URANIUM

A metal discovered by Klaproth in 1789, who named it after the planet Uranus, discovered about that time. It occurs only in two native combinations,— the pech blende of Saxony, and the uranite; of the latter, fine specimens have been found in Cornwall. Little is known of the properties of metallic uranium: it appears to be a brittle gray metal, of the specific gravity about 9. From the experiments of Berzelius and Arfwedson we deduce the number 217 for its equivalent; that of its protoxide beiitg 225, and of its peroxide (sesquioxide) 229. The salts of the oxides of uranium are of a fine gra green or yellow colour: the persalts have been most examined. Ferrocyanate of pota a produces in them a very characteristic rich brown precipitate, not unlike that formed by the persalts of copper. They are also precipitated brown by infusion of galls. [s. 1289]