GOLD AND SILVER.
The important part played by gold and silver in eveiy period of the world's history, has always led to an interest being felt, in anything concerning them far above that manifested for most other metals. But notwithstanding this, our technical literatufe has long been devoid of anything like standard and reliable works on the subject. True there is always a vast amount of floating information respecting the precious metals, and this is from time collected and embodied amongst other matter ef a similar character. But a book devoted exclusively to the mining and metallurgy of the precious metals, and treating the subject exhaustively, has never until the present time been given to the scientific world. Now, however, we are fortunate in obtaining a work of this character, which has just been prepared by Mr J. A. Phillips, who is fully qualified for the task he has undertaken and successfully carried out. Mr Phillips, as a mining engineer, is connected with various extensive metallurgical establishments, and has resided in some of the principal mining districts of Europe and America, This has afforded him an opporunity for observation and investigation, and he has thus been enabled to obtain data for his work directly from the most authentic sources. In the volume before us, we have a practical record of well authenticated facts, and of the results of the author's experience. He does not attempt to advance new theories, nor does he hunt for evidence to bolster up old ones. He modestly asserts his belief that our knowledge of chemical geology is not as yet sufficiently advanced to warrant an attempt to form a general theory of the formation of mineral veins. It would be well for the sake of science, if many who go floundering about amidst a host of apotheses—possible and impossible—would subscribe to Mr Phillips's creed. Our author, however, gives three important conclusions upon this subject to which recent observation and experience have led him. The first of these is that the ■ most productive gold bearing rocks are by no means exclusively confined to the Silux*ian period. Secondly, that aqueous agencies have been and still are actively at work in the formation i of mineral deposits. Thirdly, that . gold ledges are not more liable to i become impoverished in depth than ; ordinary metalliferous veins.
The general plan of Mr Phillips's work is as follows: —First, there is a description in each instance of the principal gold and silver producing districts, then follows a large amount of statistical information respecting
their yield and importance. We then Lave the methods employed for extracting the ores described ; and, finally, a, description, of the apparatus used in their mechanical and metallurgical treatment. The author first discusses the mode of occurrence and geological position of gold, after which he considers the gold regions of the ■world. _ This is no light talk, occupying as it does seven chapters, which are replete with information upon this important subject. Our then introduces us to the practical systems of gold getting as adopted in the various districts, and under different conditions. Those consist in washing with the pan, the cradle, the torn, the puddling-box, the sluice, <fec. The pan is indispensable to the gold miner, and is used for washing, or as a receptable for gold, amalgam, or washdirt. The cradle is a box on rockers, fitted with a perforated iron tray, beneath which is a canvas apron. The dirt is placed n the tray, water poured on it, the cradle being rocked meanwhile. The dirt and gold are washed over the apron and fall on the bottom •of the cradle, the dirt passing off, and the gold by its superior gravity lodging two bars of wood nailed across the bottom of the box. The cradle does not generally answer so well as the long torn, which is an inclined trough with apparatus attached for •retaining the gold. But the various kinds of implements are adapted for the varying conditions under which gold occurs. The sluice, of which there ;are many varieties, is the arrangement now almost universally employed by Caiifornian miners. It is : a long wooden trough, or rather ■a series of troughs, placed at an incline, ;and extending several hundred feet in length. The dirt is washed through •these troughs, arrangements being made for detaining the gold. River mining is another method ofobtaininggold, and consists in turning the stream of a river by means ot a dam in connection with a 'ditch or large wooden flume, and subsequently washing the dirt found in its bed for the gold it may contain. Beach mining is the process of extracting gold •from the sands on the sea shore, and has been extensively carried on between iCape Mendocino, in California, and the mouth of the river Untqua, in Oregon. We now come to a system of gold •mining in which more science and skill ■are brought to bear upon the subject than in those already noticed. This is •hydraulic mining, the practice of which •consists in removing the auriferous gravel down to the bed rock by the force of a column of water. This is necessary, since manual labor becomes 'too expensive when from 1500 to 4500 cubic yards of dirt have to be disposed of during each -working day of ten ■hours. The mechanical disintegration ■of the more or less indurated gravel is carried on contemporaneously with the washing of the resulting debris, and is effected by the same supply of water Provision has, of course, to be made for the ready disposal of the large ■amounts of refuse resulting from the removal of such vast masses of gravel. The water for this purpose is led from a canal to the seat of operations, with an elevation of from 120 ft to 160 ft above the level of thebedrock.whereitis conducted ■into a tank. This tank has a valve, from which the water is conveyed to , the claim by means of an iron pipe, , which leads to a cast-iron chamber - fitted w ; ith side valves and union joints. To these joints are fitted flexible hose, having bronze nozzles from 2, h in to 3 in in diameter. The powerful jets of water from these hose, under a pressure of from GO lb to to 100 lb per square inch, are directed ', against the gravelly mass, which they , soon succeed in bringing down. The ■debris becomes rapidly disintegrated, ■ and is borne along by the resistless , force of the water to the sluice, , through which it passes, and where the gold is washed from the dirt. The . hydraulic process possesses enormous . advantages over every other system of placer mining, as will be seen by the following statement given by Mr , Phillips. Taking a miner's wages at , four dollars per day, the cost of handling a cubic yard of gravel will be about 20 dollars with the pan, five dollars with the rocker, one dollar with the long torn, and 0.5 of a dollar by . the hydraulic process. So far w r e have dealt only with the means adopted for obtaining gold in placer mining, where , tee metal is found in a more or less waterworn condition, embedded in . earth, clay, sand, or gravel. But there is another class—-vein mining— . in which the gold has to be extricated from its original matrix, after that has been obtained. This process, however, we must reserve for another notice ; but, in the meantime, we cannot too strongly recommeud Mr Phillips's interesting work, as being the best that has yet appeared upon the subject of goldand silver mining. It is thoroughly
comprehensive, and on every subject the fullest information is given, even to the minutest detail. It is a work the like of which we ha/'e not seen for some time, and which is in every way a success.— Mechanics'" Magazine.
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Bibliographic details
Westport Times, Volume II, Issue 179, 26 February 1868, Page 2
Word Count
1,308GOLD AND SILVER. Westport Times, Volume II, Issue 179, 26 February 1868, Page 2
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