Description and Properties. - This is also called anhydrous sodium phosphate, Na2HPO4; it is obtained by driving off the water of crystallization of sodium phosphate (U. S. P.), which amounts to 60.3 per cent. of the latter's weight. In a given weight of the exsiccated salt there are two and a half times as much sodium phosphate as in the same weight of the crystallized salt. It is a white powder which absorbs moisture readily when exposed to the air and is gradually transformed into a salt of the composition Na2HPO4 + 7H1O, which contains about 47 per cent. of water; the latter salt is permanent.

Dose. - Average dose: 15 grains (1 Gm.), U. S. P.