Characters. - A dull green powder, which darkens in colour upon exposure to light.

Solubility. - It is insoluble in water. When it is shaken in a tube with ether nothing is dissolved.

Reactions. - Gradually heated in a test-tube, it yields a yellow sublimate, which, upon friction, or after cooling, becomes red, while globules of metallic mercury are left in the bottom of the tube.

Preparation. - By rubbing iodine and mercury together in a porcelain mortar, occasionally moistening with a few drops of spirit.

Dose.- 1 to 3 grains.

Uses. - It is employed for the purpose of combining the action of iodine with that of mercury, as in cases of secondary and tertiary syphilis occurring in persons of a scrofulous constitution, and especially in the syphilis of children.