A treatise on chemistry. Vol. II, Metals. Part II / by H.E. Roscoe & C. Schorlemmer ...

  • Henry Enfield Roscoe
Date:
1880
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Licence: Public Domain Mark

Credit: A treatise on chemistry. Vol. II, Metals. Part II / by H.E. Roscoe & C. Schorlemmer ... Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

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    occurs in light brownisli-red transparent triclinic crystals, and tepliroite, Mn^SiO^, crystallises in the quadratic system in rose- red, brown, or grey masses, and usually occurs together with rhodonite. ManganoiLS Carbonate, MnCOg, forms an isomorphous con- stituent of chalybite and dolomite, and also occurs in the pure state in the rose-red crystals of manganese spar or rhodochro- zite. All these minerals crystallise, like calc spar, in rhom- bohedrons, but manganocalcite, (MuCaMg)C03, is isomorphous with arragonite. The hydi'ated manganese carbonate is obtained as a white precipitate by mixing a solution of the chloride or sulphate of manganese with carbonate of soda. In the moist state it soon becomes brown coloured on exposure to the air; it dissolves in 8,000 parts of pure water, and readily in water containing carbonic acid. 319 Manganese and Cyanogen. Wlien a concentrated solution of acetate of manganese is warmed with solid potassium cyanide, a green precipitate is thrown down of KC]Sr,Mn(CN')2; this gradually disappears, and in its place dark blue crystals of potassium mangano-cyanide, K^Mn(CN)g + SHjO, are formed.'- The mangano-cyanide is also obtained when mangauous car- bonate is heated to a temperature of from 4.0° to 50° with a solu- tion of cyanide of potassium.^ The salt crystallises in deep violet-blue quadratic efflorescent tables. Its solution oxidises on exposure to air with formation of potassium mangani-cyanide, KgMn2(C3N3)4, which crystallises in dark-red prisms. This latter salt when brought into contact with potassium amalgam in aqueous solution is again transformed into mangano-cyanide. The constitution of these compounds, which are not double salts, will be referred to under the corresponding iron compounds. MANGANIC COMPOUNDS. 320 Mangano-Manganic Oxide or Red O.vide of Manganese, Mn304, occurs with other manganese ores, and also by itself as the mineral hausmannite. This mineral crystallises in acute quadratic pyramids, and one of its best localities is Ilmenau in Thuringia. Its specific gravity is 4-85. If manganese monoxide ^ Eaton and Fittig, Ann. Chcm. Pharm. cxlv. 157. ^ Decamps, Bull. Soc. Chim. [2], ix. 443.
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