Antimony is obtained by a kind of eluation from the minerals containing it, as is described in the article Antimony; and the regulus of antimony is procured from antimony, by the processes described in the same article, and in the article Regulus of Antimony.
Arsenic, saffre, and bismuth, are obtained generally from one ore, namely, that called cobalt. The ar- senic of the ore is separated by roasting, and adheres to the internal surface of a chimney, which is extended horizontally about 200 or 300 feet in length, and in the sides of which are several doors, by means of which the arsenic, when the operation is finished, may be swept out and collected. These chimneys are gen- erally bent in a zig-zag direction, that they may better retard and stop the arsenical flowers. These flowers are of various colours, white, grey, red, yel- low, according to the quantity of sulphur or other im- purity, with which they happen to be mixed. They are afterwards purified by repeated sublimations; while some alkaline or other substances are added to detain the sulphur, and to assist the purification.
In the same roasting of the ore by which the arsenic is expelled, the bismuth, or at least the greatest part of this semi-metal which is contained in the ore, being very fusible, and having no disposition to unite with the regulus of cobalt, which remains in the ore, is se- parated by eluation.
The remaining part of the roasted ore consists chief- ly of calx of regulus of cobalt, which not being vola- tile, as the arsenic is, nor so easily fusible as bismuth is, has been neither volatilized nor melted. It contains also some bismuth, and a small quantity of arsenic, to- gether with any silver or other fixed metal which hap- pened to be contained in the ore. This roasted ore be- ing reduced to a fine powder, and mixed with three or four times its weight of fine sand, is the powder called saffre or zaffre. Or the roasted ore is sometimes fused with about thrice its quantity of pure sand and as much pure potash, by which a blue glass, called finalt, See Smalt. is produced; and a metallic mass, called speiss, is col- lected at the bottom of the vessel in which the matters are fused. The metallic mass or speiss is composed of very different substances, according to the contents of the ore and the methods of treating it. The matters which it contains at different times are, nickel, regu- lus of cobalt, bismuth, arsenic, sulphur, copper, and silver.
Bismuth is seldom procured from any other ores but that of cobalt. It might, however, be extracted from its proper ores, if a sufficient quantity of these were found, by the same method by which it is obtained: from cobalt, namely, by eluation.
Mercury, when native, and enveloped in much earthy or other matter, from which it cannot be separated merely by washing, is distilled either by ascent or by descent. When it is mineralised by sulphur, that is, when it is contained in cinnabar, some intermediate sub- stance, as quicklime, or iron, must be added in the di- stillation, to disengage it from the sulphur.
The rich ore of Almaden in Spain is a cinnabar, with which a calcareous stone happens to be so blend-