Higher oxides of silver

Electrolysis of Silver nitrate solution at 0° C. yields at the anode a black, crystalline substance of metallic lustre. It readily loses oxygen, Silver nitrate entering into solution, and the residual crystals of silver peroxynitrate have the formula 2Ag₃O₄,AgNO₃. It changes slowly, with evolution of oxygen, into 3Ag₂O,AgNO₃. According to Weber, the presence of between 15 and 25 per cent, of nitric acid inhibits the deposition of the peroxynitrate at the anode, but produces a brown solution. Weber regards the oxide portion of the salt as having the formula Ag(AgO₂)₂, analogous to that of magnetic iron oxide, and considers it to be the silver salt of an unstable argentic acid, HAgO₂. It is a compound of silver in which the metal has a valency greater than unity.

An analogous derivative of the oxide Ag₃O₄ has been prepared by the electrolysis of silver fluoride. It has the formula 2Ag₃O₄,AgF.

A peroxide, probably Ag₂O₃, is stated to be produced by anodic oxidation of silver in acid solution. When solutions of sodium or potassium persulphate react with silver or Silver nitrate, a peroxide with a higher percentage of oxygen than Ag₂O₂ is produced, the process being attended by catalytic decomposition of the persulphate with formation of the acid sulphate. Ammonium persulphate does not yield a peroxide, but the ammonium radical becomes oxidized to nitric acid.