Manganese

Mn. At. wt. 55, sp. gr. 7.5, sp.ht..121. mpt. 1,500°-1,600° C. Discovered by Scheele 1774; white, shining metal, hard and brittle, oxidizing readily in moist air, decomposing water at 100° C., soluble in the common acids; widely distributed in nature, occurring in pyrolusite, braunite, manganite, etc. It forms four cla es of compounds, showing a IMG:content-1234.jpg:[blocks in formation] valence of two, three, six, and seven. The most stable are the manganous compounds, in which it is bivalent. It is used in the manufacture of certain varieties of steel. The compound of manganese and carbon, similar to cast iron, melts at 1,200° C.