A mixture (commonly misnamed sulphide of calcium) consisting chiefly of sulphide of calcium [CaS; 72] and sulphate of calcium [CaS04; 136], in varying proportions, but containing not less than 50 per cent. of absolute sulphide of calcium, B.P. (36 per cent. U.S.P.).

Characters. - A nearly white powder with a smell somewhat resembling that of sulphuretted hydrogen.

Preparation. - B.P. By calcining sulphate of calcium (7) with wood charcoal (1) when part of the sulphate is reduced to sulphide.

U.S.P. By calcining finely-powdered lime (100) with precipitated sulphur (90).

Dose. - 1/10-1 gr.

Action. - In large doses it is an irritant to the stomach, but medicinal doses usually cause no trouble, or at most slight discomfort, sometimes giving rise to eructations of sulphuretted hydrogen, and perhaps to some looseness of the bowels.

Uses. - It is used chiefly for its effect on the process of suppuration, hastening the discharge of pus if already formed, and checking its formation if the inflammation be still in its early stage.

Sulphite of calcium in doses of 1/10-1 gr. four or five times daily is said to do good in acne.