UC-NRLF 
 
 TESTING & WORKING 
 
 SILVER ORES 
 
 CHAS. H. AARON 
 
Wo. 
 
 Division 
 
 Range 
 
 Shelf. 
 
 Received. 
 
 
 University of California. 
 
 C-J-IF"!' OF 1 
 
 
A PRACTICAL TREATISE 
 
 TESTING AND WORKING 
 
 ORES. 
 
 BY CHAS. H. AARON. 
 1 * 
 
 L I H K A II \ 
 
 . 
 
 UNIVERSITY OF 
 
 jj 
 
 PUBLISHED' AND %OLD iv DEw'kT & XX)V * 
 
 Proprietors of the MINING AND SCIENTIFIC PRESS, San Francisco, Cal. 
 1876. 
 
Entered according to Act of Congress, in the office of the Librarian of 
 Congress, at Washington, D. C., in the year 1876, by 
 
 CHAS. H. AARON and DEWEY & Co. 
 ^^/ J o -L 
 
 Printed by SPAULDING & BARTO, 
 414 Clay St., San Francisco. 
 
X 
 
 LIBRA U Y 
 
 UNIVERSITY (>! 
 
 CALIFORNIA. 
 
 PREFACE. 
 
 In 1869, I wrote a little pamphlet on amalgama- 
 tion of silver ores, in which was set forth a method 
 of treatment by which certain ores of silver usual- 
 ly considered refractory, could be worked to 90 
 per cent, of the assay without roasting. I shortly 
 afterward introduced that method at Benton, in 
 Mono County, with such success that two mills, 
 of ten and five stamps, respectively, have since 
 been built to work it, in each case with excellent 
 results. 
 
 I myself worked the process for several years, 
 with no better crushing machinery than an arastra, 
 which, with an amalgamating barrel and separator 
 (the whole driven by a water-wheel) formed a cheap 
 and efficient mill for the purpose, though better 
 adapted to the use of a person having a mine of 
 his own, than for custom work. 
 
 A large portion of the matter of my pamphlet, 
 which was sold for 25 cents per copy, has lately 
 been published, in a slightly garbled form, as a 
 circular, with the title of ' ' Instructions for testing 
 and milling ores/' by one N. L. Turner, in Mon- 
 tana Territory, being put forth as Mr. Turner's 
 
4 PREFACE. 
 
 own production, and sold, as I am informed, at 
 the very modest price of ten dollars per copy. 
 
 In addition to the matter taken from my pamph- 
 let, this circular contains sundry passages from 
 articles written by me, and published in the MIN- 
 ING AND SCIENTIFIC PRESS, showing that Mr. Turner 
 has been a diligent and appreciative reader of my 
 writings, and I must give give him credit for hav- 
 ing been so much smarter than myself, that if he 
 has sold even a few copies at ten dollars each, he 
 has made more out of them than I ever did. 
 
 Since writing the pamphlet, I have had five 
 years experience and observation of the process 
 therein described, and as my profit has consisted 
 in part of the additional knowledge thus gained, I 
 now propose to offer to the mining public, more 
 and better information than is contained in that, 
 or in Mr. Turner's piratical circular, adding also 
 some information and suggestions in regard to 
 other processes. 
 
 I do not write for students of science, nor to 
 make a display of learning, which, for all the read- 
 er would know, might or might not be "all out of 
 my own head." My aim is simply to contribute my 
 quota to the diffusion of practical knowledge of 
 some matters pertaining to the development of 
 silver mining, and to make certain suggestions, of 
 the value of which I leave the reader to judge. 
 
 I shall, then, try to write so as to be understood 
 by common miners and prospectors, and what I 
 
PEEEACE. 5 
 
 say will be chiefly the result of my own experience 
 and my own thought; not stereotyped matter which 
 may be found in a dozen works on Metallurgy in 
 any of our libraries. 
 
 In all silver regions there is found more or less 
 silver ore in the form of small veins, or threads as 
 the Mexicans say, or in bunches, pockets and de- 
 posits of little extent, which, while they will not 
 justify the attention of capitalists, might yet fur- 
 nish profitable occupation to a number of miners, 
 if the owners only had sufficient knowledge to ex- 
 tract the silver in a cheap and simple way. 
 
 This w r ant is partly met by custom mills, but 
 aside from the fact that miners generally have a 
 strong impression that they are very often swin- 
 dled at those places, it often happens that the 
 small and rich mines spoken of are quite remote 
 from any mill. 
 
 In the mineral districts of Mexico, nearly every 
 miner has some knowledge, however rude, of met- 
 allurgical operations, which enables him to work, 
 in one way or other, any small rich "hilo" which 
 he may discover, and though in large operations 
 the Mexicans may not be able to compete with 
 more enterprising people, yet it is a fact, that 
 among miners and prospectors, a Mexican will 
 make a good living where an American would 
 starve to death. 
 
 Though I write mainly for the benefit of the 
 poor and unlearned class in our mining districts, 
 
PREFACE. 
 
 it must not be supposed that the methods of which 
 
 1 treat are not adapted to large operations; on the 
 contrary, if my modification of the old " Fond on" 
 of Alonzo Barba had been adopted for the Corn- 
 stock mines long ago, many millions of dollars 
 which are now in the Carson river, might be in the 
 pockets of stockholders, and the value of stocks 
 would be proportionally higher. I do not mean 
 to say that I am the only man who could have done 
 this, but I speak for myself, and others have the 
 same privilege. 
 
 If it be asked why I have not tried to introduce 
 my process at Virginia, I can only say that I have 
 not kept the matter secret, and it is the business 
 of those interested to see to the working of their 
 ores in the best manner. 
 
 I have to presuppose a certain amount of knowl- 
 edge on the part of the reader, in regard to the 
 general operations of milling; for to go into all the 
 details of feeding battery, charging pans or bar- 
 rels, cleaning up, pressing amalgam, retorting, etc. 
 would carry me far beyond my proposed limit. 
 Most men in the mines either have, or can easily 
 acquire, such knowledge, and my object is to en- 
 able them to use it for their own benefit, while at 
 the same time offering some suggestions to persons 
 of more advanced pretentious who may choose to 
 avail themselves thereof. 
 
 C. H. AAEON. 
 
TESTING ORES FOR SILVER. 
 
 [1.] I shall not attempt to give any instructions 
 as to the geological or lithological formations 
 in which the discovery of silver may be expected, 
 for several reasons. In the first place, such knowl- 
 edge as we have on this subject, may be obtained 
 from many standard works; in the second place, it 
 is not very easliy applied when obtained, as, aside 
 from the difficulty of at once determining the char- 
 acter of rock formation, a region consisting mainly 
 of non-metalliferous rock, which might discourage 
 a learned person from searching, may nevertheless 
 contain within it a tract rich in metals; and in the 
 third place, such knowledge is not altogether reli- 
 able, nor is the ordinary prospector qualified to 
 avail himself of it, or indeed likely to be guided 
 by anything but his own notions, derived from his 
 own, or his friends' experience. 
 
 I shall, then, suppose that the seeker after min- 
 eral wealth, having journeyed at his " own sweet 
 
8 TESTING AND WORKING 
 
 will" over desert valley and rugged mountain, has 
 at last found a vein of ore, or at least some "rich 
 looking float," and having brought a sample down 
 to his camp by the spring, is anxious to know, be- 
 fore going further, whether the "queer looking 
 stuff " contains silver, or only a base conglomera- 
 tion of, to him, worthless metals. 
 
 Now, I am not going to afflict this innocent and 
 much suffering prospector with scientific details, 
 touching the crystalline form, chemical composi- 
 tion, fracture, streak, and specific gravity of the 
 many different ores of silver, or minerals which 
 carry more or less silver, in regard to which partic- 
 ulars he is most likely either profoundly indifferent, 
 or profanely contemptuous. All he wants to know, 
 for the present at least, is whether or not the ore 
 contains silver, which he may ascertain with cer- 
 tainty by proceeding as follows: 
 
 [2.] Grind a few ounces of the ore to powder 
 between two rocks; add to it about one-tenth as 
 much salt and about half that quantity of sulphate 
 of iron, often called copperas j mix all together, 
 and put it into an old shovel or frying pan, which 
 should have been previously smeared with clay or 
 
SILVEK OEES. 
 
 9 
 
 mud, and dried; then roast it over a fire, lyeiug 
 careful to stir it often with a piece of stout iron 
 wire. Let the roasting proceed quite gently so 
 long as a smell of burning sulphur can be per- 
 cevied, not allowing the heat to exceed a dark red as 
 seen at night. When the fumes of sulphur cease, 
 let the heat increase to a rather light red, but not 
 so as to melt the 'ore, stirring it still with the wire. 
 The smell will now be that of chlorides, rather 
 pungent, often sweet as of new hay, but very easily 
 distinguished from that of sulphur. The ore will 
 swell, and appear woolly and somewhat sticky, and 
 a few minutes of this hotter roasting will finish it 
 well enough for your purpose. Now transfer the 
 roasted ore to a flat rock and let it cool; add a lit- 
 tle more salt, and enough water to make it like 
 mortar; imbed in the mass a strip of clean sheet 
 copper, and let it remain ten minutes; take the 
 copper out, and without touching the part that has 
 been in the pulp, wash the mud off it with clean 
 water. If the ore contains silver, it will invariably 
 show as a white coating on the copper, and as no 
 other metal will so coat the copper under these 
 conditions, the appearance of such a coating is 
 proof positive of the presence of silver. The white 
 1* 
 
10 TESTING AND WORKING 
 
 coating will be heavier or lighter according to the 
 richness of the ore, if very heavy it will appear 
 grey and rough. 
 
 For making the above test you will require 
 Salt, 
 
 Sulphate of Iron, 
 An old shovel or frying pan, 
 A piece of stout iron wire, 
 *A strip of sheet copper six inches long, 
 By making a few tests in this way with ore 
 which _is known to contain silver, confidence will 
 be acquired. 
 
 The Sulphate of Iron is not required if the ore 
 contains sulphurets, but as you may possibly be 
 deceived on this point by substances resembling 
 sulphurets, it is best 4 to make sure by using it in 
 every case, 
 
 [3. ] Many, in fact most silver ores, will indicate 
 the presence of silver by simply mixing about an 
 ounce with boiling water, salt and a little bluestone, 
 in a teacup, and placing the strip of copper in it for 
 a few minutes, while keeping it at a boiling heat; 
 and as this is simpler than the roasting, it is well 
 to try it first. If the copper becomes whitened 
 
SILVER ORES. 11 
 
 you may be sure you have silver, unless indeed, it 
 should be quicksilver, which however, you will 
 hardly meet with in the silver regions, and which 
 is easily known by slightly heating the copper in 
 the fire, when quicksilver will be driven off, but 
 silver will not. Most miners will find no difficulty 
 in distinguishing between the two by simply rub- 
 bing with the finger. 
 
 For this test you will require 
 
 Salt, 
 
 Bluestone, 
 
 A strip of Copper and 
 
 A teacup, 
 
 or a basin which can be set in the top of an empty 
 oyster can, in which a little water is kept boiling, 
 so that the basin with its contents is kept hot. I 
 have tried this test with many samples of silver 
 ore, and it has never failed, yet the first one is still 
 more certain. 
 
 [4.] Some prospectors test ore by heating a 
 small piece red hot, and then plunging it into 
 water, when the more fusible metals it may con- 
 tain appear on the surface in the form of globules, 
 method is not reliable, because other met- 
 
12 TESTING AND WORKING 
 
 als besides silver may show themselves, and either 
 be mistaken for silver where it does not exist, or 
 disguise it where it does. 
 
 [5.] The most generally known method of test- 
 ing for silver, is by acting upon a little ore powder 
 in a test tube with nitric acid, and adding salt to 
 the clear solution thus formed; if silver is present 
 it appears as a more or less dense white cloud, or, 
 if in very small quantity, as a slight milkiness in 
 the acid. This method is open to two objections. 
 In the first place, some of the richest ores of silver 
 are not acted on by nitric acid, and would there- 
 fore show no sign on addition of salt; and in the 
 second place, lead gives the same appearance as 
 silver, as does also quicksilver, and though an ex- 
 pert would easily distinguish one from the other, by 
 further tests, yet these defects render the method 
 unsuitable for the common prospector, be- 
 sides which, nitric acid is not a very nice thing to 
 pack with provisions and blankets, nor to handle 
 in the desert. 
 
 [6.] I say nothing about the test with the blow- 
 pipe, because, though extremely valuable in the 
 
SILVER ORES. 13 
 
 hands of an expert, the use of this instrument re- 
 quires great practice, and considerable skill in 
 manipulation, and the big fingers of miners do not 
 take kindly to such delicate work. Nor do I de- 
 scribe the usual methods of fire assay, because 
 they require an outfit which could not well be car- 
 ried about by the prospector; nor are these things 
 necessary till it is required to know the richness of 
 the ore, when it is best to apply to a regular assay- 
 er, though, when it comes to that, the blowpipe 
 assay of a carefully taken sample, or of mere spec- 
 imens, is quite accurate enough, if well made, for 
 all the purposes of the prospector, or for assorting 
 ores, and as it costs a mere trifle, I think assay- 
 ers ought to use it more than they do, as a cheap 
 and lucrative method of supplying the wants of 
 poor laboring men, who merely require to know 
 approximately, the value of their ore. I have 
 made hundreds of these assays for fifty cents each 
 in the mines, as it takes only from fifteen to twenty 
 minutes to make one. 
 
 I UNIVERSITY OF | 
 
 <'AUF()j>XiA. I 
 
 X 
 
TESTING FOR A PROCESS. 
 
 [7.] When ore has been found, which, by eith- 
 er of the foregoing tests, gives evidence of contain- 
 ing silver, it will be well to make some explora- 
 tion to ascertain if it exists in considerable quan- 
 tity, in which case a few fair samples should be 
 taken to a reliable assayer in order that its richness 
 may be known. 
 
 If the ore is very rich, it will, of course, bear 
 transportation to a market; yet the losses, expenses 
 and discounts which are inseparable from this way 
 of disposing of it, not to mention the trouble and 
 risk of fraud, have caused miners in general to en- 
 tertain a strong, and not unfounded objection to 
 selling their ore, especially when the market is 
 very distant; besides which, the quantity of such 
 ore is usually quite small, though there may be 
 considerable of a grade which would pay quite 
 well to work in a small mill near the mine, and 
 owned by the miner. 
 
SILVER OEES. 15 
 
 Of course large mills work more cheaply,in pro- 
 portion, provided they are fully supplied with ore; 
 but a man who has only a small mine must be con- 
 tent with a small mill, and as the extraction of ore 
 also costs more in this case, the profitable limit of 
 value will be higher than when the mine and mill 
 are large, and must be decided according to cir- 
 cumstances. But whether the mill is to be large 
 or small, it is equally necessary to find out, before 
 building it, whether the ore can be worked raw, or 
 must be roasted or smelted. 
 
 [8.] If fuel is abundant, smelting is preferable 
 when the ore contains a large percentage of lead, 
 and becomes indispensable if the quantity is exces- 
 sive. However, ore containing as much as thirty 
 per cent, of lead can be worked by roasting. If 
 not necessarily a smelting ore, it remains *to be 
 seen whether it can be worked without roasting or 
 not, which can be ascertained as follows, so far at 
 least as processes which I can recommend to un- 
 learned persons are concerned : 
 
 [9.] A fair average sample is taken and reduced 
 to powder, fine enough to pass through at least a 
 
16 TESTING AND WOKKING 
 
 40-mesh wire gauze. If, however, the sample is 
 large, it will suffice if it be crushed coarsely at 
 first, then, after thorough mixing, spread upon a 
 smooth floor and halved; one-half being rejected, 
 the other is crushed finer and again mixed and 
 halved, and so on until the last half equals about 
 six pounds, which is all passed through a fine sieve, 
 Of this fine pulp, again well mixed, five pounds 
 are carefully weighed for a working sample, and 
 the remainder set aside for an assay. 
 
 [10.] The working sample is put into a porce- 
 lain-lined iron kettle, such as are used in a mill for 
 carrying quicksilver; water enough to form a thin 
 pulp, and two or more ounces of salt are added. 
 The pot is then put on a stove or over a fire, and 
 heated to boiling of the pulp, while stirred with a 
 strip o*f wood to prevent the ore from settling to 
 the bottom, which would cause the destruction of 
 the enamel. When hot, a little strong solution of 
 bluestone is added to the pulp, and a piece of 
 sheet copper about five inches square, or several 
 smaller pieces, together with about four ounces of 
 quicksilver, are also put in. As the pulp will grad- 
 ually dry by evaporation, hot water is added from 
 
SILVER ORES. 17 
 
 time to time, and the whole is frequently stirred 
 with the strip of wood. 
 
 After from five to ten minutes, a clean strip of 
 iron, or the blade of a case knife, is dipped into the 
 pulp for a few seconds, then washed, without rub- 
 bing, in clean water; it should show a pretty strong 
 color of copper; if it does not, more solution of 
 bluestone is added to the pulp, and the trial re- 
 peated, and so on till the iron becomes coated 
 with copper, when it is known that enough blue- 
 stone has been used; the heat and stirring are con- 
 tinued, the sheet copper in the pot being pushed 
 about through the pulp. 
 
 It is absolutely necessary that there be copper 
 in solution in the pulp, and as there may be in the 
 ore some substance which will destroy a quantity 
 of the bluestone used, it is best to repeat the test 
 with the knife blade once or twice more, adding 
 bluestone if necessary, till it is found that a per- 
 manent reaction of copper is established; but the 
 stirring must be done with a stick, not with the 
 iron knife, as that is only used as a test to show if 
 the pulp is in proper condition. The continued 
 presence of iron would ruin the experiment. 
 
 After a short time the pieces of sheet copper will 
 
18 TESTING AND WORKING 
 
 become coated with quicksilver, and will appear 
 rough on the surface, from adhesion of silver amal- 
 gam and corrosion of the copper, and particles of 
 ore are seen to adhere slightly to the copper and 
 to the quicksilver, and this, whether in the test or 
 in the large working, is an indication that the op- 
 eration is proceeding favorably, while the cessation 
 of the phenomenon is an indication of its comple- 
 tion. 
 
 The operation is continued till a clean strip of 
 copper dipped into the hot pulp for several min- 
 utes, comes out perfectly free from a white deposit 
 of silver, which may require from three to ten 
 hours. 
 
 [11.] When about to use the copper test, the 
 pulp is made rather thin, by the addition of hot 
 water, to allow the quicksilver to settle to the bot- 
 tom, and care must be used not to touch it with 
 the copper. If, notwithstanding all precautions, 
 the copper should appear spotted with quicksilver, 
 it must be heated in the fire, scoured clean, and the 
 trial repeated. The iron test is used at the same 
 time, to make sure that the pulp is in the proper 
 condition, that is, that it contains .a solution of 
 copper. 
 
SILVER OKES. 19 
 
 In commencing this operation, it Some- 
 times happens that the iron tester is blackened, in- 
 stead of being coppered; in this case the work is 
 continued some little time without addition of 
 more bluestone, when, on repeating the trial, the 
 proper effect will usually be got. 
 
 [12. J In order to know how much bluestone 
 has been used, it is best, before beginning, to 
 weigh two ounces, and put it into a bottle which 
 will hold enough water to dissolve it, adding one 
 ounce of salt, and filling the bottle with water. 
 If, at the end of the operation, the bottle is half 
 emptied, it is clear that one ounce of the blue- 
 stone has been used, and so in proportion for less 
 quantities. It is important to know how much blue- 
 stone has been used, as calculation may then be 
 made of the expense of working on the large scale; 
 thus, if 5 Ibs., or 80 ounces of ore consumes 0.5oz. 
 of bluestone, then one ton, or 2,000 Ibs., will re- 
 quire 
 
 80: 0.5:: 2000: 12.5 pounds. 
 
 Some ores require more, but the Comstock ore 
 works well with 4 pounds to the ton. The salt 
 used on the large scale will be from 50 to 100 Ibs. 
 
20 TESTING AND WORKING 
 
 to the ton of ore, and in addition, one-half the 
 weight of the bluestone. 
 
 [13.] When the strip of copper shows that no 
 more silver can be got, although the pulp is boil- 
 ing hot, and the case knife shows the contin- 
 ued presence of a solution of copper, the adhering 
 amalgam is removed from the sheet copper, by 
 stripping it between the fingers and thumb, the 
 pulp is "panned out" of the pot, and the amal- 
 gam strained out of the quicksilver with a piece of 
 buckskin or wet drilling. The ball of amalgam 
 thus obtained, which will be white and crisp, is 
 tied up in a piece of rag, and placed in an assay 
 crucible, or any vessel which will stand heat, and 
 is slowly heated to redness. After cooling, the 
 spongy silver is assayed to ascertain its value, 
 which, multiplied by 400, gives the amount per ton 
 that the ore will yield. If the silver is clean, as it 
 ought to be when worked in this way, it may be 
 estimated, without assaying, at $1.25 per Troy 
 ounce. 
 
 For making this test, the following appliances 
 are required 
 
 A pestle and mortar (or a flat rock and small 
 boulder) ; 
 
SILVER ORES. 21 
 
 A sieve of at least 40 meshes to the linear inch ; 
 
 A porcelain-lined kettle; 
 
 A strip of sheet copper, and some scraps of the 
 same metal; 
 
 A case knife; 
 
 Quicksilver, salt and bluestone; 
 
 A strip of wood for stirring, and patience. 
 
 Persons who are accustomed to such operations 
 can make this test on 1000 grains of ore, and, to 
 such, the following statement may be more accept- 
 able than the foregoing details: A weighed quan- 
 tity of the pulverized ore is digested in a glass or 
 porcelain vessel, with a solution sulphate of copper 
 and salt, metallic copper, and quicksilver, and the 
 resulting amalgam is estimated proportionally for 
 a ton of ore. If a fire assay is made of the un- 
 worked residue of the sample, a comparison of the 
 two results will indicate the working percentage. 
 
 [14.] Almost any ore will yield a portion of its 
 silver to this treatment, and all those which give a 
 good result, can be worked in the large way by 
 Aaron's process; some by Patch en's process, and a 
 few by simple pan treatment. Ores which will not 
 yield to it cannot be treated successfully by any of 
 
22 TESTING AND WORKING. 
 
 these methods, but will in general be best worked 
 by roasting, and I know of none in this country 
 which cannot be so worked successfully. 
 
 The test by roasting cannot be made reliably on 
 a very small scale; but this is not necessary, as it 
 may be taken for granted , that, setting aside smelt- 
 ing ores, roasting will give a fair result if rightly 
 managed. 
 
WORKING ORES. 
 
 [15] Aaron's process is essentially similar to the 
 working test just described. I have called it Aaron's 
 process because I invented ic, independently, in 
 1867, being led to it by considering the reactions 
 of the Patio, and because I have reduced it to a 
 fair degree of practicability. My first operation 
 was conducted on about a grain of ore in a minute 
 porcelain cup, with the aid of a copper belt-rivet; 
 the next was on five pounds of ore in a kettle; then 
 on a ton in a wooden barrel, and subsequently, 
 thousands of tons have been worked by it, and 
 near a million dollars extracted. I soon found 
 that the process was similar to the Mexican fon- 
 don, which, however, never advanced beyond a very 
 rude and primitive stage in the hands of the Mex- 
 icans, and was in that form totally unadapted to 
 our day and country. The loss of quicksilver was 
 enormous, except when the ores consisted of chlo- 
 rides, bromides, and iodides, which do not require 
 
Z4 TESTING AND WORKING 
 
 the use of bluestone or magistral, being readily 
 worked in copper or iron pans, with salt and quick- 
 silver alone. My process, as now worked, involves 
 no greater loss of quicksilver than other methods 
 of amalgamation in barrels or pans, but rather 
 less, and the chemical and mechanical treatment 
 differ materially from the old fondon. 
 
 [16.] The ore, crushed wet or dry, and at least 
 fine enough to pass through a 40-mesh wire cloth, 
 is put into Aaron's amalgamator, or a wooden amal- 
 gamating barrel, together with a quantity of met- 
 allic copper, 50 or 100 pounds of salt, and enough 
 water to form a pulp of medium consistency. - A 
 certain quantity of dichloride of copper is added, 
 the barrel closed and put in motion, and its con- 
 tents heated by means of steam admitted through 
 the journal. When the pulp is boiling hot, a little 
 of it is taken in a small porcelain-lined sheet 
 iron saucepan, and tested for copper in solution, 
 with the blade of a case knife, as already described. 
 If no copper is found, more dichloride is put in, 
 and the test repeated after the barrel has been 
 again in motion some little time. 
 
 [17. ] When the presence of a solution of copper 
 
SILVER ORES. 25 
 
 is indicated by a deposit on the knife blade, ^re- 
 membering the remark about a black stain), quick- 
 silver is put in, and the barrel is kept in mo- 
 tion from 6 to 12 hours, during which it will 
 not usually require more steaming, and being again 
 stopped, a little pulp is taken as before, diluted 
 with some hot water, adding a little salt to main- 
 tain the strength of the brine, and is tested, while 
 kept boiling hot with a few live coals, for silver, 
 with a strip of sheet copper, just as directed for 
 making the working test. When no silver can be 
 found, the barrel is discharged into the separator 
 and recharged as before. 
 
 [18.] In treating ores raw, when crushed wet, 
 some inconvenience results from the condensation 
 of the steam used for heating, by which the pulp is 
 too much diluted. This may be remedied by using 
 superheated steam, whereby not only is the dilu- 
 tion avoided, but the pulp may even be thickened 
 if necessary. If the ore is crushed dry, a small 
 portion of the charge is kept back, till the contents 
 of the barrel, or other machine, are heated, when a 
 quantity sufficient to make the pulp of the desired 
 consistency is put in. 
 2 
 
26 TESTING AND WORKING 
 
 [19.] The dichloride of copper is prepared as 
 follows: 22 pounds, of bluestone and 10 pounds of 
 salt, dissolved in water, are boiled, together with 
 five pounds of iron borings, in a steam heated ro- 
 tating barrel, or a vat, till the iron, and copper pre- 
 cipitated by it, have quite, or almost wholly disap- 
 peared, being replaced by a light colored powder, 
 which is dichloride of copper. Or, 11 pounds of 
 bluestone and 5 pounds of salt are boiled, together 
 with a 'quantity of scrap copper, till the solution is 
 no longer green, when the same quantity of dichlo- 
 ride of copper is formed. If the salt is impure, a 
 larger proportion must be employed; an excess 
 does no harm, but in no case should the liquor be 
 thrown away, as it may contain some dissolved cop- 
 per, so that it, as well as the precipitate, should be 
 used. The dichloride of copper should not be 
 much exposed to the air, as it thereby becomes 
 changed. 
 
 [20.] Protochloride of copper, most convenient- 
 ly prepared by dissolving some bluestone, with half 
 its weight of salt, in water, may be used in place 
 of dichloride, and in precisely the same manner as 
 to tests, etc. , but, as it attacks quicksilver, the fol- 
 
S1LVEE ORES. 27 
 
 lowing precautions are necessary : The quicksil- 
 ver must not be put in till some hours after the 
 pulp has been heated and worked with the copper 
 balls, so that the chloride of copper has lost its 
 power of acting on it, and then, in order that there 
 may be no quicksilver in the amalgamator, or stick- 
 ing to the copper when the new charge of ore is 
 put in, it must be used very sparingly, not more 
 than twice the weight of the silver in the ore being 
 used, or about 3 pounds to $100. The amalgam 
 is then found mixed through 1he pulp in the form 
 of a coarse, gray powder, or little flakes, and must 
 be collected by working the pulp in a wooden pan, 
 with an additional quantity of quicksilver, and 
 slightly diluted with water, so that it may be 
 drawn off, leaving the bulk of the fine amalgam in 
 the pan, to the separator, where it is treated for 
 recovery of copper and quicksilver, as described 
 hereafter. 
 
 [21.]X()res containing carbonate of copper do 
 not require the dichloride prepared as above. In- 
 stead of it sulphate of iron is used, and is put at 
 once into the barrel with the ore and salt; it pro- 
 duces the dichloride and protochloride of copper 
 
28 TESTING AND WORKING 
 
 from the carbonate in the ore. \Sulphurousacid is 
 better than sulphate of iron for this purpose, as 
 it forms only the dichloride of copper, besides 
 having other advantages, and being much cheaper, 
 for as it is only the sulphuric acid in the sulphate 
 of iron which is useful, one pound of sulphur in 
 the form of sulphurous acid, is equal to about 10 
 pounds of sulphate of iron.'/ The sulphurous acid 
 is made by burning sulphur, and the vapors are 
 either forced into the wet ore-pulp, or condensed 
 in water, with which the dry ore powder is after- 
 wards mixed. I have a patent on this reagent for 
 the purpose of amalgamation. 
 
 [22.] I have often been asked, when working 
 this class of ores, why I used the copper balls in 
 the barrel when there was so much copper in the 
 ore. The reason is that the process requires cop- 
 per in solution, and metallic copper. Now the 
 copper in the ore is not metallic; it is not really 
 copper, it is carbonate of copper, just as iron rust, 
 though formed from iron, will not do to make a 
 crowbar of, so in our operation the balls of copper 
 must be retained. Still the copper contained in 
 such ores, can be and is utilized as follows : a cer- 
 
SILVER OEES. 29 
 
 tain quantity of iron borings is put into the barrel, 
 together with the charge of ore, salt and sulphate 
 of iron, and by a complex reaction, which I shall 
 not explain here, economizes the consumption of 
 the balls by producing copper from the ore, with- 
 out, however, diminishing the quantity in solution. 
 The quantity of iron to be used in this way depends 
 on several circumstances, and varies from 2 pounds 
 to 50 pounds to the ton of ore. Rich ore will bear 
 more than that which is poor, but it must be regu- 
 lated by the quality of the bullion, as too much 
 produces a coppery amalgam. It is not essential 
 to use it at all, but it is economical. Iron is not 
 used in this process except when working ores con- 
 taining carbonate of copper, or as already shown, 
 in preparing the dichloride, and as the quantity 
 must in all cases be under control, the process 
 cannot be worked in iron pans. 
 
 [23.] The quantity of chemicals, iron, etc., re_ 
 quired in working any given class of ore is soon 
 found, so that after working a couple of charges 
 there is no need of testing every time. In Benton 
 the average quantity of sulphate of iron used was 
 22 pounds per ton of ore. 
 
30 TESTING AND WORKING 
 
 [24.] Carbonate of lime and of lead, if in great 
 quantity, make these processes expensive by con- 
 suming too much of the chemicals, and can only 
 be overcome cheaply, by means of sulphurous acid, 
 which, moreover, has many advantages over sul- 
 phate of iron in working coppery ores. 
 
 [25.] Aaron's process has the great advantage 
 of always giving fine bullion, no matter how base 
 may be the ore, if properly managed, and the 
 quicksilver always comes out clean. Among the 
 
 ores which can be worked by it are .partzite, stete- 
 
 * * A!^K~ 
 feldtite, silver glance, carbonate of silver, ruby 
 
 silver, etc. ; galena, zincblende and copper pyrites, 
 containing silver, do not yield well. 
 
 [26.] The ores of this country are usually very 
 mixed, and often it is difficult to determine in 
 what condition or combination the silver exists in 
 them, so it is not always safe to say what process 
 will prove best, without making a trial. Some 
 ores which prove refractory in the raw state, may 
 be made workable by roasting in open or covered 
 heaps or kilns. It is easily tried by burning a 
 small pile and then taking a fair sample and mak- 
 
SILVER ORES. / * . J> 8x4^4 
 
 ing a test on 5 pounds. Chloride ores^yajreadjr/ ^ 
 stated, require no special treatment, being f eC&ty ' ' 
 worked in barrels or pans with salt and quicksilver; \y 
 but I wish to observe that of the ores commonly <^ 
 called "chlorides" by the miners, not one in a hun- 
 dred contains any chloride, being, in nearly every 
 case, simply an ochreous compound of base metal, 
 which may or may not carry some silver. 
 
 [27.] A separator with an iron bottom which is 
 scoured by wooden muller shoes, is used in con- 
 nection with this process, by which means a large 
 loss of quicksilver is avoided. The machine I have 
 found to answer best is described further on. In 
 it the warm pulp as it comes from the barrel, con- 
 taining dissolved copper, is worked, without 
 addition of water, for a greater or less length of 
 time, whereby a quantity of copper amalgam is 
 formed on the iron bottom, and nearly all the 
 mercury is saved. On this account the bulk of 
 quicksilver and amalgam is not allowed to pass to 
 the separator, where it would be mixed with the 
 base amalgam there formed, but is retained in the 
 trough through which the pulp flows, by means of 
 a riffle, or "pot," and after being sponged clean, 
 is led by an iron pipe to the strainer, 
 
32 TESTING AND WORKING 
 
 The base amalgam from the separator may be 
 disposed of in several ways 
 
 1st. It is returned to the barrel, where it 
 answers the same purpose as metallic copper, and 
 saves the consumption of the balls, but too much 
 will spoil the bullion. 
 
 2d. It is retorted, and as in this operation 
 there occurs a partial separation of the copper 
 from the silver, of which latter there is always 
 more or less present, the spongy metal is broken 
 to pieces, and assorted into two or three grades; 
 the finer part is melted and sold, and the nearly 
 pure copper is used to make the dichloride for fu- 
 ture use. 
 
 3d. The retorted metal is melted, and cast into 
 bars or balls for use in the barrel. 
 
 Thus the metallic copper consumed in the amal- 
 gamator, and with some ores that also which is 
 used as dichloride or bluestone, is recovered at 
 the expense of the iron bottom of the separator, 
 and in the case of ores containing carbonate of 
 copper, as much copper as is desired may be made 
 so long as there is any left in the ore to get out. 
 It would be perfectly possible to work copper ore 
 for copper on this plan, but we can do better by 
 leaching on the Hunt and Douglass plan. 
 
SILVER ORES. 33 
 
 In working the ores of Mono County, it was 
 found that when a separator made entirely of wood 
 was used, a large quantity of quicksilver passed off 
 in the form of a red powder, easily detected by 
 panning, but containing no visible metallic quick- 
 silver; the use of the iron bottom prevented this 
 loss by decomposing the red powder, but in order 
 to produce this effect there roust be copper in solu- 
 tion in the pulp, which however is always the case 
 if it has been properly worked in the barrel. After 
 a sufficient time the separator is filled with water, 
 and subsequently discharged in the usual way by 
 plug-holes. Amalgamators specially adapted to 
 this process, will be described in their place. 
 
 PATCHEN'S PROCESS. 
 
 [28.] The Patio is the mother of Aaron's pro- 
 cess, the Fondon is its elder sister, and Patchen's 
 process is a younger member of the same family. 
 As it is patented, a minute description is not needed 
 here. It consists essentially in treating the pulver- 
 ized ore with dichloride of copper, and without 
 quicksilver, in a copper-lined, steam-heated vessel, 
 after which it is transferred to an iron pan, and 
 worked with quicksilver. The process commends 
 2* 
 
34 TESTING AND WORKING 
 
 itself to Virginians by making use of tke iron pans 
 with which all their mills are provided, but equally 
 good results are got by Aaron's process, and as 
 the tests described for them are not applicable to 
 this, the operation is not so easily regulated, whilst 
 in some cases the bullion obtained is not fine, 
 owing to the action of the iron pan in extracting 
 copper or lead. 
 
 ROASTED ORES. 
 
 [29.] Koasted ores may be worked in ban-els 
 with scrap iron or copper balls, or in iron pans. 
 Ores containing much copper, lead, etc., will not 
 yield fine bullion in pans, unless the roasted ore is 
 first washed in filter vats with acidulated water, to 
 dissolve out the salt which may remain after roast- 
 ing, and the base metal chlorides, some of which 
 are not soluble in plain water. Barrels with scrap 
 iron give a finer bullion from such ores, than pans, 
 but any roasted ore will yield fine bullion if worked 
 in barrels with copper balls, or in the new machine 
 hereafter described. When these machines or bar- 
 rels are used, it is sometimes necessary to sift the 
 ore to remove lumps formed in the furnace, which 
 are either returned to the battery or ground in a 
 
SILVER 
 
 pan. On this account, pans are usi 
 though the wisdom of the choice is 
 especially if the ore is base. I have in some 
 got 90 per cent, of the silver from roasted ore, in 
 barrels, without sifting. As nearly all the salt used 
 in roasting is decomposed or evaporated, it is very 
 advantageous to add a little to the pulp in the 
 amalgamator; it acts by dissolving the chloride of 
 silver, which aids its reduction to metal. . The 
 quality of bullion obtained from base roasted ore, 
 when worked in iron pans, may be improved by 
 adding a certain quantity of lime or ashes, but an 
 excess must be avoided. 
 
 [30.] It is a common error to suppose that the 
 object of roasting is to " destroy" the base metals, 
 and this absurdity has been encouraged by some 
 who ought to know better; hence many think that 
 roasted ore ought always to yield fine bullion. 
 The truth is, that silver ore is roasted with salt for 
 the purpose of changing the various and refractory 
 compounds of silver into one known and easily 
 reduced compound, namely, chloride. Now if 
 this could be done without affecting the base 
 metals at all, we should always get fine bullion, 
 
36 TESTING AND WORKING 
 
 because the base metals would not be extracted by 
 the pan; but it unfortunately happens that the 
 roasting', which aids us to get the silver, puts the 
 copper, lead, etc. into a similar condition, and 
 they are not driven off to any great extent in the 
 operation. It is true that, by a certain modifica- 
 tion of the roasting process, the base metals can 
 again, in a measure, be changed so as not to be 
 amalgamated, but this causes loss and expense, and 
 is never fully effective, besides which the chemical 
 action in the pan is such as first to reproduce and 
 then decompose the base metal chlorides, so that 
 after all they find their way into the amalgam more 
 or less; nor can this action be entirely prevented 
 by the use of potash or lime in the pan, since the 
 quantity of these which would produce the re- 
 quired effect, would also interfere with the amal- 
 gamation of silver. 
 
 [31.1 The chloridizing roasting of silver ore is 
 not so mysterious or difficult an operation as some 
 suppose, and others pretend that is, practically. 
 The proof of this is the success attained by many 
 persons of no scientific attainments, and of quite 
 moderate ability. What is principally necessary, 
 is courage to try, and then courage to try again. 
 
SILVER ORES. 37 
 
 Of course in a custom mill, where different kinds 
 of ore are constantly coming in, and where no fail- 
 ures are allowable, knowledge and experience are 
 indispensable in the operator; but any person of 
 common intelligence may soon learn to roast a 
 given kind of ore, especially when he is his own 
 boss, with no one to grumble at his mistakes. In 
 large operations the mechanical roasters, such as 
 Stetefeldt's, White's or Bruckner's, should be used; 
 but for a small mill, working about two tons of ore 
 per day, and owned by the miner himself, a rever- 
 beratory, such as I shall describe, will answer per- 
 fectly, though if one can afford to, get a Bruckner 
 and run it, say one or two days in a week, the 
 work will be done cheaper. 
 
 [32.] To roast ores well requires practice, the 
 directions I shall give, will therefore be brief and 
 general in their character, to be interpreted and 
 applied with judgment. A knowledge of the 
 theory should be indispensable to the professional 
 man, who ought to know the why, as well as the 
 how, to do things; but our "honest miner" only 
 wants to know how to get a fair percentage of the 
 silver out of his particular ore, 
 
38 TESTING AND WORKING 
 
 [33.] The essentials of chloridizing roasting are 
 heat, air, sulphur and salt. Heat is obtained by 
 means of fire; air enters the furnace through the 
 fire-place, and through openings in the sides; salt 
 is supplied by the operator, and sulphur either 
 exists naturally in the ore, or is added to it in some 
 shape. Ores having lime in them, require more 
 sulphur than such as have a quartz gangue. 
 
 [34.] Night is the best time to study roasting, 
 as the different degrees of heat are then most 
 readily seen, and for the same reason the furnace 
 is best in a place where there is not too much light 
 in daytime. What I say about the heat must be 
 considered as referring to appearances as seen at 
 night, and when the fire is not flaming. 
 
 [35.] The furnace is heated to a dark red, the 
 ore is put in, spread on the hearth, and stirred at 
 short intervals with hoe or rake. From 5 to 10 
 per cent, of salt is charged with the ore. It is best 
 to begin with the larger quantity, and when the 
 roasting is found to yield a good result, less salt 
 may be tried, till the lowest quantity that will 
 answer is found. If, on stirring the ore, the sul- 
 
SILVER ORES. 39 
 
 phur is seen to burn with a blue flame, the fire is 
 kept very low, and the ore stirred continually till 
 no more sulphur is seen to burn, which may, in 
 extreme cases, take several hours, during which 
 the fire is allowed to almost go out. The heat is 
 then raised slowly to about a cherry red, the ore 
 still being stirred, and not till a sample, taken 
 from the furnace with a drill spoon, smells no longer 
 of burning sulphur, is the heat raised, gradually, 
 to a light red, approaching to white, but not so as 
 to slag the ore, which at this time assumes a con- 
 dition which has been described as woolly, spongy 
 or feathery, and swells greatly, while, whereas at 
 an earlier stage it appeared very mobile, running 
 and spreading like water, it is now rather sticky, 
 and "stays put." As at this time less constant 
 stirring is needed, this is a good opportunity to 
 scrape the ore thoroughly out of all the corners, 
 piling it in the middle of the hearth, after which it 
 is again spread. When all the ore is equally heated, 
 so that on stirring clear to the bottom, and in the 
 corners, no black places are seen, the fire is allowed 
 to go down, ready for another charge, the ore 
 being drawn away from the bridge, and moved 
 only enough to prevent any part from getting so 
 
40 TESTING AND WORKING. 
 
 hot as to melt. It is well to draw it into a heap 
 ready for discharging, which is done as the fur- 
 nace cools off. 
 
 [36.] On taking a sample of the roasted ore, 
 and panning it down in a saucer, no raw sulphurets 
 should be seen. Lumps, more or less, there will 
 be, but there should be no slagged or sintured 
 ones, except as occasionally, by accident, a little 
 ore has stuck to the bricks, and after being slightly 
 melted, has been scraped off again; and right here 
 I want to say something about stirring. Never 
 push the hoe so as to jam the ore against the side 
 of the furnace, but when it is within about a foot 
 of the bricks, lift it clear of the ore by lowering 
 the handle, push it on over the ore, and then let it 
 down and move it the other way. Thus you will 
 avoid plastering the sticky ore on to the bricks, 
 and sare much trouble. 
 
 [37.] The chief danger in roasting is in apply- 
 ing too high a heat at first, but ores which contain 
 little sulphur may be heated more rapidly than 
 those which have much. Some ores with calca- 
 reous gangue roast to 90 per cent, without at any 
 
SILVER ORES. 41 
 
 time smelling strongly of sulphur or of chlorides. 
 The color of the roasted ore varies greatly, depend- 
 ing on the constituents, the degree of heat to 
 which it is exposed, and the exposure to air, both 
 in the furnace and after it is withdrawn. The 
 knowing just when to discharge the ore is a mat- 
 ter of judgment and experience, the only reliable 
 test of its being well roasted, except by working- 
 it, being such as to require a knowledge of assay- 
 ing. There is however, a test, in addition to that 
 by washing in a saucer already spoken of, which 
 may afford a clue. It consists in throwing a little 
 of the red hot ore into a dish of water; well roasted 
 ore will diffuse a white cloud in the water, whilst 
 if the roasting is not finished, the cloud will be 
 more or less yellow. 
 
 [38.] Ore which fails to roast well for want of 
 sulphur, requires the addition of 2 or 3 per cent, 
 of iron pyrites, or sulphate of iron, or a little pul- 
 verized sulphur. 
 
 LEACHING PROCESSES. 
 
 [39.] Leaching processes are of several kinds, 
 for gold, silver, or copper, or all three combined. 
 
42 * TESTING AND WORKING 
 
 They all involve the necessity of roasting, with or 
 without salt. The roasted ore is put into filtering 
 vats, and the metals are extracted, just as lye is 
 extracted from ashes, by passing through the mass 
 a fluid which dissolves them, after which they are 
 separated from the fluid by the addition of a sub- 
 stance which throws them down, either in a metal- 
 lic state, or as insoluble compounds, which must be 
 again treated for the pure metal. These processes 
 are very admirable, and in many cases cheaper 
 than amalgamation. Some difficulty is frequently 
 found in getting the dissolving fluid through the 
 ore fast enough, and to overcome this, I have con- 
 trived two different machines, to be described 
 hereafter. 
 
 SMELTING. 
 
 [40.] It has already been mentioned that, in 
 certain circumstances, smelting is the best process 
 for extraction of silver. As I have no experience 
 in this line, any instructions I could give would 
 only be copied from some one else, to which some 
 one else I therefore beg to refer the reader who is 
 anxious to smelt his ore. He can find much about 
 it in various books, after studying which he will 
 still have much to learn. 
 
/%> *& 
 
 SILVER ORES. / K 4O < 
 
 /^\ V^;' > 
 
 [41.] When a Mexican finds 
 get galena in the vicinity, he puts up a litfl^tfur- ^ 
 nace of adobes, smelts out his silver-lead, refinery 
 in another little furnace, and buys his beans wit3j "M. , 
 the proceeds. Why cannot intelligent Americans, 
 who have opportunities of seeing smelting carried 
 on, go and do likewise ? In course of time the 
 knowledge would spread, and many honest miners 
 might profit by their discoveries, instead of wait- 
 ing for capital, or abandoning their mines, because 
 they cannot sell them. 
 
 A MEXICAN PROCESS. 
 
 [42. ] The terreros, containing fragments of ores, 
 consisting of oxides and sulphides, are ground to 
 an impalpable powder in the arrastra, with addition 
 of the new magistral, for some hours, at the ex- 
 piration of which period quicksilver is added, and 
 the grinding continued till all the silver be amal- 
 gamated. Ores containing chloride, or iodide of 
 silver do not yield'to this process, and compounds of 
 chlorine in every form must be carefully excluded. 
 The grinding must be done in stone, not in iron 
 arrastras. Excess of the magistral is to be avoided, 
 as it vitiates the amalgam. 
 
44 TESTING AND WOBKING 
 
 The new magistral is made by digesting sub- 
 oxide of copper with sulphuric acid, in equivalent 
 proportions, which forms an intimate mixture of 
 sulphate of copper and finely divided metallic 
 copper. 
 
 For the above description I am indebted to Mr. 
 John Scott, of San Francisco, Assay er. I know 
 nothing more about the process, but it is not clear 
 to me that a mixture of cement, copper and blue- 
 stone would not answer as well as the above prep- 
 aration, which must be rather expensive. 
 
 KRCENCKE'S PROCESS. 
 
 See ^B 
 
 [43.] Kroencke's process is practiced in Copiapo, 
 Chili, and is described as follows in the American 
 Chemist: 
 
 " The ores of this district, consisting of the 
 chloride, iodide and bromide of silver, together 
 with various sulphides of silver, occur in Jura lime- 
 stone and marl, diabase and porphyry, and have 
 associated with them, as veinstones, calcite, heavy 
 spar, gypsum, amianthus, kaolin, and in the upper 
 levels, ferruginous clay. There has never been 
 any difficulty in completely extracting the metal 
 from the chloride, bromide and iodide by amal- 
 
SILVEB OEES. 45 
 
 gamation, while the sulphurets have alway's been 
 the cause of large losses in the residues. Krcencke 
 first based his process on the treatment of these 
 residues and subsequently extended it so as to 
 treat the pure sulphides, arsenides and antimo- 
 nides of silver. The writer made a series of experi- 
 ments in order to arrive at a theory of the process. 
 He found : 
 
 1st. If ruby silver be digested in a finely pul- 
 verized condition with a hot concentrated solution 
 of cupric sub-chloride and sodium chloride, a 
 chemical reaction is soon perceptible, the powder 
 turning black. An analysis of this powder shows 
 the formation of argentic sulphide and cupric sub- 
 sulphide, while antimonic chloride is found in the 
 solution. The reactions are 
 
 3AgS,SbS ; ,+3(Cu 2 Cl)+NaCl=3AgS + SbCl 3 +3(Cu 2 S) + 
 NaCl. 
 
 2d. If the silver sulphide thus obtained be 
 again treated in a hot solution with cupric sub- 
 chloride and sodium chloride, and zinc is added, 
 metallic silver is almost instantaneously formed. 
 The reactions are 
 
 The zinc probably acts as electro-positive metal, 
 
46 TESTING AND WORKING 
 
 predisposing the atoms of argentic sulphide and 
 cupric sub-chloride to a mutual exchange, so that 
 the cupric sub-sulphide and argentic chloride are 
 formed; which last is decomposed in a nascent 
 state by the zinc, with the formation of zinc chlo- 
 ride and silver. If the very finely divided argentic 
 sulphide obtained in the first experiment be taken, 
 the action of the reagents is almost instantaneous. 
 If, however, the experiment be made with a small 
 piece of argentite (AgS) in contact with a small 
 piec 3 of zinc, a dull white coating is formed on the 
 surface of the argentite, which is probably argentic 
 chloride, and which only assumes a metallic ap- 
 pearance with prolonged action of the zinc. 
 
 3d. If in the second experiment mercury be 
 also added, the reduction of .the silver takes place 
 still more rapidly, while at the same time amalgam 
 is formed. Lead can be used instead of zinc and 
 both act more powerfully when used in the form of 
 amalgam. The chief points in this method of 
 treatment are : .. 
 
 1st. The use of a hot concentrated solution of 
 cupric sub- chloride and sodium chloride, especially 
 of the latter, in order to retain a larger amount of 
 cupric sub-chloride in solution, and to prevent the 
 formation of basic copper salts. 
 
SILVER ORES. 47 
 
 2d. The use of perfectly dry ore, finely pulver- 
 ized, in order that it may easily absorb the solu- 
 tion. Wet ores cause the formation of basic salts, 
 and hence loss of effective cupric sub-chloride, as 
 well as imperfect impregnation. 
 
 3d. The use of cupric sub-chloride and of lead 
 or zinc in combination with mercury as amalgam, 
 in such quantities that the reactions described may 
 take place through all the ore without any excess 
 of the last-mentioned metals. Since an excess of 
 cupric sub-chloride is generally used, this last will 
 be decomposed by the lead (or zinc) and copper 
 formed, which pass into the amalgam and whose 
 removal is always troublesome when present in 
 large quantities. Krcencke treats very cuperif erous 
 amalgam, after having been squeezed and ground 
 in a centrifugal apparatus, with a hot solution of 
 cupric chloride in order to extract the copper. 
 (OuCl+Ciu=Cu 9 Cl.) 
 
 4th. It is always advisable, so far as practicable, 
 to treat ore of constant composition, as otherwise 
 experiments on a small scale must be constantly 
 made, even when but slight variations occur in the 
 nature of the ore. The presence of mere traces of 
 blende make the process much more expensive, 
 
48 TESTING AND WOKKING- 
 
 while large amounts of the same render the use of 
 this method impossible, as the cupric sub-chloride 
 solution is instantly decomposed by the blende." 
 
 THE CHILIAN PROCESS. 
 
 [44.] The Chilian process, described in the 
 Mining and Scientific Press of January 10th, 1874, is 
 similar to Aaron's process, and presents no advan- 
 tages over the latter. Other methods are treated 
 of in standard works on the subject. 
 
~ 
 
 PULVERIZING MACHINES%/ 
 
 [45.] On this subject I shall confine my re- 
 marks to machines which are calculated for small 
 operations. The splendid stamp batteries no\\ 
 used in our first-class mills call for neither descrip- 
 tion nor comment here. 
 
 THE ARRASTRA. 
 
 [46.] The arrastra is the poor man's mill. It 
 consists of a circular pavement of stone, upon 
 which the ore is crushed by drawing over it heavy 
 stone drags, attached by chains to a horizontal 
 beam, or two crossed beams, pivoted to a post in 
 the center of the pavement, motion being imparted 
 either by water, steam or horse-power. The stone 
 pavement is surrounded by a low wall of rock or 
 wood, to retain the ore and water during the 
 grinding, and in which is a gate for discharging 
 the pulp. The Mexicans often build an arrastra 
 and water wheel in one, the beams to which the 
 drags are attached being prolonged to form the 
 3 
 
50 TESTING AND WORKING 
 
 spokes of a horizontal reaction wheel, surrounding 
 the arrastra, which is driven by a stream of water 
 from an inclined sluice. 
 
 [47. 1 When used for grinding silver ore, as the 
 quicksilver is not put into the arrastra, there is no 
 need for nicety in its construction, nor for tamping 
 between the bottom stones. The pavement is 
 made of rather thin stones set up edgwise on a bed 
 of sand, and should not be laid nearer than six 
 inches from the outer wall, or the center post, 
 otherwise it cannot be kept flat as it wears down. 
 The spaces thus left are filled with gravel or clay. 
 The first charge worked in a new arrastra consists 
 of some barren rock and clay, by which all inter- 
 stices are filled, to avoid loss of valuable ore. An 
 arraslra of 10 feet diameter, with drags as heavy as 
 can be drawn by a 2-horse power water wheel, or 
 about 40 miners' inches of water, on a 30 foot over- 
 shot wheel, will grind from 1J to 2 tons of ore in 24 
 hours, in charges of 1,000 to 1,500 pounds. It 
 is placed so that the pulp, when sufficiently ground, 
 flows directly from it to the amalgamator, which is 
 on a lower level. The pulp is kept as thick as is 
 consistent with good grinding. 
 
SILVER ORES. 51 
 
 [48.] The arrastra may be made to grind and 
 discharge continuously, by making part of the sur- 
 rounding wall to consist of a fine screen of wire 
 cloth, through which the pulp flows into a circular 
 trough, and thence to a vat. Water flows in con- 
 tinuously, and is regulated so that while the pulp 
 is thin enough to flow through the screen when 
 fine, yet the sand is not allowed to settle so as to 
 pack on the bottom. Ore is fed in at inter- 
 vals of about half an hour. The water which flows 
 from the settling vat is either returned to the 
 arrastra by means of a wooden pump, or an archim- 
 edian screw, or it is led into a reservoir where all 
 suspended matter is deposited. From 8 to 10 
 revolutions per minute is the proper speed for a 
 10-foot arrastra. The drags are as heavy as the power 
 will allow, and so arranged as to keep the bottom 
 flat as it wears; they are attached to the beams by 
 chains, hooking into iron eyebolts set into the rock 
 with melted lead. The lead after being poured in, 
 shrinks in cooling, so that it is a little loose, and 
 it is tightened by being driven down with a set or 
 punch. The drags are so hung that the forward 
 end is lifted a little, which prevents catching and 
 jerking; they are also retained in the required 
 position by stay chains at the rear ends. 
 
52 TESTING AND WORKING 
 
 [49.] The arrastra will grind dry as well as wet, 
 the only trouble is to get the ore ore out as fast as 
 it is ground, which is done while the machine is in 
 motion, with a shovel, and it is sifted by a rotating 
 cylindrical sieve, so arranged that the coarse stuff 
 falls again into the arrastra. This is very poor 
 work, and I think it might be done much more 
 conveniently by making the enclosing wall to con- 
 sist of a set of fine screens on a circular framework; 
 then, by means of a sort of scoop, somewhat sim- 
 ilar to a plowshare, attached to one of the rotating 
 beams, the ore will be thrown forcibly against the 
 screen, and the fine portion will pass through. 
 Such an arrastra should be worked at 15 to 20 
 revolutions per minute, should have a light remov- 
 able cover, and the bottom, instead of being flat, 
 should be conical, deepest in the center, where the 
 ore should be fed in at intervals. By this arrange- 
 ment very coarse ore will never reach the screens 
 to break them. This machine should be driven by 
 a belt, to avoid serious damage in case of a drag 
 getting loose. 
 
SILVER ORES. 53 
 
 STAMP BATTERIES. 
 
 [50.] Stamp Batteries with 4 light stamps of 
 400 pounds each, are preferable to those with two of 
 800 pounds each, because the parts are more easily 
 handled, and the strain on the machinery is more 
 even. In wet crushing the water should never, in 
 a silver mill, be allowed to run off, but should be 
 pumped, or raised with a screw, from the settling 
 tank, and passed again to the battery. It is a 
 good plan to saturate the water with salt, which 
 facilitates the settling of slimes, and in cold- 
 weather, tends to prevent its freezing. Ore can be 
 crushed nearly as fast dry as wet, provided it can 
 be got out of the mortar as fast as it is reduced 
 fine enough. The discharge is facilitated by the 
 following arrangement: 
 
 [51.] In place of the usual fine screen in the 
 mortar, a coarse one of 8 or 10 meshes to the lin- 
 ear inch is used; the ore passing rapidly through, 
 falls on to an inclined apron, formed of fine wire 
 cloth stretched on a frame, which is hung to the 
 battery posts by hooks and eyebolts, and by iron 
 
54 TESTING AND WORKING 
 
 rods, arranged with buckle screws, by which they 
 can be lengthened or shortened to alter the inclin- 
 ation as required. This apron is five or six feet 
 wide one way, and as wide as the mortar the other 
 way. The fine ore passes through into a receptacle 
 below, while the coarser part passes over the apron 
 and falls into another box. In some cases the 
 coarse matter consists almost entirely of gangue, 
 and is too poor to be worked, so that a certain 
 concentration of the richer part is effected,, but 
 otherwise it is returned to the battery together 
 with fresh ore. In large mills conveyors and 
 elevators dispose of the coarse and fine material 
 respectively, as may be desired, but in a small one 
 this is done by hand. No " joggler" is required to 
 shake the apron, as the jarring of the battery to 
 which it is attached is sufficient. In order to be 
 crushed fast, and pass readily through the screens, 
 ore must be thoroughly dried by artificial heat, es- 
 pecially if it contains clay or talc. It may appear 
 perfectly dry and yet contain as much as 7 per 
 cent, of water, which will evaporate in the heat 
 produced in crushing, and by condensing on the 
 screens, will cause the fine dust to stick. The 
 drying may be done in a kiln or oven, and the ore 
 
SILVER ORES. 
 
 55 
 
 fed into the battery quite hot. Where the ore 
 has to be burned in heaps before working, it will 
 be crushed very easily. 
 
 CROCKER'S TRIP-HAMMER 
 BATTERY. 
 
 [52.] Crocker's Trip-hammer Battery is a ma- 
 chine of which, on theoretical grounds, I think 
 very favorably, and I can state from observation 
 that it crushes rock very fast. The advertisement 
 states that it crushes 600 pounds per hour, requir- 
 ing one-horse power to drive it. The advantage of 
 applying a given amount of power in the form 
 of a light hammer, moving at high velocity, 
 
 rather than a heavy one at low velocity, is well 
 known, and is illustrated by the breaking of stone 
 for macadamized roads in England, which is 
 
56 TESTING AND WORKING 
 
 always done with a light hammer on a long handle. 
 In this battery the velocity of the blow is obtained 
 by means of wooden springs, acting under the 
 short arms of the levers to which the hammers are 
 attached. As to the stated power required, it is 
 probably under- estimated, as a calculation by the 
 usual empirical formula of mechanics, based on the 
 width and speed of belt used, gives three-horse 
 power as the result. These calculations, however, 
 are not exact unless the tension and material of the 
 belt, and extent of contact are strictly taken into 
 account; and I find that a calculation based on the 
 number of drops, height of lift, and weight of 
 hammers, gives but little over half a horse power 
 as the theoretical amount required ; to which must 
 be added an unknown quantity for friction, and 
 for the excess of weight of the longer ends of the 
 arms over that of the shorter ends. The truth 
 probably lies between the two estimates. Allow- 
 ing, however, that it takes three-horse power, the 
 performance of the machine shows an immense 
 gain over that of the common battery, while its 
 small size and weight, being only 1,500 pounds; 
 and the fact that it requires no building up, being 
 all ready for use when bought, and may be taken 
 
SILVEK OHES. 57 
 
 to pieces and set up by one man, combined with 
 the low cost, entitle it to the favorable consider- 
 ation of miners, and adapt it especially to the use 
 of that class of small mine owners, to whom prin- 
 cipally I address myself. 
 
 In working, the springs are not compressed by 
 the direct action of the cams, but are so adjusted, 
 that if the cam shaft be revolved slowly, no com- 
 pression takes place; but at the high speed used 
 in actual work, the acquired momentum of the 
 rising hammers, carries the levers beyond the 
 direct range of the cams, and causes the short ends 
 to come in contact with the springs, by the elas- 
 ticity of which they are driven upward, causing 
 the hammer to descend with great velocity. The 
 information I have been able to obtain at the 
 foundry does not indicate any undue liability to 
 breakage. 
 
 PAUL'S 
 PULVERIZING BARREL. 
 
 [53.] Paul's Pulverizing Barrel is a happy con- 
 ception, the value of which is not yet generally ap- 
 preciated. It is most advantageously used to fol- 
 3* 
 
58 
 
 TESTING AND WORKING 
 
 low a battery which crushes dry through a screen 
 of about 30 meshes to the linear inch, and is excel- 
 lently adapted to the preparation of silver ores for 
 
 mr 
 
 raw working, or of roasted ores for amalgamation 
 in machines which do not grind, as barrels. As 
 rock is used to grind rock, there is less wear of 
 
SILVEB OEES. 59 
 
 iron than in other iron pulverizers, a point which is of 
 great advantage when treating ores by those pro- 
 cesses which depend on the use of solutions of cop- 
 per, except indeed, in those cases of copperous ores, 
 in which, as already explained, a certain quantity 
 of iron may be used with advantage. There is an 
 impression among some, that this machine works 
 very slowly, but I think this judgment has been 
 formed without due consideration of the work done. 
 A machine which will take 10 tons of ore, as it 
 comes through a 30-mesh screen, and will pass it 
 all through a screen of 120 meshes to the linear 
 inch in 24 hours, using only 4-horse power to do 
 it, performs an enormous work, and this, I am told 
 by disinterested parties, is what Paul's barrel does. 
 
 If coarser screens were used it would of course 
 
 
 
 work faster, but the unprecedented fineness of the 
 screens preferred by Mr. Paul in working 'gold 
 ores, is justified by the increased yield of the ore. 
 In treating silver ores this extreme degree of fine- 
 ness might not be required; it is a point to be reg- 
 ulated by trial that which is on the whole most 
 profitable being the best. 
 
 I wish it to be distinctly understood, that in 
 speaking of Paul's pulverizer, I do not mean Paul's 
 
60 TESTING AND WORKING 
 
 dry amalgamation process, which, though it seems 
 to be a good thing for gold, is not yet proved to be 
 so for silver, as the two metals exist in a totally 
 different condition in ores. 
 
 PULVERIZING BARREL. 
 
 [54. j A pulverizing barrel may be made of wood, 
 not to discharge continuously like Paul's, which 
 also feeds itself, but to work by charges It is 
 made like the amalgamating barrel, and lined in 
 same way. The ore is coarsely crushed before 
 being put in ; and a quantity of small iron balls, or 
 pieces of hard rock, are put in with it. A proper 
 adjustment of the speed with which the barrel ro- 
 tates, causes the ore and balls to roll over with a 
 grinding action, without much wear of the barrel. 
 A grating keyed in the bunghole of the barrel, 
 when discharging, retains the balls, and allows the 
 pulverized ore to come out. The barrel may be 
 mounted on a wooden shaft passing clear through, 
 and with broad bands of iron on the ends for jour- 
 nals, and friction rollers under them; or it may be 
 arranged in any of the ways described for amal- 
 gamating barrels, omitting of course the hollow 
 
SILVER ORES.-^A 
 
 ? >> 
 ^V^* 
 
 journals for steam, and the precautions regarding 
 iron inside, both of which are needless/ Y\ 
 
 KENDALL'S BATTERY. 
 
 [55. 1 Kendall's battery is another recent inven- 
 tion, designed for small operations, which, like 
 Crocker's, is ready for use when bought. It can 
 strike any required number of blows per minute, 
 but has no springs. I should think it a good 
 machine for small operations. [For cut of this 
 Battery see next page.] 
 
 NOICES' PULVERIZER. 
 
 1 56. | Noices' pulverizer is a queer looking ma- 
 chine, in which the rolling action of the Chili mill 
 is combined with the grinding of the arrastra. It 
 seems simple and efficient, is worked with water, 
 and though designed especially for crushing and 
 amalgamating gold rock, would work well in treat- 
 ing silver ore without roasting. From this machine 
 I have derived the idea of a cheap rock breaker, or 
 
 grinder, now to be described. 
 
 4 
 
TESTING AND WORKING 
 
SILVER ORES. 
 
 63 
 
 A CHEAP ROCK BREAKER. 
 
 [57.] In the above cut, a, is an inclined table, 
 made of one or more pieces of rock, enclosed by a 
 low wall of rocks or wooden lags. On the table 
 rests a mass of rock b, which is connected by the 
 iron rod c, with the crank d; another iron rod e, 
 also fastened into the rock b, passes through a 
 slot in the post/ 1 . The ore to be broken is thrown 
 upon the table in front of the moving rock, which, 
 by the rotation of the crank in the direction of the 
 arrow, is lifted and drawn forward over the ore. As 
 the crank continues its rotation, the weight of the 
 rock, and the sliding movement imparted to it, crush 
 
64 TESTING AND WORKING. 
 
 the ore beneath it, and cause it gradually to work 
 out at the lower end of the table, when it may be 
 transferred to a pulverizing barrel, or sifted, and 
 the coarser part reground in the machine. This is 
 merely a suggestion, and improvements will doubt- 
 less be made by intelligent miners. 
 
AMALGAMATORS. 
 
 [58.] The man who, though poor 'in pocket, has 
 rich ore, need not despair of getting along, if he 
 has energy and some ingenuity. A five gallon 
 beer barrel will make an admirable amalgamator 
 for 50 pounds of ore, which, if worth $500 per ton, 
 
 will yield as much money as a ton of Comstock 
 ore at $12.50 per ton. A 10 gallon barrel will suf- 
 fice to extract the same sum from 100 pounds of 
 $250 ore, and either of these, or even a larger cask, 
 may be mounted, as follows: 
 
66 TESTING AND WORKING 
 
 Find the centre of each head, and cut a hole, 
 three inches square for the smallest barrel, and 
 large in proportion for other sizes. Make a wood- 
 en shaft to fit tightly in the holes, and long enough 
 to form journals at each end. On one end fix a 
 crank, and in the' center of the other bore a f inch 
 hole, far enough to reach inside the barrel when 
 the shaft is in place, and connecting with a cross 
 hole through the shaft, so as to communicate with 
 the interior of the barrel. Put the shaft in its 
 place through the barrel, and enlarge the bung- 
 hole, either round or square, and make a bung to 
 fit. Mount the barrel on supports, just as you 
 would a windlass. Next, get a tin boiler, have the 
 cover soldered on, and an inch hole made in it, to 
 pour water in with a funnel. Next get a piece of 
 J-inch gas pipe with a stop-cock in the middle, and 
 a flange made of a collar soldered on two inches 
 from one end, and solder the other end into the 
 boiler near the top; and it will be best to have two 
 small faucets set in, one six inches from the bottom 
 of the boiler, the other higher up, for try cocks to 
 show how much water you have. The hole in the 
 top must not be plugged, but an iron or lead 
 weight must be used to close it; if the hole be one 
 
SILVER ORES. 67 
 
 inch diameter, the weight may be from one to two 
 pounds; this forms a safety valve. Mount the 
 boiler, with a fire place below it, so that the 
 steam pipe may enter the hole in the end of the 
 barrel shaft as far as the flange. Get from 5 to 20 
 pounds of copper, in the form of balls, from ^ to*l 
 inch in diameter, or little bars, or pieces of any 
 kind, not too thin so as to break up when used; 
 pieces of J-inch sheet are good for a very small 
 operation. When the barrel is charged with ore, 
 and a little water, let the steam from the boiler 
 pass into it before putting in the bung, to drive 
 out the air, then put the bung in securely, and 
 tie a cord round the barrel to keep it in. Turn 
 the barrel by hand or foot, by dog, squaw, china- 
 man, horse, water or steam power, and you have a 
 perfect amalgamator for working Aaron's process. 
 
 [59.] The ore may be ground in any of the 
 machines described for that purpose, or if very 
 rich, even in a large hand mortar, with the pestle 
 attached by a cord to a spring pole. A wash tub 
 fitted with some simple kind of stirrer, will answer 
 for a separator. Work your ore precisely as di- 
 rected, using bluestone instead of dichloride of 
 
68 TESTING AND WORKING 
 
 copper, unless you choose to make the dichloride 
 in your porcelain-lined pot. 
 
 [60.] I have supposed, thus far, that you have 
 already tested the ore, according to the directions 
 given, and found it to yield satisfactorily; but the 
 same barrel, without the boiler, will answer for 
 working roasted ore, only instead of the pieces of 
 copper, it is best to use scraps of iron, in quantity 
 from 10 pounds upward, according to size of bar- 
 rel. If the ore must be roasted, you may build 
 with rocks and mud, a little furnace similar to that 
 described hereafter, but simpler, and as each 
 square foot of hearth will take about 10 pounds of 
 ore, a hearth four feet square will be ample for 
 something over 100 pounds. A barrel for Aaron's 
 process, to contain 1-J tons of ore, is 5J feet long 
 by 4J feet diameter inside, and is mounted either 
 on journals, or on rollers. The ordinary Freiberg 
 barrel answers if the journals be made hollow to 
 admit steam. In calculating the size of a barrel 
 for working unroasted ore, I allow from 20 to 25 
 cubic feet for each ton of ore, and it must be re- 
 membered that, owing to the necessity of admit- 
 ting steam at the center, the barrel can never be 
 
SILVER ORES. 69 
 
 quite half filled, so that a barrel of 100 cubic feet 
 capacity would contain about 2 or 2J tons. 
 
 The barrel is lined with blocks, cut from 3-inch 
 plank, and so placed that the grain of the wood is 
 vertical to the axis of the barrel. These blocks 
 are cut at the saw mill, and before being put in are 
 bevelled at the sides with a jack plane, to suit the 
 circle of the barrel, but the backs need not be 
 rounded, nor is any nicety required in the work, 
 but the bevel should be too much, rather tlian too 
 little. Mechanics are too apt to make a bad job 
 of lining a barrel, simply because they do the work 
 too well; instead of requiring close joints, it is 
 better if the blocks are somewhat rough, and 
 warped sideways, so that in bevelling them the 
 warp should not be taken off with the plane, and 
 in placing them they should be put with two bulg- 
 ing sides, or two hollow sides together, which 
 leaves room for swelling without bursting the bar- 
 rel, or making the lining bulge inward, leaving a 
 space behind it to get full of amalgam. I have 
 known $3,000 of amalgam to be taken from be- 
 hind the lining of a single barrel, which was lined 
 by a good mechanic ; and this accumulation is very 
 troublesome and injurious, by destroying the equi- 
 
70 TESTING AND WORKING 
 
 libriuin of the machine. In putting in a lining, it 
 is only necessary to nail one piece here and there, 
 just to keep them in place till the circle is complete, 
 when they key themselves, and when wet swell 
 tight. When worn through, the lining is removed 
 and a new one put in, for which purpose the bar- 
 rel is furnished with a manhole in the head, which 
 is closed with a door, just as in a steam boiler, but 
 made of wood. 
 
 The staves are made of 3 x 4 scantling, not 
 rounded outside or inside, the heads of 3-inch 
 plank of the hardest pine. There are four hoops 
 of 3 x -J inch iron, with lugs and bolts to set them 
 tight. The lining is two inches thick, and before 
 putting it in, about 20 pounds of roofing petro- 
 leum is melted, and poured into the barrel, into 
 which steam is admitted by the hollow journal, 
 and it is put in motion. The petroleum soaks 
 into the staves, and makes the barrel steam tight; 
 the lining is then put in. For the purpose of 
 charging and discharging, there is a 6-inch bung 
 hole, and a bung which, when in place, comes flush 
 with the lining inside, and is secured by an iron 
 hasp. A small plug in the end of the barrel serves 
 for taking out a sample of pulp for examination 
 when required. 
 
/V f &p 
 
 SILVER ORES. --f^> iPl 
 
 0*,%,%, ** 
 
 [61.] The copper used is^a thMfijjp,of ba4&> j . 
 or small bars of not more than one- go 
 
 The balls are cast, and the bars are sometimes ^ * 
 from long round cast bars, but flat pieces, either 
 cast, or cut from J-inch rolled sheet, are to be 
 preferred, as exposing more surface to a given 
 weight. When the pieces become so small as to 
 be with difficulty separated from the amalgam, 
 they are first passed through the retort, to recover 
 adhering quicksilver, and then remelted and cast. 
 Rolled copper retains quicksilver on the surface 
 only, but that which is cast sometimes become 8 
 permeated throughout with it. The quantity of cop- 
 per used varies with the richness of the ore, a great 
 excess giving rise to a poor quality of bullion, from 
 the fact that more is worn off than can be consum- 
 ed in the chemical action. About 50 square feet of 
 copper surface answers generally for a barrel of \\ 
 tons capacity. 
 
 [62. | One way of preventing the mechanical 
 wear of the copper, is to use only so much quick- 
 silver as to form a hard amalgam, which then ad- 
 heres to the copper. This method was practiced 
 in one of the mills at Benton, and was supposed to 
 
72 TESTING AND WORKING 
 
 economize quicksilver, though I beg leave to 
 doubt this, not on theoretical grounds alone, but 
 because I did not find it so in my mill. The 
 actual consumption of copper, in proportion to 
 silver extracted, has not been determined. 
 
 [63.] There are three ways to use the quicksil- 
 ver in this process: Firstly at least one flask is 
 used for each $100 of silver in the barrel. This gives 
 a liquid amalgam, which comes out free from sand, 
 and the copper balls are simply coated with quick- 
 silver. Secondly only enough is used to form 
 hard amalgam, which sticks to the copper, as al- 
 ready stated, making it necessary to put the balls 
 into a pot of quicksilver to get it off, and yielding 
 an amalgam which is mixed with sand. Thirdly 
 so little is used that the copper balls come out free 
 from quicksilver and amalgam, and the latter floats 
 through the pulp in the form of gray flakes and 
 pellets. The last is probably the best, as it leaves 
 the surface of the copper free, so that the ore 
 comes in direct contact with it, and the whole of 
 the quicksilver comes out of the barrel with the 
 pulp, but it requires the use of a wooden vessel, 
 intermediate between the barrel and the separator, 
 
SILVER ORES. 
 
 73 
 
 in which the floating amalgam may be gathered by 
 means of an additional quantity of quicksilver, for 
 as already remarked the iron bottom of the sep- 
 arator causes the production of copper amalgam. 
 
 [64.] I have used a barrel in which the copper 
 was fixed, in the form of one inch bars, of which 
 there were 20, extending the whole length of the 
 barrel, and fixed at the distance of one-half inch 
 from the staves. It depends on how the quicksil- 
 ver is used whether the amalgam sticks to the bars 
 or not. This barrel needs no lining, as the cop- 
 per, being fixed, does not wear it. The entering 
 a barrel to line it, to fix the copper, or to remove 
 amalgam, is a disagreeable job, and when it must 
 be done, considerable time is consumed in cooling 
 it for the workman to enter. To avoid this, and 
 other inconveniences of the barrel, I have invented 
 a machine which I will describe after I have fin- 
 ished about barrels. 
 
 [65.] The following drawing represents the 
 
 Freiberg barrel used for roasted ore at Palmetto, 
 
 Nevada. By drilling through the journals, or 
 
 having them cast larger and hollow, and lining 
 
 4 
 
74 
 
 TESTING AND WORKING 
 
 with blocks as directed, this barrel will answer for 
 working unroasted ore; its capacity without lining 
 is one ton of ore. 
 
 
 
 
 
 
 c 
 
 'A; 
 
 j 
 
 
 
 
 
 c 
 
 A 
 
 
 A 
 
 
 A 
 
 
 
 I 
 
 A. 
 
 
 
 A $ 
 
 I 
 
 B D 
 
 D 
 
 
 
 
 
 
 
 
 D 
 
 C 
 
 xj 
 
 
 
 
 
 
 
 
 
 
 FREIBERO BARREL. 
 , hoops. B, journal. C and B, iron flange. 
 
 bolts. 
 
 [66.] A cheap barrel is made as follows : a 3-inch 
 square bar of iron of the proper length, with jour- 
 nals six inches long turned on the ends, is bored 
 at each end, precisely as directed for the wooden 
 shaft of the small barrel. This iron shaft passes 
 through the barrel, and is secured by cast flanges 
 bolted to the barrel heads. The flanges are cast 
 
SILVER ORES. 75 
 
 in two parts, with a strong hub through which the 
 shaft passes, and the two sections are fastened to- 
 gether by means of a rib along each edge of the 
 joint, through which bolts pass. This is not 
 absolutely necessary, however. The square 
 
 FLANOE. 
 
 x, bolt holes, y, holes for lag bolts running into head of barrel. 
 
 opening in the hub is slightly smaller than 
 the shaft, and is so placed that the division 
 of the two sections of the flange crosses it diag- 
 onally. The places for the flanges being 
 
76 TESTING AND WORKING 
 
 accurately marked on the shaft, they are 
 secured by a wrought iron band shrunk on to the 
 hub. The barrel heads are then fastened to the 
 flanges by bolts passed from within, with the nuts 
 outside, and the heads supported by 3-inch coun- 
 tersunk cast washers, sunk flush into the wood. 
 These are protected by a covering of putty, (better 
 than white lead,) or a mixture of linseed oil and 
 dust, and further by a wooden cap soaked in hot 
 petroleum, with which the whole inside of the head 
 is also painted. The shaft being mounted, the 
 heads are turned true, the iron shaft encased with 
 wood soaked with petroleum, and having in it holes 
 corresponding to the cross holes in the iron, lined 
 with short pieces of pipe tapped into the iron shaft 
 to keep the steam from the wood; and a wooden 
 cap, opening horizontally, is pinned on over each 
 hole to keep the pulp from falling in The staves, 
 which should be grooved and tongued for a lined 
 barrel, are then put on, and nailed, to hold hold 
 them until the bands are on and tightened with 
 the draw bolts, after which the barrel is treated 
 with hot petroleum and steam, as already describ- 
 ed, and is then ready for lining. Some use a stuff- 
 ing box in the end of the shaft where the steam 
 
SILVER ORES. 
 
 77 
 
 pipe enters, but a simple flange on the pipe is suf- 
 ficient. It is important that no iron work be left 
 exposed inside the barrel, as the action of the 
 chemicals would soon destroy it. 
 
 [67.] The trough or launder into which the 
 barrel is discharged, and which conveys the pulp 
 to the separator, is arranged in any convenient 
 way, the best being that in use at Freiberg, as seen 
 
 in the cut, the bottom being made of a solid tim- 
 ber, and the sides of matched boards, and extend- 
 ing under any number of barrels, mounted end to 
 end. At some convenient part, between the bar- 
 rels and the separator, is a pot to retain the quick- 
 silver as already said. 
 
78 
 
 TESTING AND WORKING 
 
 1 a t ... v^LUU.. 
 
 'I . - \\\VQ?- I'-.xV v \\M >\ \\\\\\-.-t '- V -\ i: ; 
 
 >M\\\\\^NtS\\NX\\\NK 
 
 a, stave, b, lining, c, iron shaft, d, cast flange, e, wrought band. 
 /, manhole, g, cap over steam hole. 
 
 o 
 
SILVER ORES. 
 
 79 
 
 [68.] A barrel of any required capacity, even up 
 to 50 tons, may be mounted on rollers as in the 
 sketch. The rollers work on a cast, circular 
 flanged rail, which surrounds the barrel. Mr. GL 
 F. Deetken has built such a barrel, with which to 
 work copper solutions, which is 12 feet long by 8 
 feet diameter; it is moved by a screw working into 
 a circular rack surrounding the barrel. This bar- 
 rel may be charged while in motion, through the 
 circular opening in the end, steam being admitted 
 at the other end. 
 
 AARON'S AMALGAMATOR. 
 
 [69.] Figure 1 is a perspective view of my de- 
 vice. Fig. 2 is a transverse vertical section. 
 
 A is a vessel of cylindrical or nearly cylindrical 
 form, of which the lower portion is fixed and the 
 upper portion is movable as a lid or cover, and 
 within which is mounted a paddle wheel, B, with 
 oblique floats c c c, and which is provided with 
 openings d d, in each end, as shown. The wheel 
 rotates in close proximity to the bottom of the ves- 
 sel A, so as to pass through a mass of pulp, and 
 dip in a bath of mercury contained therein. 
 
80 TESTING AND WORKING. 
 
 I prefer to construct the vessel in an oval form 
 with its longest diameter in a horizontal plane, so 
 
 Fig. 1. 
 
 that a space will be left in front and rear of the 
 wheel, while it moves close to the bottom and top 
 of the wheel in its rotation. 
 
 The floats c c c, of the paddle - wheel may be 
 made of any suitable material, but preferably of 
 
SILVER ORES. 
 
 81 
 
 wood, faced with copper on the inner surfaces, and 
 the wheel is secured upon a shaft, E, which bears 
 upon opposite sides of a hinged frame, F. This 
 frame, F, is so connected with the vessel, A, by 
 means of its hinges as to admit of its being lifted 
 at one end so as to raise the paddle-wheel out of 
 the lower half of the vessel. The upper half or 
 
 Fig. 2. 
 
 lid of the vessel A, is also hinged concentrically 
 with the frame F, and may be raised together 
 therewith, or separately. The vessel A, may be 
 constructed of iron, or in cases where the pres- 
 ence of metallic iron is objectionable, of enameled 
 iron, or of wood, or other suitable substance. 
 4* 
 
82 TESTING AND WORKING SILVER ORES. 
 
 Motion is given to the paddle-wheel B, by means 
 of a belt and pulleys revolving concentrically with 
 the frame, so that the rotation of the paddle 
 wheel is not interfered with by raising it to- 
 gether with the frame. 
 
 The vessel, A, is provided with an opening, h, in 
 the upper part or cover, and has a plug, i, in the 
 lower part, to facilitate the introduction and dis- 
 charge of the ore to be treated. 
 
THE SEPARATOR, 
 
 [70.] The ordinary separator is not suitable for 
 use in connection with barrels, especially when 
 treating unroasted ore by Aaron's process. The 
 
 Fig. 1. 
 
 kind I prefer for this purpose is shown in Fig. 1, 
 and consists simply of a wooden tub six feet in 
 diameter and four feet deep, in the bottom of which 
 is an iron annular disc, raised an inch and a half 
 from the bottom of the tub by a smaller disc of 
 
84 
 
 TESTING AND WORKING 
 
 wood under it, which leaves the iron disc project- 
 ing about two inches. The muller is made of 
 scantling in the manner shown in Fig. 2, and the 
 arms are short, not reaching to within six inches of 
 the side of the tub. 
 
 Fig. 2. 
 
 The mortises are arranged with keys, so that the 
 muller can be clamped tightly to the square 
 wooden shaft, the lower end of which runs on a 
 low wooden cone having a core of mountain ma- 
 hogany, and rising from the bottom of the tub up 
 through the iron disc to a height of several inches. 
 The upper end of the wooden shaft is connected 
 with a short iron shaft, working in boxes attached 
 
SILVEK ORES. 85 
 
 to the framing, and carrying the pulley or gearing. 
 The wooden shaft should be arranged to slide upon 
 the iron portion, so that the muller may drop as it 
 wears away, or may be raised with a lever in case 
 of accident. The shorter the arms are the higher 
 speed is used, and it should be such that the sand 
 and particles of quicksilver are kept in continual 
 suspension, till the latter, gathering together in a 
 mass, settles into the annular space around the 
 iron disc, where it remains undisturbed, while the 
 sand remaining in suspension is drawn off with the 
 water by successive plug-holes in the side of the 
 tub. Any pieces of rock or copper, etc., which 
 may accidentally find their way into the machine 
 lodge under the projecting edge of the iron disc. 
 
 The pulp, as discharged still warm from the bar- 
 rel, always contains copper dichloride in solution. 
 By working it for an hour or two before adding 
 water, in a separator with an iron bottom, which 
 is scoured by a wooden muller, a copper amalgam 
 is formed, thus preventing a large loss of quicksil- 
 ver. It is for this reason that the bulk of fine 
 amalgam from the barrel is not allowed to enter 
 the separator, where it would become mingled 
 with the base amalgam there produced. 
 
RETORTS. 
 
 [71.] A small retort is improvised by cutting 
 the top off a quicksilver flask, the cover being 
 formed of the upper part of another flask, into 
 which is screwed a piece of pipe about four feet 
 long, curved near where it enters the cover, so as 
 to incline downwards when the retort is in work. 
 The cover is stretched on the horn of the anvil so 
 as to overlap the body of the retort, and an iron 
 band is slipped over the joint, which is well plas- 
 tered with a stiff paste made of sifted ashes and 
 water, with which also the inside of the retort is 
 painted before putting the amalgam in. The pipe 
 is wrapped with sacking, on which water drips 
 continually from a barrel. The end of the pipe 
 must not dip into the water in the receiving pot, 
 as there is danger of an explosion from the water 
 being drawn up the pipe into the retort. A retort 
 should not be more than two-thirds filled if the 
 amalgam is fine, nor more than half when much 
 
SILVER ORES. 
 
 87 
 
 base metal is present. It is a good plan to have a 
 piece of stout wire or nailrod passing through the 
 
 ROASTING FURNACE. 
 
 a, hearth, b, bridge, c, fire-place, d, flue, e, stack. /, working 
 door, g, discharging door, h, binder, i, hopper, k, iron to support 
 working door. I, a dust chamber into which the flues open, and which 
 being drawn into a square above the flues becomes the stack, e. m, 
 roller. 
 
 pipe into the retort, with which the operator may 
 assist in the expulsion of any dirt which may pass 
 
88 TESTING AND WORKING 
 
 over and obstruct the pipe. The fire is made on 
 the top of the retort first, and the operation must 
 never be hurried, but allowed to proceed gently 
 till nearly all the quicksilver has passed over, when 
 the heat may be raised to a dark red, and so kept 
 till no more quicksilver can be got. The retorted 
 spongy silver may be sent to the mint, without 
 being first melted into bars. Explosions only oc- 
 cur through ignorance or carelessness. If there is 
 good reason to think that the pipe is stopped, as 
 sometimes happens through the swelling of the 
 amalgam, when overcharged, or if, as sometimes 
 happens with cast retorts, quicksilver is seen es- 
 caping from a crack, the fire must instantly be 
 drawn, or the operator must emigrate. 
 
 For quantities of amalgam up to 200 pounds, 
 cast iron pot retorts are used; beyond that, the 
 cylindrical or D patterns, permanently set in ma- 
 sonry, and provided with a water jacket for the 
 pipe. 
 
 1 72. | The hoes for stirring the ore are 16 feet 
 long, and in order to use them with convenience, 
 an iron roller resting on bearings built into the 
 brickwork, is placed before the working door, a 
 
SILVEB ORES. 89 
 
 little above the level of the hearth. The shank or 
 handle of the hoe is best made of gas pipe, all but 
 about five feet next the head, which is solid. The 
 head or blade is either of cast or wrought iron, and 
 as they do not last long, several spare ones are 
 kept on hand. There must always be several hoes 
 in readiness for use, so that they may be changed 
 when too hot. A fire hook is also necessary for 
 trimming the fire, and some use long-handled iron 
 spades for moving the ore from end to end of the 
 furnace, as must be done several times in order 
 that all may be equally heated, but workmen soon 
 learn to do this with the hoe. Bakes with cast iron 
 heads are also sometimes used, as they are more 
 easily drawn through the ore than hoes, but the 
 hoe cannot be dispensed with, and in some mills 
 nothing else is used. 
 
 The working door of the furnace is kept open 
 nearly all the time when roasting, but is closed 
 when required, by a piece of boiler iron, cut to fit 
 the opening, and furnished with two small holes, 
 about four inches apart, to receive the prongs of an 
 iron fork with which to lift it; when in place it 
 rests against the iron strap, K, which is built into 
 the opening, and forms a rabbet. The fire door, 
 
90 TESTING AND WORKING 
 
 and that at the back, are also of boiler iron, hung 
 upon pintles set in the masonry. The ashpit opens 
 on the opposite side from the fire door, which 
 causes the heat to be more even in the fire place. 
 The dust chamber should be as large as possible. 
 It is a good plan to carry the flue under the drier 
 in front of the battery, forming a dust- chamber, 
 and using the waste heat from the furnace to dry 
 the ore for crushing . The draught of a furnace 
 must not be too strong, but just enough to keep 
 the fumes from coming out of the open door. To 
 regulate the draught a damper is provided, which 
 may be conveniently placed in the stack, being sim- 
 ply a piece of sheet iron turning on a pivot, just 
 like the damper in a stove pipe. 
 
 [73. ] The main body of the furnace may be built 
 of rocks and mud, the hearth, or sole, walls and 
 arch, of brick; those in the sole being laid on a bed 
 of sand. The bricks in the arch are laid end up 
 on a form made of moist sand, which is drawn out 
 as soon as the work is done, to let the arch settle 
 as it dries, for which reason, also, it is built with 
 a little more spring than is wanted. In addition 
 to the longitudinal curve, it is slightly arched 
 
SILVER ORES. 91 
 
 transversely. In the walls every alternate course 
 should be headers (bricks laid crosswise), and they 
 must be supported by binders, formed of strong 
 posts set into the ground, and united at the top by 
 an iron rod, or a tie-beam, across and above the 
 furnace. If the ends of the furnace, forming abut- 
 ments to the arch, are built very heavy, as repre- 
 sented, it is not necessary to bind it lengthwise. 
 Adobes will answer for building a furnace, though 
 they will not last so long as bricks. The bridge, 
 being exposed to great heat and hard knocks, is 
 best made of one or two pieces of fire stone, or of 
 firebrick mixture beaten, while moist, into a 
 mould; but common bricks answer pretty well. 
 
 [74. ) In a much smaller furnace the walls may 
 be made of a concrete of mud and small rocks, and 
 the arch of adobe material, laid, like plaster, on a 
 form of damp sand covered with paper. The plas- 
 ter is laid on two inches thick, and as it will crack 
 some in drying, it is cut through with the trowel in 
 squares; before it is quite dry another layer is put 
 on, and so on till it is thick enough, the support- 
 ing sand being drawn out as soon as the arch will 
 stand. 
 
92 
 
 TESTING AND WORKING 
 
 [75.] I have given these details about the fur- 
 nace for the benefit of those whose situation makes 
 it necessary to make a start with as little cash out- 
 lay as possible; but, as soon as circumstances will 
 allow, I strongly advise the use of a revolving 
 cylinder that of Bruckner being the best for a 
 small operation. 
 
 AARON'S LEACHINO APPARATUS, No. 1. 
 [Patent to be applied for.] 
 
 a 
 
 a is an ordinary leaching vat; b is a wooden vac- 
 uum chamber; c and d are pipes, either of wood or 
 rubber, furnished with stop-cocks; e is a precipitat- 
 ing vat; f a flannel bag; and g a steam pipe con- 
 necting with a boiler. The ore being placed in a, 
 and saturated with the leaching fluid, (the cock in 
 c being closed) the chamber b is filled with steam, 
 
/' &\ <J / J 
 
 SILVER ORES. ff ^* ./ v v 
 
 O ^ : / j ^ 
 
 the air being expelled through d w^c^Ti^(o^)en' d is* / ^ 
 then closed, and steam shut off, when eyeing /f^ii-, 
 
 ^^ / ^ \ 
 
 ed, a vacuum is formed in b by condensation of the' >'*/ 
 steam with which it was filled. The pressure of 
 the atmosphere on the surface of the fluid in a, 
 forces it rapidly through the bed of ore into b; the 
 cock c is closed, that in d opened, and steam again 
 admitted into b, and by its pressure forces the 
 solution through d, into e, where it is treated with 
 the precipitating agent, and when clear, is drawn 
 off and passed again to , through the flannel bag 
 f t by which any floating particles of precipitate are 
 retained. The bulk of precipitate remaining in c, 
 is then removed. 
 
 [76.] This is the simplest form of the apparatus, 
 and is given merely for the purpose of explanation. 
 
 The following is a better arrangement 
 ] , 2, 3, 4, are leaching vats; a is the vacuum 
 chamber. No. 1 being charged with ore, and the 
 leaching solution, No. 2 is also filled with ore, and 
 the solution being drawn from 1, by means of the 
 vacuum chamber, is thrown into 2, while 1 is sup- 
 plied with a fresh lot of the solution from the pre- 
 
94 
 
 TESTING AND WORKING 
 
 cipitating vat, not represented as it is above a. In 
 like manner the solution from 2 is passed to 3, that 
 from 1 to 2 again; from 3 to 4; again from 2 to 3 
 and 1 to 2; then Irom 4 to the precipitating vat, 
 from 3 to 4, 2 to 3 and 1 to 2 again. The silver or 
 other metal of 1 will by this time be exhausted, 
 and it is emptied, and recharged with fresh ore, 
 
 and the next discharge from 4 is passed into it, 
 and from it to the precipitator, so that it now be- 
 comes the fourth in the series, the former No. 2 
 becoming No. 1; and so the operation goes on, the 
 
SILVER ORES. 95 
 
 last vat charged with fresh ore being always No. 4 
 of the series, and the solution from it being passed 
 to the precipitator saturated with metal. In this 
 way a concentrated solution of metal is always had 
 for precipitation, the metal is dissolved rapidly out 
 of the ore by the constant movement of the dissolv- 
 ing solution, and the finished ore is quickly 
 drained. 
 
 [77.] If the vacuum vat is divided vertically in- 
 to four compartments, by cross partitions not ex- 
 tending to the top, all four vats can be drained at 
 once, and the fluid thus passing more continuous- 
 ly the metal will be dissolved still more rapidly, 
 for it is well known that sugar, or any other solu- 
 ble substance, is dissolved sooner if stirred in 
 water than if left at rest; and still sooner if placed on 
 a filter and fresh water constantly passed through; 
 so, in like manner the metal in the first vat is 
 quickly dissolved by the constant flow of fresh 
 liquid, while the inconvenience of operating on the 
 weak solution which comes from it towards the 
 last, is obviated by passing it through the other 
 vats, and lastly through one containing a fresh 
 charge of ore, where it becomes saturated. In 
 
96 TESTING AND WORKING 
 
 case of ores requiring several distinct leachings, or 
 washing before leaching, there may be two or more 
 sets of vats, mounted on trucks, and running on 
 tramways; also, as many vacuum chambers. The 
 vats then replace each other in the respective sets, 
 and when one is finished it is wheeled to a dump- 
 ing place, emptied, and after being recharged, 
 takes its place in the first set. Large stationary 
 vats may be built with the filters inclined, and the 
 exhausted material washed out with a stream of 
 water from a hose. Boasted silver ores are washed 
 before leaching for silver, by passing through 
 them acidulated water, obtained by causing the 
 fumes from the roasting furnace to pass through, 
 or in contact with water, either by means of a 
 Cagriiardell's condenser, or a blower, or a stack 
 with shelves, rocks or coke in it, which are kept 
 wet by a stream of water. 
 
 [78.] APPARATUS, No. 2 (Patent to be applied 
 for.) I have devised another apparatus, in which 
 the dissolving fluid is caused to circulate contin- 
 uously, either through the same vat, or through a 
 series, by means of centrifugal iorce. This may 
 be used for extraction of gold with chlorinated 
 
SILVER ORES. 
 
 97 
 
 water, or of gold and silver, together, with chlorin- 
 ated brine. The following diagram shows its oper- 
 ation : 
 
 [79.] The leaching tub is securely bolted to the 
 revolving iron table a; the ore is seen at b, occupy- 
 ing the annular chamber formed by the circular 
 partition c, and cover d. The partition c is con- 
 structed of perforated wood, and canvas, so that 
 the dissolving fluid, being poured into the central 
 opening, and the tub being made to rotate 
 rapidly by a belt working on the cone pulley /, it 
 is driven by centrifugal force through the ore 6, 
 into channels between the blocks g, and reaching 
 5 
 
98 TESTING AND WORKING 
 
 the sloping side of the tub h, flows upward and 
 into the channel i y which is attached to, and sur- 
 rounds the tub. A fixed scoop and pipe k, dips 
 into this revolving channel, and the fluid, charged 
 with metal, is forced up through the pipe k, to 
 which is attached a piece of rubber tube j, and is 
 delivered into the center of another similar ma- 
 chine, or a precipitating tank, or back to the center 
 of the tub from which it came, to pass again 
 through the ore. The cone m, is simply to occupy 
 a portion of the needless space in the tub. 
 
 [80.] When the ore is exhausted and drained, 
 the machine is stopped, the cover d, removed, and 
 the tub being again put in motion the ore is 
 scooped out of the annular chamber by a fixed 
 scoop not shown in the diagram. The speed of 
 rotation is regulated as required, by means of the 
 cone pulley. 
 
 [81.] The sketch represents a mill for working 
 two or three hundred pounds of rich ore per day. 
 The large wheel may be a water wheel, or tread- 
 mill; the pulverizing barrel a, is a beer or wine 
 
SILVEB ORES. 
 
 99 
 
 cask, as is also the amalgamating barrel b; the sep- 
 arator/, is a large washtub. Beneath the pulver- 
 izing barrel is a seive c, to retain the balls or lumps 
 of rock, the ore falling into the box d. Under the 
 amalgamating barrel, which is driven by a belt 
 
 A VERY SMALL MILL. 
 
 from a, is a trough e, to carry the pulp to the sep- 
 arator, which is worked by a half -twisted belt from 
 a pulley on the shaft of b. The boiler for heating 
 the barrel is not represented. In a larger affair 
 the pulverizer a, may be replaced by a small arras- 
 tra. 
 
 Perhaps the best way to utilize a very small 
 
100 TESTING AND WORKING. 
 
 power, is to apply it all to one part of the process 
 at a time. Thus, ore may be crushed for several 
 days in succession, and then amalgamated in one 
 day. In this way there are not so many things to 
 attend to at once, which is one of the difficulties 
 of a small mill; of course, however, the machin- 
 ery to work a given quantity of ore per day must 
 be larger than when it is all used at once, and each 
 machine will be idle a part of the time. How- 
 ever, where only two or three tons of ore are 
 worked per day, this plan must be adopted to 
 some extent in order to use a roasting cylinder to 
 advantage. 
 
 The power of two chinamen, working turn about, 
 will work 200 or 300 pounds of ore a day; that of 
 two common horses, 400 to 500 pounds, and 60 
 miners' inches of water, or about 100 cubic feet 
 per minute, on a 30 -foot overshot wheel, with a 
 small battery or an arrastra, will work from two to 
 three tons in 24 hours. 
 
 [82.] An error into which inexperienced per- 
 sons are apt to fall, on first starting a mill, is being 
 needlessly alarmed at the small yield of amalgam, 
 and the disappearance of a quantity of quicksilver, 
 
SILVEK ORES. 101 
 
 owing to the retention of both in the various ves- 
 sels through which it passes. Positive results can 
 only be arrived at, after a run of several days or 
 weeks, by a thorough clean up, when the dies of 
 pans must be lifted, and the lining of barrels re- 
 moved. An examination of the tailings, by pan- 
 ning, will show whether much quicksilver is being 
 lost mechanically; and as a chemical loss is usually 
 accompanied by granulation, and consequent me- 
 chanical loss, or at least a difficulty in "settling," 
 and the appearance of white or brown powder in 
 the tailrace, a careful examination will afford a 
 good indication of the actual loss. An assay of a 
 true sample of the tailings compared with the value 
 of the ore, will at any time indicate the percentage 
 to which the ore is being worked. The best way I 
 know of to take a sample of tailings, is to take a 
 little pulp from each pan or barrel, as it is being 
 discharged, then, after thoroughly mixing the gen- 
 eral sample, take a small portion in a saucer, and 
 carefully pan it into a vessel of water, retaining 
 all the amalgam in the saucer. After the water 
 has settled clear, pour it off as far as possible with- 
 out losing any earthy matter, dry the residue and 
 assay it. The result will at least not be too high, 
 
102 TESTING AND WORKING 
 
 because the sample being taken before the pulp 
 entered the separator, it will be richer than the 
 final tailings by as much as is extracted by the 
 separator. However the error is on the right side, 
 for no one who thinks he is doing well will grum- 
 ble at finding that he is doing better than he sup- 
 posed. 
 
 [83.] I will now describe an invention which I 
 have made, to replace the settling tank in a wet- 
 crushing mill, which will obviate twice handling 
 the ore, once to remove it from the tank, and again 
 to put it into the pans. This apparatus has also the 
 advantage of retaining all the slimes, together with 
 the sandy portion of the pulp, a point which mill- 
 men will appreciate, and it may, in addition, be 
 arranged so as to be used as a preparing vessel, in 
 which to treat the ore with chemicals. 
 
 a is a vat furnished with a stirrer 6, and a false 
 bottom c, which forms a filter. The pulp from the 
 battery is delivered into a by the trough d, and by 
 the action of the stirrer is prevented from settling. 
 The water passing through the filter c, fills the 
 pipe e, the lower end of which dips into a vessel of 
 water g. The cock /, being now opened, a sue- 
 
SILVER ORES. 
 
 103 
 
 tion is established through the pipe by the weight 
 of the column of water within, and the surplus 
 water in the pulp is rapidly drawn off, the flow 
 from the battery being diverted at the proper time 
 into another similar machine. "When the pulp in 
 a is of the proper consistency, the cock/, is closed, 
 the plughole h, opened, and the contents of the 
 
 a 
 
 vat discharged into the pan i. Previous to this, 
 however, the pulp in a may, if desired, be treated 
 with chemicals and steam, to prepare it for amal- 
 gamation. The machine may of course be geared 
 from Iclc'N Ji 
 
104 TESTING AND WORKING 
 
 In large mills the vat or tank would be in the 
 usual form, with two or more stirrers, as shown in 
 Kg. 2. 
 
 FIG. 2. 
 
 Oj X./ o\ T 
 
 v\ 
 
 4- C X 
 
 fh 
 
 a is a row of four batteries, with sluices leading 
 into either of the vats b b, each of which has three 
 stirrers, c c c. The entire bottom of each vat, ex- 
 cept the rests for the stirrers, is a filter, and each 
 vat holds enough pulp to charge all the pans. 
 
 The vats may be arranged for upward filtration, if 
 desired, as in Fig. 3, in which the letters corres- 
 pond with those in Fig. 1. 
 
 The filter c, in this arrangement, can be easily 
 cleaned if it should become choked, as, by turning 
 the pipe e t in the side of the vat, its position can 
 be reversed. It may also be arranged around the 
 sides of the vat. A vat with a stirrer or stirrers 
 may be used with or without a filter. In the lat- 
 
SILVER OBES. 
 
 105 
 
 ter case, the stirrer is best made in the form of an 
 obtuse cone, with the apex downward, thus, X, in 
 order that it may easily work its way into the sedi- 
 ment, and it is arranged to be raised or lowered at 
 pleasure ; the pulp is allowed to settle, and the 
 
 FIG. 3. 
 
 surplus water to flow out, by gates or plugs, just 
 as in the common ore tank, and when a sufficient 
 quantity of ore has entered, the incoming stream 
 of pulp is stopped, and the water being reduced 
 by the plug-holes to the required quantity, the 
 stirrer is put in motion, and gradually lowered to 
 5* 
 
106 TESTING AND WORKING 
 
 stir up the sediment, so that, forming with the wa- 
 ter a semi-liquid mass, or pulp, it may flow through 
 the spout h into the amalgamator, or it may even 
 be ground or amalgamated in the vessel a, if said 
 vessel is so constructed as to answer these pur- 
 poses. 
 
 [84.1 NOTE. In case persons desiring to use di- 
 chloride of copper should be deterred from so doing 
 by the fact of a patent having been granted on the 
 use of that substance " in barrels, pans or tubs," 
 and which patent has been sold to certain parties 
 for a large sum of money, the following from the 
 Mining and Scientific Press, written by Dr. Lansz- 
 weert, may be useful, antedating, as it does by 
 some years, and therefore invalidating, the patent: 
 
 The Problem of Gold and Silver Extraction A 
 General Review, No, 16, 
 
 BY PEOF. L. LANSZWEERT. 
 
 In continuing my remarks upon silver processes, 
 the last of which appeared in your issue of July 
 29th, I would say that in the Freiburg process, it 
 
SILVER ORES. 107 
 
 is of the utmost importance that no free proto- 
 chloride of copper should be present in the reduc- 
 tion of silver ores, as by giving up to the mercury 
 one-half of its chlorine, a considerable loss of 
 that metal is produced by chemical reaction. 
 When this does occur, lime is added for the pur- 
 pose of decomposing the excess of chloride of 
 copper, and its prejudicial action on the mercury 
 is arrested. 
 
 USE OF BICHLORIDE OF COPPER IN THE PAN PROCESS. 
 
 To avoid this loss, which, at the end of the year 
 forms a considerable item in the expenses of a 
 mill, and to facilitate a more direct and easy de- 
 composition of the sulphurets of silver in the 
 Washoe ores (admitting the rationale of the theory 
 of the patio process as explained in my last num- 
 ber), I availed myself, during my stay in Washoe, 
 of the opportunity to try the direct use of dichlo- 
 ride of copper (cu 2 cl.) on the different ores there 
 presented. The success realized quite surpassed 
 my expectations. The results were obtained by 
 comparative experiments made on a large scale, 
 by reducing from five to five hundred tons of the 
 
108 TESTING AND WOBKING 
 
 various Washoe ores, such as Gould & Curry No. 
 2, Chollar, Potosi, Olney, Bogers, Gold Hill, etc., 
 and were attested by certificates from Guido Kus- 
 tel, Col. Breevort, Mr. Lambert, J. Corey, Joseph 
 Trench and others, as the experiments were con- 
 ducted at their several mills. They averaged, ac- 
 cording to the nature of the ores, from within five 
 to twenty per cent, of the assay value of the ores. 
 
 The quantity of dichloride of copper used was 
 based on the analysis of the ores, and the percent- 
 age of the sulphide of silver they contained. 
 Taking, for example, an ore assaying $100 per ton, 
 we would have, according to analysis, sixty -two 
 ounces of sulphide of silver, equal to fifty-four 
 ounces of metallic silver, at $1.29 per ounce^ 
 which is worth $70, and free silver at $30 $100. 
 
 The patio process requires for the reduction of 
 the above amount of sulphide of silver 125 ounces 
 of sulphate of copper, 590 ounces of salt, and 100 
 ounces of mercury ; the mercury being lost by de- 
 composition as a chloride of mercury the calomel 
 of the apothecary. 
 
 Now, if we use, instead of the above, the dichlo- 
 ride of copper, 47 ounces (the quantity required 
 for the reduction for the amount of sulphide of 
 
SILVER ORES. 109 
 
 jr> ' y, ' / 
 
 silver present), plus 400 ounces of salt and 100 
 ounces of mercury, there will be no loss of the 
 mercury. 
 
 In nearly all enterprises of this kind a great 
 many obstacles are thrown in the way of success, 
 by reason of the stubbornness, incapacity or avidity 
 of those having charge of the different works. So 
 in this case; notwithstanding the proof was abun- 
 dant of more favorable results than were being ob- 
 tained by the old processes, still such was the sys- 
 tematic opposition presented by superintendents, 
 amalgamators and others interested in retaining 
 present positions, or in continuing the use of other 
 processes, the writer found it impossible to intro- 
 duce his process into permanent use in any of the 
 numerous mills in Washoe. Time and circum- 
 stances will eventually accomplish for the mining 
 interest of that locality, what the stubbornness or 
 incapacity of the early operators there refused to 
 allow; although thousands of dollars might there- 
 by have been saved to individual companies alone. 
 
 Although the preparation of dichloride of cop- 
 per is very easy and simple, still a great many at- 
 tempts to prepare it have failed; the operators pre- 
 paring instead, a mixture containing a large per- 
 
110 TESTING AND WORKING 
 
 centage of protochloride and very little dichloride 
 of copper; and being in consequence disappointed 
 in the results from the use of this preparation, they 
 have condemned a process which my own careful 
 experiments on a working scale have proven to be 
 the best yet adopted for the reduction, without 
 roasting, of a certain class of Washoe ores. 
 
TABLE OF CONTENTS. 
 
 TESTING OEES FOE SILVEB. 
 Subject. Section. Page. 
 
 Kock Formation 1 7 
 
 Test for Silver 2 8 
 
 Silver, Indication of Presence 3 10 
 
 Silver Test with Heat and Water 4 11 
 
 Silver Test with Nitric Acid 5 12 
 
 Silver Test with Blow-pipe 6 13 
 
 TESTING FOB A PBOOESS. 
 
 Extent and Kichness of Ore 7 14 
 
 Smelting Ores 8 15 
 
 Selecting Sample 9 16 
 
 Working Sample 10 16 
 
 Copper Test 11 18 
 
 Bluestone 12 19 
 
 Appliances for Testing 13 20 
 
 Boasting 14 21 
 
 WOBKING OBES. 
 
 Aaron's Process 15 23 
 
 Superheated Steam 18 25 
 
112 TABLE OF CONTENTS. 
 
 Subject. Section. Page. 
 
 Dichloride of Copper, Preparation 19 26 
 
 Protochloride of Copper 20 26 
 
 Carbonate of Copper Ores 21 27 
 
 Use of Copper and Iron 22 29 
 
 Quantity of Chemicals 23 29 
 
 Carbonate of Lime -.* ... 24 30 
 
 Class of Ores Worked by Aaron's Process 25 30 
 
 Chloride Ores 26 30 
 
 Amalgam 27 31 
 
 Patchen's Process 28 33 
 
 BOASTED OBES. 
 
 Working Eoasted Ores 29 34 
 
 Base Metals 30 35 
 
 Chloridizing Boasting 31 36 
 
 Directions for Boasting 32 37 
 
 Stirring 36 40 
 
 Heat 37 40 
 
 Want of Sulphur 38 41 
 
 LEACHING PEOCESSES. 
 
 Classes of Leaching Processes 39 41 
 
 Smelting 40 42 
 
 Mexican Process 42 43 
 
 Kroencke's Process 43 44 
 
 'Chilian Process 44 48 
 
TABLE OF CONTENTS. 113 
 
 * 
 
 PULVERIZING MACHINES. 
 Subject. Section. Page. 
 
 Arrastra 46 49 
 
 Operation of Arrastra . , 47 50 
 
 FeedandSpeed + 48 51 
 
 Dry Grinding of Arrastra 49 52 
 
 Stamp Batteries 50 53 
 
 Screens 51 53 
 
 Crocker's Trip Hammer Battery 52 55 
 
 Paul's Pulverizing Barrel 53 57 
 
 Pulverizing Barrel 54 60 
 
 Kendall's Battery 55 61 
 
 Noice's Pulverizer 56 61 
 
 Cheap Rock Breaker 57 63 
 
 AMALGAMATOBS. 
 
 Cheap Amalgamator 58 65 
 
 Grinding the Ore 59 67 
 
 Directions for Making a Barrel 60 68 
 
 Copper 61 71 
 
 Preventing Mechanical Wear 62 71 
 
 Using Quicksilver 63 72 
 
 Copper in Bars 64 73 
 
 Freiberg Barrel 65 73 
 
 Cheap Barrel 66 74 
 
 Trough 67 77 
 
 Barrel on Kollers 68 79 
 
 Aaron's Amalgamator 69 79 
 
 Separator 70 83 
 
114 TABLE OF CONTENTS. 
 
 EETOETS. 
 
 Subject. Section. Page. 
 
 Improvised Ketort 71 86 
 
 Boasting Furnace 72 88 
 
 Furnace Tools 72 88 
 
 Furnace Building 73 90 
 
 {Smaller Furnace , 74 91 
 
 MISCELLANEOUS. 
 
 Aaron's Leaching Apparatus 75 92 
 
 Another Arrangement 76 93 
 
 Apparatus No. 2 78 96 
 
 A Small Mill 81 99 
 
 Sampling Tailings 82 101 
 
 Settling Tanks 83 102 
 
 Bichloride of Copper 84 106 
 
ADVERTISEMENT. 
 
 THE CALIFORNIA 
 ZFO"WID:Ei:R, "VSTOIR/IKS, 
 
 W 
 
 Santa Cm GIIOI fe 
 
 s 
 
 cb 
 
 o 
 
 Pn 
 
 00 
 
 w 
 
 Pacific Rifle and Pistol Powder, ^ 
 
 SHOT, ROUND GRAIN, 
 
 CAPS, BRIGHT GLAZE, 
 
 WADS, IN IRON AND 
 
 AMMUNITION, WOODEN KEGS, FUSE, ETC., ETC. 
 
 No. 314 CALIFORNIA STREET, 
 
 SAN FRANCISCO, CAL. 
 
ADVERTISEMENT. 
 
 WHITE'S PATENT 
 Revolving Cylinder Furnace 
 
 FOB 
 
 ROASTING ORES. 
 
 This Furnace was patented first in 1864, and subsequently in 1865, covering 
 any arrangement of an incline cylinder furnace. It consists of an iron cylinder 
 mounted upon bearing drums or wheels at a suitable inclination, with a fire- 
 place at either the upper or lower end of the cylinder as desired. The cylinder 
 is revolved by suitable power, and the ore is fed into the upper end of the cyl- 
 inder continuously, and passes through its entire length. 
 
 During its passage the ore is raised by projections on the inside of the cylinder 
 and allowed to drop through the passing heat, thus completely roasting it. 
 The operation is continuous and requi.es but comparatively little skill and at- 
 tention in working. It is s'rnply constructed in sections, easily transported, 
 and can be moved and reset at moderate cost. After thorough trial it is found 
 to reduce a large variety of ores economically, and is now superseding fur- 
 naces of perhaps greater, but briefer notoriety. 
 
 Favorable terms will be offered to purchasers. Address for further informa- 
 tion, 
 
 OEO. W. WHITE, 
 
 Care of Etna Foundry, Fremont Street, near Folsom, 8. F. 
 
 NOTICE TO PARTIES ORDERING FURNACES. The mining public is 
 hereby notified that all persons who represtnt themselves to be my agents or to 
 have authority under my patents to build and use, or to contract with others 
 for the light to build and use a Cylindrical Rotary Roasting Furnace (except in 
 Lander county, Nevada,) are frauds, and any person or persons that constructs 
 one of my furnaces either with or without additions, alterations, or supposed 
 improvements, or attempts to use one constructed under a contract with any 
 such, unauthorized person, will be prosecuted as infringers of my rights on 
 the premises. I have made arrangements to have all my furnaces constructed 
 by the Etna Iron Works in this city, and no other foundry has a right to make 
 one without my written consent. For rights to build and use, address 
 
 <JEO. W. WHITE, Patentee, care of Etna Iron Works. 
 
 San Francisco, Aug. 22d, 1876. 
 
ADVERTISEMENT, iii 
 
 /ETNA IRON WORKS, 
 
 Fremont St., Bet. Howard and Folsom, San Francisco. 
 PENDE 'ROAST & SMITH, Proprietors. 
 
 Manufacturers of 
 IKON CASTINGS & MACHINERY OP ALL KINDS. 
 
 nartz Mill 
 
 AND OTHEB 
 
 MINING MACHINERY 
 
 A SPECIALTY. 
 
 The Proprietors of these works have been long established in 
 the business, are practical machinists and foundrymen, who know 
 well the wants of customers ia their line of business, and are pre- 
 pared to give the fullest satisfaction in all particulars. 
 
 They have a full complement of tools in perfect order, handled 
 by superior workmen. 
 
 Drawings and patterns of the best and most approved mining 
 machinery are at the service of the patrons of this foundry. 
 
 Miners, mill-men and metallurgists are invited to send for es- 
 timates or any desired information. 
 
 THOS. PENDERGAST. HENRY S. SMITH. 
 
iv 
 
 ADVEBTISEMENT. 
 
 W. T. C APR ATT, 
 
 Manufacturer of 
 
 Hooker's Celebrated Steam Pump, 
 
 The best cheap- 
 est and most 
 
 reliable 
 STEAM PUMP 
 
 KNOWN. 
 
 Over 3 000 
 In use on the 
 
 Pacific Coast, 
 
 Giving entire 
 
 SATISFACTION. 
 
 IMPORTER OF 
 
 Iron Pipe and Malleable Iron Fittings. 
 Brass and Bell Foundry, 
 
 CHURCH, 
 
 Steamboat 
 
 BELLS & GONGS, 
 
 WATER GAUGES, 
 STEAM GAUGES, 
 
 Steam Whistl s, 
 Engineers' 
 
 Findings. 
 
 CORNER FREMONT & NATOMA STREETS, 
 SAN FKANCISCO. 
 
 Hydraulic Pipes 
 
 AND 
 
 NOZZLES 
 
 For Mining Parpo. 
 
 sea, and a 
 
 GENERAL 
 
 ASSORTMENT OP 
 
 BRASS WORK. 
 
ADVERTISEMENT. 
 
 HENDY'S 
 
 ORE FEEDER. 
 
 o 
 
 Diagram Showing Plan of 
 Attaching Feeder to Battery. 
 Attacked to the second stamp 
 
 A Tappet. B Lever. C 
 Lower Guide. D Hopper. 
 E Carrier Table. F 
 Chut =. Q Bumper. 
 
 JOSHUA~HENDY, 
 
 No, 32 FREMONT ST., S. F. 
 Patent 
 
 Ore Concentrators, 
 
 BATTERY ORE FEEDERS, 
 
 ! IIIIIJIIIIIIIIHlIi 
 
 CIRCULAR SAW MILLS, 
 Machinists' Tools. 
 
 Dealer in all kinds of Ma- 
 chinery. 
 
 Steam Engine Governors. 
 
 8^" Send for Illustrated 
 Circulars. 
 
ADVERTISEMENT. 
 
 DEWEY & CO. 
 
 U. 8. and Foreign 
 
 Paleni Agenls, 
 
 No. 224 Sansome St. 
 San Francisco. 
 
 Patents Obtained 
 Promptly. 
 
 Caveats Filed Expe- 
 ditiously. 
 
 Patent Reissues Ta- 
 ken Out. 
 
 Patents Secured in 
 Foreign Lands. 
 
 Assignments Made 
 and Recorded in Le- 
 gal Form. 
 
 Copies of Patents and 
 Assignments Pro- 
 cured. 
 
 Examinations of Pat- 
 ents made here and 
 at Washington. 
 
 Examinations Order- 
 ed and Reported by 
 TELEGRAPH. 
 
 Examinations msde of 
 Assignments Record- 
 ed in Washington. 
 
 Interferences Prose- 
 cuted. 
 
 Opinions Rendered re- 
 garding the Validi- 
 ty of Patents and 
 Assignments. 
 
 Rejected Cases taken 
 up and Patents Ob- 
 tained. 
 
 Every Legitimate 
 Branch of Patent 
 Soliciting. 
 Business promptly 
 
 and thoroughly con- 
 
 ducted. Send for Cir- 
 cular. 
 
 A. T. DEWEY, 
 W. B. EWER, 
 OEO. H. STRONG, 
 JNO. L BOONE. 
 
 Mining and Scientific Press, 
 
 Started in 1860, is one of the oldest weekly journals now 
 published in San Francisco. It has been conducted 
 by its present proprietors for 13 years, during which 
 period it has been repeatedly enlarged and constantly 
 Improved. The active and steadfast efforts of its pub. 
 lishers have gained for its conduct an amount of practi- 
 cal experience greater than any other publishers have 
 accumulated on this coast, of a weekly journal. 
 
 The sum paid by us for the best editorial talent ob- 
 tainable for our special class journal; for engravings, 
 for interesting news and correspondence, and for print- 
 ing a large-sized, handsome sheet, is unequalled by that 
 of any other American weekly west of the Mississippi. 
 As a PBACTICAL MINING JOURNAL it has no rival on 
 this Continent. 
 
 It is the only MECHANICAL, and the only SonamFio 
 Journal of the Pacific States. 
 Miners, Assayers, Millman, and Metallurgist in the 
 
 United States should take it. 
 
 Pacific Coast Mechanics, Engineers, Inventors, Manu- 
 facturers, Professional Men, and Progressive and 
 Industrial Students should patronize its columns of 
 fresh and valuable information. 
 
 SCning Engineers, Superintendents, Metallurgists, Mine 
 Owners and Mine Workers throughout the world 
 should profit by its illustrations a d descriptions 
 of New Machinery, Processes, Discoveries and 
 Record of Mining Events. 
 
 Intelligent thinkers throughout the land, in high or 
 humble situation, who would avoid literary trash 
 for genuine information, should SUBSCRIBE AT 
 ONCE. Postage paid, H a year. Send for sam- 
 ple copy. 
 
 DEWEY & CO., Publishers, S.F. 
 
 N. B. Valuable books on Mining, Metallurgy, etc., 
 published and sold. Send for circulars. 
 
UNIVERSITY OF CALIFORNIA LIBRARY, 
 BERKELEY 
 
 THIS BOOK IS DUE ON THE LAST DATE 
 STAMPED BELOW 
 
 Books not returned on time are subject to a fine of 
 50c per volume after the third day overdue, increasing 
 to $1.00 per volume after the sixth day. Books not in 
 demand may be renewed if application is made before 
 expiration of loan period. 
 
 APR 30 
 
 22Apr'59JflI 
 
 REC'D LD 
 
 'APR 12 1959 
 
 JUL29 
 
 i 
 
 20m-l,'22 
 
VB 15530 
 
 X