Page:The American Cyclopædia (1879) Volume XI.djvu/112

104 MANGANESE in m ki-ttles until it is wholly fused, and is then, after cooling, broken up, boiled with water in a large pot, and allowed to settle; the clear liquor is decanted and evaporated to crystallization. In this way, from 180 Ibs. of oxide of manganese, 98 to 100 Ibs. of potas- sium permanganate, in beautiful long needles, can -be obtained. For the bleaching of en- irr:i ings and paper stock, for the purification of drinking water, as a disinfectant in hospi- tals, as a deodorizer of tainted meat in culinary operations, as a tooth wash under the name of Condy's liquid, for the evolution of ozone oxy- gen, and for chemical analysis, there are few agents more valuable than potassium perman- ganates. Various colors or dyes are prepared from salts of manganese. Nuremberg violet is made by fusing finely pulverized pyrolusite and phosphoric acid in proper proportions, di- gesting in ammonia, filtering, evaporating to dryness, and treating with water, when a violet powder remains. Barium manganate affords a fine green pigment, much safer than arsenic colors. Potassium permanganate dyes wood in imitation of mahogany and nut wood. The employment of manganese in glass manufac- ture was one of the earliest uses of this element. The oxide of manganese is put into the glass mixture to counteract the effect of oxides of iron ; but in course of time it is itself oxidized by the light and air, and colors the glass red. As red glass intercepts the chemical rays of light, the skylights of photographers and the sashes of greenhouses have to be provided with glass to which no manganese has been added. The manufacture of oxygen on a commercial scale, according to the process of Tessi6 du Motay, is founded upon the property of the black oxide of manganese, when fused with caustic soda, to take up oxygen from a current of hot air, which it yields up again to super- heated steam, thus offering a cheap and con- tinuous process. As the principal application of the oxides of manganese is in the manufac- ture of bleaching powders, their commercial value depends upon the amount of oxygen they can furnish, or, which comes to the same thing, the quantity of chlorine which they are capable of eliminating when treated with hydrochloric acid. The methods of assaying the oxides of manganese may be classed under four heads : 1. The determination of the amount of oxygen disengaged by sulphuric acid ; 2, the oxidation of oxalic acid ; 3, the evolution of chlorine from hydrochloric acid ; 4, volumetric estima- tion. For the details of these methods the reader is referred to Fresenius's " Chemical Analysis." The chloride of manganese, ob- tairi.-.! by crystallization from the residues in the manufacture of chlorine from the dioxide and hydrochloric acid, is regenerated so as to recover the dioxide to be employed again, by neutralizing its solution with excess of manga- nese and treating with hypochlorite of lime ; by slightly elevating the temperature chlorine is disengaged, and the hydrate of the dioxide is MANGO precipitated in great purity, thus accomplishing a great saving in the quantity of hydrochloric acid and manganese required in this important industry. Several salts of manganese have been used in medicine, the most important of which are the dioxide, iodide, sulphate, and phosphat'e, and permanganate of potassium. The first of these is said, when slowly introduced into the system, as happens to those engaged in grinding the mineral, to act as a poison, finally inducing paraplegia ; but this is by no means a common occurrence. It has been used as a tonic, and also as a local remedy in dyspepsia. The iodide, sulphate, and phos- phate are used together with or instead of the corresponding salts of iron, and are supposed to have a similar action. Minute quantities of manganese have been found in the body, but it is extremely doubtful whether its presence is of physiological importance, or is in fact any- thing more than an accident. Although the therapeutic value of these compounds may be doubted on theoretical grounds, yet practical- ly they have been occasionally found of ser- vice. Cases of anaemia that have proved re- bellious to chalybeates will sometimes yield to the salts of manganese. In chronic nervous debility also these salts sometimes act favor- ably as a tonic to the nervous system in some unexplained way. The dose of the sul- phate of manganese is from 5 to 10 grains. The sirup of the iodide is one of the best prep- arations of manganese for medicinal use; its dose is from 10 to 20 drops three times a day, and should be given in water soon after eating. MANGEL WURZEL. See BEET. MANGLES, James, a British traveller, born about 1785, died about 1861. He entered the navy in March, 1800, took part in the expedi- tion to the Cape of Good Hope, and became a commander in 1815. In 1816 he visited the Levant, went up the Nile, and joined Belzoni in clearing away the sand from the entrance to the great temple of Ipsambul. They then crossed the desert to Syria and the Dead sea, whence in 1820 they returned to England. In 1823 they printed for private circulation a selection from the letters written by them while absent, republished in 1844 under the title of "Travels in Egypt and Nubia, Syria, and the Holy Land." MANGOUSE, or Mongons. See ICHNEUMON. MANGO, the native name of an East Indian fruit, of species of mangifera, of which 14 are known; some of them have been cultivated and become completely naturalized in the West Indies and other tropical countries. The genus belongs to the anacardiacece or cashew family, of which our native representatives are the sumachs. The most important species is M. Indica, of which there are numerous varieties ; it is a large spreading tree, with simple, entire, leathery, lanceolate leaves, and large terminal panicles of flowers ; the calyx is four- or five- parted, petals six ; the stamens four or five, only one or two of which are fertile ; ovary