Definition. - Chiefly manganese dioxide with small amounts of other oxides of manganese, corresponding to not less than 80 per cent. of manganese dioxide.

Origin. - Manganese sulphate, 50; ammonia water, 250; solution of hydrogen dioxide, 250; water q. s.

Description and Properties. - A heavy, very fine black powder, without odor or taste; permanent in the air; insoluble in water or alcohol.

Dose. - 5-40 grains (0.3-2.60 Gm.) [4 grains (0.25 Gm.), U. S. P.].