URANIUM. The fracture is passes into uneven. is imperfect and flat conchoidal, which edg^cT fiagmentS are indetorminate angular, and sharp- _ It sometimes occurs in curved lamellar distinct concre tions. I It yields readily to the knife. In the streak, neither colour nor lustre is changed. It is brittle. ° It is completely infusible, without addition, before the blowpipe With soda or borax it forms a grey, muddy, slaggy-like globule ; with phosphoric salts a transparent green bead.^ It dissolves imperfectly in sulphuric and muriatic acids ; but it is nearly completely dissolved in nitric and nitro-muriatic acids ; and from this solution, which has a pale orange yellow colour, the uranium is precipitated brownish-red by prussiate of potash, and yel low by the alkalies. It is uncommonly heavy. Specific gravity, 6.3785, Gmjton; 6.5304, IJauy ; 7.500, Klaproth. Chemical Characters. Constituent Parts. Silica, Oxide of Uranium, Black Oxide of Iron, Galena or Lead-glance, Joachimsthal. Klaproth, Beit. b. ii. s. 221. Geognosiic