Calcium Hydrophosphite, CaHPO₃

Calcium Hydrophosphite, CaHPO₃, or neutral calcium phosphite, is obtained as a white crystalline powder by precipitating calcium chloride with ammonium phosphite. The crystals have the composition H₄Ca₂P₂O₇.2H₂O or 2CaHPO₃.2H₂O, and lose 1 molecule of water at 100° C. and the rest between 200° and 300° C. The dry salt is decomposed at red heat and the solution on boiling.