(Epsom Salt.)

Origin. - Obtained by the action of sulphuric acid upon native magnesium carbonate, treated with water, filtered, and the nitrate evaporated to crystallization.

Description and Properties. - Small, colorless, rhombic prisms or acicular crystals, without odor, and having a cooling, saline, and bitter taste; slowly efflorescent in dry air. Soluble in 1.5 parts of water; insoluble in alcohol.

Dose. - 1/4-1 ounce (8.0-32.0 Gm.) [1/2 ounce (16 Gm.), U. S. P.].

Antagonists and Incompatibles. - Magnesium sulphate is incompatible with alkaline carbonates, phosphoric acid, phosphates, lead acetate, silver nitrate, and lime water.

Synergists. - Saline purgatives.