Characters. - A reddish-brown powder, destitute of taste and not magnetic.

Solubility. - It dissolves completely, though slowly, with the aid of heat, in hydrochloric acid, diluted with half its volume of water.

Reactions. - The solution gives the reactions of a ferric salt only.

Dose. - 5 to 30 grains.

B.P. Preparation.

Emplastrum Ferri. Iron Plaster. - Hydrated peroxide of iron in fine powder, Burgundy pitch, and lead plaster (1 part in 11).

Uses. - Not astringent. Given in powder or electuary chiefly in cases of tic and neuralgia.

Iron plaster is often called 'strengthening plaster.' It forms a mechanical support to weak parts and keeps them warm. Used in pains or weakness across the loins in females, in rheumatic pains, as lumbago, weak joints, etc.