SILVER.
1. Silver is a metal of a fine white color, and, in brilliancy, inferior to none of the metals except steel. In malleability, it is next to gold, it being capable of reduction into leaves not more than the ⅟160000 of an inch in thickness, and of being drawn into wire much finer than a human hair.
2. The relative value of silver and gold has varied considerably in different ages. In the prosperous period of ancient civilization, one pound of gold was worth twelve of silver. In Great Britain, the relative value of the two metals is one to fifteen and one-fifth, and, on the continent of Europe, it is about one to fifteen. In the United States, the relative value of these two metals has been recently established by Congress at one to sixteen. In China and Japan, it is said to be one to nine or ten.
3. There are two methods of separating silver from its various ores, and these are called smelting and amalgamation. In the former method, the ore and a due proportion of lead are heated together; and the latter, from its great affinity for silver, unites with it, and separates it from other substances. The two metals are afterwards separated from each other, by melting them on a cupel, and then exposing them to a current of atmospheric air, by which the lead is converted into an oxyde, while the silver remains untouched. This process is called cupellation.
4. In the other method, the first thing done is to roast the ore, to expel the sulphur and other volatile parts. It is then reduced to an impalpable powder by machinery; and having been sifted, it is agitated sixteen or eighteen hours in barrels, with a quantity of quicksilver, water, and iron, combined in certain proportions. This agitation causes the several substances composing the charge, to unite according to their respective affinities.
5. The silver and mercury combine, forming an amalgam, which, having been put into a leather sack, a part of the latter is separated from the rest by filtration, still leaving six parts of this metal to one of the silver. The amalgam is next submitted to the action of heat in a distilling furnace, by which the mercury is sublimated.
6. The value of the silver annually taken from the mines in all parts of the world, is supposed to be about $20,000,000, of which Mexico and South America yield the greater part. The several silver mines of Europe and Asia produce about two millions and a half.