Bismuth

[Fr. bismuth; N. Lat. bismuthum; 0. Ger. wi muth- wei , white, and muth, mettle.] (Chem.) A metal (symbol Bi) readily distinguished by its peculiar reddish lustre and its highly crystalline structure, which is very perceptible upon a freshly broken surface; large cubical crystals of B. are easily obtained by melting a few ounces in a crucible, allowing it to cool till a crust has formed upon the surface, and pouring out the portion which has not yet solidified, when the crystals are found lining the interior of the crucible; atomic weight 213; sp. grav. 9-8. It is hard, brittle, and but slightly malleable. It fuses at 507°, and is obtained in fine cubical crystals by slow cooling. The peculiar property it po e es of expanding as it cools, renders its alloys of great use to the type-founder and die-sinker. It also increases the fusibility of other metals with which it is united. The remarkable alloy known as fusible metal contains one equivalent of B., one of lead, and two of tin; fuses below 2120, and, by a certain admixture of cadmium, can be melted at a still lower temperature. It is also occasionally employed in cupellation, and some of its compounds are used as pigments, the hydrated oxy chloride being used as a cosmetic under the name of pearl-white. B. occurs in nature principally in the metallic form in the clay-slate and gnei formations, its principal source being Schneeberg, in Saxony. B. is extracted from the ore by heating it in inclined cast-iron tubes with cups attached. The tubes are brought to a white heat, and the B. flows into the cups, which are at the lowest part of the incline. B. forms two oxides, - the teroxide, BiOg, and an acid oxide, BiOs, or bismuthic acid. Teroxide of B. may be obtained by heating the nitrate to low redne ; it is a yellow insoluble powder. The hydrated teroxide, which is white, may be obtained from a salt of B. by precipitation with ammonia. - Bismuthic acid, or peroxide of bismuth, is formed when hydrated teroxide of bismuth is digested with a concentrated solution of potash, through which chlorine is pa ed. A red solution of bismuth ate of potash is formed, and a red precipitate falls to the bottom, which, on being well washed and digested in cold nitric acid, leaves behind a red powder, which is the hydrated acid. - Nitrate of B. is prepared by di olving the metal in dilute nitric acid with the aid of heat, which gives rise to four-sided prisms, which are decomposed by water into an acid nitrate, which remains in solution; and a basic nitrate, the tri snit rate of B., falls as a precipitate. It is used as a pigment, and also as a cosmetic. This salt was formerly called magistery of B. The other compounds of B. are too unimportant to be described. B. occurs in nature a ociated with cobalt, silver, tin, and arsenic; also as an oxide, in B. - ochre; as a sulphide, in Bismu thine or B. glance; as an arsenide, or carbonate, and a silicate, in B. - blende, and Bismutite.