“ Manganese may be estimated quantitatively by precipitation as carbonate, this salt being then converted into the oxide, Mn3O4 by ignition; or by precipitation as hydrated dioxide by means of ammonia and bromine water, followed by ignition to Mn3O4. The valuation of pyrolusite is generally carried out by means of a distillation with hydrochloric acid, the liberated chlorine passing through a solution of potassium iodide, and the amount of iodine liberated being ascertained by means of a standard solution of sodium thiosulphate. ”

“ Manganous Carbonate, MnCO3, found native as manganese spar, may be prepared as an amorphous powder by heating manganese chloride with sodium carbonate in a sealed tube to 150° C., or in the hydrated form as a white flocculent precipitate by adding sodium carbonate to a manganous salt. In the moist condition it rapidly turns brown on exposure to air. ”

“ It is a hard black solid which readily loses oxygen when strongly heated, leaving a residue of Mn3O4. When heated with concentrated hydrochloric acid it yields chlorine, and with concentrated sulphuric acid it yields oxygen. It is reduced to the monoxide when heated in a current of hydrogen. It is a strong oxidizing agent. ”