Modern Gasworks Practice

CHAPTER XI GAS-MAKING AND OTHER COALS Coal, the natural gift to which our country may be said to owe its commercial pre-eminence, provides as fascinating a problem as can be met with in any of the highways of modem science. The phenomena surrounding its formation are as yet open to controversy, while the more material question of its economic utilization presents a subject which provides one of the most pressing th.ein.es for the inves-tigation of the present and firture generations. Coal has been described as a store of primæval solar energy, slowly accumulated during untold millenniums, which mankind nowadays draws upon as a source of practically the whole of his available light, heat, and power in artificial form. That coal is mineralized vegetation is a point upon which all doubt has been removed. It may be simply defined as the product of the decay of vegetable matter under the prolonged influence of pressure, heat and moisture. Stopes and Wheeler 1 suggest tliat coal may be defined as “ a compact, stratified mass of mummified plants (which. have in part suffered arrested decay to varying degrees of completeness) free from all save a very low percentage of other matter.” Veins partings, etc., which are found in nearly all coals, are local impurities, and are not part of the coal itself. The classification of coals is based upon the geological period of their formation, the two main groups being known as “ carboniferous ” and “ tertiary.” It is the former which are generally distinguished by the name of “ true ” coals, and in this category are included steam coals and anthracites, cannel coals, and the mis-named bituminous types which, almost solely, are suitable for gas-making purposes. The tertiary coals, on the other hånd, embrace those types of the nature of lignite or brown coal. Scientific records appertaining to the gradual formation of coal from vegetable matter prove of little iaterest to the practical gas-maker, and the same almost may be said of the composition of coals as determined by ordinary laboratory mcthods. Nowadays, the gasworks valne of a coal is gauged, not by its specific gravity or its unoxidized hydrogen ” content, but by its capability to conform with certain practical expectations. The Constitution, as distinet from the composition, of coal is still more or less shrouded. in mystery, although recent investigators have classified the main components in a manner which is of di st inet service to those direetly interested in carbonization. Composition as determined by ultimate 1 The Constitution of Coal, 1918. 355