Present name. - Hydro-disodic Phosphate. Na2Hpo4,l2H1O.

Common Phosphate of Soda, purified by re-crystallization.

Characters and Tests. - In transparent colourless rhombic prisms, terminated by four converging planes, efflorescent, tasting like common salt. It imparts a yellow colour to flame. Its solution has a faintly alkaline reaction, it gives a yellow precipitate with Nitrate of Silver, the resulting fluid acquiring an acid reaction. Heated to dull redness, it loses 63 per cent. of its weight, leaving a residue width, when dissolved in w:tter, gives with Chloride of Barium a precipitate almost entirely soluble in diluted Nitric Acid.

Preparations. - Trituration. Solution in distilled water.