Silver uranate

Uranous Hydroxide.—The addition of alkali to a solution of a uranous salt produces a reddish-brown gelatinous precipitate, which darkens in colour on boiling the solution. If dried in vacuo it becomes black and has the composition UOg.HgO. This rapidly oxidises in the air and readily dissolves in dilute acids, forming uranous salts. It acts upon a neutral solution of silver nitrate, first precipitating silver oxide and forming a green solution which, however, soon turns yellow, and the oxide is reduced to metallic silver as the uranyl salt forms in solution, thus ... 

Silver Diuranate, Ag2U2 7 separates as an orange-red precipitate w hen freshly precipitated silver oxide is added to a solution of uranyl nitrate. It is also formed by the action of potassium uranate on fused silver nitrate. 

Uranous sulphate, even in acid solutions, is a strong reducing agent and can precipitate silver and gold from solutions of their salts. The sulphate is readily oxidised in solution by atmospheric oxygen. Both these reactions are accelerated by the presence of catalysts, especially copper salts, and in less degree platinum black or traces of iron salts. -... 

Uranous Nitrate has not been obtained in the solid form. It appears to exist in the unstable green solution obtained on the addition of uranous hydroxide to a neutral solution of silver nitrate (see p. 302). A light green basic nitrate has been obtained by short exposure to light of an eoholic solution of uranyl nitrate, and rapid filtration of the product. ... 

A special procedure must be used when titanium is not present alone since chromotropic acid reacts also with other metal salts. Ferric salts give a deep green color, uranyl salts a brown. These colors can be easily discharged by the addition of a hydrochloric acid solution of stannous chloride the resulting ferrous and uranous salts do not react with chromotropic acid. Those mercury salts which dissociate give a yellow color and silver salts form a black stain on filter paper if spotted with chromotropic acid. The presence, however, of these two products does not materially interfere, since the titanium color is still perceptible. The same is true of iron, because the titanium color usually appears as a brown-red fleck in the center of the green iron stain. When there is uncertainty as to the identity of the other elements present, the following procedure should be used. 

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