Molybdenum

Molybdenum (sym. Mo; atomic weight, 96; sp. gr. 8.62) is a rare metal, which, in a state of purity, is of a silvery white colour, has a strongly metallic lustre, is brittle, and very difficult of fusion. It never occurs native, and its principal ore is the bisulphide, which much resembles graphite. It is also occasionally found oxidised, in molybdate of lead. The metal may be obtained by roasting the bisulphide in a free current of air, when the sulphur goes off oxidised as sulphurous acid, and the molybdenum is also oxidised into Molybdic Acid ($\backslash text\{MoO\}\_3$), and remains in the vessel. By the action of charcoal, the reduced metal is then obtained from the acid. Molybdenum forms three compounds with oxygen—the protoxide ($\backslash text\{MoO\}$), the binoxide ($\backslash text\{MoO\}\_2$), and molybdic acid ($\backslash text\{MoO\}\_3$). Of these three the last alone has any practical value. Molybdic acid is a white, glistening, crystalline powder, which is sparingly soluble in water, fuses at a red heat to a straw-coloured glass, and mites with bases to form well-marked salts, the molybdates, which are either colourless or yellow. A solution of molybdate of ammonia is one of the most delicate tests for phosphoric acid. Molybdenum forms various compounds with sulphur, chlorine, &c., none of which are of any practical importance, except the native bisulphide.