The Romance of Modern Chemistry

NATURES STORES OF FUEL The gas consists almost exclusively of methane or marsh gas, the simplest compound of carbon and hydrogen. The origin of solid fuel has already been discussed and is fairly evident, but it is much more difficult to specify the source of all the petroleum which has been obtained so abundantly during the last forty years. Some authorities assign to it an inorganic origin, and suppose that the hydrocarbons of which petroleum con- sists have been produced by the action of water on carbides. These substances are compounds of metals with carbon, and are decomposed by water in such a way that the carbon of the carbide forms a new com- pound—a hydrocarbon—with the hydrogen in the water. Many readers doubtless are familiar with one carbide which is in common use, namely, calcium carbide. This substance on contact with water generates acetylene, a hydrocarbon which has many advantages as an illuminat- ing gas. Bicycle lamps, for example, are made in which acetylene is burned, the gas being prepared in the lamp by allowing water to drop on lumps of calcium carbide. So it may be supposed that water, penetrating through fissures in the crust of the earth, has acted on subterranean masses of carbides with the production of petroleum. Another explanation, which on the whole has more support, regards petroleum as derived from an organic source, animal rather than vegetable. According to this view, the animal remains of past ages have under- gone a change, whereby all nitrogenous and other matters, except the fats, were removed. Subsequently these fats, being subjected to distillation by the combined action of heat and pressure, or of pressure alone, yielded the petroleum which we get to-day. In connection with all these fuel supplies — coal, 137