The NH₄⁺, K⁺ || H₂PO₄^–, Cl^– - H₂O system has been studied either in broader extent^1,3 or in terms of the diagonal NH₄H₂PO₄^– - KCl - H₂O.^2,4 Formation of solid solutions between both dihydrogenphosphates and chlorides is the prominent feature of this system. The data in the different reports cannot be compared with each other because of different experimental conditions. The phase diagram of Ref. 2 - see Fig. 26 - can be accepted tentatively.