The filtrate contains the uranium as uranous and the iron as ferrous salt.
Metallic uranium, as shown by Peligot, can be obtained by the reduction of a mixture of dry chloride of potassium and dry uranous chloride, UC1 4, with sodium at a red heat.
If forms two series of salts, one, the uranous compounds, are derived from the oxide U02, the other, the uranyl compounds, contain the divalent group U02.
Uranous Compounds.-Uranium dioxide, UO 2 (Berzelius's metal), is a brown to copper-coloured powder, obtained by heating U308 or uranyl oxalate in hydrogen.
It fires when heated in air, and dissolves in acids to form uranous salts.
Uranous hydrate is obtained as reddish-brown flakes by precipitating a uranous solution with alkali.
Uranous chloride, UC14, was first prepared by Peligot 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 octahedra.
With hydroflouric acid it yields uranous fluoride, UF 4, which forms double salts of the type MF UF 4.
Uranous bromide, UBr4, and uranous iodide, U14, also exist.
Solutions of uranyl salts (nitrate, &c.) behave to reagents as follows: sulphuretted hydrogen produces green uranous salt with precipitation of sulphur; sulphide of ammonium in neutral solutions gives a black precipitate of UO 2 S, which settles slowly and, while being washed in the filter, breaks up partially into hydrated UO 2 an sulphur; ammonia gives a yellow precipitate of uranate of ammonia, characteristically soluble in hot carbonate of ammonia solution; prussiate of potash gives a brown precipitate which in appearance is not unlike the precipitate produced by the same reagent in cupric salts.