Sulphate of manganese should be kept in well-stopped bottles. Colorless, or pale rose-colored, transparent, right-rhombic prisms, crystallized at a temperature between 20° and 30° 0. (68° to 86° F.), slightly efflorescent in dry air, odorless, having a slightly bitter and astringent taste, and a faintly acid reaction. Soluble in 0.7 part of water at 15° C. (59° F.) and in 0.8 part of boiling water; insoluble in alcohol. Manganese sulphate enters for the same purpose as manganese chloride, and can also be kept in stock in solution which will not oxidize on exposure to air. The solution is added to mixture in fountain after the removal of atmospheric air. (See Manganese Chloride.) Manganese sulphate of commerce contains water in various proportions; its solution should, therefore, be regulated by its specific gravity. Dissolve one part by weight of the commercial salt in nine parts of distilled water. Filter. Specific gravity 1.068 at 15° C. This solution will contain 10 per cent, of the hydrous or commercial salt. Proportion 10 to 1.