Arsenic

(ar'se-nik.) (Chem.) A metallic element known (in its compounds) from an early date, but first investigated chemically by Brandt in 1733. It is occasionally found native, but more frequently in combination with iron, copper, cobalt, and nickel ores. In the metallic state, it is of a steel-gray color, is very brittle, and crystallizes in rhombohedrons. When heated it volatilizes with fusion at a dull red heat At. weight 75; sp. gr. 5.62 to 5.96; Symbol As.-It forms 2 oxides: the trioxide or arsenious acid, and the pentoxide or arsenic acid. The former, called white arsenic, is one of the most virulent poisons of the mineral kingdom. It is a white, solid, crystalline, or amorphous substance; it volatilizes at 414°. When thrown on incandescent coals, it evaporates in white fumes, with a strong smell of garlic. Sp. gr. of the crystalline variety, 3-7385; of the amorphous, 2-695. Form. AsO3.-Arsenious acid unites with bases forming arsenites. Arsenite of copper (2CuO.HO.AsO3) is the Scheele's Green, a poisonous color used to impart a bright green tint to paper hangings. When exce of hydrated sesquioxide of iron is mixed with solution of arsenious acid, the whole of the matter unites to form Arsenite of Iron. Owing to this property, hydrated sesquioxide of iron is one of the best antidotes to arsenious acid; it should be administered in great exce , and freshly precipitated. [s. 1]