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340 These latter, however, are isolated cases, for we see that its economy as a fuel gradually beat down prejudice and opposition, and the consumption steadily increased; but up to the beginning of the eighteenth century the only purpose for which it was used was for the production of heat in houses. It was now to enter upon its second grand phase of usefulness—that for the generation of force, as manifested through the agency of the steam-engine, which was first used for mining purposes. By this application of steam not only was the mining of the coal made cheaper, but the facilities for distributing it enlarged, and as engines were improved from time to time, their number increased, because they could be economically employed in a greater number of industries, and therefore the demand for this class of fuel rapidly extended.

About 1805 light established a new market and demand for the black diamonds. For a hundred years or more there were various experiments on the distillation of coal in order to produce tar and oils, while the practical application of the invisible gases that were set free was not thought of till 1793, when William Murdoch, engineer to Bolton & Watt, employed coal-gas for lighting his house and offices, at Redruth in Cornwall. The earliest application of this light, on a large systematic scale, was in Manchester, where an apparatus for illuminating the cotton-mills of Messrs. Phillips & Lee was fitted up in 1804 and 1805, under the direction of Mr. Murdoch. This new invention rapidly spread, and in 1807 public streets were thus lighted. During 1877 the gas companies in New York City and the immediate vicinity alone required about 450,000 tons.

At Coalbrook Dale, in England, between 1730 and 1735, Abraham Darby made successful experiments in substituting coal for charcoal, in the manufacture of iron, in the blast-furnace, and thus made the first step in an industry that now requires millions of tons annually; though it was not till 1830 that this trade really began to assume the gigantic proportions which it now has. At that date Neilson, in Scotland, applied the hot-blast to iron-furnaces, for the purpose of economizing fuel, and succeeded so well that a ton of coal now reduces three times as much iron as it did before. This, like all other inventions tending to economy, increased the manufacture of iron, and consequently demanded more fuel, exactly as the merchant finds it to his advantage to have quick sales and small profits.

During the last twenty years chemistry has discovered many minor but none the less striking applications of coal in utilizing the once waste products of its distillation for gas. Among these may be cited solid paraffin, which, when made into candles, equals in beauty those of wax; from its analine are obtained many of the most exquisite dyes, whose shades and tints please the eye and gratify our tastes; it seems almost past belief that some of the delicate toilet perfumes come from it, and that flavoring extracts to pander to our palates are distilled from the same black substance.