These present less variety than those of many other metals; and on account of the peculiar properties of the metal, the management of its ores, whether for the purposes of analysis or reduction, is less complicated and difficult. In order to analyse the ore of native mercury, or native amalgam, it may be dissolved in nitric acid. The gold, if any is present, remains in the state of powder, and may be estimated by its weight. The affusion of water precipitates the bismuth, if the solution happens to contain any. Common salt precipitates the silver, and also part of the mercury, but the latter may be redis-solved by a sufficient quantity of water, or, which is far better, of oxymuriatic acid, while the muriate of silver remains insoluble; lastly, the mercury may be precipitated by sulphate of iron, and estimated. Native cinnaoar may be treated with a mixture of three parts muriatic, and one part nitric acid, which dissolves the mercury, and leaves the sulphur. Muriate of mercury may be digested in muriatic acid, till the whole is dissolved. Muriate of barytes precipitates the sulphuric acid, 100 parts of which are equivalent to 186 of sulphate of mercury, and the proportion of this salt being known, we have that of the muriate.
A very simple process is followed for reducing the ores of mercury; the best and most scientific method is that practised at the mines of Deaux Ponts and Poria. The ore, as it is brought out of the mine, is carefully sorted by the hand, and those parts which seem destitute of metal are rejected. It is next reduced to powder, and accurately mixed with one fifth of quicklime, which has fallen to powder by exposing it to the air, the quantity of quicklime being regulated by the proportions of cinnabar contained in the ore. The mixture being thus prepared, is introduced into iron retorts, which are capable of holding about sixty pounds weight. The retorts, to the number of forty or fifty, are fixed in a long furnace, and a glass receiver is attached to each, but it is not luted. A moderate heat is then applied, for the purpose of driving off the whole of the moisture, and when this is done, the joinings of the vessels must be closely stopped with tempered clay, and a full red heat is to be applied, and continued for seven or eight hours, at the end of'which time the whole of the mercury will be volatilized, and condensed in the receiver.
By this process, it is found that from six to ten ounces of metal are produced from one hundred pounds of the ore.