Summary 1. The ternary system A~~SO~-HZSO~-H~O has been studied at 25' to the limit of 98% sul- furic acid by weight. 2. The solid phases observed were the normal sulfate, AgzS04, and the bisulfate, AgHS04. 3. Two solubility curves have been obtained for the 1: 1 addition compound, the stable solu- bility curve being that for the alpha form of the bisulfate, the metastable curve being that for the beta form, both forms already having been re- ...