Characters. - A blue crystalline salt, in oblique prisms.

Preparation. - Vide p. 674.

Solubility. - It is soluble in water, forming a pale blue solution which strongly reddens litmus.

Reactions. - The aqueous solution gives the reactions of copper and a sulphate.

Dose. - As an astringent, 1/4 to 2 grains; as an emetic, 5 to 10 grains.