Chemistry of the Bleaching of Silver by Mercury (II) Chloride(*)

Abstract

The chemical reactions which occur during the bleaching of the silver image by a solution of mercury (II) chloride are simulated in a gelatin-free suspension of silver powder. As the reaction progresses the chemical composition of the solid phase changes. First the metallic silver is converted to silverchloride and a silveramalgam. From a 50% molar conversion on metallic mercury persists, and forms by a dismutation reaction with mercury(II) chloride, mercury(I) chloride. There is no evidence for the intermediate formation of a double chloride of mercury(I) and silver.

Notes

Research sponsored by the “ Instituut tot anmoediging van het Wetenschappelijk Onderzoek in Nijverheid en Landbouw” (I.W.O.N.L.) of Belgium.