Page:The American Cyclopædia (1879) Volume XI.djvu/111

 MANGANESE 103 ^ jts glass easily, does not change in moist air, is not attracted by a magnet and is not itself magnetic, and has the specific gravity of 7*16. Deville reduced manganese oxide by mixing it with one tenth its weight of sugar charcoal and exposing it for three hours to a white heat in a lime crucible enclosed in a brasqued crucible. The product was a crystalline mass, the powder of which decomposed water rapidly ; color like bismuth; specific gravity 8'01 5. Loughlin has subjected the above methods and numerous others to a careful repetition in his laboratory, and comes to the conclusion that the task of producing perfectly pure manganese is one of great difficulty. The discrepancy between the specific gravities, ranging from 6*85 to 8'015 as given by different experimenters, leads to the conclusion either that manganese has several allotropic modifications, or that the pure metal has not yet been made. Some of the alloys of manganese are of great value. With copper it yields a product which possesses the color and properties of German silver, while costing much less. Elliot Savage of West Meriden, Conn., has invented a process for preparing this alloy by reducing pyrolusite and copper ore directly in a gas furnace. Dr. Prieger of Bonn and Valenciennes of Paris have pre- pared several alloys of manganese and iron and manganese and copper. An intimate mixture of black oxide of manganese, powdered char- coal, and iron filings or turnings is made in a black-lead crucible holding 30 to 50 Ibs. A covering is made of charcoal, fluor spar, and common salt, and the contents of the crucible are exposed for several hours to a white heat. The alloy of manganese and copper is prepared in a similar way, and both are very hard and capable of a high polish. In England there are 36 patents involving the use of manganese in iron and steel, the earliest of which was taken out in 1799. Berthier made a large number of alloys of manganese, and described their prop- erties. Much use is now made of manganese in the metallurgy of iron and steel, and the frank- linite ore of New Jersey is largely employed in the United States in the manufacture of crys- talline burglar-proof iron and spiegel iron. Manganese does not occur native, but is found widely diffused in association with other ele- ments. The following are the principal man- ganese minerals, the first being the chief ore of commerce : pyrolusite, braunite, manganite, rhodonite, hausmannite, alabandine, diallagite, wad, psilomelane, franklinite, crednerite, col- umbite, wolfram, triphiline, and manganese alum. Mines of manganese have been worked at Bennington, Vt., West Stockbridge and Shef- field, Mass., and later in North Carolina and Virginia. In 1871 $20 a ton was paid in New York for 70 per cent. Virginia ore. The an- nual production of manganese ore in Europe may be approximately stated as follows : Huelva, Spain. 1,000,000 cwts. Prussia 581,422 " Thuringia 82.103 " Saxony 18,579 cwts. Austria 9,292 " Sweden 2,400 " Nearly nine tenths of the manganese of com- merce is consumed in the manufacture of chlo- rine and bleaching powders ; the other tenth is employed in the following industries : to color and decolorize glass ; in the manuf ature of iron and steel ; in the painting and glazing of por- celain and pottery ; in the production of oxy- gen ; and in the preparation of the various salts required in medicine and the arts. Manganese enters as a base into two classes of compounds, the manganous and manganic ; and also as an acid into two classes of salts, the manganates and permanganates. There are five well character- ized oxides. 1. Manganous oxide, or manganese monoxide, MnO, is a basic body furnishing a series of manganous salts, pink-colored, which rapidly absorb oxygen, and pass into a higher state of oxidation. The pure oxide is a green- ish powder obtained by heating the carbonate in absence of air ; the hydrate is precipitated as a white gelatinous mass, when an alkali is added to a solution of a manganous salt. Of the manganous salts the chief soluble ones are the sulphate, MnS0 4 + 5H 2 O, and the chloride, MnCl 2 +4H 2 O. The sulphide, MnS, and the carbonate, MnCO 3, are insoluble. 2. Manganic oxide, or manganese sesquioxide, Mn 2 O 3, exists in nature as braunite, and may be prepared ar- tificially by exposing manganous oxide to a red heat. It forms a series of insoluble salts, of which manganese alum is one of the most in- teresting. 3. Red or mangano-manganic ox- ide, Mn s O4, is a neutral body, corresponding to the magnetic oxide of iron, and occurring in nature as hausmannite. 4. Black oxide or manganese dioxide, MnO 2, is the chief ore of commerce, the magnesia nigra of the ancients, and termed pyrolusite by modern mineralo- gists. It can be artificially formed by adding a solution of bleaching powder to a manganous salt. This compound yields one third of its oxygen when heated to redness, and one half its oxygen when heated with sulphuric acid. Ac- cording to Gorgeu, Mn0 2 is capable of form- ing manganite salts with alkaline bases. 5. Permanganic acid, H 2 Mn 2 8, is a dark green heavy liquid, obtained by the action of strong cold sulphuric acid upon potassium perman- ganate. Manganic trioxide, its corresponding hydrate, manganic acid, and the anhydride of permanganic acid, are not known in a free state. The salts of the permanganates, notably the potassium permanganate, are now largely employed as disinfectants, for bleaching, and in the laboratory for the purpose of volumetric analysis. Among numerous methods for the preparation of potassium permanganates, the following may be recommended : 500 Ibs. of freshly prepared potash lye of 45 B. are mixed with 105 Ibs of pure potassium chlorate, and concentrated by evaporation in an iron kettle ; and then, under constant stirring, 182 Ibs. of finely pulverized black oxide of manganese are added, and the heat continued until the whole is fluid ; it is then stirred until cold ; the gran- ular mass is again heated to redness in small