The art of obtaining metals from their ores, comprising the processes of assaying, refining, smelting, &c. By assaying is meant, the particular manner of examining an ore or mixed metal, according to its nature, so as to discover not only what metals and what proportions of metal may be obtained from it, but also what other mineral substances or earths may be contained in it.
What do the terms Refining and Smelting signify?
Refining is the art of rendering the metal free from all impurities. Smelting means the melting of a metal from its ore in a smelting furnace, in order to separate the metallic parts from the sulphur, arsenic, and the earthy and stony substances with which they may be combined.
What is Sulphur?
An inflammable, fossil substance, of a dry, solid, friable nature, melting with a small proportion of heat;—when fired in the open air, burning almost entirely away with a blue flame and noxious vapor. It is abundantly diffused in many places, especially where metallic minerals are found; but more particularly in those districts where subterranean fires and volcanoes exist. It is also found combined with many different substances.
Describe the nature of Sulphur, and the places where it is mostly found.
Sulphur almost pure, called native or virgin sulphur, is found in volcanoes and grottoes, in the form of transparent crystals; but the greatest quantity which exists naturally is combined with metals in ores. Sulphur is both fusible and volatile,—which qualities enable us to procure it from those minerals by the process of sublimation: it unites easily, in different degrees, with all metallic matters, excepting gold, platina, and zinc.
Sublimation, the act of bringing a solid substance into the state of vapor by heat, and condensing it again by cold.
Are not its uses very extensive?
Yes, both in the arts and in chemistry: it is well known to be a principal ingredient in the preparation of gunpowder and fire-works; it is also used for whitening wool, straw, silk, &c.; many other matters exposed to the vapors of sulphur when burning, quickly lose their color, which no other substance had been able to destroy. Sulphur is also frequently found in mineral waters.