METHANE ( from m ethyl ), MARSH GAS, FIRE-DAMP (Ger. Sum pf gas) , CIL. The simplest of the compounds of carbon and hydrogen, usu ally prepared by heating a mixture of sodium acetate and It is one of the gase ous products of the decay of vegetable mat ter (especially cellulose) under water, and it is therefore a constituent of the gases bubbling up in the stagnant water of marshes; it is also one of the gases evolved in petroleum wells. It oc curs in considerable quantities in some coal mines, where it has often caused disastrous ex plosions, it is a colorless and odorless gas burn ing with a non-luminous flame. It is formed in the destructive distillation of organic matter. sueh as wood, coal, etc., and is, therefore. one of the principal constituents of ordinary illuminat ing gas, which contains 30-40 per cent. of meth ane. A very large number of organic compounds van he derived from methane. And since the gradual building up of these compounds from the elements is a matter of great importance in or ganic chemistry, the synthesis of methane it self. as the first step in innumerable processes
;employed in producing organic compounds, formed a valuable contribution to chemical science. The synthesis of methane was first ef fected by Ilerthelot, who showed that the gas is produced when a mixture of carbon disulphide and water-vapor is passed over red-hot copper. The reaction taking place is represented by the following chemical equation: CS, + 2H,0 GCu = CH, + 2Cu,S 2CuO. Carbon di- Water Copper Methane Cuprous Cupric sulphide sulphide oxide In this manner any quantity of methane can be obtained by using nothing but elementary sub stances as starting material; for carbon disul phide and water can he prepared by the direct union of their elements.