Present name. - Hydro-diammonic Phosphate. (Nh4)2Hpo4.

Made by neutralizing Phosphoric Acid with strong solution of Ammonia.

Characters and Tests. - In transparent colourless prisms. Soluble in water, insoluble in rectified spirit When heated with Caustic Potash, Ammonia is evolved. The aqueous solution gives a yellow precipitate with Nitrate of Silver. If 20 grains of this salt be dissolved in water and solution of Ammonio-sulphate of Magnesia added, a crystalline precipitate falls, which, when well washed upon a filter with solution of Ammonia diluted with an equal volume of water, dried, and heated to redness, leaves 16.8 grains.

A notice of this is given in Marcy and Peters' New Mat. Med.

Preparation. - Solution in distilled water up to 1, then use distilled water to which 5 per cent. of rectified spirit has been added for 3x and 2, dilute alcohol for 3, and afterwards rectified spirit.