Page:The New International Encyclopædia 1st ed. v. 12.djvu/888

* MANGANESE. 794 poumls of iiiangantse, see Manganic and Peb- MANoA>ic Alius. MANGANIC AND PERMANGANIC ACIDS, lljMnO, ami HMnO,, respectively. Two iiii(Hjilaut acid coiiipouuds of manganese. The former is miknown in the free state, but is well known in the form of certain of its salts, termed tiiaiiguiiales. The most important of these are the manganatcs of potassium (KjjMnOj) and barium (BaMnO,). Potassium mangnnate is ob- tained by fusiniu' manganese dioxide with caus- tic potash and potassium clilorate; on cooling, the mass is dissolved in a moderate quantity of ■water, and the solution is allowed to evaporate in vacuo. The salt thus obtained is unstable, being readily decomposed by acids, or even by an e.cess of water, into potassium permanganate (see further l)elow), caustic potash, and man- ganese dioxide. It is this reaction that causes tlic well-known change of color in solutions of potassium manganate. The manganate of barium is obtained by heating barium o.xide with man- ganese dioxide: it may be used as a green pig- ment, ilatiganic anhydride, or manganese tri- oxide (MnOj), may be obtaine<l by dissolving potassium permanganate in strong .sulpuric acid and heating the solution. I'ermangiinic acid may be obtained in the uncond)ined state by the action of sulphuric acid on barium permanganate; but the resulting solu- tion decomposes with extreme readiness and hence the acid cannot be isolated from it. The solu- tion is deejired in color and has powerful oxidiz- ing and bleaching properties. The most impor- tant among the pcrmiiiigandlcs, or salts of per- manganic acid, is the permanganate of potas- sium (KMnO, ), which forms long prismatic crystals having a deep-red color by transmitted light and a green metallic lustre. It may be pre- pared by healing one of the oxides of manganese with an alkali and i)otassium chlorate or some other o.xidizing agent, and heating the resulting mass with water, when manganese dioxide is precipitated and potassium permanganate re- mains in solution. A method of ])reparation often employed consists in adding potassium chlorate to a solutiim of caustic jiotash, adding finely powdered mineral manganese dioxide to the solution, evaporating to dryness, heating the residue to a semi-li<piid condition, allowing to cool, dissolving the resulting mass in hot water, and passing into the solution a current of carbonic acid gas, until the transformation appears to be complete. The solution is then filtered through guncotton, concentrated by evaporation, and al- lowed to crystallize. In the solid state, as well as in- concentrated solutions, potassium perman- ganate is very readily decomposed, llixed with sulphur and phosphorus, solid potassium per- manganate can be ignited by striking, ilixed with charcoal, it can be ignited by moderate heat- ing. Its saturate<l solution (one part in 15 parts of water at ordinary temperature) decom- poses on the application of gentle heat and even on standing for some time at ordinary tem- peratures. Kven in dilute solution potassium permanganate acts as a powerful oxidizing agent, and upon this are based many of its uses in medicine, analytical chemistry, and the arts. Sugar and many other organic substances are readily oxidized by it. Potassium iodide (in solution) is converted by it into potassium iodate. If a solution of potassium permanganate is mixed MANGE. with one of peroxide of hydrogen (another oxidiz- ing agent), the two substances give up [lart of their o.ygen simultaneously, so that both are reduced at the same time. The oxidizing power of potassium permanganate is considerably in- creased in the presence of acids. Among the uses of the jjcrmanganate may be mentioned its use for the preparation of o.xygen, its use as a bleaching agent, its use in the purification of water, ammonia, and carbonic acid gas, its use in i)hotography, and finally its use as a disin- fectant, deodorant, and antiseptic in medicine. It is employed as a deodorant for bed-pans and as a wa^h for the hands, the solution commonly used being known as 'Condy's red fluid.' In a very dilute form it may be used as a mouth- wash or gargle and as an injection in cases of gonorrhiFal and other morbid discharges. Ac- cording to some authors, if given internally in the form of pills, potassium permanganate has an action much like that of the salts of iron. The permanganate of sodium is very similar to that of potassium, and is prepared by an analogous method. In the arts, sodium permanganate is often employed in place of the potassium salt, but the latter alone is employed in chemical analysis. Permanganic anhydride, or manga- nese heptoxide, JMujO,, is extremely unstable. MAN'GANTTE (from mangan-esc, from Neo- Lat. manganc.siam, arbitrarily altered from mag- nesimn). A hydrated manganese peroxide that has a submetallic lustre, and is dark steel-gray to iron-black in color. It usually occurs in veins associated with calcite and barite in the older rocks. Manganite is found in the Harz, Thu- ringia, Sweden, Norway, Kngland, and in the United States at various localities in Michigan and Colorado. In common with other manganese minerals it is used in the manufacture of alloys, as spiegeleisen and ferromanganese. and as a coloring material in calico printing and dyeing, for coloring glass and pottery, and in the manu- facture of paints. MANGATAREN, man-gii'ta-rSn'. A town of Luzon, Philippines, in the Province of Pan- gasinSn (Map: Philippine Islands, E 4). It is situated on the Agno River Road, 17 miles south of Lingayen. Population, about 10,150. MANGE (OF. mangeue, mangue, manjue, menjiie, itch, voracity, food, from Lat. mandu- eare, to chew, devour). A disease of horses, dogs, and cattle, similar to scab in sheep, and itch or acariasis in the human subject, resulting from the attacks of minute mites, which burrow in the skin, especially if it be dirty and scurfy, cause much irritation, heat, and itching, and tae eruption of minute ])imples, with dryness, scurfiness, bald- ness, and bleaching of the skin. The treatment consists in destroying the mites and insuring the cleanliness and health of the skin, both of which objects are etTected by washing the parts thor- oughly every second day with soft soap and water, and dressing daily with sulphur or mild mercurial ointments, or with a solution contain- ing four grains cither of corrosive sublimate or arsenic to the ounce of water. Castor-oil seeds, bruised and steeped for twelve hours in butter- milk, are very successfully used by the native Indian farriers. Where the heat and itching are great, as is often the case in dogs, a few drops of tincture of belladonna may be added to the usual dressing, or applied with a little glycerin.