Origin. - Obtained by heating manganese dioxide with sufficiently strong sulphuric acid, evaporation, and crystallization.

Description and Properties. - Colorless or pale rose-colored, transparent, tetragonal prisms, odorless, and having a slightly bitter and astringent taste; slightly efflorescent in dry air. Soluble in 0.7 part of water and in 0.53 part of boiling water; insoluble in alcohol. Manganese sulphate should be kept in well-stoppered bottles. Dose. - 2-5 grains (0.1-0.3 Gm.) [4 grains (0.25 Gm.), U. S. P.].

(For Potassium Permanganate see section on Antiseptics.)

Antagonists and Incompatibles. - The salts of lead, silver, and mercury are incompatible with manganese.

Synergists. - Iron is theoretically synergistic, and the salts of zinc, copper, and silver are similar in their action on the nervous system.

Physiological Action. - Externally and Locally. - The two salts above mentioned have no important local action.

Internally. - In large doses these salts, especially the sulphate, irritate the gastro-intestinal tract, while excessive doses may even occasion gastro-enteritis. The sulphate acts as an emeto-cathartic and possesses cholagogue properties.

As is the case with many other drugs of this character, small doses may even promote the appetite and improve the digestive function. Manganese dioxide is held by many observers to play some role as a tissue oxidizer; serving in this function a purpose similar to that of iron. It has been suggested that manganese has a certain catalytic power in the bodily cells. Large doses, or the continued administration of these preparations, affect the system more like zinc than iron, producing great depression, muscular weakness and waste, diminishing the pulse-beat, weakening the heart, and lowering arterial tension. There is, moreover, a tendency to fatty degeneration of the muscles and liver.

Therapeutics. - The manganese dioxide is highly beneficial in amenorrhea and dysmenorrhea, and has been used in the treatment of gastralgia, pyrosis, and simple ulcer of the stomach. Its action probably resembles that of bismuth, though it is a much less efficient remedy than the latter drug.

It is of interest to note that many practitioners say that they derive no benefit from the use of manganese salts alone in the treatment of amenorrhea.

The sulphate is used occasionally as a cholagogue purgative in malarial jaundice, although why it should be preferred to many other and superior cholagogues it is difficult to understand. Gouty dyspepsia appears to have been much improved by the use of manganese. The association of iron and manganese makes a valuable combination in the treatment of chlorosis and many variations of secondary anemia.