Properties. - In minute, colourless, transparent, acicular crystals, whose form is a rhombic prism. They look exactly like sulphate of zinc. Its taste is bitter, and it is called in Germany Bittersalz. This distinguishes it from zinc sulphate, which has a strong metallic taste.

Solubility. - It readily dissolves in water.

Reactions. - The solution gives the reactions of magnesium (p. 658) and a sulphate (p. 595).

Impurities. - Calcium and iron.

Tests. - Its aqueous solution is not precipitated at ordinary temperatures by oxalate of ammonium (no calcium), nor does it give a brown precipitate with chlorinated lime or soda (no iron).

Dose. - As a purgative, half an ounce to an ounce and a half for a single dose. In repeated doses, especially if taken fasting, 60 to 120 grains. As a diuretic, 20 to 60 grs.

Officinal Preparations.

B.P

Enema Magnesii Sulpnatis. Mistura Sennae Composita.

U.S.P

Infusum Sennae Compositum.