MANGANESE, man-ga-nes', a metallic element which is widely distributed in nature, though it never occurs except in combination with other elements. The dioxide was believed to be a compound of iron until 1774, when Scheele proved it to he a compound of a pre viously unknown metal; and in the same year Gahn prepared the element in its metallic form. It was first called from the fact that it was prepared from a compound then called "magnesia nigra° (and now known as manganese peroxide or dioxide) ; but in 1808 the name was arbitrarily changed to utnanganese? by Buttmaun.
Manganese may be prepared in the metallic form by reducing any of its oxides with carbon at a white heat, and this is the method fol lowed commercially. For experimental pur poses, however, it is easier to obtain it by re ducing the chloride with metallic sodium or magnesium. The physical properties of man ganese vary somewhat according to the precise way in which the metal is obtained. Its melt ing-point may be taken as 3500° F., its specific gravity as 7.4 and its specific heat is 0.122. It is a gray, hard, brittle, lustrous metal, suscepti ble of taking a high polish, and resembling iron in most respects, both physically and chem ically. It is not magnetic, however. The pure metal does not appear to be affected by dry air, hut moist air oxidizes it, at least super ficially. Some authorities describe it as oxidiz ing readily in common air, and as decomposing water with almost as great a facility as potas sium; but it appears probable that the specimens from which these results were obtained con tained impurities of some sort. Metallic man ganese is not used in the arts, but some of its alloys with iron, aluminum and copper are valu able. It is particularly valuable in steel, its presence in small amount increasing the hard ness, tenacity and elasticity of the metal. It is added to the molten steel, in the process of manufaoture, in the form of an iron-manganese alloy containing from 10 to 80 per cent of the latter metal, and known in the arts as "spiege 'else& or ° f erromangan ese.° The °manganese
of commerce is usually not the metal itself, but a mixture of its oxides. Manganese is used in the steel industry almost entirely in the form of two alloys, ferromanganese and spiegeleisen. These are both alloys of iron, manganese and carbon. Ferromanganese may contain as much 80 per cent of manganese, but averages in this country about 70 per cent. In spiegeleisen the percentage of manganese is much lower; the standard figure upon which the price is based is 20 per cent. The average manganese content is about 18 per cent. Both alloys are high in combined carbon, the amount of which runs up to 7 per cent. Theese alloys are added to molten steel or open hearth furnace, for the purpose of in troducing bothnese and carbon. The manganese cleanses steel by combining with the contained oxygen and, to some extent, with the sulphur, and then carries these impurities into the slag. The carbon is for the purpose of giving the steel the required hardness and strength. By adding larger amounts of the alloys, manganese steel is produced, which is noted for its hardness, tenacity and durability. It is much used in the wearing parts of heavy machinery. In recent years the tendency has been to use more ferromanganese and less spiegeleisen, on account of the much smaller amount of ferromanganese that it is necessary to add to the steel. Spiegeleisen usually has to be melted in a cupola furnace before using. but ferromanganese can be added direct. The latter also introduces less carbon, which some times is an advantage. Ferromanganese and spiegeleisen are produced by smelting a mixture of manganese ore and iron ore in an ordinary blast furnace. A high temperature is requirt! and the amount of fuel used is much grime than in iron smelting. A considerable armlet of the manganese goes into the slag. The slag, from a ferromanganese furnace may contain as much as 10 per cent of manganese. A con siderable tonnage of the iron manganese alloys is now produced in the electric furnace.