oxidation of
+the oxidisable minerals which it is desired to extract.
+
+The rate, or speed, of revolution of this revolving furnace obviously
+depends upon the character of the ore under treatment; it may vary
+from two revolutions per minute down to one revolution in thirty
+minutes. Any kind of fuel is available, but that of a gaseous
+character is stated to be by far the most efficient.
+
+Any ordinary cylinder of a length of 25 ft., and a diameter of 4 ft. 6
+in., inclined 1 ft. 6 in. in its length, will calcine from 24 to 48
+tons per diem.
+
+Another form of rotating furnace is one in which the axis is
+horizontal. It is much shorter than the inclined type, and the feeding
+and removal of the ore is effected by the opening of a retort lid door
+provided at the side of the furnace. Openings provided at each end of
+the furnace permit the passage of the flame through it, and the
+revolution of the furnace turns over the powdered ore and brings it
+into more or less sustained contact with the oxidising flame. The
+exposure of the ore to this action is continued sufficiently long to
+ensure the more or less complete oxidation of the ore particles.
+
+/Third or C Process./--In this process the powdered ore is allowed to
+fall in a shower from a considerable height, through the centre of a
+vertical shaft up which a flame ascends; the powdered ore in falling
+through the flame is heated to an oxidising temperature, and the
+sulphides are thus depleted of their sulphur and become oxides.
+
+Another modification of this direct fall or shaft furnace is that in
+which the fall of the ore is checked by cross-bars or inclined plates
+placed across the shaft; this causes a longer oxidising exposure of
+the ore particles.
+
+When the sulphur contents of pyritous ores are sufficiently high, and
+after the ore has been initially fired with auxiliary carbonaceous
+fuel, it is unnecessary, in a properly designed roasting furnace, to
+add fuel to the ore to enable the heat for oxidation to be obtained.
+The oxidation or burning of the sulphur will provide all the heat
+necessary to maintain the continuity of the process. The temperature
+necessary for effecting the elimination of both sulphur and arsenic is
+not higher than that equivalent to dull red heat; and provided that
+there is a sufficient mass of ore maintained in the furnace, the
+potential heat resulting from the oxidation of the sulphur will alone
+be adequate to provide all that is necessary to effect the
+calcination.
+
+
+TYPES OF FURNACES OF THE DIFFERENT CLASSES
+THAT ARE IN ACTUAL USE.
+
+"A" OR REVERBERATORY CLASS.
+
+The construction of this furnace has already been sufficiently
+described. If the roasting is performed in a muffle chamber, the
+arrangement employed by Messrs. Leach and Neal, Limited, of Derby, and
+designed by Mr. B. H. Thwaite, C.E., can be advantageously employed in
+this furnace, which is fired with gaseous fuel. The sensible heat of
+the waste gases is utilised to heat the air employed for combustion;
+and by a controllable arrangement of combustion, a flame of over 100
+feet in length is obtained, with the result that the furnace from end
+to end is maintained at a uniform temperature. By this system, and
+with gaseous fuel firing, a very considerable economy in fuel and in
+repairs to furnace, and a superior roasting effect, have been
+obtained.
+
+Where the ordinary reverberatory hearth is fired with solid coal from
+an end grate, the temperature is at its maximum near the firing end,
+and tails off at the extreme gas outlet end. The ores in this furnace
+should therefore be fed in at the colder end of the hearth and be
+gradually worked or "rabbled" forward to the firing end.
+
+One disadvantage of the reverberatory furnace is the fact that it is
+impossible to avoid the incursion of air during the manual rabbling
+action, and this tends to cool the furnace.
+
+The cost of roasting, to obtain the more or less complete oxidation,
+or what is known in mining parlance as a "sweet roast" (because a
+perfectly roasted ore is nearly odourless) varies considerably, the
+variation depending of course upon the character of the ore and the
+cost of labour and fuel.
+
+There are several modifications of the reverberatory furnace in use,
+designed mechanically to effect the rabbling. One of the most
+successful is that known as the Horse-shoe furnace. In plan the hearth
+of the furnace resembles a horse-shoe.
+
+The stirring of the ore over the hearth is effected by means of
+carriages fixed in the centre of the furnace and having laterally
+projecting arms, carrying stirrers, that move along the hearth and
+turn over the pulverised ore.
+
+In operation, half the carriages are traversing the furnace, and half
+are resting in the cooling space, so that a control over the
+temperature of the stirrers is established.
+
+This furnace is stated to be more economical in labour than other
+mechanically stirred reverberatory furnaces, and there is also said to
+be an economy in fuel.
+
+Usually the mechanical stirring furnaces give trouble and should be
+avoided, but the horse-shoe type possesses qualifications worthy of
+consideration.
+
+"B."--THE REVOLVING CYLINDER FURNACE.
+
+Of these the best known to me are: The Howell-White, the Bruckner, the
+Thwaite-Denny, and the Molesworth.
+
+The Bruckner is a cylinder, turning on the horizontal axis and carried
+by four rollers.
+
+The batch of ore usually charged into the two charging hoppers weighs
+about four tons. When the two charging doors are brought under the
+hopper mouth, the contents of the hopper fall directly into the
+cylinder.
+
+The ends or throats of the furnace are reduced just sufficiently to
+allow the flame evolved from a grated furnace to pass completely
+through the cylinder.
+
+A characteristic size for this Bruckner furnace is one having a length
+of 12 feet and a diameter of 6 feet. A furnace of this capacity will
+have an inclusive weight (iron and brickwork) of 15 tons.
+
+The time of operation, with the Bruckner, will vary with the character
+of the ore under treatment and the nature of the fuel employed. Four
+hours is the minimum and twelve hours should be the maximum time of
+operation.
+
+By the addition of common salt with the batch of ore, such of its
+constituents as are amenable to the action of chlorine are chlorinated
+as well as freed from sulphur.
+
+Where the ore contains any considerable quantity of silver which
+should be saved, the addition of the salt is necessary as the silver
+is very liable to become so oxidised in the process of roasting as to
+render its after treatment almost impossible. I know a case in point
+where an average of nearly five ounces of silver to the ton, at that
+time worth 30s., was lost owing to ignorance on this subject. Had the
+ore been calcined with salt, NaCl, the bulk of this silver would have
+been amalgamated and thus saved. It was the extraordinary fineness of
+the gold saved by amalgamation as against my tests of the ore by fire
+assay that put me on the track of a most indefensible loss.
+
+/The Howell-White Furnace./--This furnace consists of a cast iron
+revolving cylinder, averaging 25 feet in length and 4 ft. 4 in. in
+diameter, which revolves on four friction rollers, resting on truck
+wheels, rotated by ordinary gearing.
+
+The power required for effecting the revolution should not exceed four
+indicated horse-power.
+
+The cylinder is internally lined with firebrick, projecting pieces
+causing the powdered ore to be raised over the flame through which it
+showers, and is thereby subjected to the influence of heat and to
+direct contact oxidation.
+
+The inclination of the cylinder, which is variable, promotes the
+gradual descension of the ore from the higher to the lower end. It is
+fed into the upper end, by a special form of feed hopper, and is
+discharged into a pit at the lower end, from which the ore can be
+withdrawn at any time.
+
+The gross weight of the furnace, which is, however, made in segments
+to be afterwards bolted together, is some ninety to one hundred tons.
+
+The furnace is fired with coal on a grated hearth, built at the lower
+end; it is more economical both in fuel and in labour than an ordinary
+reverberatory furnace.
+
+/The Thwaite-Denny Revolving Furnace./--This new type of furnace,
+which is fired with gaseous fuel, is stated to combine the advantages
+of the Stetefeldt, the Howell-White, and the Bruckner.
+
+It is constructed as follows:--Three short cylinders, conical in shape
+and of graduated dimensions, are superimposed one over the other,
+their ends terminating in two vertical shafts of brickwork, by which
+the three cylinders are connected. The powdered ore is fed into the
+uppermost cylinder and gravitates through the series. The highest
+cylinder is the largest in diameter, the lowest the smallest.
+
+The gas flame, burnt in a Bunsen arrangement, enters the smallest end
+of the lowest cylinder and passes through it; then returns through the
+series and the ore is reduced by the expulsion of its sulphur,
+arsenic, etc., as it descends from the top to the bottom. The top
+cylinder is made larger than the one below it and the middle cylinder
+is made larger than the lowest one in proportion to the increased bulk
+of gases and ore.
+
+The powdered ore in descending through the cylinders is lifted up and
+showers through the flame, falling in its descent a distance of over
+1000 feet. By the time it reaches the bottom the ore is thoroughly
+roasted.
+
+Provision is made for the introduction of separate supplies of air and
+gas into each cylinder; this enables the oxidising treatment to be
+controlled exactly as desired so as to effect the best results with
+all kinds of ore. Each cylinder is driven from its own independent
+gearing, and the speed of each cylinder can be varied at will.
+
+The output of this type of furnace, the operations of which appear to
+be more controllable than those of similar appliances, depends, of
+course, upon the nature of the ore, but may be considered to range
+within the limits of twelve to fifty tons in twenty-four hours, and
+the cost of roasting will vary from 2s. 6d. to 4s. per ton, depending
+upon the quality of ore and of fuel.
+
+The gaseous fuel generating system permits not only the absolute
+control over the temperature in the furnace, but the use of the
+commonest kinds of coal, and even charcoal is available.
+
+The power required to drive the Thwaite-Denny furnace is four
+indicated horse-power.
+
+/The Molesworth Furnace/ also is a revolving cylindrical appliance,
+which, to say the least of it, is in many respects novel and
+ingenious. It consists of a slightly cone-shaped, cast-iron cylinder
+about fourteen feet long, the outlet end being the larger to allow for
+the expansion of the gases. Internal studs are so arranged as to keep
+the ore agitated; and spiral flanges convey it to the outlet end
+continually, shooting it across the cylinder. The cylinder is encased
+in a brick furnace. The firing is provided from /outside/, the
+inventor maintaining that the products of combustion are inimical to
+rapid oxidisation, to specially promote which he introduces an excess
+of oxygen produced in a small retort set in the roof of the furnace
+and fed from time to time with small quantities of nitrate of soda and
+sulphuric acid. Ores containing much sulphur virtually calcine
+themselves. I have seen this appliance doing good work. The
+difficulties appeared to be principally mechanical.
+
+There are other furnaces which work with outside heat, but I have not
+seen them in action.
+
+"C."--SHAFT TYPE OF FURNACE
+
+In one form of this furnace, instead of allowing the ore to descend in
+a direct clear fall the descent is impeded by inclined planes placed
+at different levels in the height of the shaft, the ore descending
+from one plane to the other.
+
+/The Stetefeldt Shaft Furnace./--Although very expensive in first
+cost, has many advantages. No motive power is required and the
+structure of the furnace is of a durable character. Its disadvantages
+are:--Want of control, and the occasionally imperfect character of the
+roasting originating therefrom.
+
+Three sizes of Stetefeldt's furnaces are constructed:
+
+  The largest will roast from 40 to 80 tons per diem.
+  The intermediate will roast from 20 to 40 tons per diem.
+  The smallest will roast from 10 to 20 tons per diem.
+
+A good furnace should bring down the sulphur contents even of
+concentrates so as to be innocuous to mercuric amalgamation. The
+sulphur left in the ore should never be allowed to exceed two per
+cent.
+
+A forty per cent pyritous or other sulphide ore should be roasted in a
+revolving furnace in thirty to forty minutes, and without any
+auxiliary fuel.
+
+For ordinary purposes a 40-foot chimney is adequate for furnace work;
+such a chimney four feet square inside at the base, tapering to 2' 6"
+at the summit, will require 12,000 red bricks, and 1500 fire-bricks
+for an internal lining to a height of 12 feet from the base of the
+chimney shaft.
+
+When second-hand Lancashire or Cornish boiler flues are available,
+they make admirable and inexpensive chimneys. The advantage of
+wrought-iron or steel chimneys lies in the convenience of removal and
+erection. They should be made in sections of 20 feet long, three steel
+wire guy-ropes attached to a ring, riveted to a ring two-thirds of the
+height of the chimney, and attached to holdfasts driven into the
+ground; tightening couplings should be provided for each wire.
+
+Flue dust depositing chambers should be built in the line of the flues
+between the furnace and the chimney; they consist simply of carefully
+built brick chambers, with openings to enable workmen to enter and
+rapidly clear away the deposited matters. The chambers, three or four
+times the cross sectional area of the chimney flue, and ten to twenty
+feet long, can be built of brickwork, set in cement; the walls are
+provided with a cavity, filled with sand or Portland cement, so that
+there will be no danger of the incursion of air. In all furnace work
+the greatest possible precautions should be taken to prevent the least
+cracking of either joints or bricks. It is surprising how much the
+inadequate draft of a good chimney is due to cracks or orifices in the
+flues; and therefore a competent furnace-man should see to it that his
+flues are thoroughly sound, and free from openings through which the
+air can enter.[*]
+
+[*] For full details of the most recent improvements in the cyanide
+    process and in other methods of extraction, the reader is referred
+    to Dr. T. K. Rose's "Metallurgy of Gold," third edition.
+
+
+
+CHAPTER IX
+
+MOTOR POWER AND ITS TRANSMISSION
+
+It is unnecessary to describe methods by which power for mining
+purposes has been obtained--that is, up to within the last five years
+--beyond a general statement, that when water power has been available
+in the immediate locality of the mine, this cheap natural source of
+power has been called upon to do duty. Steam has been the alternative
+agent of power production applied in many different ways, but
+labouring under as many disadvantages, chief of which are lack of
+water, scarcity of fuel and cost of transit of machinery. Sometimes
+condensing steam-engines have been employed. For the generation of
+steam the semi-portable and semi-tubular have been the type of boiler
+that has most usually been brought into service. Needless to say, when
+highly mineralised mine water only is available the adoption of this
+class of boiler is attended with anything but satisfactory results.
+
+Recently, however, there is strong evidence that where steam is the
+power agent to be employed the water-tube type of boiler is likely to
+be employed, and to the exclusion of all other forms of apparatus for
+the generation of steam. The advantages of this type, particularly the
+tubulous form (or a small water tube), made as it is in sections,
+offers unrivalled facilities for transport service. The heaviest parts
+need not exceed 3 cwt. in weight, and require neither heavy nor yet
+expensive brickwork foundations.
+
+
+WATERLESS POWER.
+
+The difficulties in finding water to drive a steam plant are often of
+such a serious character as to involve the abandonment of many payable
+mines; therefore, a motive power that does not require the aqueous
+agent will be a welcome boon.
+
+It will be a source of gratification to many a gold-claim holder to
+know that practical science has enabled motive power to be produced
+without the necessity of water, except a certain very small quantity,
+which once supplied will not require to be renewed, unless to
+compensate for the loss due to atmospheric evaporation.
+
+Any carbonaceous fuel, such as, say, lignite, coal, or charcoal, can
+be employed. The latter can be easily produced by the method described
+in the Chapter on "Rules of Thumb," or by building a kiln by piling
+together a number of trunks of trees, or fairly large-sized branches,
+cut so that they can be built up in a compact form. The pile, after
+being covered with earth, is then lighted from the base, and if there
+are no inlets for the air except the limited proportion required for
+the smouldering fire at the base, the whole of the timber will be
+gradually carbonised to charcoal of good quality, which is available
+for the waterless power plant.
+
+The waterless power plant consists of two divisions: First, a gas
+generating plant; secondly, an internal combustion or gas engine in
+which the gas is burnt, producing by thermo-dynamic action the motive
+power required. The system known as the Thwaite Power Gas System is
+not only practically independent of the use of water, but its
+efficiency in converting fuel heat into work is so high that no
+existing steam plant will be able to compete with it.
+
+The weight of raw timber, afterwards to be converted into charcoal,
+that will be required to produce an effective horse-power for one hour
+equals 7 lb.
+
+  If coal is the fuel 1 1/3 lb. per E.H.P. for one hour's run.
+  If lignite is the fuel 2 1/2 lb. per E.H.P. for one hour's run.
+
+The plant is simple to work, and as no steam boiler is required the
+danger of explosions is removed. No expensive chimney is necessary for
+the waterless power plant.
+
+Where petroleum oil can be cheaply obtained, say for twopence per
+gallon, one of the Otto Cycle Oil Engines, for powers up to 20
+indicated horse-power, can be advantageously employed.
+
+These engines have the advantage of being a self-contained power,
+requiring neither chimney nor steam boiler, and may be said to be a
+waterless power. The objection is the necessity to rely upon oil as
+fuel, and the dangers attending the storage of oil. A good oil engine
+should not require to use more than a pint of refined petroleum per
+indicated horse-power working for one hour.
+
+Fortunately for the mining industry electricity, that magic and
+mysterious agency, has come to its assistance, in permitting motive
+power to be transmitted over distances of even as much as 100 miles
+with comparatively little loss of the original power energy.
+
+Given, that on a coal or lignite field, or at a waterfall, 100 horse-
+power is developed by the combustion of fuel or by the fall of water
+driving a turbine, this power can be electrically transmitted to a
+mine or GROUP OF MINES, say 100 miles away, with only a loss of some
+30 horse-power. For twenty miles the loss on transmission should not
+exceed 15 horse-power so that 70 and 85 horse-power respectively are
+available at the mines. No other system offers such remarkable
+efficiencies of power transmission. The new Multiphase Alternating
+Electric Generating and Power Transmission System is indeed so perfect
+as to leave practically no margin for improvement.
+
+The multiphase electric motor can be directly applied to the stamp
+battery and ore-breaker driving-shaft and to the shaft of the
+amalgamating pans.
+
+
+APPROXIMATE POWER REQUIRED TO DRIVE THE MACHINERY OF A MINE.
+
+  Rock breaker                           10    effective horse-power
+  Amalgamating pan                        5    effective horse-power
+  Grinding pan                            6    effective horse-power
+  Single stamp of 750 lb. dropping
+    90 times per minute                   1.25 effective horse-power
+  Settlers                                4    effective horse-power
+  Ordinary hoisting lift                  20   effective horse-power
+
+Allow 10 per cent in addition for overcoming friction.
+
+
+Besides this electrical distribution power, which should not cost more
+than three farthings per effective horse-power per hour, the
+electrical energy can be employed for lighting the drives and the
+shafts of the mine. The modern electrical mine lamps leave little to
+be desired. Also it is anticipated that once the few existing
+difficulties have been surmounted electric drilling will supplant all
+other methods.
+
+Electric power can be employed for pumping, for shot firing, for
+hauling, and for innumerable purposes in a mine.
+
+Electricity lends itself most advantageously to so many and varied
+processes, even in accelerating the influence of cyanide solutions on
+gold, and in effecting the magnetic influence on metallic particles in
+separating processes; while applied to haulage purposes, either on
+aerial lines or on tram or railroads, it is an immediate and striking
+success.
+
+It is anticipated that in the near future the mines on the Randt,
+South Africa, will be electrically driven from a coalfield generating
+station located on the coalfields some thirty miles from Johannesburg.
+Such a plant made up of small multiples of highly efficient machines
+will enable mine-owners to obtain a reliable power to any extent at
+immediate command and at a reasonable charge in proportion to the
+power used. This wholesale supply of power will be a godsend to a new
+field, enabling the opening up to be greatly expedited; and no
+climatic difficulties, such as dry seasons, or floods, need interfere
+with the regular running of the machinery. The same system of power-
+generation at a central station is to be applied to supply power to
+the mines of Western Australia.
+
+
+
+CHAPTER X
+
+COMPANY FORMATION AND OPERATIONS
+
+All the world over, the operation of winning from the soil and
+rendering marketable the many valuable ores and mine products which
+abound is daily becoming more and more a scientific business which
+cannot be too carefully entered into or too skilfully conducted. The
+days of the dolly and windlass, of the puddler, cradle, and tin dish,
+are rapidly receding; and mining, either in lode or alluvial working,
+is being more generally recognised as one of the exact sciences. In
+the past, mining has been carried on in a very haphazard fashion, to
+which much of its non-success may be attributed.
+
+But the dawn of better days has arrived, and with the advent of
+schools of mines and technical colleges there will in future be less
+excuse for ignorance in this most important industry.
+
+This chapter will be devoted to Company formation and working, in
+which mistakes leading to very serious consequences daily occur.
+
+It is not necessary to go deeply into the question why, in the mining
+industry more than any other, it should be deemed desirable as a
+general rule to carry on operations by means of public Companies, but,
+as a matter of fact, few names can be mentioned of men who mine
+extensively single handed. Yet, risky as it is, mining can hardly be
+said to be more subject to unpreventable vicissitudes than, say,
+pastoral pursuits, in which private individuals risk, and often lose
+or make, enormous sums of money.
+
+However, it is with Mining Companies we are now dealing, and with the
+errors made in the formation and after conduct of these Associations.
+
+The initial mistake most often made is that sufficient working capital
+is not called up or provided in the floating of the Company. Promoters
+trust to get sufficient from the ground forthwith to ensure further
+development; the consequence being that, as nearly 99 per cent of
+mining properties require a very considerable expenditure of capital
+before permanent profits can be relied on, the inexperienced
+shareholders who started with inflated hopes of enormous returns and
+immediate dividends become disheartened and forfeit their shares by
+refusing to pay calls, and thus many good properties are sacrificed.
+In England, the companies are often floated fully paid-up, but the
+same initial error of providing too little money for the equipment and
+effective working of the mine is usually fallen into.
+
+Again, far too many Companies are floated on the report of some self-
+styled mining expert, often a man, who, like the schoolmaster of the
+last century, has qualified for the position by failing in every other
+business he has attempted. These men acquire a few geological and
+mining phrases, and by more or less skilfully interlarding these with
+statements of large lodes and big returns they supply reports
+seductive enough to float the most worthless properties and cause the
+waste of thousands of pounds. But the trouble does not end here.
+
+When the Company is to be formed, some lawyer, competent or otherwise,
+is instructed to prepare articles of association, rules, etc.; which,
+three times out of four, is accomplished by a liberal employment of
+scissors and paste. Such rules may, or may not, be suited to the
+requirements of the organisation. Generally no one troubles much about
+the matter, though on these rules depends the future efficient working
+of the Company, and sometimes its very existence.
+
+Then Directors have to be appointed, and these are seldom selected
+because of any special knowledge of mining they may possess, but as a
+rule simply because they are large shareholders or prominent men whose
+names look well in a prospectus. These gentlemen forthwith engage a
+Secretary, usually on the grounds that he is the person who has
+tendered lowest, to provide office accommodation and keep the
+accounts; and not from any particular knowledge he has of the true
+requirements of the position.
+
+The way in which some Directors contrive to spend their shareholders'
+money is humorously commented on by a Westralian paper which describes
+a great machinery consignment lately landed in the neighbourhood of
+the Boulder Kalgoorlie.
+
+"It would seem as if the purchaser had been let loose blindfold in a
+prehistoric material-founder's old iron yard, and having bought up the
+whole stock, had shipped it off. The feature of the entire
+antediluvian show is the liberal allowance of material devoted to
+destruction. Massive kibbles, such as were used in coal mines half a
+century ago, are arranged alongside a winding engine, built in the
+middle of the century, and evidently designed for hauling the kibbles
+from a depth of 1000 feet. Nothing less than horse-power will stir the
+trucks for underground use, and their design is distinctly of the
+antique type. The engine is built to correspond--of a kind that might
+have served to raise into position the pillars of Baalbec, and the
+mass of metal in it fairly raises a blush to the iron cheek of frailer
+modern constructions. The one grand use to which this monster could be
+put would be to employ it as a kedge for the Australian continent in
+the event of it dragging its present anchors and drifting down south,
+but as modern mining machinery the whole consignment is worth no more
+than its value as scrap-iron, which in its present position is a
+fraction or two less than nothing."
+
+Next, a man to manage the mine has to be obtained, and some one is
+placed in charge, of whose capabilities the Directors have no direct
+knowledge. Being profoundly ignorant of practical mining they are
+incompetent to examine him as to his qualifications, or to check his
+mode of working, so as to ascertain whether he is acting rightly or
+not. All they have to rely on are some certificates often too
+carelessly given and too easily obtained. Finally, quite a large
+proportion of the allottees of shares have merely applied for them
+with the intention of selling out on the first opportunity at a
+premium, hence they have no special interest in the actual working of
+the mine.
+
+Now let us look at the prospects of the Association thus formed. The
+legal Manager or Secretary, often a young and inexperienced man, knows
+little more than how to keep an ordinary set of books, and not always
+that. He is quite ignorant of the actual requirements of the mine, or
+what is a fair price to pay for labour, appliances, or material. He
+cannot check the expenditure of the Mining Manager, who may be a rogue
+or a fool or both, for we have had samples of all sorts to our sorrow.
+The Directors are in like case. Even where the information is honestly
+supplied, they cannot judge whether the work is being properly carried
+out or is costing a fair price, and the Mining Manager is left to his
+own devices, with no one to check him nor any with whom he can consult
+in specially difficult cases. Thus matters drift to the almost certain
+conclusion of voluntary or compulsory winding up; and so many a good
+property is ruined, and promising mines, which have never had a
+reasonable trial, are condemned as worthless. But let us ask, would
+any other business, even such as are less subject to unforeseen
+vicissitudes than mining, succeed under similar circumstances?
+
+It is now very generally agreed that to the profitable development of
+mining new countries, at all events, must look mainly for prosperity,
+while other industries are growing. Therefore, we cannot too seriously
+consider how we may soonest make our mines successful.
+
+What is the remedy for the unsatisfactory state of affairs we have
+experienced? The answer is a more practical system of working from the
+inception. Although it may evoke some difference of opinion I consider
+it both justifiable and desirable that the State should take some
+oversight of mining matters, at all events in the case of public
+Companies. It would be a salutary rule that the promoters of any
+mining undertaking should, before they are allowed to place it on the
+market, obtain and pay for the services of a competent Government
+Mining Inspector, who need not necessarily be a Government officer,
+but might, like licensed surveyors, be granted a certificate of
+competency either by a School of Mines or by some qualified Board of
+Examiners. The certificate of such Inspector that the property was as
+represented, should be given before the prospectus was issued. It is
+arguable whether even further oversight might not be properly be taken
+by the State and the report of a qualified officer be compulsory that
+the property was reasonably worth the value placed upon it in the
+prospectus.
+
+Probably it will be contended that such restrictions would be an undue
+interference with private rights, and the old aphorism about a fool
+and his folly will be quoted. There are doubtless fools so infatuated
+that if they were brayed in a ten hundred-weight stamp-battery the
+"foolishness that had not departed from them" would give a highly
+payable percentage to the ton. Yet the State in other matters tries by
+numerous laws to protect such from their folly. A man may not sell a
+load of wood without the certificate from a licensed weighbridge or a
+loaf of bread without, if required, having to prove its weight; and we
+send those to gaol who practise on the credulity and cupidity of fools
+by means of the "confidence trick." Why not, therefore, where
+interests which may be said to be national are involved, endeavour to
+ensure fair dealing?
+
+Then with regard to the men who are to manage the mines, seeing that a
+man may not become captain or mate of a river steamboat without some
+certificate on competency, nor drive her engines before he has passed
+an examination to prove his fitness, surely it is not too much to say
+that the mine manager or engineer, to whose care are often confided
+the lives of hundreds of men, and the expenditure of thousands of
+pounds, should be required to obtain a recognised diploma to prove his
+qualifications. The examinations might be made comparatively easy at
+first, but afterwards, when by the establishment of Schools and Mines
+the facilities have been afforded for men to thoroughly qualify, the
+standard should be raised; and after a date to be fixed no man should
+be permitted to assume the charge of a mine or become one of its
+officers without a proper certificate of competency from some
+recognised School of Mines or Technical College. The effect of such a
+regulation would in a few years produce most beneficial results.
+
+In New Zealand, whose "progressive" legislature I do not generally
+commend, they have, in the matter of mine management, at all events,
+taken a step in the right direction. There a mine manager, before he
+obtains his certificate, must have served at least two years
+underground, and has to pass through a severe examination, lasting for
+days, in all subjects relating to mining and machinery connected with
+mining. In addition, he must prove his capacity by making an
+underground survey, and then plotting his work. The examination is a
+stiff one, as may be judged from the fact that between 1886 and 1891,
+only 27 candidates passed. Then the conditions were made easier, and
+from that date to 1895, 19 passed. Of the 46 students who gained
+first-class honours, 30 have left for South Africa or Australia, in
+both of which countries New Zealand certificated men are held in high
+estimation.
+
+But returning to the formation of the Company, care should be taken in
+appointing Directors that at least one member of the Board is selected
+on account of his special technical knowledge of mining, and others
+for their special business capacity. The ornamental men with high
+sounding names should not be required in legitimate ventures. Also, it
+is most important that the business Manager or Secretary should be a
+specially qualified man, who by experience has learned what are the
+requirements of a mine doing a certain amount of work, so that a
+proper check may be kept on the expenses. The more Companies such a
+Secretary has the better, as one qualified man can supervise a large
+staff of clerks, who would themselves be qualifying for similar work,
+and gaining a useful and varied experience of mining business. An
+office of this description having charge of a large number of mines
+is, in its way, a technical school, and lads trained therein would be
+in demand as mine pursers, a very responsible and necessary officer in
+a big mine.
+
+With respect to the men to whom the actual mining and treatment of
+ores and machinery is committed the greatest mistakes of the past have
+been that too much has been required from one man, a combination not
+to be found probably in one man in a thousand. Such Admirable
+Crichtons are rare in any profession or business, and that of mining
+is no exception. Men who profess too much are to be distrusted. Your
+best men are they who concentrate their energies and intellects in
+special directions. The Mining Manager should, if possible, be chosen
+from men holding certificates of competency from some technical mining
+school and, of course, should, in addition, have some practical
+experience, not necessarily as Head Manager. He should understand
+practical mine surveying and calculation of quantities, be able to
+dial and plot out his workings, and prepare an intelligible plan
+thereof for the use of the Directors, and should understand sufficient
+of physics, particularly pneumatics and hydraulics, to ensure
+thoroughly efficient pumping operations without loss of power from
+unnecessarily heavy appliances. Any other scientific knowledge
+applicable to his business which he may have acquired will tell in his
+favour, but he must, above all things, be a thoroughly practical man.
+Such men will in time be more readily procurable, as boys who have
+passed through the various Schools of Mines will be sent to learn
+their business practically at the mines just as we now, having given a
+lad a course of naval instruction, send him to sea to learn the
+practical part of his life's work.
+
+But, of course, more is wanted on a mine than a man who can direct the
+sinking of shafts, driving of levels, and stoping of the lode. Much
+loss and disappointment have resulted in the past from unsuitable,
+ineffective, or badly designed and erected machinery, whether for
+working the mine or treating the ores. To obviate this defect a first-
+class mining engineer is required.
+
+Then, also, day by day we are more surely learning that mining in all
+its branches is a science, and that the treatment of ores and
+extraction of the metals is daily becoming more and more the work of
+the laboratory rather than of the rule-of-thumb procedure of the past.
+Every mine, whether it be of gold, silver, tin, copper, or other
+metal, requires the supervision of a thoroughly qualified metallurgist
+and chemist, and one who is conversant with the newest processes for
+the extraction of the metals from their ores and matrices.
+
+It has then been stated that to ensure effective working each mine
+requires, in addition to competent directors, a business manager,
+mining-manager, and assistants, engineer, chemist, and metallurgist,
+with assistant assayers, etc., all highly qualified men. But it will
+be asked, how are many struggling mines in sparsely populated
+countries to obtain the services of all these eminent scientists? The
+reply is by co-operation. One of the most ruinous mistakes of the past
+has been that each little mining venture has started on an independent
+course, with different management, separate machinery, etc. Can it
+then be wondered at that our gold-mining is not always successful?
+
+Under a co-operative system all that each individual mine would
+require would be a qualified, practical miner capable of opening and
+securing the ground in a miner-like manner, and a good working
+engineer; and in gold-mining, where the gold is free in its matrix, a
+professional amalgamator, or lixiviator. For the rest, half a dozen or
+more mines may collectively retain the services of a mine manager of
+high attainments as general inspector and superintendent, and the same
+system could be adopted with respect to an advising metallurgist and
+an engineer. For gold, as indeed for other metals, a central
+extracting works, where the ores could be scientifically treated in
+quantity, might be erected at joint cost, or might easily be arranged
+for as a separate business.
+
+A very fruitful cause of failure is the fatuous tendency of directors
+and mine managers to adopt new processes and inventions simply because
+they are new. As an inventor in a small way myself, and one who is
+always on the watch for improved methods, I do not wish to discourage
+intelligent progress; but the greatest care should be exercised by
+those having the control of the money of shareholders in mining
+properties before adopting any new machinery or process.
+
+We have seen, and unfortunately shall see, many a promising mining
+company brought to grief by this popular error. The directors of
+mining companies might, to use an American saying, "paste this in
+their hats" as a useful and safe aphorism. "LET OTHERS DO THE
+EXPERIMENTING; WE ARE WILLING TO PAY ONLY FOR PROVED IMPROVEMENTS." I
+can cordially endorse every word of the following extracts from
+Messrs. McDermott and Duffield's admirable little work, "Losses in
+Gold Amalgamation."
+
+"Some directors of mining companies are naturally inclined to listen
+to the specious promises of inventors of novel processes and new
+machinery, forgetting their own personal disadvantage in any argument
+on such matters, and assuming a confidence in the logic of their own
+conclusions, while they ignore the fruitful experience of thousands of
+practical men who are engaged in the mining business. The repeated
+failures of directors in sending out new machinery to their mines
+ought by this time to be a sufficient warning against increasing risks
+that are at once natural and unavoidable, and to deter them from
+plunging their shareholders into experiments which, in ninety-nine
+cases out of a hundred, result in nothing but excessive and needless
+expenses.
+
+"It is certain that new machines and new processes are, and will be,
+given attention by mining men in proportion to their probable merits;
+but the proper place for experiments is in a mill already as
+successful as under known processes it can be made. In a new
+enterprise, even when the expense of an experiment is undertaken by
+the inventor, the loss to the mine-owner in case of failure must be
+very great, both in time and general running expenses. Directors
+should not believe that a willingness to risk cash in proving an
+invention is necessarily any proof of value of the same; it is only a
+measure of the faith of the inventor, which is hardly a safe standard
+to risk shareholders' money by.
+
+"The variety of modifications in approved processes ought at least to
+suggest the desirability of exhausting the known, before drawing on
+the unknown and purely speculative. It should also be borne in mind
+that what might appear at first sight to be new processes, and even
+new machinery, are, in fact, often nothing but old contrivances and
+plausible theories long ago exploded among practical men.
+
+"Many mining companies have been ruined, without any reference to
+their mines, through men deciding on the reasonableness of new process
+and machinery who have no knowledge of the business in hand. It is
+assumed often, that if an inventor or manufacturer of new machinery
+will agree to guarantee success, or take no pay if not successful, the
+company takes no risk. In actual fact a whole year is wasted in most
+cases, failure spoils the reputation of the company, running expenses
+have continued, and further working capital cannot be raised, because
+all concerned have lost confidence by the failure to obtain returns
+promised. All this in addition to the regular, unavoidable risks of
+mining itself, which may, at any moment during the year lost, call for
+increased expenses and increased faith in ultimate success. To the
+mining man who makes money by the business, the natural risks of
+mining is all he will take; it is sufficient; and when he invests more
+money in machinery he takes good care that he takes no chances of
+either failure or delay.
+
+"The following are rules which no mining company or individual mine-
+owner can afford to neglect.
+
+"(1) The risk should be confined to mining. No body of directors is
+justified in taking a shareholder's money and investing it in new
+processes or machinery when the subscription was simply for a mining
+venture. Directors are invariably incapable of deciding whether a so-
+called improvement in machinery or process is really so or not, and
+the reasonable course is to follow established precedents.
+
+"(2) The risk of selecting an incompetent manager should be reduced to
+minimum by taking a man with a successful record in the particular
+work to be done. The manager selected should be prohibited, as much as
+the directors, from experimenting with new methods or machinery. A
+really experienced man will require no check in this direction, as he
+will not risk ruining his reputation.
+
+"(3) The only time for a company to experiment is when the mine is
+paying well by the usual methods, and the treasury is in a condition
+to speculate a little in possible improvements without jeopardising
+regular returns."
+
+Probably this is the best place to insert another word of warning to
+directors who are not mining specialists, and also to investors in
+gold mining shares. Assays of auriferous lode material are almost
+invariably worthless as a guide in the real value of the stone in
+quantity. The one way to decide this is by battery treatment in bulk,
+and then only after many tons have been put through. The reason is
+obvious. First, the prospector or company promoter, if he knows it, is
+not in the least likely to pick the worst piece of stone in the heap
+for assay; and, secondly, even should the sample be selected with the
+sole object of getting a fair result, no living man can judge the
+value of a gold lode by the result of treatment of an ounce of stone.
+So when you see it stated that Messrs. Oro and Gildenstein, the
+celebrated assayers, have found that a sample of rock from the Golden
+Mint Mine, Golconda, assays at the rate of 2,546 oz. 13 dwt. and 21
+gr. to the ton, and that there are thousands of tons of similar stone
+in sight, the statement should be received with due caution. The assay
+is doubtless correct, but the deductions therefrom are most
+misleading.
+
+A few words of advice also to directors of mine-purchasing companies
+and syndicates, of which there are now so many in existence, may
+probably be found of value. It is not good policy as a general rule to
+buy entirely undeveloped properties, unless such have been inspected
+by your own man, who is both competent and trustworthy, and who should
+have indeed an interest in the profits. Large areas, although so
+popular in England, do not compensate for large bodies of payable ore;
+the most remunerative mine is generally one of comparatively small
+area, but containing a large lode formation of payable but often low
+grade, ore.
+
+It is worse still, of course, to buy a practically worked out mine,
+though this too is sometimes done. It must be remembered that mining,
+though often so profitable, is nevertheless a destructive industry,
+thus differing from agriculture, which is productive, and
+manufactures, which are constructive. Every ton of stone broken and
+treated from even the best gold mine in the world makes that mine the
+poorer by one ton of valuable material; thus, to buy a mining property
+on its past reputation for productiveness is, as a rule, questionable
+policy, unless you know there is sufficient good ore in sight to cover
+the purchase cost and leave a profit.
+
+One of the greatest causes of non-success of gold-mining ventures,
+particularly when worked by public companies, is the lack of actual
+personal supervision, and hence, among other troubles, is that ultra-
+objectionable one--gold stealing from the mills, or, in alluvial
+mining, from the tail races. As to the former, the following appeared
+in 1893 in the London /Mining Journal/, and is, I think, worthy of the
+close consideration of mine directors in all parts of the world:--
+
+"No one that has not experienced the evil of gold thieving from
+reduction mills can have any idea of the pernicious element it is, and
+the difficulty, once that it has got 'well hold,' of rooting it out.
+It permeates every class of society in the district connected with the
+industry, and managers, amalgamators, assayers, accountants, aye, even
+bank officials, are 'all on the job' to 'get a bit' while there is an
+opportunity. To exterminate the hateful monster requires on the part
+of the mine proprietors combined, stern and drastic measures
+undertaken under the personal supervision of one or more of their
+directors, and in many instances necessitating the removal of the
+whole of the official staff."
+
+The writer narrates how about twenty years ago he was led to suspect
+that in an Australian mine running forty head of stamps, in which he
+held a controlling interest, the owners were being defrauded of about
+a fourth of the gold really contained in the ore, and the successful
+steps taken to check the robbery.
+
+"We first of all dispensed with the services of the general manager,
+and then issued the following instructions to the mine and mill
+managers, I remaining at the mine to see them carried out until I
+substituted a practical local man as agent, who afterwards carried on
+the work most efficiently:--
+
+"(a) Both of these officials to keep separate books and accounts; in
+other words, to be distinct departments.
+
+"(b) The ore formerly was all thrown together and put through the
+mill. I subdivided it into four classes, A, B, C, and D, representing
+deep levels north and upper levels north, deep levels south and upper
+levels south, and allotted to each class ten heads of stamps at the
+mill.
+
+"(c) The mine manager to try three prospects, forenoon and afternoon
+of each day, from the dumps of each of the four classes and record in
+a book to be kept for that purpose the estimated mill yield of each
+one.
+
+"(d) The mill manager was required to do the same at the mill and keep
+his record.
+
+"(e) There were four underground bosses in each shift, twelve in all.
+I had a book fixed at the top of the shaft in which I required each of
+these men, at the expiry of every shift, to record any change in the
+faces of the quartz and particularly in regard to quality.
+
+"(f) Having divided the ore into four classes I instructed the
+amalgamators, of which there were two in each shift, six in all, that
+I required the amalgam from each to be kept separate, with the object
+of ascertaining what each part of the mine produced.
+
+"(g) I procured padlocks for the covering boards of the mercury tables
+and gave the keys to the amalgamators with instructions that they were
+not to hand them over to any one except the exchange shift without my
+written authority, and instructed them that they should clean down the
+plates every three hours, and after cleaning down the amalgam, buckets
+to be placed in the cleaning room, which I instructed to be kept
+locked and the key in charge of the watchman night and day.
+
+"(h) The whole of the amalgam taken from the plates during each
+twenty-four hours to be cleaned and squeezed by the two amalgamators
+on duty every forenoon at nine o'clock in the presence of the mill
+manager, who should weigh each lot and enter it in a book to be kept
+for the purpose, and the entry to be signed by the mill manager and
+both amalgamators as witnesses.
+
+"(i) Every alternate Friday the mortars (boxes) to be cleaned out; the
+work to be commenced punctually at eight A.M. by the six amalgamators
+in the presence of the mill manager, assisted by the three amalgam
+cleaning room watchmen and the four battery feeders on duty,
+prohibiting any of them from leaving until the cleaning up was
+finished, and the amalgam cleaned, squeezed and weighed, and the
+amount entered by the mill manager in the record look and attested by
+the amalgamators.
+
+"I think the intelligent readers (particularly those with a knowledge
+of the business) will see the drift of the above regulations, viz.,
+for there to be any peculation the whole of the battery staff--
+fourteen in all--would have to participate in it, and the number was
+too many to keep a secret. Formerly the amalgam cleaning room was
+sacred to the mill manager, and on announcing to that official the new
+instructions he at once tendered his resignation in a tone of offended
+dignity, immediately followed by that of the mine manager. It is a
+significant fact that shortly afterwards these two officials purchased
+a large mill and other property at a cost of ten thousand pounds, and
+that the mine yielded for the following three years during which I was
+connected with it an average of over 17 dwt. to the ton, as against
+formerly 10 to 12 dwt.
+
+"The reader must draw his own conclusions. I used to make it a
+practice to visit the mine daily and prospect the ore, and having the
+mine and mill managers' daily prospecting as a guide as well as my
+own, every man at the mill knew it was impossible for them to thieve
+without my detecting it; moreover, I made it a rule to discharge any
+of the mill employees that I discovered were interested in any small
+private claims.
+
+"The crux of the whole thing is having a practical miner at the head
+of affairs, and it is impossible for him to thieve if the work is
+carried out in the manner I have described."
+
+To bring the whole matter to a conclusion. It may be taken as a safe
+axiom that to make gold mining in the mine as distinct from mining on
+the Stock Exchange really profitable the same system of economy, of
+practical supervision, and scientific knowledge which is now adopted
+in all other businesses must be applied to the raising and extraction
+of the metal. Then, and not till then, will genuine mining take the
+place to which it is entitled amongst our industries.
+
+
+
+CHAPTER XI
+
+RULES OF THUMB
+
+This chapter has been headed as above because a number of the rules
+and recipes given are simply practical expedients, not too closely
+scientific. My endeavour has been to supply practical and useful
+information in language as free from technicalities as possible, so as
+to adapt it to the ordinary miner, mill operator and prospector, many
+of whom have had no scientific training. Some of the expedients are
+original devices educed by what we are told is the mother of
+inventions; others are hints given by practical old prospectors who
+had met with difficulties which would be the despair of a man brought
+up within reach of forge, foundry, machine shop, or tradesmen
+generally. There are many highly ingenious and useful contrivances
+besides these I have given.
+
+LIVING PLACES
+
+The health of the prospector, especially in a new country, depends
+largely on his housing--in which particular many men are foolishly
+careless, for although they are aware that they will be camped out for
+long periods, yet all the shelter they rely on is a miserable calico
+tent, often without a "fly," while in some cases they sometimes even
+sleep on the wet, or dusty, ground. Such persons fully deserve the ill
+health which sooner or later overtakes them. A little forethought and
+very moderate ingenuity would render their camp comparatively healthy
+and comfortable.
+
+In summer the tent is the hottest, and in winter the coldest of
+domiciles. The "pizie" or "adobie" hut, or, where practicable, the
+"dugout," are much to be preferred, especially the latter. "Pizie" or
+"adobie" is simply surface soil kneaded with water and either moulded
+between boards like concrete, to construct the walls, or made into
+large sun-dried bricks. Salt water should not be used, as it causes
+the wall to be affected by every change of weather. A properly
+constructed house of this material, where the walls are protected by
+overhanging eaves, are practically everlasting, and the former have
+been standing for centuries. There are buildings of pizie or adobie in
+Mexico, California and Australia which are as good as new, although
+the latter were built nearly a century ago.
+
+Adobie dwellings are warm in winter and cool in summer, and can be
+kept clean and healthy by occasional coatings of lime whitewash.
+
+The dugout is even more simple in construction. A cutting, say ten
+feet wide, is put into the base of a hill for say twelve feet until
+the back wall is, say, ten feet high, the sides starting from nothing
+to that height. The front and such portion as is required of the side
+walls are next constructed of pizie or rough stone, with mud mortar,
+and the roof either gabled or skillion of bough, grass, or reed
+thatch, and covered with pizie, over which is sometimes put another
+thin layer of thatch to prevent the pizie being washed away by heavy
+rain. Nothing can be more snug and comfortable than such a house,
+unless the cows, as Mark Twain narrates, make things "monotonous" by
+persistently tumbling down the chimney.
+
+When the Burra copper mines were in full work in Australia, the banks
+of the Burra Creek were honeycombed like a rabbit warren with the
+"dugout homes" of the Cornish miners. The ruins of these old dugouts
+now extend for miles, and look something like an uncovered Pompeii.
+
+When water is scarce and the tent has to be retained, much can be done
+to make the camp snug. I occupied a very comfortable camp once, of
+which my then partner, a Dane, was the architect. We called it "The
+Bungalow," and it was constructed as follows: First we set up our
+tent, 10 ft. by 8 ft., formed of calico, but lined with green baize,
+and covered with a well set fly.
+
+Next we put in four substantial forked posts about 10 ft. high and 15
+ft. apart, with securely fixed cross pieces, and on the top was laid a
+rough flat roof of brush thatch; the sides were then treated in the
+same way, but not so thickly, being merely intended as a breakwind.
+
+The tent with its two comfortable bunks was placed a little to one
+side, the remaining space being used as a dining and sitting room all
+through the summer. Except in occasional seasons of heavy rain, when
+we were saved the trouble of washing our dishes, the tent was only
+used for sleeping purposes, and as a storehouse for clothes and
+perishable provisions. I have "dwelt in marble halls" since then, but
+never was food sweeter or sleep sounder than in the old bush bungalow.
+
+A BUSH BED
+
+To make a comfortable bush bedplace, take four forked posts about 3
+ft. 6 in. long and 2 to 3 in. in diameter at the top; mark out your
+bedplace accurately and put a post at each corner, about 1 ft. in the
+ground. Take two poles about 7 ft. long, and having procured two
+strong five-bushel corn sacks, cut holes in the bottom corners, put
+the poles through, bringing the mouths of the sacks together, and
+secure them there with a strong stitch or two. Put your poles on the
+upright forked sticks, and you have a couch that even Sancho Panza
+would have envied. It is as well to fix stretchers or cross stays
+between the posts at head and foot.
+
+In malarial countries, sleeping on the ground is distinctly dangerous,
+and as such districts are usually thickly timbered, the Northern
+Territory hammock is an admirable device, more particularly where
+mosquitoes abound.
+
+NORTHERN TERRITORY HAMMOCK
+
+This hammock, which is almost a standing bedplace when rigged, is
+constructed as follows:--To a piece of strong canvas 7 feet long and 2
+1/2 feet wide, put a broad hem, say 3 1/2 inches wide at each end.
+Into this hem run a rough stick, about 2 feet 8 inches by 2 inches
+diameter. Round the centre of the stick pass a piece of strong three-
+quarter inch rope, 8 to 10 feet long and knot it, so as to leave a
+short end in which a metal eye is inserted. To each end of the two
+sticks a piece of quarter-inch lashing, about 6 feet long, is securely
+attached.
+
+To make the mosquito covering take 18 feet of ordinary strong cheese
+cloth, and two pieces of strong calico of the same size as the canvas
+bed; put hems in the ends of the upper one large enough to take half-
+inch sticks, to all four extremities of which 8 feet of whipcord is to
+be attached. The calico forms the top and bottom of what we used to
+call the "meat safe," the sides being of cheese cloth. A small,
+flapped opening is left on the lower side. When once inside you are
+quite safe from mosquito bites.
+
+To rig the above, two trees are chosen 7 to 8 feet apart, or two
+stayed poles can be erected if no trees are available. The bed is
+rigged about 3 feet from the ground by taking the rope round the trees
+or poles, and pulling the canvas taut by means of the metal eyelet.
+Then the lashings at the extremities of the sticks are fixed about 3
+feet further up the trees and you have a bed something between a
+hammock and a standing bed. The mosquito net is fixed above the
+hammock in a similar manner, except that it does not require the
+centre stay.
+
+An old friend of mine once had a rather startling experience which
+caused him to swear by the Northern Territory hammock. He was camped
+near the banks of a muddy creek on the Daly River, and had fortunately
+hung his "meat safe" about four feet high. The night was very dark,
+and some hours after retiring he heard a crash among his tin camp
+utensils, and the noise of some animal moving below him. Thinking his
+visitor was a stray "dingo," or wild dog, he gave a yell to frighten
+the brute away, and hearing it go, he calmly went to sleep again. Had
+he known who his caller really was, he would not have felt so
+comfortable. In the morning on the damp ground below, he found the
+tracks of a fourteen foot alligator, which was also out prospecting,
+but which, fortunately, had not thought of investigating the "meat
+safe."
+
+PURIFYING WATER
+
+There is not a more fertile disease distributor, particularly in a new
+country, than water. The uninitiated generally take it for granted
+that so long as water looks clear it is necessarily pure and
+wholesome; as a matter of fact the contrary is more usually the case,
+except in very well watered countries, and such, as a rule, are not
+those in which gold is most plentifully got by the average prospector.
+I have seen foolish fellows, who were parched with a long tramp, drink
+water in quantity in which living organisms could be seen with the
+naked eye, without taking even the ordinary precaution of straining it
+through a piece of linen. If they contracted hydatids, typhoid fever,
+or other ailments, which thin our mining camps of the strong, lusty,
+careless youths, who could wonder?
+
+The best of all means of purifying water from organic substances is to
+boil it. If it be very bad, add carbon in the form of the charcoal
+from your camp fire. If it be thick, you may, with advantage, add a
+little of the ash also.
+
+I once rode forty-five miles with nearly beaten horses to a native
+well, or rock hole, to find water, the next stage being over fifty
+miles further. The well was found, but the water in it was very bad;
+for in it was the body of a dead kangaroo which had apparently been
+there for weeks. The wretched horses, half frantic with thirst, did
+manage to drink a few mouthfuls, but we could not. I filled our
+largest billycan, holding about a gallon, slung it over the fire and
+added, as the wood burnt down, charcoal, till the top was covered to a
+depth of two inches. With the charcoal there was, of course, a little
+ash containing bi-carbonate of potassium. The effect was marvellous.
+So soon as the horrible soup came to the boil, the impurities
+coagulated, and after keeping it at boiling temperature for about half
+an hour, it was removed from the fire, the cinders skimmed out, and
+the water allowed to settle, which it did very quickly. It was then
+decanted off into an ordinary prospector's pan, and some used to make
+tea (the flavour of which can be better imagined than described); the
+remainder was allowed to stand all night, a few pieces of charcoal
+being added. In the morning it was bright, clear, and absolutely
+sweet. This experience is worth knowing as many a bad attack of
+typhoid and other fevers would be averted if practical precautions of
+this kind were only used.
+
+TO OBTAIN WATER FROM ROOTS
+
+The greatest necessity of animal life is water. There are, however,
+vast areas of the earth's surface where this most precious element is
+lamentably lacking, and such, unfortunately, is the case in many rich
+auriferous districts.
+
+To the practical man there are many indications of water. These, of
+course, vary in different countries. Sometimes it is the herbage, but
+probably, the best of all is the presence of carnivorous animals and
+birds. These are never found far from water. In Australia the not
+over-loved wily old crow is a pretty sure indicator of water within
+reasonable distance--water may be extracted from the roots of the
+Mallee (/Eucalyptus dumosa/ and /gracilis/)--the Box (/Eucalyptus
+hemiphloia/) and the Water Bush (/Hakea leucoptera/). To extract it
+the roots are dug up, cut into lengths of about a foot, and placed
+upright in a can; the lower ends being a few inches above the bottom.
+It is simply astonishing how much wholesome, if at times somewhat
+astringent, water may thus be obtained in a few hours, particularly at
+night.
+
+/Hakea leucoptera/. "Pins and needles."--Maiden, in his work "Useful
+Native Plants of Australia," says: "In an experiment on a water-
+yielding /Hakea/, the first root, about half an inch in diameter and
+six or eight feet long, yielded quickly, and in large drops about a
+wine-glass full of really excellent water."
+
+This valuable, though not particularly ornamental shrub (for it never
+attains to the dimensions of a tree), is found, to the best of my
+belief, in all parts of Australia, although it is said to be absent
+from West Australia. As to this I don't feel quite sure. I have seen
+it "from the centre of the sea" as far west as Streaky Bay, and
+believe I have seen it further West still. Considering the great
+similarity of much of the flora of South Africa to that of Australia,
+it is probable that some species of the water-bearing /Hakea/ might be
+found there. It can readily be recognised by its acicular, needle-like
+leaves, and more particularly by its peculiarly shaped seed vessel,
+which resembles the pattern on an old-fashioned Indian shawl.
+
+If the water found is too impure for drinking purposes and the trouble
+arises from visible animalculae only, straining through a pocket-
+handkerchief is better than nothing; the carbon filter is better
+still; but nothing is so effective as boiling. A carbon filter is a
+tube with a wad of compressed carbon inserted, through which the water
+is sucked, but as a rule clay-coloured water is comparatively
+innocuous, but beware of the bright, limpid water of long stagnant
+rock water-holes.
+
+TO MAKE AN EFFECTIVE FILTER
+
+Take a nail-can, keg, cask, or any other vessel, or even an ordinary
+wooden case (well tarred inside, if possible, to make it water-tight).
+Make a hole or several holes in the bottom, and set it over a tank or
+bucket. Into the bottom of the filter put (1) a few inches of washed
+broken stone; (2) about four inches of charcoal; (3) say three inches
+of clean coarse sand (if not to hand you can manufacture it by
+crushing quartz with your pestle and mortar), and (4) alternate layers
+of charcoal and sand until the vessel is half filled. Fill the top
+half with water, and renew from time to time, and you have a filter
+which is as effective as the best London made article. /But it is
+better to boil your water whether you filter afterwards or not./
+
+Clear the inside of the water-cask frequently, and occasionally add to
+the water a little Condy's fluid, as it destroys organic matter. A
+useful cement for stopping leaky places in casks is made as follows:
+Tallow 25 parts, lard 40 parts, sifted wood ash 25 parts. Mix together
+by heating, and apply with a knife blade which has just been heated.
+
+CANVAS WATER BAGS
+
+Are easily made, and are very handy for carrying small supplies of
+drinking-water when prospecting in a dry country; they have the
+advantage of keeping the water cool in the hottest weather, by reason
+on the evaporation. The mouthpiece is made of the neck of a bottle
+securely sewn in.
+
+MEDICINE CASE
+
+Medicine is also a matter well worthy of thought. The author's worst
+enemy would not call him a mollycoddle, yet he has never travelled in
+far wilds without carrying something in the way of medicine. First,
+then, on this subject, it cannot be too often reiterated that if
+common Epsom salts were a guinea an ounce instead of a penny the
+medicine would be valued accordingly, but it is somewhat bulky. What I
+especially recommend, however, is a small pocket-case of the more
+commonly known homeopathic remedies, "Mother tinctures," which are
+small, light, and portable, with a small simple book of instructions.
+Though generally an allopath in practice, I once saved my own life,
+and have certainly helped others by a little knowledge in diagnosing
+complaints and having simple homeopathic remedies at hand to be used
+in the first stages of what might otherwise have been serious
+illnesses.
+
+PRODUCING FIRE
+
+Every one has heard, and most believe, that fire may be easily
+produced by rubbing together two pieces of wood. I have seen it done
+by natives, but they seldom make use of the operation, which is
+generally laborious, preferring to carry lighted fire sticks for
+miles. I have never succeeded in the experiment.
+
+Sometimes, however, it is almost a matter of life or death to be able
+to produce fire. The back of a pocket knife, or an old file with a
+fragment of flint, quartz, or pyrites struck smartly together over the
+remains of a burnt piece of calico, will in deft hands produce a spark
+which can be fanned to a glow, and so ignite other material, till a
+fire is produced.
+
+Also it may not be generally known that he who carries a watch carries
+a "burning glass" with which he can, in clear weather, produce fire at
+will. All that is required is to remove the glass of your watch and
+carefully three parts fill it with water (salt or fresh). This forms a
+lens which, held steadily, will easily ignite any light, dry,
+inflammable substance.
+
+When firearms are carried, cut a cartridge so that only about a
+quarter of the charge of powder remains. Damp some powder and rub it
+on a small piece of dry cotton cloth or well-rubbed brown paper. Push
+a loose pellet of this into the barrel, insert your half cartridge,
+fire at the ground, when the wad will readily ignite, and can be blown
+into flame.
+
+TO COPY CORRESPONDENCE
+
+The prospector is not usually a business man; hence in dealing with
+business men who, like Hamlet, are "indifferent honest," he frequently
+comes to grief through not having a copy of his correspondence. It is
+most desirable, therefore, either to carry a carbon paper duplicating
+book and a stylus, or by adding a little sugar to good ordinary black
+ink you may make a copying ink; then with the aid of a "yellow back"
+octavo novel, two pieces of board, and some ordinary tissue paper, you
+may take a copy of any letter you send.
+
+TO PROVIDE A SIMPLE TELEGRAPHIC CODE
+
+Buy a couple of cheap small dictionaries of the same edition, send one
+to your correspondent with an intimation that he is to read up or down
+so many words from the one indicated when receiving a message. Thus,
+if I want to say "Claim is looking well," I take a shilling
+dictionary, send a copy to my correspondent with the intimation that
+the real word is seven down, and telegraph--"Civilian looking weird;"
+this, if looked up in Worcester's little pocket dictionary, for
+instance, will read "Claim looking well." Any dictionary will do, so
+long as both parties have a copy and understand which is the right
+word. By arrangement this plan can be varied from time to time if you
+have any idea that your code can be read by others.
+
+A SERVICEABLE SOAP
+
+Wood ashes from the camp fire are boiled from day to day in a small
+quantity of water, and allowed to settle, the clear liquid being
+decanted off. When the required quantity of weak lye has been
+accumulated, evaporate by boiling, till a sufficient degree of
+strength has been obtained. Now melt down some mutton fat, and, while
+hot, add to the boiling lye. Continue boiling and stirring till the
+mixture is about the consistency of thick porridge, pour into any
+convenient flat vessel, and let it stand till cool. If you have any
+resin in store, a little powdered and added gradually to the melting
+tallow, before mixing with the lye, will stiffen your soap.
+
+TO CROSS A FLOODED STREAM
+
+Take a half-gallon, or larger, tin "billy can," enclose it in a strong
+cotton handkerchief or cotton cloth, knotting same over the lid,
+invert, and, taking the knot in the hand, you have a floating
+appliance which will sustain you in any water, whether you are a
+swimmer or not. The high silk hat of civilisation would act as well as
+the can, but these are not usually found far afield.
+
+TO MAKE A HIDE BUCKET
+
+At times when prospecting in an "incline" or "underlay" shaft,
+particularly where the walls of the lode are irregular, a hide bucket
+will be found preferable to an iron one. The mode of manufacture is as
+follows: Procure an ox hide, "green," if possible; if dry, it should
+be soaked until quite soft. Cut some thin strips of hide for sewing or
+lacing. Now shape a bag or pocket of size sufficient to hold about a
+hundredweight of stone, and by puncturing the edges with a knife,
+marline-spike, or other pointed tool, sew together; make a handle of
+twisted or pleated hide, and having filled your bucket with dry sand
+or earth let it stand till the whole is quite dry, when it will be
+properly distended and will maintain its shape until worn out.
+
+TO MAKE A "SLUSH LAMP"
+
+Where candles are scarce and kerosine is not, a "slush lamp" is a
+useful substitute. Take an old but sound quart tin pannikin, half fill
+it with sand or earth, and prepare a thin stick of pine, round which
+wrap a strip of soft cotton cloth. The stick should be about half an
+inch longer than the depth of the pannikin. Melt some waste fat, fill
+the pannikin therewith, push the stick down into the earth at the
+bottom, and you have a light, which, if not equal to the electric or
+incandescent gas burner, is quite serviceable. In Australia the soft
+velvety core of the "bottle brush," /Banksia marginata/, is often used
+instead of the cotton wick.
+
+
+
+CHAPTER XII
+
+RULES OF THUMB
+
+MINING APPLIANCES AND METHODS
+
+A TEMPORARY FORGE
+
+What prospector has not at times been troubled for the want of a
+forge? To steel or harden a pick or sharpen a drill is comparatively
+easy, but there is often a difficulty in getting a forge. Big single
+action bellows are sometimes bought at great expense, and some
+ingenious fellows have made an imitation of the blacksmith's bellows
+by means of sheepskins and rough boards.
+
+With inadequate material and appliances to hand, the following will be
+found easier to construct and more lasting when constructed. Only a
+single piece of iron is required, and, at a pinch, one could even
+dispense with that by using a slab of talcose material, roughly
+shaping a hearth therein and making a hole for the blast. First,
+construct a framing about the height of an ordinary smith's forge.
+This can made with saplings and bark, or better still, if available,
+out of an empty packing case about three feet square. Fill the frame
+or case with slightly damped earth and ram it tight, leaving the usual
+hollow hearth. Then form a chamber below the perforated hearth opening
+to the rear. Now construct a centrifugal fan, such as is used for the
+ventilation of shallow shafts and workings. Set this up behind the
+hearth and revolve by means of a wooden multiplying wheel. A piece of
+ordinary washing line rope, or sash line rope, well resined if resin
+can be got--but pitch, tar, or wax will do by adding a little fine
+dust to prevent sticking--is used as a belt. With very rough materials
+a handy man can thus make a forge that will answer ordinary
+requirements.--N.B. Do not use clay for your hearth bed unless you can
+get a highly aluminous clay, and can give it full time to dry before
+the forge fire is lit. Ordinary surface soil, not too sandy, acts
+well, if damped and rammed thoroughly. Of course, if you can get an
+iron nozzle for your blower the whole operation is simplified.
+
+SIMPLE WAY OF MAKING CHARCOAL
+
+Dig a pit 5 feet square by 3 feet deep and fill with fuel. After
+lighting, see that the pit is kept full. The hot embers will gradually
+sink to the bottom. The fuel should be kept burning fiercely until the
+pit seems almost full, when more fuel should be added, raising the
+heap about a foot above the level of the ground. The earth dug out of
+the pit should then be shovelled back over the burning mass. After
+leaving it to cool for 24 hours the pit will be found nearly full of
+charcoal. About one-quarter the weight of the dry fuel used should be
+recovered in charcoal.
+
+ROUGH SMELTING ON THE MINE
+
+Rough smelting on the mine is effected with a flux of borax, carbonate
+of soda, or, as I have often done, with some powdered white glass.
+When the gold is smelted and the flux has settled down quietly in a
+liquid state, the bulk of the latter may be removed, to facilitate
+pouring into the mould, by dipping an iron rod alternately into the
+flux and then into a little water, and knocking off the ball of
+congealed flux which adheres after each dip. This flux should,
+however, be crushed with a pestle and mortar and panned off, as, in
+certain cases, it may contain tiny globules of gold.
+
+MISFIRES IN BLASTING
+
+One of the most common sources of accident in mining operations is due
+either to carelessness or to the use of defective material in
+blasting. A shot misses, generally for one of two reasons; either the
+explosive, the cap, or the fuse (most often the latter), is inferior
+or defective; or the charging is incompletely performed. Sometimes the
+fuse is not placed properly in the detonator, or the detonator is not
+properly enclosed in the cartridge, or the fuse is injured by improper
+tamping. If several shots have been fired together, particularly at
+the change of a "shift," the men who have to remove the broken
+material may in so doing explode the missed charge. Or, more
+inexcusable still, men will often be so foolish as to try to clear out
+the drill hole and remove the missed cartridge. When a charge is known
+to have missed all that is necessary to do in order to discharge it
+safely is to remove a few inches of "tamping" from the top of the
+drill hole, place in the bore a plug of dynamite with cap and fuse
+attached, put an inch or two of tamping over it and fire, when the
+missed charge will also be exploded. Of course, judgment must be used
+and the depth of the drill taken into consideration. As a rule, miners
+use far more tamping than is at all requisite. The action of the
+charge will generally be found quite as effective with a few inches of
+covering matter as with a foot or more, while the exploding of misfire
+cartridges is rendered simple, as no removal of tamping is required
+before placing the top "plug" in case of misfire.
+
+TO PREVENT LOSS OF RICH SPECIMENS IN BLASTING
+
+When blasting the cap of a lode, particularly on rich shutes of gold,
+the rock is apt to fly, and rich specimens may be thrown far afield
+and so be lost. A simple way of avoiding this is to procure a quantity
+of boughs, which tie into loose bundles, placing the leafy parts
+alternately end for end. Before firing, pile these bundles over the
+blast and, if care is used, very few stones will fly. The same device
+may be used in wide shallow shafts.
+
+A SIMPLE MODE OF RETORTING SMALL QUANTITIES OF AMALGAM
+
+Clean your amalgam and squeeze it as hard as possible through strong
+calico or chamois leather. Take a large sound potato, cut off about a
+quarter from one end and scoop out a hole in the centre about twice as
+big as the ball of amalgam. Procure a piece of flat iron--an old spade
+will do as well as anything--insert the amalgam, and, having placed
+the potato, cut side downwards, thereon, put the plate of iron on the
+forge, heat up first gently, then stronger, till separation has taken
+place, when the gold will be found in a bright clean button on the
+plate and the mercury in fine globules in the potato, from which it
+can be re-collected by breaking up the partly or wholly cooked tuber
+under water in an enamelled or ordinary crockery basin.
+
+  TO RETORT SMALL QUANTITIES OF MERCURY FOR AMALGAMATING ASSAY TESTS
+
+Get two new tobacco pipes similar in shape, with the biggest bowls and
+longest stems procurable. Break off the stem of one close to the bowl
+and fill the hole with well worked clay (some battery slimes make the
+best luting clay). Set the stemless pipe on end in a clay bed, and
+fill with amalgam, pass a bit of thin iron or copper wire beneath it,
+and bend the ends of the wire upwards. Now fit the whole pipe, bowl
+inverted, on to the under one, luting the edges of both well with
+clay. Twist the wire over the top with a pair of nippers till the two
+bowls are fitted closely together, and you have a retort that will
+stand any heat necessary to thoroughly distil mercury.
+
+  A SIMPLE MODE OF ASCERTAINING THE NOMINAL HORSE-POWER OF AN ENGINE
+
+Multiply the internal diameter of the cylinder by itself and strike off
+the last figure of the quotient. The diameter is
+
+     20" X 20"
+     20
+    ___
+    400. The H.P. is 40.
+
+The following rules will be found more professionally accurate from an
+engineering standpoint, though the term "horse-power" is not now
+generally employed.
+
+/To find the Nominal Horse-power/.--For /non-condensing/ engines:
+Multiply the square of the diameter of the cylinder in inches by 7 and
+divide the product by 80. For /condensing/ engines: Multiply the
+square of the diameter of the cylinder in inches by 7 and divide the
+product by 200.
+
+/To find the Actual Horse-power/ of an engine, multiply the area of
+the cylinder in square inches by the average effective pressure in
+pounds per square inch, less 3 lb. per square inch as the frictional
+allowance, and also by the speed of the piston in feet per minute,
+dividing the product by 33,000, and the quotient will be the actual
+horse-power.
+
+"SCALING" COPPER PLATES
+
+To "scale" copper plates they may be put over a charcoal or coke fire
+to slowly sublimate the quicksilver. Where possible, the fireplace of
+a spare boiler can be utilised, using a thin red fire. After the
+entire evaporation of the quicksilver the plates should be slowly
+cooled, rubbed with hydrochloric acid, and put in a damp place
+overnight, then rubbed with a solution of sal ammoniac and nitre in
+equal parts, and again heated slowly over a red fire. They must not be
+allowed to get red hot; the proper degree of heat is indicated by the
+gold scale rising in blisters, when the plates should be taken from
+the fire and the gold scraped off. Any part of the plate on which the
+gold has not blistered should be again rubbed with the solution and
+fired. The gold scale should be collected in a glass or earthen dish
+and covered with nitric acid, till all the copper is dissolved, when
+the gold can be smelted in the usual way; but after it is melted
+corrosive sublimate should be put in the crucible till a blue flame
+ceases to be given off.
+
+/A Second Method/
+
+The simplest plan I know is to have a hole dug nine inches deep by
+about the size of the plate to be scaled; place a brick at each
+corner, and on each side, halfway between, get up a good fire; let it
+burn down to strong embers, or use charcoal, then place the plate on
+three bars of iron extending between the three pairs of bricks, have a
+strong solution of borax ready in which soak strips of old "table
+blanket," laying these over the plate and sprinkling them with the
+borax solution when the plate gets too hot. After a time the deposit
+of mercury and gold on the plate will assume a white, efflorescent
+appearance, and may then be readily parted from the copper.
+
+/Another Method/
+
+Heat the plate over an open fire, to drive off the mercury; after
+which, let it cool, and saturate with dilute sulphuric acid for three
+hours, or longer; then sprinkle over the surface a mixture of equal
+parts of common salt and sal ammoniac, and heat to redness; then cool,
+and the gold scale comes off freely; the scale is then boiled in
+nitric or sulphuric acid, to remove the copper, previous to melting.
+Plates may be scaled about once in six months, and will under ordinary
+circumstances produce about one ounce of clean gold for each
+superficial foot of copper surface employed. I always paint the back
+of the plate with a mixture of boiled oil and turpentine, or beeswax
+dissolved in turpentine, to prevent the acid attacking the copper.
+
+HOW TO SUPPLY MERCURY TO MORTAR BOXES
+
+I am indebted for the following to Mr. J. M. Drake, who, speaking of
+his experience on the Wentworth Mine, N.S.W., says:
+
+"Fully 90 per cent of the gold is saved on the outside plates, only a
+small quantity remaining in the mortar. The plates have a slope of 2
+in. to 1 ft. No wells are used, the amalgam traps saving any
+quicksilver which may leach off the plates. The quicksilver is added
+every hour in the mortar. The quantity is regulated by the mill
+manager in the following manner: Three pieces of wood, 8 in. wide by
+12 in. long by 2 in. thick, have 32 holes 1 in. deep bored in each of
+them. These holes will just take a small 2 oz. phial. The mill manager
+puts the required quantity of quicksilver in each bottle and the
+batteryman empties one bottle in each mortar every hour; and puts it
+back in the hole upside down. Each block of wood lasts eight hours,
+the duration of one man's shift." This of course is for a 20-head mill
+with four mortars or "boxes."
+
+I commend this as an excellent mode of supplying the mercury to the
+boxes or mortars. The quantity to be added depends on circumstances. A
+careless battery attendant will often put in too much or too little
+when working without the automatic feeder. I have known an attendant
+on suddenly awaking to the fact half through his shift, that he had
+forgotten to put in any mercury, to then empty into the stamper box
+two or three pounds weight; with what effect may be easily surmised.
+
+HOW WATER SHOULD ENTER STAMPER BOXES
+
+The following extract which relates to Californian Gold Mill practices
+is from Bulletin No. 6 of the California State Mining Bureau. I quite
+agree with the practice.
+
+"The battery water should enter both sides of the mortar in an even
+quantity, and should be sufficient to keep a fairly thick pulp which
+will discharge freely through the grating or screen. About 120 cubic
+feet of water per ton of crushed ore may be considered an average, or
+8 to 10 cubic feet per stamp per hour.
+
+"Screens of different materials and with different orifices are used;
+the materials comprise wire cloth of brass or steel, tough Russian
+sheet iron, English tinned plate, and, quite recently, aluminium
+bronze. The 'aluminium bronze' plates are much longer lived than
+either of the other kinds, and have the further advantage that, when
+worn out, they can be sold for the value of the metal for remelting;
+these plates are bought and sold by the pound, and are said to contain
+95 per cent of copper and 5 per cent of aluminium. Steel screens are
+not so much used, on account of their liability to rust."
+
+I have had no experience with the aluminium bronze screen. I presume,
+however, that it is used only for mills where mercury is not put in
+the mortars, otherwise, it would surely become amalgamated. The same
+remark applies to brass wire cloth and tinned plate. Unless the metal
+of which they are composed will not readily amalgamate with mercury, I
+should be chary of using new screen devices. Mercury is a most
+insidious metal and is often found most unexpectedly in places in the
+battery where it should not be. Probably aluminium steel would be
+better than any substance mentioned. It would be hard, light, strong,
+and not readily corrodible. I am not aware if it has been tried.
+
+Under the heading of "Power for Mills" the following is taken from the
+same source.
+
+POWER FOR MILLS
+
+"As the Pelton wheel seems to find the most frequent application in
+California, it may be convenient for millmen to have the following
+rule, applicable to these wheels:
+
+"When the head of water is known in feet, multiply it by 0.0024147,
+and the product is the horse-power obtainable from one miner's inch of
+water.
+
+"The power necessary for different mill parts is:
+
+For each 850lb. stamp, dropping 6 in. 95 times per minute,  1.33 h.-p.
+For each 750lb. stamp, dropping 6 in. 95 times per minute,  1.18 h.-p.
+For each 650lb. stamp, dropping 6 in. 95 times per minute,  1.00 h.-p.
+For an 8-inch by 10-inch Blake pattern rock-breaker         9.00 h.-p.
+For a Frue or Triumph vanner, with 220 revolutions per min. 0.50 h.-p.
+For a 4-feet clean-up pan, making 30 revolutions per min.   1.50 h.-p.
+For an amalgamating barrel, making 30 revolutions per min.  2.50 h.-p.
+For a mechanical batea, making 30 revolutions per min.      1.00 h.-p."
+
+The writer has had small practical experience of the working of that
+excellent hydraulic motor, the Pelton wheel, but if by horse-power in
+the table given is meant nominal horse-power, it appears to be high.
+Working with 800 cwt. stamps, 80 blows a minute, one horse-power
+nominal will be found sufficient with any good modern engine, which
+has no further burden than raising the stamps and pumping the feed
+water. It is always well, however, particularly when providing engine
+power, to err on the right side, and make provision for more than is
+absolutely needed for actual battery requirements. This rule applies
+with equal potency to pumping engines.
+
+TO AVOID LOSS IN CLEANING UP
+
+The following is a hint to quartz mill managers with respect to that
+common source of loss of gold involved in the almost inevitable loss
+of mercury in cleaning up operations. I have known hundreds of pounds'
+worth of gold to be recovered from an old quartz mill site by the
+simple process of washing up the ground under the floor.
+
+If you cannot afford to floor the whole of the battery with smooth
+concrete, at all events smoothly concrete the floor of the cleaning-up
+room, and let the floor slope towards the centre: where a sink is
+provided. Any lost mercury must thus find its way to the centre, where
+it will collect and can be panned off from time to time. Of course an
+underground drain and mercury trap must be provided.
+
+IRON EXTRACTOR
+
+When using self-feeders, fragments of steel tools are especially
+liable to get into the battery boxes or other crushing appliance where
+they sometimes cause great mischief. I believe the following plan
+would be a practicable remedy for this evil.
+
+By a belt from the cam or counter shaft, cause a powerful electric
+magnet to extract all magnetic particles; then, by a simple ratchet
+movement, at intervals withdraw the magnet and drop the adhering
+fragments into a receptacle by automatically switching off the
+electric current. A powerful ordinary horseshoe magnet might probably
+do just as well, but would require to be re-magnetised from time to
+time.
+
+TO SILVER COPPER PLATES
+
+To silver copper plates, that is, to amalgamate them on the face with
+mercury, is really a most simple operation, though many batterymen
+make a great mystery of it. Indeed, when I first went into a quartz
+mill the process deemed necessary was not only a very tedious one, but
+very dirty also.
+
+To amalgamate with silver, in fact, to silver-plate your copper
+without resort to the electro-plating bath, take any old silver
+(failing that, silver coin will do, but is more expensive), and
+dissolve it in somewhat dilute nitric acid, using only just sufficient
+acid as will assist the process. After some hours place the ball of
+amalgam in a piece of strong new calico and squeeze out any surplus
+mercury.
+
+About an ounce of silver to the foot of copper is sufficient. To apply
+it on new plates use nitric acid applied with a swab to free the
+surface of the copper from oxides or impurities, then rub the ball of
+amalgam over the surface using some little force. It is always well
+when coating copper plates with silver or zinc by means of mercury to
+let them stand dry for a day or two before using, as the mercury
+oxidises and the coating metal more closely adheres.
+
+Only the very best copper plate procurable should be used for battery
+tables; bad copper will always give trouble, both in the first
+"curing," and after treatment. It should not be heavily rolled copper,
+as the more porous the metal the more easily will the mercury
+penetrate and amalgamate. I cannot agree that any good is attained by
+scouring the plates with sand and alkalies, as recommended in some
+books on the subject; on the contrary, I prefer the opposite mode of
+treatment, and either face the plates with nitrate of silver and
+nitrate of mercury, or else with sulphate of zinc and mercury, in the
+form of what is called zinc amalgam. If mine water, which often
+contains a little free sulphuric acid, is being used, the latter plan
+is preferable.
+
+The copper should be placed smoothly on the wooden table and secured
+firmly thereto by copper tacks. If the plate should be bent or
+buckled, it may be flattened by beating it with a heavy hammer, taking
+care to interpose a piece of inch-thick soft wood between hammer and
+plate.
+
+To coat with mercury only, procure some nitrate of mercury. This is
+easily made by placing mercury in an earthenware bowl, pouring
+somewhat dilute nitric acid on it, and letting it stand till the
+metallic mercury is changed to a white crystal. Dense reddish-brown
+fumes will arise, which are injurious if breathed, so the operation
+should be conducted either in the open air, or where there is a
+draught.
+
+Having your silvering solution ready, which is to be somewhat diluted
+with water, next take two swabs, with handles about 12 inches long,
+dip the first into a basin containing dilute nitric acid, and rub it
+rapidly over about a foot of the surface of the plate; the oxide of
+copper will be absolutely removed, and the surface of the copper
+rendered pure and bright; then take the other swab, wet with the
+dilute nitric of mercury, and pass it over the clean surface, rubbing
+it well in. Continue this till the whole plate has a coating of
+mercury. It may be well to go over it more than once. Now turn on the
+water and wash the plate clean, sprinkle with metallic mercury,
+rubbing it upwards until the plate will hold no more.
+
+A basin with nitrate of mercury may be kept handy, and the plates
+touched up from time to time for a few days until they get amalgamated
+with gold, after which, unless you have much base metal to contend
+with, they will give no further trouble.
+
+It must be remembered, however, that an excessive use of nitric acid
+will result in waste of mercury, which will be carried off in a milky
+stream with the water; and also that it will cause the amalgam to
+become very hard, and less active in attracting other particles of
+gold.
+
+If you are treating the plate with nitrate of silver prepared as
+already mentioned, clean the plate with dilute nitric acid, rub the
+surface with the ball of amalgam, following with the swab and fairly
+rubbing in. It will be well to prepare the plate some days before
+requiring to use it, as a better adhesion of the silver and copper
+takes place than if mercury is applied at once.
+
+To amalgamate with zinc amalgam, clean the copper plate by means of a
+swab, with fairly strong sulphuric acid diluted with water; then while
+wet apply the zinc-mercury mixture and well rub in. To prepare the
+zinc-amalgam, clip some zinc (the lining of packing cases will do)
+into small pieces and immerse them in mercury after washing them with
+a little weak sulphuric acid and water to remove any coating of oxide.
+When the mercury will absorb no more zinc, squeeze through chamois
+leather or calico (as for silver amalgam), and well rub in. The plate
+thus prepared should stand for a few days, dry, before using. If,
+before amalgamation with gold takes place, oxide of copper or other
+scum should rise on this plate a little very dilute sulphuric acid
+will instantly remove it.
+
+Sodium and cyanide of potassium are frequently used in dressing-
+plates, but the former should be very sparingly employed, as it will
+often do more harm than good by taking up all sorts of base metals
+with the amalgam, and so presenting a surface which the gold will pass
+over without adhering to. Where water is scarce, and is consequently
+used over and over again, lime may be added to the pulp, or, if lime
+is not procurable, wood ashes may be used. The effect is two-fold; the
+lime not only tends to "sweeten" sulphide ores and keep the tables
+clean, but also causes the water to cleanse itself more quickly of the
+slimes, which will be more rapidly precipitated. When zinc amalgam is
+used, alkalies would, of course, be detrimental.
+
+When no other water than that from the mine is available, difficulties
+often arise owing to the impurities it contains. These are various,
+but among the most common are the soluble sulphates, and sometimes
+free sulphuric acid evolved by the oxidisation of metallic sulphides.
+In the presence of this difficulty, do one of two things; either
+/utilise/ or /neutralise/. In certain cases, I recommend the former.
+Sometime since I was treating, for gold extraction, material from a
+mine which was very complex in character, and for which I coined the
+term "polysynthetic." This contained about half a dozen different
+sulphides. The upper parts of the lode being partially oxidised, free
+sulphuric acid (H2SO4) was evolved. I therefore, following out a
+former discovery, added a little metallic zinc to the mercury in the
+boxes and on the plates with excellent results. When the free acid in
+the ore began to give out in the lower levels I added minute
+quantities of sulphuric acid to the water from time to time. I have
+since found, however, that with some water, particularly West
+Australian, the reaction is so feeble (probably owing to the lime and
+magnesia present) as to make this mode of treatment unsuitable.
+
+HOW TO MAKE A DOLLY
+
+I have seen some rather elaborate dollies, intended to be worked with
+amalgamating tables, but the usual prototype of the quartz mill is set
+up, more or less, as follows: A tree stump, from 9 in. to a foot
+diameter, is levelled off smoothly at about 2 ft. from the ground; on
+this is firmly fixed a circular plate of 1/2 in. iron, say 9 in. in
+diameter; a band of 3/16 in. iron, about 8 or 9 in. in height, fits
+more or less closely round the plate. This is the battery box. A beam
+of heavy wood, about 3 in. diameter and 6 ft. long, shod with iron, is
+vertically suspended, about 9 in. above the stump, from a flexible
+sapling with just sufficient spring in it to raise the pestle to the
+required height. About 2 ft. from the bottom the hanging beam is
+pierced with an augur hole and a rounded piece of wood, 1 1/2 in. by
+18 in., is driven through to serve as a handle for the man who is to
+do the pounding. His mate breaks the stone to about 2 in. gauge and
+feeds the box, lifting the ring from time to time to sweep off the
+triturated gangue, which he screens through a sieve into a pan and
+washes off, either by means of a cradle or simply by panning. In
+dollying it generally pays to burn the stone, as so much labour in
+crushing is thus saved. A couple of small kilns to hold about a ton
+each dug out of a clay bank will be found to save fuel where firewood
+is scarce, and will more thoroughly burn the stone and dissipate the
+base metals, but it must be remembered that gold from burnt stone is
+liable to become so encrusted with the base metal oxides as to be
+difficult to amalgamate.
+
+ROUGH WINDLASS
+
+Make two St. Andrew's crosses with four saplings, the upper angle
+being shorter than the lower; fix these upright, one at each end of
+the shaft; stay them together by cross pieces till you have
+constructed something like a "horse," such as is used for sawing wood,
+the crutch being a little over 3 feet high. Select a leg for a
+windlass barrel, about 6 in. diameter and a foot longer than the
+distance between the supports, as straight as is procurable; cut in it
+two circular slots about an inch deep by 2 in. wide to fit into the
+forks; at one end cut a straight slot 2 in. deep across the face. Now
+get a crooked bough, as nearly the shape of a handle as nature has
+produced it, and trim it into right angular shape, fit one end into
+the barrel, and you have a windlass that will pull up many a ton of
+stuff.
+
+PUDDLER
+
+This is made by excavating a circular hole about 2 ft. 9 in. deep and,
+say 12 ft. in diameter. An outer and inner wall are then constructed
+of slabs 2 ft. 6 in. in height to ground level, the outer wall being
+thus 30 ft. and the inner 15 ft. in circumference. The circular space
+between is floored with smooth hardwood slabs or boards, and the whole
+made secure and water-tight. In the middle of the inner enclosure a
+stout post is planted, to stand a few inches above the wall, and the
+surrounding space is filled up with clay rammed tight. A strong iron
+pin is inserted in the centre of the post, on which is fitted a
+revolving beam, which hangs across the whole circumference of the
+machine and protrudes a couple of feet or so on each side. To this
+beam are attached, with short chains, a couple of drags made like V-
+shaped harrows by driving a piece of red iron through a heavy frame,
+shaped as a rectangular triangle.
+
+To one end of the beam an old horse is attached, who, as he slowly
+walks round the circular track, causes the harrows and drags to so
+puddle the washdirt and water in the great wooden enclosure that the
+clay is gradually disintegrated, and flows off with the water which is
+from time to time admitted. The clean gravel is then run through a
+"cradle, "long Tom," or "sluice," and the gold saved. This, of course,
+is the simplest form of gold mining. In the great alluvial mines other
+and more intricate appliances are used but the principle of extraction
+is the same.
+
+A MAKESHIFT PUMP
+
+To make a temporary small "draw-lift" pump, which will work down to a
+hundred feet or more if required, take a large size common suction
+Douglas pump, and, after removing the top and handle, fix the pump as
+close to the highest level of the water in the shaft as can be
+arranged. Now make a square water-tight wooden column of slightly
+greater capacity than the suction pipe, fix this to the top of the
+pump, and by means of wooden rods, work the whole from the surface,
+using either a longer levered handle or, with a little ingenuity,
+horse-power. If you can get it the iron downpipe used to carry the
+water from the guttering of houses is more easily adapted for the pipe
+column; then, also, iron pump rods can be used but I have raised water
+between 60 and 70 feet with a large size Douglas pump provided only
+with a wooden column and rods.
+
+SQUEEZING AMALGAM
+
+For squeezing amalgam, strong calico, not too coarse, previously
+soaked in clean water, is quite as good as ordinary chamois leather.
+Some gold is fine enough to escape through either.
+
+MERCURY EXTRACTOR
+
+The mercury extractor or amalgam separator is a machine which is very
+simple in construction, and is stated to be most efficient in
+extracting quicksilver from amalgam, as it requires but from two to
+three minutes to extract the bulk of the mercury from one hundred
+pounds of amalgam, leaving the amalgam drier than when strained in the
+ordinary way by squeezing through chamois leather or calico. The
+principle is that of the De Laval cream separator--i.e., rapid
+centrifugal motion. The appliance is easily put together, and as
+easily taken apart. The cylinder is made of steel, and is run at a
+very high rate of speed.
+
+The general construction of the appliance is as follows: The casing or
+receiver is a steel cylinder, which has a pivot at the bottom to
+receive the step for an upright hollow shaft, to which a second
+cylinder of smaller diameter is attached. The second cylinder is
+perforated, and a fine wire cloth is inserted. The mercury, after
+passing through the cloth, is discharged through the perforations.
+When the machine is revolved at great speed, the mercury is forced
+into the outside cylinder, leaving the amalgam, which has been first
+placed in a calico or canvas bag, in a much drier state than it could
+be strained by hand. While not prepared to endorse absolutely all that
+is claimed for this appliance, I consider that it has mechanical
+probability on its side, and that where large quantities of amalgam
+have to be treated it will be found useful and effective.
+
+SLUICE PLATES
+
+I am indebted to Mr. F. W. Drake for the following account of sluice
+plates, which I have never tried, but think the device worth
+attention:
+
+"An addition has been made to the gold-saving appliances by the
+placing of what are called in America, 'sluice plates' below the
+ordinary table. The pulp now flows over an amalgamating surface, 14
+ft. long by 4 ft. wide, sloping 1 1/2 in. to the foot, and is then
+contracted into a copper-plated sluice 15 ft. long by 14 in. wide,
+having a fall of 1 in. to the foot. Our mill manager (Mr. G. C. Knapp)
+advocated these sluice plates for a long time before I would consent
+to a trial. I contended that as we got little or no amalgam from the
+lower end of our table plates there was no gold going away capable of
+being recovered by copper plates; and even if it were, narrow sluice
+plates were a step in the wrong direction. If anything the
+amalgamating surface should be widened to give the particles of gold a
+better chance to settle. His argument was that the conditions should
+be changed; by narrowing the stream and giving it less fall, gold,
+which was incapable of amalgamation on the wide plates, would be
+saved. We finally put one in, and it proved so successful that we now
+have one at the end of each table. The per-centage recovered on the
+sluice plates, of the total yield, varies, and has been as follows:--
+October, 9.1 per cent; November, 6.9 per cent; December, 6.4 per cent;
+January, 4.3 per cent; February, 9.3 per cent."
+
+MEASURING INACCESSIBLE DISTANCES
+
+To ascertain the width of a difficult gorge, a deep river, or
+treacherous swamp without crossing and measuring, sight a conspicuous
+object at the edge of the bank on the farther side; then as nearly
+opposite and square as possible plant a stake about five feet high,
+walk along the nearer margin to what you guess to be half the distance
+across (exactitude in this respect is not material to the result),
+there plant another stake, and continuing in a straight line put in a
+third. The stakes must be equal distances apart and as nearly as
+possible at a right angle to the first line. Now, carrying in hand a
+fourth stake, strike a line inland at right angles to the base and as
+soon as sighting over the fourth stake, you can get the fourth and
+second stakes and the object on the opposite shore in line your
+problem is complete. The distance between No. 4 and No. 3 stakes is
+the same as that between No. 1 and the opposite bank.
+
+TO SET OUT A RIGHT ANGLE WITH A TAPE
+
+Measure 40 ft. on the line to which you wish to run at right angles,
+and put pegs at A and B; then, with the end of the tape held carefully
+at A, take 80 ft., and have the 80 ft. mark held at B. Take the 50 ft.
+mark and pull from A and B until the tape lies straight and even, you
+will then have the point C perpendicular to AB. Continue straight
+lines by sighting over two sticks in the well-known way.
+
+/Another method/.--Stick a pin in each corner of a square board, and
+look diagonally across them, first in the direction of the line to
+which you wish to run at right angles, and then for the new line sight
+across the other two pins.
+
+A SIMPLE LEVELLING INSTRUMENT
+
+Fasten a common carpenter's square in a slit to the top of a stake by
+means of a screw, and then tie a plumb-line at the angle so that it
+may hang along the short arm, when the plumb-line hangs vertically and
+sights may be taken over it. A carpenter's spirit-level set on an
+adjustable stand will do as well. The other arm will then be a level.
+
+Another very simple, but effective, device for finding a level line is
+by means of a triangle of wood made of half-inch boards from 9 to 12
+ft. long. To make the legs level, set the triangle up on fairly level
+ground, suspend a plummet from the top and mark on the cross-piece
+where the line touches it. Then reverse the triangle, end for end,
+exactly, and mark the new line the plumb-line makes. Now make a new
+mark exactly half way between the two, and when the plumb-line
+coincides with this, the two legs are standing on level ground. For
+short water races this is a very handy method of laying out a level
+line.
+
+TO MEASURE THE HEIGHT OF A STANDING TREE
+
+Take a stake about your own height, and walking from the butt of the
+tree to what you judge to be the height of the timber portion you
+want, drive your stake into the ground till the top is level with your
+eyes; now lie straight out on your back, placing your feet against the
+stake, and sight a point on the tree. AB equals BC. If BC is, say 40
+ft., that will be the height of your "stick of timber." Thus, much
+labour may be saved in felling trees the timber portion of which may
+afterwards be found to be too short for your purpose.
+
+LEVELLING BY ANEROID BAROMETER
+
+This should be used more for ascertaining relatively large differences
+in altitudes than for purposes where any great nicety is required. For
+hills under 2000 ft., the following rule will give a very close
+approximation, and is easily remembered, because 55 degrees, the
+assumed temperature, agrees with 55 degrees, the significant figures
+in the 55,000 factor, while the fractional correction contains /two
+fours/.
+
+Observe the altitudes and also the temperatures on the Fahrenheit
+thermometer at top and bottom respectively, of the hill, and take the
+mean between them. Let B represent the mean altitude and b the mean
+temperature. Then 55000 X B - b/B + b = height of the hill in feet for
+the temperature of 55 degrees. Add 1/440 of this result for every
+degree the mean temperature exceeds 55 degrees; or subtract as much
+for every degree below 55 degrees.
+
+TO DETERMINE HEIGHTS OF OBJECTS
+
+/By Shadows/
+
+Set up vertically a stick of known length, and measure the length of
+its shadow upon a horizontal or other plane; measure also the length
+of the shadow thrown by the object whose height is required. Then it
+will be:--As the length of the stick's shadow is to the length of the
+stick itself, so is the length of the shadow of the object to the
+object's height.
+
+/By Reflection/
+
+Place a vessel of water upon the ground and recede from it until you
+see the top of the object reflected from the surface of the water.
+Then it will be:--As your horizontal distance from the point of
+reflection is to the height of your eye above the reflecting surface,
+so is the horizontal distance of the foot of the object from the
+vessel to its altitude above the said surface.
+
+/Instrumentally/
+
+Read the vertical angle, and multiply its natural tangent by the
+distance between instrument and foot of object; the result is the
+height.
+
+When much accuracy is not required vertical angles can be measured by
+means of a quadrant of simple construction. The arc AB is a quadrant,
+graduated in degrees from B to A; C, the point from which the plummet
+P is suspended, being the centre of the quadrant.
+
+/When/ the sights AC are directed towards any object, S, the degrees
+in the arc, BP, are the measure of the angle of elevation, SAD, of the
+object.
+
+TO FIND THE DEPTH OF A SHAFT
+
+/Rule/:--Square the number of seconds a stone takes to reach the
+bottom and multiply by 16.
+
+Thus, if a stone takes 5 seconds to fall to the bottom of a shaft--
+
+  5 squared = 25; and 25 X 16 = 400 feet, the required depth of shaft.
+
+DESCRIPTION OF PLAN FOR RE-USING WATER
+
+Where water is scarce it may be necessary to use it repeatedly. In a
+case of this kind in Egypt, the Arab miners have adopted an ingenious
+method which may be adapted to almost any set of conditions. At a is a
+sump or water-pit; b is an inclined plane on which the mineral is
+washed and whence the water escapes into a tank c; d is a conduit for
+taking the water back to a; e is a conduit or lever pump for raising
+the water. A certain amount of filtration could easily be managed
+during the passage from c to a.
+
+COOLING COMPOUND FOR HEATED BEARINGS
+
+Mercurial ointment mixed with black cylinder oil and applied every
+quarter of an hour, or as often as expedient. The following is also
+recommended as a good cooling compound for heavy bearings:--Tallow 2
+lb., plumbage 6 oz., sugar of lead 4 oz. Melt the tallow with gentle
+heat and add the other ingredients, stirring until cold.
+
+CLEANING GREASY PLUMMER BLOCKS
+
+When, through carelessness or unpreventable cause, plummer blocks and
+other detachable portions of machinery become clogged with sticky
+deposits of grease and impurities, a simple mode of cleansing the same
+is to take about 1000 parts by weight of boiling water, to which add
+about 10 or 15 parts of ordinary washing soda. Keep the water on the
+boil and place therein the portions of the machine that are to be
+cleaned; this treatment has the effect of quickly loosening all
+grease, oil, and dirt, after which the metal is thoroughly washed and
+dried. The action of the lye is to form with the grease a soap soluble
+in water. To prevent lubricating oil hardening upon the parts of the
+machinery when in use, add a third part of kerosene.
+
+AN EXCELLENT ANTI-FRICTION COMPOUND
+
+For use on cams and stamper shanks, which will be harmless should it
+drop into the mortar or stamper boxes, is graphite (black-lead) and
+soft soap. When the guides are wooden, the soft soap need not be
+added; black-lead made into a paste with water will act admirably.
+
+TO CLEAN BRASS
+
+Oxalic acid 1 oz., rotten stone 6 oz., powdered gum arabic 1/2 oz.,
+sweet oil 1 oz. Rub on with a piece of rag.
+
+A SOLVENT FOR RUST
+
+It is often very difficult, and sometimes impossible, to remove rust
+from articles made of iron. Those which are very thickly coated are
+most easily cleaned by being immersed in a nearly saturated solution
+of chloride of tin. The length of time they remain in this bath is
+determined by the thickness of the coating of rust. Generally from
+twelve to twenty-four hours is long enough.
+
+TO PROTECT IRON AND STEEL FROM RUST
+
+The following method is but little known, although it deserves
+preference over many others. Add 7 oz. of quicklime to 1 3/4 pints of
+cold water. Let the mixture stand until the supernatant fluid is
+entirely clear. Then pour this off, and mix with it enough olive oil
+to form a thick cream, or rather to the consistency of melted and re-
+congealed butter. Grease the articles of iron or steel with this
+compound, and then wrap them up in paper, or if this cannot be done,
+apply the mixture somewhat more thickly.
+
+TO KEEP MACHINERY FROM RUSTING
+
+Take 1 oz. of camphor, dissolve it in 1 lb. of melted lard; mix with
+it (after removing the scum) as much fine black-lead as will give it
+an iron colour; clean the machinery, and smear it with this mixture.
+After twenty-four hours rub off and clean with soft, linen cloth. This
+mixture will keep machinery clean for months under ordinary
+circumstances.
+
+FIRE-LUTE
+
+An excellent fire-lute is made of eight parts sharp sand, two parts
+good clay, and one part horse-dung; mix and temper like mortar.
+
+ROPE-SPLICING
+
+A short splice is made by unlaying the ends of two pieces of rope to a
+sufficient length, then interlaying them, draw them close and push the
+strands of one under the strands of the other several times. This
+splice makes a thick lump on the rope and is only used for slings,
+block-straps, cables, etc.
+
+
+
+
+
+End of The Project Gutenberg Etext of Getting Gold, by J. C. F. Johnson
+
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