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CLAUDET, •VriBIHTIMOIHT or THB aOTXBMMIIT ▲IIAT OftlCl, BBITUa COLUMBIA. rtlHTIO AT TUB OVf lOB OV TBB " UAIBLABD •VABDULB,'* BIW WBBTMIHBTBB, B. 0. 18T1. aam ^ P !{ E F A C E . Although Uiii is a gold producing country, and tho precious metal passes through the hands of so nianj, there is, doubtless, a large number cf persons quite un- informed with respect to the conditions under which gold occurs in nature, the various processes by which it is obtained, and its commercial value after it has beeu collected. This little pamphlet has been written with the view of presenting the subject to the Public in as condensed a form as possible, in order to enable tho^e who cannot spare the time, or who may not have the patience, to read through a large work, to acquire, by the perusal of a few pages, an insight into some of tlie most important features oi an interesting and useful Branch of Study. 140757 ■i History and Properties of Gold. Gold has been known from the earliest ages of the world, and has been universally employed as a medium of exchange. Wo hear of its having been used by the Ilebrows, Egyptians, Greeks, Romans and otlier ancient nations, in about the same manner as it is at the present day. The first allusion made to gold in the Bible occurs in the 2nd chapter of Genesis, v. 11 and 12. Hut the earliest prac- tical application of the use of gold appears to be thr.t mentioned in the 24th chapter of Genesis, v. 22, B. C , 1857, where it is evident that the precious metal was not only knotrn but wrought. Eleazer, the servant of Abraham, gave to Rebecca, the future wife of Isaac, nn earring and two bracelets of gold. It is also men- tioned by Moses in the 31st chapter of Numbers . where he says, "Only the gold and the silver, the brass, the iron, tho tin, and the lead, everything that may abide the fire, ye shall make it pass through the fire and it shall be clean." The alchymists designated it by the name, and gave it the symbol of Sol. It is the most precious of all the metals, possesses a beau* tifully rich yellow color, and has no perceptible taste or emell. When pure its specific gravity is 19.3, being, with the exception of Platinum and Iridiam, the heaviest of all knovm substances. In its native state the specific gravity varies from 18 to 18. „,.r.RT iN» rK..««T... ^.- "O'-'- It i, rre-em.m.">ly •'■'"« ,„ ^.i.. H.«t o„. dcR.. Fal.renUeit. ^^^„;^ „^t„_ bat U CM w iuvar,aWy foun m ' j. j„„„ ■ roponioiis, ami t)em„ = ^^u. ,„L•,uo.of..n.|.e^ •"" '"f" ':•;.," d, „Mch are, how- g„W, another w.tl> '^".'"'""" , „( g„ld and mercury. ^ There is aUo a natu'e »""''S ™ °' f,i„, „„ aecoant of The Bcctru,,, of rUny. »» "^^^ ''l^^^ „„„,p„„„d ; its amber color, seems '» Klaproth, were specimens f,om ^'^^^i/J^^^i^nl .0 parts of sUver. l-oaod to contam b* parts o. g ^^^.^^^ ^^j^ „,, There are few P"ts ° *° ^^j, ^ut it occurs very „„t been found more or less to e„ < .„ ,„,„„ i„egularl,, here and there .n-t^ ^^^ great Califor- pUeesiutninutequanl y. l.^_^^ countries in Europe, „ia„ discovery, m SIT, .,,„j„a i^rgo suppl.es Asia,AfricaandAm rca a ^^^^^^^^^^ ^_.__^^ „f of t„e precious ■""'^•Ji^ Transylvania, which bare ,,,ich, iu Europe, -2'\2\! the Uomans. been worked s.nce the tune <" j^j^i^,, u.oso on There arc mines .« """>"' ""'^ by some historians ,Ue Mozambique Coast '" 7; !/,„» of Solomon. .„ have been the '^^'^ „ O,„fornia and Austral a , !::Xo>.rr: r '~ or -1-.- >«-. D. HISTORY AND PROPERTIES OF QOLD. 7 11) m:\Ue&lila liu that oua ductile ilmt vire 500 fuel t about 2020 state, but ii ill different kted with small rliich are, how- il importance, illed Palladium ium gold, d and mercury, u on account of lite compound ; Klaproth, were ;6 parts of silver, which gold has It it occurs vory ludauce, iu some 36 great Califor- itries in Europe, ted large supplies jbrated mines of rania, which havo nans. Africa : those on y some historians time of Solomon. rniaand Australia^ comparative insig- nificance, as these two regions now produce more tlian four times the amount yielded by all the o:lier couiittii.'a put together. Further discoveries of considerable importance con- tinuc to be made, among wliieh those in liiitidh Columbia occupy a prominent position. Gold id largely o'»tained frtim alluvial washing?", in the fihape of fine panicles and uuter-worn pluios and scales* but crys Hized specimens are occasionally met with. These crystals are in forms belonging to the monometric system, such as cubes and octuiit'drons, generally the latter. Sometimes larger lumps, or "nuggets," are found, weighing several ounces, and iu a few rare instances, many pounds. Geological Position of Gold. There are four different lithological situations in which gold occurs : — 1. In veins, generally enclosed in metkn)orphic slate?. 2. In small threads, traversing the quartzose veins of the more highly crystalline rocks. 3. In placer deposits formed by ancient river-systems, known as "deep diggings." 4. In placer deposits, distributed by the present river- system, giving rise to what are called " shallow diggings." The most productive gold-bearing quartz is generally found to be that vhich intersects lalcose, chloritic and argillaceous schists, although valuable gold veins aro occasionally met with in granite, gneiss and porphyry. These veins have mosc frequently the same " dip" and "strike" as the slaty rocks in which ihey are enclosed. Their width varies from a fraction of an inch to several feet, some have been known to attain the extraordinary wtoLoaiCAL Position or uolu. tliicktioss (if a hundred foct; and tlicir richness in gold id ('(innlly uncertaiti. When rocks remain stratified, in nearly the sumo posi- tion in wliicli they were originally deposited, they are rirely found to be highly auriforous ; but when they have been upheaved, or raised on edge, by eruptive masses, mid have a:«suined a crystalline- texture, there is good reason to cxpcot the presence of tiie precious metal. The auriferous veins are presumed, by some geologists, to have originated at the time of the nietamorphic action, by which the change in tho strxta was etfected. Thii action docs not, however, appear to have beer ccnfined to any particular geological epoch, and it is probablo that these alterations, which are most likely very slow in their progress, may have been repeated at periods of time exceedingly distant from each other. The widest veins arc not usually the richest, and it has been found that some of ihe laminai running parallel with the enclosing wails are uniformly more productive than others. It therefore not unfrequently happens that a portion of a vein, rich enough to be treated with ad- vantage, is separated from another band, comparatively worthless, by a distinct heading, or false wall. As a general rule those veins are most productive which allbrd considerable quantities of sulphides ; al- though, near the surface, these have, almost invariably, become decomposed, thereby liberating tho enclosed granular gold, aud staining the quartz of a brown or redilish color. When gold is found in white quartz, without sulphides, it is in most instances in Hakes and granules of consider- able size, and is consequently visible to the naked eye ; but such veins, although affording fine specimens, are rot often regularly and remuneratively productive. 3 in gold imo posi- tliey are ,hey have ) masses, is good etal. >oIogista, ic action, Bd. Thi« confined probable •y slow in leriods of md it has g parallel iroductivo ipens that 1 with ad- paratively iroductivo lides ; al- Qvariably, enclosed browu or sulphides, ' consider- iked eye ; imens, are live. GEOLOGICAL POSITION OP GOLD. a The roo8t profitable Teins are generally onlj of mod- •rate size, and seldom exhibit visible gold. It was formerly believed that veins of auriferous quartz become gradually less productive as greater depths from the surface aro attained, but experience has shown that this is in io».ity not the case. If is true that gold mine? ' ave fluctuated considerably in their richness at different depths, but it has not been found that these variations correspond with a gradual impover- ishment in the deeper levels. An illustration of this fact is found in many veins in California. The North Star vein is now worked on its inclination to a depth of 750 feet, and affords quartz yielding, on au average, gold of the value of $35 per ton of 2000 lbs., whereas in the upper levels the value did not exceed $20 per ton. Ilayward*s mine, in Amador County, is another still more striking instance of the produce of a vein not de- creasing as it goes down. This ledge has been worked on its inclination to a depth of over 1250 feet, and yields quartz of much greater value than that obtained from he same vein nearer the surface. The yield of the quartz veins of Victoria has also no* )een found to decrease in depth. Some mines have L en orked 600 feet from the surface and have experienced 10 diminution in their produce. The greater portion of the gold of commerce, bow- 3ver, is derived from *'gold-washings," or the separation >f the metal from the superficial detritus, which is in- ^uded by Geologists among the drift and alluvial deposits. The process by which these auriferous deposits have >een formed is a qiestioa which has aot yet been satis- actorily solved. 1* 10 GEOLOGICAL POSITION OP GOLD. The prevailing opinion is that, by various operations of nature, the gold has been br»ken away from the rock or vein in which it was elaborated, and has been carried by water some distance and then deposited along with the fragments of the rocks and minerals with which it was ai^sociated. Professor Whitney says : " The separation of the gold from its original matrix and its deposition among the .strata of gravel, sand and clay, cr beneath them upou the surface of the rock, has been the result of causes acting through an immense period of time ; and which have not yet ceased to operate, although their energy , seems no longer equal to what it must have been at a \ former epoch. The rocky strata if the earth are con (iitantly undergoing abrasion from the combined action of various meteorological causes; of which one of the most powerful at present is the alternate freezing and thawing of water in fissures and cavities, which tends to wear away and disintegrate the most elevatad portions, especially of the slaty beds, and to carry down the abraded and loosened materials, and spread them out in the adjacent valleys. In lofty and rugged mountain chains, where torrents of rain frequently fall, and the streams, suddenly swollen to a great volume, rush with tremendous violence down rapidly declining valleys, their J force becomes capable of wearing away the rocks with great rapidity." "This mechanical action is frequently aided by a chemical o.ie ; the strata undergoing a molecular change which softens them and renders their abrasion easj. ^9 the enclosing rocks are thu« worn away, the quartz- veins become disaggregated by the oxidation of the iron I they contain, and are themselves crushed into fragments^ and borne down into the valleys, where the metallic par- J GEOLOGICAL POSITION OF GOLD. 11 ous operations from the rock IS been carried ed along with with which it ion of the gold on among the iath them upon redult of causes ime ; and which ;h their energy have been at a > earth are con* nbiocd action of one of the most sing and thawing h tends to wear eratad portions, carry down the read them out in ugged mountain itly fall, and the olume, rush with ling valleys, their ly the rocks with ntly aided by a molecular changer ir abrasion easy.' away, the quartz- dation of the ironf ed into fragments ) the metallio paH tides, having by far the highest specific gravity, are first deposited and eink to the bottom, while the lighter earthy portions are carried farther." Sir Roderick Murchison asserts that the more or loss superficial deposits which contain gold, and known as " deep diggings," are not to be confounded with detritus formed by present atmospheric action, but rather that they are the result of diluvial currents connected with, and originating in, physical changes in the earth's sur> face, such as the elevation of mountain chains. Another explanation of the formation of deep diggings has been advanced by Davison, which is perhaps entitled to a certain amount of consideration, although the great majority of Geologists incline to the opinions of Sir Roderick Murchison and Professor Whitney. Davison asserts that placer gold has been distributed and deposited by means of some igneous liquid rock, or lava, and that quartz-veins and dykes have been the fissures of discharge. His reasons for this conclusion are, that alluvial gold often has a fused appearance, and has a ragged and ir- regular surface, which must have been destroyed by abrasion; that it is found upon "bedrocks" in such shape and position that the agency of water alone could not have so placed it, and that it also occurs richly deposit- ed in the neighborhood of ancient volcanic disturbance. However much Geologists may differ with regard to the origin of "deep diggings," there can be no doubt that the distribution of gold by the present river-system, constituting the "shallow diggings" is purely referable to the natural grinding away of auriferous rocks, a;jd the deposition of the gold by the agency of water. It Extraction of Gold. Gold mines may be divided iito two distinct classes,, riz : placer mines, in which the metal is found embedded in clay, sand, or gravel ; and quartz or vein mines, in which it is met with in its original matrix. In the former, the gold producing material is called ** pay*dirt," which on being subjected to the action of water, becomes disintegrated, and the lighter portion s are mechanically carried off, whilst the gold, being hei^ier, remains behind. In the latter, the rock has to be first obtained by the ordinary mining operations, as practiced with regard to other metals, then reduced to powder by mechanical means, and finally the gold is collected, either by wash- ing or amalgamation. Placer mines are generally those which first attract, attention in a new country, and from which profitable returns are most easily obtained. Water is the great agent by which placer mining is carried on. These mines are of two classes, the shallow and the deep ; the former are geaerally found in the beds of ravines, on the bars and in the beds of modern rivers, and on shallow flats. In the latter, the pay dirt is often found at great depths from the surface, and is frequently covered by thick beds of lava, or volcanic ash, as in the case of the deposits under Table Mountain, Tuolumne County, and near Nevada City, California. Id. distinct classes,, bund embedded vein miDes, in kterial is called to the action of lighter portion s be gold, being obtained by th« with regard to by mechanical either by wash- icb first attract, vbich profitable )lacer mining i§ shallow and the in the beds of f modern rivers, found at great itly covered by I the case of the ine County, and H^TBACTION OF OOLD. 13 In the deeper placers, the gold drifts are reached either by shafts, or by means of tunnels. The pay dirt is thus extracted, conveyed to the surface and subjected to the process of washing. In other instances, hydraulic mining is resorted to. Jets of water, under a great presnre, obtained from a high column, are directed against the deposits of sand and gravel, which are thus disintegrated and carried away by the current. This is the most econemical and expeditious method of working placer mines, when a sufficient supply and pressure of water can be obtained, and there is enough declivity below the auriferous beds to allow of the de- tritus being readily disposed of. The pay dirt is almost invariably covered by layers of barren clay and sand, which are, in the shallow diggings, removed by the use of the pick and shovel; but in hydraulic workings, the whole is washed away by the force of a stream of water playing against it, and any particles of gold which it may contain are caught in the sluices through which the lighter materials pass. According to their topographical position, placer mines, besides being classed as shallow and deep, are subdivided into hill, bench, flat, bar, gulch and river diggings. Uill diggings are in the sides of hills ; bench diggings are on narrow benches on the declivities of Mllf, and above the level of existing rivers ; fiat digginfi;s are those on flats or small plains ; bar diggings are usually in sand and gravel, on the sides of streams, and, ordin- arily, above the surface of the water ; gulch diggings are found in ravines and gullies, through which water passes only in time^ jf excessive floods ; river diggiugb are those which exist in the beds of rivers. IV 14 EXTRACTION OF GOLD. Tlie terms sluice, hydraulic, tunnel, dry diggings, &c., arc used to describe the different means employed for reaching the auriferous deposits, and separating and coU Iccting the gold. The most simple appliance for the separation of gold is the well-known pan, which is used either for washing or as a receptacle for gold, amalgam, kc. After a cer- tain amount of practice the miner is able to get rid of the whole of the sand, clay and stones, retaining in the angle of the pan the gold and a small quantity of black sand, which is too heavy to bd separated from the gold by washing. It can, however, after drying, be, to a great extent, removed by the process of blowing and the use of the magnet. The cradle consists of a box usually about forty inches in length and twenty in width, with one end from fifteen to twenty inches in height, the sides being sloped off at the lower extremity like those of a coal-scuttle, the whole standing on rockers. At the upper end of the cradle is the hopper, or riddle box, twenty inches square and six in depth, of which the bottom is composed of sheet iron, perforated with holes half an inch in diameter. This is not fastened to the cradle, but can be lifted on and off at pleasure and fits in so as to be quite steady ^hen in its right posi- tion. Beneath the riddle is an apron, made by stretching a piece of canvass on a framework resting on fillets, inclined from the bottom edge of the riddle towarda the head of the cradle. Across the bottom are two riffle bars, about three-quarters of an inch in height, one towards the middle, and the other at the lower end. The dirt is shovelled into the hopper, and the miner rocks the cradle with one band, whilst with the other he « EXTRACTION OF GOLT). 15 gings, &c,, iployed for ag and col* on of gold or washing fter a cer- get rid of ling in the ,y of black )m the gold e, to a great and the use forty inches from fifteen loped off at •scuttle, the 1 hopper, or in depth, of , perforated not fastened r at pleasure ts right posi- stretching a g on fillets, I towardi the ire two riffle height, one nrer end. nd the miner the other he pours water upon the dirt. The action of the water and motion together disintegrates the dirt, which paasea through the riddle and falls upon the apron, finally escaping at the lower end, leaTing the gold, black sand iind heavier particles of grarel behind the riffle bnrs. Mercury is sometimes used in the rocker but is not generally recommended. But by far the most important arrangemeit is the sluice, which is now almost universally employed for the collection of gold from placer mines. The sluice is a long wooden trough, having a con- siderable inclination, into which the pay dirt is shovelled, and through which a rapid stream of water is continu- ally flowing. At the bottom of this trough is a series of riffles, generally containing quicksilver, by which the gold is retained, whilst the clay, sand and gravel are carried off by the force of the current. The ordinary sluice is composed of a series of rough wooden boxes, each twelve feet in length, and from six- teen to tw»"ty inches in width, and from ten inches to a foot in depth. The descent of a sluice is called its "grade," and is commonly from ten to eighteen inches on each box of twelve feet in length. This " grade " is regulated by the position and length of the apparatus and the nature of the dirt to be washed. It is important to guard against giving too great an incl'nation, as there would be danger of losing the fine particles of gold; while, when clay is present in quantity, a small inclination will not easily effect its disiutpg ra- tion. A good deal of practice and judgment is obviously necessary to ensure the smallest loss of gold. As a general rule, however, a fall of less than ten inches, or more than twenty inches, on the length of a 16 XXTEACnON OF GOLD. tweIve>foot box, is not suitable for the ordinary sluice. If the pay dirt contain large bloekn of stone and boul- ders, a large body of water and a rapid current are required. The upper part of a aluice is sometimes made Bteep in order to effect the disintegration of the dirt, whilst the lower is placed at a less inclination for the purpose of collecting the gold, and this arrangement is often found advantageous. When the clay is very tenacious and rolls into balls, the lumps should be broken up at the head of the sluice, as balls of plastic clay, passing through the boxes, not only retain any particles of gold they may contain, but are also liable to pick up others over which they may pass in their course. Sluice boxes are provided with a false bottom for the purpose of retaining the gold, which would otherwise not only be taken away by the force of the current, but the bottoms themselves be rapidly worn out by the attrition of the stones and gravel passing over them. Generally these false bottoms consist of longitudinal bars, from two to four inches in thickness, from three to seven inches in width, and about five feet and a half in length. They are wedged in the boxes, an inch or two apart, by cross pieces, so that two lengths of bars are fitted in the bottom of each box. In the depressions thus formed, the gold, mercury, and amalgam are eaught. When the sluice boxes have been all joined together, i>^d the bars wedged into the bottom of each, the apparatus is ready for working, and the pay dirt is shoveled in at the head. About an hour or two after ttie commencement of sluicing, some quicksilver is poured into the head of the apparatus, whence it gradually finds its way downwards. The greater the amount of fine gold present, the larger mms^. EXTBACnON OP GOLD. 17 r sluice, and boul- irrent are nes made the dirt, >n for the gement is nto balls, he sluice, •oxef), not otain, but they may m for the otherwise rrent, bat It by the them, igitudinal a three to a half in ch or two ' bars are mercury, >xes have d into the king, and ement of ;ad of the wnwards. the larger must be the quantity of mercury used. Small quantities of quicksilver are also sometimes introduced between the bars and various other plAces in the boxes. When the gold is exceedingly fine an amalgamated cop- per plate is sometimes resorted to. This plate is about three feet by six, Is set nearly level, and, when the sluioe is very large, the stream is frequently divided into two or three separate portions, each of which is conducted over a distinct amalgamated plate. A well amalgamated cop- per plate is considered as effective for saving fine gold, «8 an equal surface of pure mercury, and is not only vheaper, but also more easily managed. The amalgamation is eifected by washing the plate with dilute nitric acid, and then rubbing on, with a rag, ^quicksilver, on which a little dilated nitric acid has beeu first poured. When a plate has been once well covered, this operation need never be repeated, it being onljr necessary to sprinkle its surface occasionally with a little Iresh quicksilver, in proportion as the gold caught con- verts it into a solid amoilgam. In order that these plates should work well, the current should be slow, and the water shallow, otherwise a eeissiderable portion of the fine gold might escape without coming in contact with the face of the plate. The collection of the dirt which accumulates in the boi* torn of the sluice, and the separation from it of the gold, amalgam, and quicksilver, is called the "cleaning-up," and the time between one cleaning-up and another ii called a "run." A run comr'only lasts about a week, :ind the cleaning-up is not unfrequwntly reserved for the Sunday. This occupies about half a day. The amalgam and mercury taken from the sluice are first separated from nny sand, &c., by panning, tbeu «(raincd through buckskin, or close canvas, which allows 18, EXTRACTION OP GOLt). the quicksilver to pass through, but retains the amalgam. To obtain the gold, the amalgam is heated to volatilize the quicksilver; the gold is left in the form of a poroun mass of a light yellow color. This operation is most economically performed in a cast iron retort, provided with a refrigerator, by which the mercury is condensed and can be collected for sub- sequent use. But the miners often drive off the quick- silver by simply heating the amitlgam in a sliovel. In small sluices, the bars are sometimes placed in a series of zigzngs, instead of longitudinally or transversely. The "under-current sluice" is a modification which in often found advantageous. A grating is placed in the bottom of the lower ex- tremity of the last box in the series, and beneath this is introduced another sluice with a lower grade and fresh supply of water. The impetus acquired by the large boulders, in the first sluice, causes them to roll off over the grating, and, together with a portion of the water, to escape at the lower end; whilst the introduction of clear water, tbo less inclination, and more moderate current, arrest many particles of gold that would, under ordinary circum- stances, be lost. There are also "rock sluices," but they are more -difficult to clean up. In "tail sluices" stone bottoms are used, having an inclination of about an inch to the foot. To clean up it is necessary to remove the stones. Tail 8lui''.es are useY are only only require nr. They are s of stone, or EXTRACTION OF GOLD. 19 wood placed on end, and often aficrd large profits to their proprietors. "Ground sluices " are used in localities where there is a large supply of water, plenty of pay dirt of low pro- duce, and the necessary declivity. A small gutter is first made with a certain inclination, and into this is directed a stream of water, by the action of which th« channel rapidly becomes deepened and enlarged. Xo mercury or riffles are employed in the ground iluice, but unless the bottom conoists of a rough and ir- regular bed rock, some large stones should be roughly thrown in for the purpose of arresting the gold, which, if the surface were not uneven, would be liable to pa^si off* and be lost. . In " river mining " tho stream of a river is turned by means of a dam in connection with a ditch or large wooden flume. The dirt is subsequently washed. The streams selected for this purpose are generally mere mountain torrents, of which the banks are steep and irregular. This sort of mining can only be successfully carried on during the summer and early fall, when the water is not only low, but when there is also no danger of a sudden freshet which might sweep before it, flume, dam, and ^ools together. Hydraulic Mining. iu order to treat moat successfully the extensive bedt «f detritus forming the deep placers, the following con- ditions are inrolved: — 1. Whatever may be the depth of the auriferous gravd, the whole must be removed down to the bed rock. 2. This must be effected by the force of a column of water, manual labor being too expensive for the purpose. 3. The mechanical disintegration of the more or less indurated gravel must go on at the same time as the cashing of the resulting debris, and be effected by tho same supply of water. 4. Provision must be made for readily disposing of j the large amounts of refuse resulting from the removal of fuch vast masses of auriferous gravel. To fulfil these conditions, after having selected a suf- ficient extent of suitable ground, water is brought from i a canal, by side flumes or aqueducts, to the head of the mining ground, with an elevation of from 120 tof 140 feet above the level of the bed rock, where it i« conducted into a wooden tank, into which it constantly! flows. This box is provided with a valve from which tb«l water is conveyed to the bottom of the claim by meanal of a strong sheet iron pipe, from eight to fourteenl inches in diameter, communicating at the bottom with al thick rectangular cast iron chamber, in the sides of whicbj are apertures provided with slide valves and union jointt(,j to which are fitted strong flexible hose, terminating ii bronze nozzles from two and a half to three inches ia| diirtr'^ter. or extensive bed* following COD* •iferous granl, ed rock. of a column of the purpose. more or less me time as the effected by the ily disposing of m the remoYal ; selected a sttf- is brought from to the head of )f from 120 to rock, where it '» th it constantly J from which tb« claim by mean* Tht to fourteen le bottom with « \xQ sides of which and union joints, ), terminating in three inchei w BTDRAULIC MININO. 21 The hose are asually made of cIo8cly*sewn heavy duok, and will, without external support, bear the prC'- sure of a column of about fifty feet in perpendicular height. When, as is frequently the case, the pre8Su<« employed is greater than this, they require to b« •trengtbencd by iron rings. When so made, the hose will support the pressure of a column a hundred and •ighty feet in height. Sometimes a netting of cord ia •sed instead of iron rings. Streams of water are directed from the nozzles against the face of the gravel to be washed, with a force which is astonishing. Very often four or five such streams ai* made to act simultaneously, under a pressure of from 00 to 100 pounds to the square inch, against the face of the same bank. Large masses of gravel are thus brought down, which fall with violence, rendering it necessary for the work- men to exercise great caution to avoid accidents. The debris thus produced becomes rapidly disintegrated and is carried forward by the force of the water to th* alulce, through which it passes with the whole volume of Ihe turbid stream. Banks of more than 80 feet in height are usually worked in two benches. The upper half is never so rich as the lower, but is, m a rule, less compact and more easily removed by the ao- tion of the water. Sometimes the lower section is so indurated that it requires the aid of gunpowder to looaen it. The sluices employed in hydraulic mining are mad* wider than those used for other purposes, and are loroe- times provided with wooden riffles, kept apart by slips •f wood. In some the bottoms are paved with stone. The gold Li oollected io the cavitiet formed by the a '12 nYDUAUi.IC MI.>(1N(J. (liffrfiit hlooks of wood coiintitiiliug the riflies. Betwc( a llie-e riftle l)lo,.'IvS quicksilver id placed. Kx])cri«'tue luii prctvt'd llint a lnr^cr proporlioii of flirt proci')u.'< nf'tiil is citlloctod by thiti lluiii bj any oihcr prooe^d, and at tiu< saine time the cost of liandling a iuliic yard of dirt is infinitely less. As :in evidence of the iuiinenso .idvjinlagcs of tlio lirdiaulio process over every otlier system of placer niiiiinj;, it may bo stated that the comparative cost of lundiitif,' ;i cubic yard of gravel will be nenrly an Lollows: — With the pan flO 00. " rocker i 00. Uy hydraulic process 06. Beiwc« I* )n of th(» iiiy olliLi' kudling a >s of tljrt of placer c cost of icarly a* ) 00. i 00. 00. Vein Mining. Having K'^'^'n* i^ i-^ hoped, a toleniblv olcnr id^a of ihe various processcB of gold wasliing, it i.s not proptised in the present littlo treatise to furnish more tlian a hlimt description of tlic opcitions of vein ntiriing, for iii« subject of quartz, or .ciu miniiipr, U one of such n a; - nituJe and importance, that justice could not be rendered t^ it without enlarging thin f umphlet to a size far exceed- ing that which was originally intended. In vein mining, the minor undertakes through liis own fikill and industry, by breaking up the original ninirii and extracting the frecioua metal which it enclose.*", to elloct that which, at some earlier period of the world*.^ liistory has, in placer.-', been done for him by nature on a gigantic scale. The processes employed for the extraction of gold quartz, are identical with the ordina'-y mining operation* in use for working regular mineral veins. From the irregularity of the produce, it is impossible to ascertain the average yield of a vein without crushing und e.xperinienting on large quantities. IJut to judge, approximately, of the value of rock, a RHJall quantify is pounded up fine and sifted. The sieve is examined to see if any flattened grains of gold remain on i(. The sand or powder thus obtained is washed in a Rhallow iron pan. Most of the gold is thus left in the angle of the pan. By continuing i\u>> process upon successive quantities of pulverized quartz, and when th« bulk baa been reduced to a manageable quantity, the i - V. Hi !! VFIN MINING. f^ld is Rinalgamated with quicksilver, the amnlgam atrained to Bcparate excess of mercury, and fiaally heated to expel the whole of it, leaving the gold. After concentrating the gold in a smiU quantity of piind and pyrites, the residue may be subjected to th« fire assay, by which, of course, a much more accural* result can be obtained than by amalgamation. The processes employed for the extraction of gold are Ttirious. The two principal methods are "amalgama' tion" and "chlorination." AuALOAUATioN IN Arrastras. — This is an old method used by Mexican gold miners, but it gives tolerably good results. It is useful for testing the value of newly dli' covered quartz veins. The arrastra consists of a circular pavement of stone about twelve feet in diameter, on which the quartz is ground by means of large stones dragged in a circjlar way by chains, fastened to four arms of a strong upright wooden shaft. One of these arms is made sufficiently lo»g to allow mules to be attached for working the machine. Round the stone pavement arc wooden sides about two feet in Jieight. Six to ten revolutions per minute are performed by the 1)locks of stone, each of which weighs from three to four liundred pounds. One and a half to two tons of rock, which has been previously broken in pieces about tho »ire ot an egg, can be ground in 24 hours. The crrastra is cbarged with about two hundred pouiidH of quartz, and is set in motion, a little water being added from time to time. When tbe ore hiis assumed the consistency of thick vreum, quicksilver is sprinkled over its surface in lli« proportion of one ounce and a half for every ounci* of l(o!d supposed to be contaiued in th.' rock. lifted its on riou fitrucl ' Tilt platcf the b, disclif plat.' towjir The VEIN MINING. 2^ The grinding is then continued for about twoliotlM.' AVhen the amalgamation ia considered complfite,*wia^er is admitted into the paste so aft to render it thin, and the machine is turned more slowly, to allow the pattlclef of gold and amalgam to sink to the bottom. After nbout half an hour the thin mud is allowed to ruti'oft^ Jearing behind it, in the bottom of the arrastfa, the g61d combined with the quicksilver in the form of amalgarii'. Another charge of broken quartz is now put in aiid treated in the eame way, and so on till it is thought desirable to stop to clean «p. Sometimes one hundre'd lo one hundred and fifty tons are thus worked through in one *' run." Amalgamation in Iron Pans. — There are sevletail kinds of pans, named af er tlei! differeat inventory, araoijg which the Wheeler pan occupies a favorabl* position. The two conditions, friction and contact with mercurV, are accomplished in a high degr^; in this pan, by whicli" as much as 95 per cent, of the jC^olil present is obtainied. Amalgamation in the Battery. — The battery ot fitampiiij mill consists of a series of heavy pestles, work-* ing in a reetanguliu- mortar, each of which is alternatelr lifted by means of a cam, and then allowed to full with its own weight upon the qunrtx, which has been pre- riou ly broken up in small lumps. The number of blows etruck by eacii stamper is from GO to 80 per minute. ■ The ba'tcries are provided with amalgamated copper' plates, three to five inches widt^, having the length oi' the battery ; one on the feed sidxj and the other at the discliargi', the former being protected by the iron feed plate. Tlit'v each incline at an angle of 35 to 40 degrees towards the stampeis. * The ouantity of quiohsllver reqiircd depends uooo tf^f* w w Ht mii: . > "m» I I u nf VEIN 411 NINO. quantity of gold in the ore. Each ounce of gold (alfes vae, to one and a half, ounues of quirksiiver, which ii iutroUuced from lime to time by the feeder, during tha «iiHn;piug. iiy thi.s .process 60 to 75 per cent, of the gold present may be extracted. hi some places the rock is crushed without the use of iiuicksilver in the mill. Tiie sand and water isi>uing from tl^e battery are conducted over blankets fipread on the bottoms of shallow troughs, inclined at an angle of threo or four degrees. Beyond tlie blankets there are generally riffles or amalgamated copper plates to catch the gold which may have escaped the blankets. The stampers are generally kept at work day and night, and the cleaning up of the battery takes pluuti About once a week. When quicksilver is used in the battery, a large pro- portion of the go'd obtained is taken from it in tlie form of amalgam, and even when this n'etal is not introduced' n considerable percentage of the the produce is obtained ill cleaning up, having accumulated in the caviliis Around the dies in the shape of metallic spangles. The coarser the gold in the rock, the larger is the iwrcentage of the total produce retained in the battery. The *'tChloiiniiiion process" gives satisfactory result.-* wijen the gold i.s in a-finely-divided state. It is especially imod lor ex racting ».he gold from tailings, and is based »>ii the property of chlorine, of combining with gold, lorming terchloride of gold. The tailingH are first roasted to expel the sulpliur, Mrttoniu, &c., sometimes a little suit or charcoal is add<.'d, I'ljo former, however, causes a loss of gold. Alter six to eight hours roasiing the ore is ppread ou; ti» «ool, and then sprinkhd over with wnter aud turnel} *».vec liU ro^ulrtrly and snitablv mostcued. i! 1 YEIN MINrS'G. 27 1 taVefl hich W ing tli« prese n6 ; use of ng ficm on the of thre« [cnerally the gold day and ces pluutf irge pro- tlie form itroduced obtained cavUit.s» es. trer 13 tl'c battery, ry resullH eppecial'y d is based ith gold, Hulpliur, is added, spread oui Lud turtielt The stuff" is llien introduced into tubs about sev^n' ffet in di.imeter nnd twenty-five or thirty inches dfeef*-' These tnbs have false bottoms through "which chloifitte gas ii allowed to enter into the mass of danip'tflilin|»P. At the bottom of each tub are two holes, one for the in-' itoduction of the chlorine, the other for rutining offthe solutions. , The gas is made from a mixlM-e of salt, peroxide oV manganese and sulphuric acid, and tlie evolution is ke|)& lip from twelve to fifteen- hours, during which time the' tubs are covered. The covers are then removed and clean water intro- dTJced until it reaches the surface of the tailings, when the discharge pipe is opened and the liquid, containing' the dissolved chloride of gold, its drawn off into giants vessels. Sulphate of iron is added, which precipitates the gold as a brown powder,, whioh is easily separated by decan- tation and filtration, and then ntcltedi into burs which arc about 995 fine. MTSRMINATION OF THE VALDE OV A 8PKCIMKN OF OOL1> QUARTZ, WITHOUT DESTROYING TIIK 8PECIMKN. Let a represent the specific gravily of the metal. Hi •• b ti tt It it " «« 44 it it " w «t 41 weight of lh« •♦ X 44 41 «t ti Then x a (c-b) •a. W ti stone, lump. ti gold. c (a-b) The specific gravity of the metal and that of the stone kave of course to be assumed, as they var; according in- •ireumstances. itt a general rule in thete Calculations the form4»r in- HHmuaamm t^ VSIK HINIMG. token at 19, ttje latter at i.6. A convenient, waj of taktag the specific gravity when no apparatus is at band, i^ to fill a glass YrsBtl with water, to a mark. Then pour, or.4raw. off into snother smaller vessel, so much of th 20066400. 20066400 — i 43 = $4666.60. The "net" value of gold bullion is equal to the value ' of the gold plus tie value of the silver alloyed theire-. with, less the expense of coining and refining. In refining, that is the separation of the silver froia lh6^oId, it has been found expedient in practice ta>' f 1 I i 30 CAtClLATrONS OF THE VALUE • T'GOLD: ! ; lea re a certain small proportion of silver in the goM, fine* fo extract the whole would bn a much more cxpsiiHift operation, and, for commerciHl purpo8e.>:, not a neccs8ar)r •no. The amount of ailrer which is retained in the gold III *<)uul to 1-99 ot the weight of the fine gold, in other words, the gold i» refined^to 990 fine. It is usual to essume in^cnlculating the vnluc of ballior, that there are ten thousandths ( Olo) of base metal present. The following examples will serve to explain the manner in which* the net value of a deposit is obtainedi fiupposiiig we have a bar weighing loO oz?. gold 9(n) fine, value of the gold $1860.4i8 fjOzs, pure silver, less- 1-99 of 90 ozs. pure gold equals .909, which, deducted from 9 oz^. purfr . filver, equals 8.09 ozs. multiply this by the value of pure silver, $1.29'29, and the value of the silver is 10.46* Premium on silver in San Francisco Mints, 4 percent .49 T'lilue ot the gold and silver $1871.94 Deduct charges : 8 cts. per oz. for refining, $8.00 , ^ of 1 per cent for coining, $9.38 17. S6 Xft value in gold coin at San Francisco.. $1853.99 In the preceding, case the net value in coin U $6.47 hess than the value stamped on the bar, which is that of the gold alone; it being the custom to look upon th« wlver as pajing the expense of refining and coining, or - to other words the conversion of the buliion into coin. According to the proportion of the two metals tbo b«1., value varies. In the example above given there was a >e#8. Wo may take another example in which ike net 99 of lor > itt a GALCDLATlOXS OF TIIE VAtUF, OF GOLD. i>i THlue of the bar exceeds the stamood vuhio of the jrold, nwin^ to the lower (ineness of the ktter and consequrnt •larger proportion of silver. 100 ozii. gold, 800 fine, value of the gold $1053 79 10 0Z9. pure silver, less 1-99 of 80 oz^. pure gold equals .808, wl ich deducted from 19 oz-«. pure silver, equrtls 18.19 07-s. multiply this by |!1.2929, and the value of the silver is 23 68 -I'remium on silver in San Francisco, 4 per cent .iH Value of the gold and silver $1678.21 Deduct charges: 8 cts. p^r. oz. for refining, $8.00 i of 1 per cent, for coining, $8.39 1 6 ao Xet value in gold coin in San Francisco $1661.82 Gain $8.07. A simple method of calculating (he value of the gold «nd silver in a bar is to reduce the 'proportion to fine Rold and fine silver, and multiply by the value per o». of pure gold and pure silver. For example a bar 250 ounces, 850 fine of gold, 140 f^ne of silver. 250 X 850 == 212| 07.9. pure gold, (o^ 20.6718, = $4392.76 250 X 140 =" 35 ozs. pure fcilver, @ 1.2929, =- 45.25 Value of cold and silver $4438 00 The above calculations give the Fan Francisco Mint value of gold bars, that is the value of bars converted into coin in San Francisco. Besides this there is the commercial value. Largn quaniiiies of unrefined bullion are required for exportn- tion to Europe and the Eastern States, and the unpailelt ,»;old n.ay be said to vary in price like any other cod»- luodity according to the supply and demand. When gold bar; are ^itcd At <900 par, it incani tl.kt lii iiH 3f CALCrLATI.NS OF THE VALUK OF GOLD. the price U ^18 CO per ouncp, i. c. the viilne of gold «f the fineness of 900: ami bars of a lower finenfss wciiM rontinHiK] a preiniiim wliile tliose having a higher fii.«- iif-M would bo subject to a "discount. For every decree of lincneas above pir, 1-100 of 1 ] er cent, is deducted, and lor every degree of fine- ness bel<»\v the par rate, 1-100 of 1 per cent, is added fo the value of the bar. Suppose 850 to be par. a bar 890 fine must be d\r- eonnied 4-10 of 1 per cent, because it is deficient .04<'» in silver as compared with par rate. But if the bar be S .0 fin , a premium of 4-10 ofl per cent must be allow- rd, because it contains .040 of silver njore than the par rate requires. In Eng'and the coinage of money is done by the Government without any cliarge, and the United Statfi (lovernment has lately had under consideration the euL" joct of ciLher reducing ihe charsjo of -J of 1 per cent, or of abolishing it altogether, M'iih the view of stopping, as fir as possible, the outflow of bullion, and increasing ilie coinage of tho country. If such a measure should lake effect, no doubt ihe export of bullion from the United States would be to some extent cheeked, and the calcu- iiitions of tl'.c value of gold given above would require •ome movllficatiun. Miscellaneous. A cubic inch of fine gold weighs 10.1609 ounces, and is worth $209.84. A cubic foot of the same is worth $362,600. A cubic inch of United States Standard gold weighs 9.0989, and is worth $169,28. A cubic foot of the same is worth $292,500. The Troy ounce is equal to 480 grains. The U. S. $20 piece weighs 616 grains. The specific grarity of U. S. Standard sold is 17.3. -: 2 c = .,. c T' T^ 'r^ 'yi /^ ^- ,^ ;- = o ^ r.5 ~ f: » 1 r/5 CO f/; -r a: -'. «c CO oc oc .oo sr: cr oo 70 -y »;• iw tr tr >^ o :r cr li- -T 'c cs c. »-' «s -j -I t— ' o Iw — ) v_ Cl CO >-» -1 t,< '>^ l-i ■" '^' 10 oOOoo~ooco,- 000020 C/j 00 V3 ^ r/; 00 o O '"'" "^ -^ O fX CO iT 'O C; W I L I— 1 O". C. ►— l-t CO •n 1; to ic 10 li • : yi c w ic li. f- t>' oi cx) 00 c - • -1 T rw H -1 <•/;' rt k-i b— J t-^ iHt (— t f.^ t-U 1— J ^«ri y 4 ^ Cr. C'l -1 — T C: C -^1 -4 Ol -I -0 ~J C-. OT c: -^7 — T c: i'l oi -1 t" CO ti >u — ' C: -T t.-i H-i H- ^3 c ct 0; cyj >— cc 1— ' 01 Uj c ^ 01 10 C-. li ^J ►^ 0000000 00000 l-i t-J >-» — ■ !_-' |_l i_i _ I-* 1— ' -7 tn a> ^i ~T -I 00 00 Ct -I CO Ti -T c-. a CC '>0 "xa CO to ri ^ 1-'- M c-5 -I -- — .■- >-« t*' Ot Or 1 »-» e» »*»• i* ci 4» L^:' -^ ti CO CO 4- cw 4- CO 00 N • ^•- -i 1 m 03 00 oc «o 00 00 00 CO QO 00 QO 'X) lA '" CT 05 ►-' CO CO I—- 1—1 '*• ►-* ►^ i^OiCOH-'tr'CCOCslO CO Cin t* C% CO rf». CS if- 3 3 . ■# ' 3 o Hi M O < O ri U2 O W P ^ O «* Arerage value of dust per oa. p» Or ;^ ~I -a to ^«o ^ *-• CO MH-i «OK'bo>*kOo^o->J-^t*boto o o