Prep. By treating common salt with sulphuric acid in the process for making hydrochloric acid; it is found native, and exists in sea-water.

Prop. & Comp. It forms six-sided oblique rhombic prisms, which are deeply channelled; colourless, transparent, neutral, with a bitter saline taste; effloresces in air, soluble in water; in a dilute solution scarcely any precipitate is produced with nitrate of silver, showing only a trace of chloride to be present; it contains 55.5 per cent. of water, and yields with chloride of barium 71 per cent. of sulphate of baryta. Composition (Na O, So3 + 10 HO).

Therapeutics. It acts as a saline purgative, and in small doses as a diuretic; was formerly much employed, but at present sulphate of magnesia is generally substituted for it on account of its more agreeable taste. The so-called Cheltenham Salts consist chiefly of sulphate of soda.

Dose. 1/2 oz. to 1 oz. When effloresced, the dose is smaller.

Acetate of Soda. Appendix A.

Prop. & Comp. Acetate of soda is a crystalline salt having the formula, Na O, C4 H5 O3 + 6 HO. It is soluble in water, but slightly so in alcohol. The watery solution, when dilute, should not be precipitated by chloride of barium or nitrate of silver, showing the absence of sulphates and chlorides. It is used in the preparation of glacial acetic acid, and also as a test solution for qualitative analysis.

Therapeutics. Acetate of soda is rarely used as medicine; it acts as a mild diuretic, less powerful than acetate of potash.

Dose. 20 gr. to 60 gr.