6. Munganic acid (31n0,). Equal parts of caustic potash and binoxide of manganese are fused together, the mass being frequently stirred to promote absorption of oxygen. The resulting green mass is manganate of potash..
7. Permanganic acid (11n,0,). Hypermanganic acid. When a strong solution of inanganato of potash is poured into warm water, it imme diately commences to pass through several successive changes of colour, and hence has received the name of mineral chameleon. The final colour is a purple, and is owing to permanganate of potash. The latter salt is however more quickly prepared by fusing binoxide of manganese with caustic alkali and a nitrate or chlorate.
The permanganates Are far more stable Bette than the manganates, and are mostly crystallisable. The potash salt occurs in beautiful prismatic) crystals. Permanganic acid may be isolated, but not man genie acid.
Tho manganates and permanganates have of Late years come into use an oxidising agents, especially for purposes of disinfection, as they readily yield up their oxygen to organic matter.
Manganese and sulphur form one compound, namely,— Sulphide of manganese (MnS). Manganous sulphide. It occurs native AA manganese blends, and is precipitated of a &all colour when an alkaline sulphide Is added to a solution of a manganona salt. It is soluble In acetic acid, a property taken advantage of in separating man genteel) from nickel and cobalt.
The iodide, bromide, and fluoride of manganese are unimportant salts.
Manganese and chlorine forin Protochloride of manganese (31nCI) is the only important chloride. It is largely produced in the preparation of CHLORINE. By evaporation its solution yields pink crystals containing four equivalents of water of crystallisation.
Carbonate of manganese (MnO, CO,) is a buff-coloured powder pre cipitated when an alkaline carbonate is added to a manganous salt.
Sulphate of manganese (MoO, SO, + 7H0, and sometimes MnO, SO, +5H0). Formed by treating the binoxide with strong sulphuric acid. It is a rose-coloured soluble salt, isomorphous with sulphate of mag nesia. It is largely used in dyeing and calico-printing. It forms double salts with alkaline sulphates.
Nitrate of manganese is a deliquescent salt occuring in acicular crystals.
Silicates of manganese. Several of these occur native. [MANGANESE, in NAT. HIST. Div.] Tests for anese.—The non-precipitation by sulphuretted hydro gen, and the formation of the sulphide and hydrated oxide in the manner already indicated, readily characterise the protosalts of man ganese. Manganese is also detected by the production of an ame thystine bead when a very small quantity of the substance under examination is heated with borax in the blow-pipe flame.
Estimation of man7anese.—Except for the valuation of the binoxide, this is usually effected by precipitating the carbonate and igniting it in an open crucible, whereby the red oxide is produced, containing per cent of metal.