“ These results were adopted until Péligot in 1840 discovered that Berzelius’s (and Klaproth’s) metal contains oxygen, and that his (Ur2) O3 really is (U6O6) ·O3=3U2O3, where U=120 is one equivalent weight of real uranium. Péligot’s results, though called in question by Berzelius, have been amply confirmed by all subsequent investigators; only now, on theoretical grounds, first set forth by Mendeléeff, we double Péligot’s atomic weight, so that U now signifies 240 parts of uranium, while UO3 stands as the formula of the yellow oxide, and UO2 as that of Berzelius’s metal. ”

“ Uranous Compounds.—Uranium dioxide, UO2 (Berzelius’s metal) , is a brown to copper-coloured powder, obtained by heating U3O8 or uranyl oxalate in hydrogen. It fires when heated in air, and dissolves in acids to form uranous salts. It may be obtained as jet black octahedral (isomorphous with thoria) by fusion with borax. Uranous hydrate is obtained as reddish-brown flakes by precipitating a uranous solution with alkali. The solution in sulphuric acid deposits green crystals of the sulphate, U (SO4) 2·8H2O, on evaporation. ”

“ Uranous chloride, UCl4, was first prepared by Péligot by heating an intimate mixture of the green oxide and, charcoal to redness in a current of dry chlorine; it is obtained as sublimate of black-green metallic-looking octahedral. The chloride is very hygroscopic. By heating in hydrogen it yields the trichloride, UCl3, and by direct combination with chlorine the pentachloride, UCl5. ”