BISMUTH, one of the brittle and easi ly fused metals. The ores of this metal are very few in number, and occur chief ly in Germany. This, in some measure, accounts for the ignorante of the Greeks and Arabians, neither of whom appear to have been acquainted with bismuth. The German miners, however, seem to have distinguished it at a-pretty early period, and to have given it the name of bismuth ; for Agricola describes it under that name as well known in Germany, and considers it as a peculiar metal. The miners gave it also the name of tectum argenti ; and appear to have considered it as silver be ginning to form, and not yet completed. Mr. Pott collected, in his dissertations on bismuth, every thing respecting it con tained in the writings of the alchymists. Beecher seems to have been the first chemist who pointed out some of its most remarkable properties. Bismuth is of a reddish white colour, and almost destitute both of taste and smell. It is composed of broad brilliant plates, adhering to each other. The figure of its particles, accord ing to Hauy, is an octahedron, or two four sided pyramids, applied base to base. Its specific gravity is 9.82. When hammered cautiously, its density, as Muschenbroeck ascertained, is considerably increased. It is not therefore very brittle : it breaks, however, when struck smartly by a ham mer, and consequently is not malleable. Neither can it be drawn into wire. Its tenacity, from the trials of NIuschen broeck, appears to be such, that a rod one eighteenth of an inch in diameter is capable of sustaining a weight of nearly 29/br. When heated to the temperature of it melts ; and if the heat be much increased it evaporates, and may be dis tilled over in close vessels. When allow ed to cool slowly, and when the liquid metal is withdrawn as soon as the surface congeals, it crystallizes in parallelopipeds, which cross each other at right angles.
When kept melted at a moderate heat, it becomes covered with an oxide of a greenish grey or brown colour. In a more violent heat it is volatile, and may be su blimed in close vessels ; but with the access of air, it emits a blue flame, and its oxide exhales in a yellowish smoke, condensible by cold bodies. This oxide is very fusible ; and is convertible by heat into a yellow transparent Om. Sul phuric acid acts on bismuth, and sulphur. ous acid is disengaged. A part of the bis muth is dissolved, and the remainder is_ changed into an insoluble oxide. Nitric acid dissolves bismuth with great rapidi ty. To one part and a half of nitric acid, at distant intervals, add one of bismuth, broken into small pieces. The solution is crystallizable. It is decomposed when added to water ; and a white substance is precipitated, called magistery of bismuth, or pearl-white. This pigment is defect. tive, inasmuch as it is liable to be chang ed by sulphuretted hydrogen, and by the vapours of petrifying substances in ge. neral. Muriatic acid acts on bismuth. The compound, when deprived of water by evaporation, is capable of being su blimed, and affords a soft salt, which de. liquesces into what has been improperly called butter of bismuth. Bismuth is ca pable of forming the basis of a sympathe tic ink. The acid employed for this pur pose must he one that does not act on paper, such as the acetic. Characters written with this solution become visible when exposed to sulphuretted hydrogen.