The Underground World: A mirror of life below the surface

by Thomas Wallace Knox

It is not a beautiful place of residence, and those who dwell there are almost entirely devoted to the production and preparation of silver.

An idea of the richness of the mines may be formed, when it is known that between 1556 and 1800 the mines of Potosi alone yielded nine hundred and twenty-five million dollars’ worth of silver.

PROCESS OF AMALGAMATION.

Silver mines are pretty much alike in all parts of the world. They are also not much unlike mines of other metals. They are opened by shafts, tunnels, and the like, the same as other mines, though each locality has some processes of operations peculiar to itself. The ordinary methods of separating silver from its ores are based either upon forming an amalgam of the metal with the mercury, or in bringing it into combination with lead, and afterwards separating it. The ores of Mexico and Peru are treated by both processes. Some of the richest ores are picked out and thrown into the furnace. The amalgamating process, which was long used in the silver mines of Mexico and Peru, and is still generally practised there, was invented more than three hundred years ago. The ores are crushed by stamping machines, and then ground with water, in machines called arastras, a sort of circular mill, run by mule power. It is ground to as fine a condition as possible, and, after being allowed several days to dry, is spread out in circular heaps, about fifty feet in diameter and a foot in depth. To every ton of this substance three bushels of salt are added, and the whole is then carefully mixed. A chemical substance, of a coppery character, is then added, and a sort of fermentation takes place, in which great heat is thrown out. Quicksilver is then added, in small quantities at a time, and crudely mixed in, until the whole mass forms an amalgam. The whole process occupies from four to six weeks. The amalgam is then separated from the mass of ore by a system of washing similar to that practised in collecting gold. The mercury is then separated from the amalgam by the ordinary process of evaporation, and in the same manner as if removing it from gold.

Sometimes silver is found in masses which are nearly pure; but this is very rarely the case. The largest quantities have been discovered in the copper mines of Lake Superior, and in some of the mines of Norway and Saxony. Some of these masses exceed five hundred pounds in weight, but ordinarily they weigh but a few ounces or pounds.

Specimens of native silver are frequently found in the beds of rivers, very far from any other deposits of this metal. The richest mines of this metal, at the present day, are in the United States, particularly in Nevada and Utah. The great Comstock lode has already been referred to. In November, 1859, the discovery of silver mines at Lake Washoe became known, and in the following year the products of the mines were sent out in such large quantities as to lead many people to suppose that the commercial value of silver would be greatly cheapened.

SILVER MINES OF NEVADA.

Mines have been opened in various localities throughout Nevada, but the richest of them, and, in fact, almost the only ones, of any great value, are on the Comstock lode. Its ores are very rich. The vein is of unusual width, and it has made fortunes for a great many men, and, on the other hand, has taken fortunes from a great many others. Some of the most extensive mining speculations ever known in California have been in these mines. Their value has greatly fluctuated; in some years the product has exceeded twenty millions of dollars, and the price of shares in the mines increased accordingly; then the product would suddenly fall off, and down would go the stock. Sometimes dividends would be made every month, and suddenly they would be followed by left-handed dividends, or assessments. In San Francisco a single day has witnessed the reduction to beggary of men who at sunrise could boast of considerable wealth; the following day might witness their return to wealth, or the return of others to poverty. Nearly all the men who made money in Nevada a few years ago, and did not kill themselves by riotous living, are now poor, and have a brilliant prospect of remaining so.