Page:Encyclopædia Britannica, Ninth Edition, v. 10.djvu/98

.ating power equal to 14,‘; candles. 88 hydrocarbons issuing from and through pet-roleum deposits. In the province of Szechuen in China, gas is obtained from beds of rock-salt at adepth of 1500 or 1600 feet: being brought to the surface, it is conveyed in bamboo tubes and used for lighting as well as for evaporating brine ; and it is asserted that the Chinese used this naturally evolved gas as an illuminant long before gas-lighting was introduced among European nations. At a salt mine in the comitat of Marmaro in Hungary, gas is obtained at a depth of about 120 feet, and is used for illuminating the works of the mine. Again at Fredonia (New York State) a natural emission of gas was discovered in a bituminous limestone, over the orifice of which a gasholder has been erected, and thus about 1000 cubic feet of a gas composed of marsh gas and hydride of ethyl has been made available for illumination. In the city of Erie (Pa.) there are 13 gas-wells, each yielding from 10,000 to 30,000 feet per day, the gas escaping from one of them at a pressure of 200 lb per square inch. At lloomfield, Ontario co., New York, there is a spring which yields daily no less than 800,000 feet of gas of an illumin- The city of East Liverpool (Ohio) is entirely illuminated, and to a large extent heated, by gas-wells which exist in and around the town. The light is of extraordinary brilliancy, and is so abundant and free that the street lamps are never extin- guished, and much of the manufacturing steam-power of the town, which embraces 22 potteries, giving employment to 2000 hands, is derived from the gas. The first “ well,” 450 feet deep, was opened in 1859, and up to the present year (1879) neither it nor any of those tapped at later dates show any sign of failing. In many other parts of America similar gas-wells exist ; and several such natural jets of gas have been observed in England. By general consent the merit of the discove1‘y and appli- -cation of artificial gas belongs to Great Britain, and the name most honourably connected with the beginning and early stages of gaslighting is that of a Scotchman—'illiam Murdoch. But previous to Murdoch’s time there occur numerous suggestive observations and experiments as to inflammable air and its sources. In the Pit-z'losopItz'cal Transactions of the Royal Society for 1667 the existence of a “bur11iug spring” in the coal district of Vigan is noticed by Thomas Shirley, who traced its origin to the underlying coal. In the same Transactions for 1739 is printed a letter addressed to the Hon. Robert Boyle, who died in 1691, in which the Rev. John Clayton details a series of experiments he made in distilling eoal in a retort, showing, not only that he had observed the inflammable gases evolved, but that he collected and stored them for some time in bladders. In Dr Stephen IIales’s work on Vegetable Staticlcs, published in 1726, more precise state- ments are made as to the distillation of coal, he having obtained from 158 grains of Newcastle coal 180 inches of .inflammable air. In 1787 Lord Dundonald, in working a patented process for obtaining coal-tar, experimented with the gas evolved in the process, and occasionally used it for lighting up the hall of Culross Abbey. None of these observations, however, led to distinct practical results; and it was not till the year 1792 that Villiam Murdoch, then residing at Redruth in Cornwall, began the investigations into the properties of gases given off by various substances which eventuated in the establishment of coal-gas as an illuminating agent. In 1797 he publicly showed the system he had matured, and in 1798, being then employed in the famous Soho (Birmingham) workshop of Boulton & Watt, he fitted up an apparatus for the manufacture of gas in that establishment, with which it was partly lighted. Thereafter the apparatus was extended, and the gas manufactured by it was introduced to other neighbouring workshops and factories. Among others who helped most materially to GAS develop the infant art in England were Dr Henry of Manchester, and Mr Clegg, who, succeeding Mr Murdoch at Boulton & Watt's, introduced many improvements in gas manufacture, and ultimately became the most skilful and famous gas engineer in the United Kingdom. In 1801 M. Lebon introduced gas distilled from wood into his own house in Paris, and the success of his experi- ment attracted so much notice and comment as t.o give rise to an impression that he is entitled to the credit of the invention. Lebon’s experiment came under the notice of Mr I". A. Winsor, who took up the subject with a zeal and unwearying patience which led to a recognition of the advantages of the system, and the breaking down of the powerful prejudice which existed in England against the innovation. In 1803, through Winsor’s efforts, the Lyceum Theatre was lighted with gas ; but it was not till 1810 that he succeeded in forming a public company for manufacturing gas, and in obtaining an Act of Par- liament for the Gas—Light and Coke Company. In 1813 Vestminster Bridge was first lighted with gas, and in the following year the streets of Westminster were thus illuminated, and in 1816 gas became common in London. So rapid was the progress of this new mode of illumination that in the course of a few years after its introduction it was adopted by all the principal towns in the kingdom, for lighting streets as well as shops and public edifices. In private houses it found its way more slowly, partly from an apprehension of danger attending its use, and partly from the annoyance which was experienced in many cases through the careless and imperfect manner in which the service-pipes were at first fitted up. SOURCES or GA s. Artificial gas is now distilled from a variety of substances, among which are coal, shale, lignite, petroleum, turf, wood, resins, oils, and fats; and it is also prepared by carburetting or impregnating with volatile hydrocarbons other non- luminiferous gases. Of the very numerous systems of gas- making which have been proposed since the early part of the century, none can compete for general purposes with the ordinary coal-gas process, when a supply of the raw material can be obtained at a moderate expense. Coal-G'us.—Coals, varying greatly as they do in chemical constitution, differ also, as might be expected, as widely in their value and applicability for the manufacture of gas. Taking the leading varieties of coal to be included under anthracite, bituminous coal, and lignite or brown coal, we find that it is the class bituminous coal alone that yields varieties really serviceable for gas-making. Anthracite may be regarded as a natural coke from which the volatile con- stituents have been already driven off, and the more anthracitic any coal is, the less is it capable of yielding gas. Lignite also is rarely used for distillation, owing to the large proportion of oxygen and the amount of water in its com- position. Of the bituminous coals again, it is only the caking or pitch coals, and the cannel or parrot coals, that are in practice used in gas-works. These also vary within very wide limits in their gas-making value, not only from the great difference among them in yield of gas, but also in the illuminating value of the gas they evolve. As a rule the coals which yield the largest percentage produce also the most highly illuminating qualities of gas. The cannel coals, which are specially recognized as “ gas-coal,” are most abundantly developed in Scotland and in Lanca- shire, and the fact of the unequalled qualities of Scotch cannel and of the allied substance, bituminous shale, for gas- making, has had the effect of rendering illumination by gas much more general and satisfactory in Scotland than in any

other country. It is only a very imperfect valuation of any