Characters. - Brilliant dark-red crystalline masses, or a fine bright scarlet powder, permanent in the air, odourless and tasteless.

Solubility. - It is insoluble in water, alcohol, nitric or hydrochloric acid, or in dilute solutions of alkalis.

Reactions. - It is dissolved by nitrohydrochloric acid, and on adding an excess of stannous chloride, metallic mercury is precipitated.

Uses. - It is used for mercurial fumigation. Thirty grains may be used instead of calomel, in the way already described (p. 471).