THE SOLUSILITY OF GYPSUM I N SOLUTIOSS O F AMMONIUM SULPHATE1 BY J. M. BELL A N D TV. C. 'I'ABER
The solubility of gypsum in ammonium sulphate solutions has been investigated by Droeze' a t 9'C, by Cohn3 a t 2 2 O . 5 C and by Sullivan4 at 2 j ' C. Theresultsof Cohn and of Sullivan indicate that the solubility decreases at first with increasing amounts of ammonium sulphate, but as the concentration becomes large there is an increasing amount of gypsum i n , solution. Neither of these experimenters have observed the formation of any double sulphate of calcium and amrr,onium, although the compound CaSO,. (NH,),SO,. H,O has been reported by Popp, Fassbenderj and D i t t t e Passbender evaporated a concentrated solution of ammonium sulphate containing gypsum and filtered off the motherliquor at 40-50' C. It seems probable therefore that the double compound is not stable as low as 25' but is stable in the neighborhood of 4o°C. As a double, sulphate of calcium and potassium (syngenite) has already been found of the formula CaSO,.I
