Characters. - In transparent, colourless, rhombic prisms, terminated by four converging planes, efflorescent, tasting like common salt. It imparts a yellow colour to flame.

Reactions. - Its solution has a faintly alkaline reaction; it gives a yellow precipitate with nitrate of silver, the resulting fluid acquiring an acid reaction (phosphate).

Dose. - As a purgative, 1/4 to 1 ounce. As an alterative, 20 to 40 grains.

Uses. - It is used as a purgative in children and in delicate persons, both because it acts gently and has little or no taste. It may be easily given to children in a little soup without their knowing it.

It has been used in fevers as a purgative, and in rickets in order to supply phosphoric acid to the bones. It has been found especially useful in children with hepatic derangement, as shown either by white or green stools, or by jaundice. The dose for them is 3 to 10 grains given in food or milk.