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 being 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. 1300]