Gold is found mostly in the metallic state, ,though generally alloyed with sil ver, copper, iron, or all three. It is found either in separate lumps, or visible grains, among the sands of rivers, in many parts of Europe and elsewhere. The quantity is, for the most part, insufficient to pay the cost of separating it; but it is thought to be more universally diffused in sands and earths than any other metal, except iron. The greatest quantity of gold is imported into Europe from South Ame rica. Some is brought from the East In dian islands and China, and some from the coast of Africa. The principal gold mines in Europe are those of Hungary.— Some sands afford gold by simple wash. ing ; the heavy metallic particles subsid ing soonest : but when it is bedded in earths, or stones, these substances are pounded, and boiled with one-tenth of their weight of mercury together with water. The mercury, after a certain time, absorbs the gold, and may be sepa rated by pressure through leathern bags, and subsequent distillation Or, other wise, if the sand be heated red hot, and quenched in water several times, for the purpose of cracking and dividing it, and the whole be then melted into glass, with twice its weight of the oxide of lead, call ed and charcoal powder be then added, the lead will be revived in the tallic state, and will carry the gold along with it. By exposure to a proper degree
of heat, with access of air, the lead may again be converted into litharge, and the gold will be left pure. This last opera tion is, in fact, a method of assaying sands which contain gold, rather than of obtain ing it from them in the large way.
Gold.is also found in certain martial pyrites in Sweden and elsewhere ; from which it may be extracted by torrefaction, or burning of the sulphur, and subsequent digestion in aqua-regia.
To obtain gold in a state of purity, or to ascertain the quantity of alloy it may con tain, it is exposed to a strong heat, toge ther with lead, in a porous crucible. This operation is called cupellation.
After gold has passed the cupel, it may still contain either of the other perfect metals, platina or silver. The former is seldom suspected ; the latter is separated by the operations called quartation and parting, For all these operations, see As