WATER GAPS. See DELAWARZ Want Gee; STREAM Pinner; TRELLISED DRAINAGE a mixture of gases produced by the action of steam on incandescent carbon. The carbon first decomposes the steam, forming hydrogen and carbon dioxide, and the latter gas then combines with more carbon to form the inflammable carbon monoxide. Thus water-gas may be considered economically a mixture of hydrogen and carbon monoxide with certain impurities. Its especial value as a fuel lies in the fact that 90 per cent of its solume is com bustible, while the ordinary producer-gas is but 30 per cent combustion. Pure water-gas is non luminous, but it is rendered luminous by mix ing with it various gases obtained from pe troleum, the luminous mixture being known as carbureted water-gas. Two chief methods are employed for the manufacture of water•gas for illuminating purposes In the first of these, the Lowe process, the preparation of the pure gas and the carbureting are performed in one operation. The apparatus consists essentially of a generator, filled with anthracite or coke, in which the non-carbureted gas is produced; a carbureter, a circular chamber lined with fire brick and filled with a checkerwork of the same material; and a superheater, a taller circular chamber similarly filled. By means of air blasts and the producer-gas from the anthracite of the generator, the fire-bricks of the car bureter and the superheater are raised to a red heat, and then superheated steam is passed through the incandescent carbon. The product
at this stage is known as 'blue water-gas' and burns with a very hot, non-luminous flame. It is useful for many manufacturing purposes. To make it available for Minnie/ding the water gas formed is carried over into the c.arbureter, where it becomes mixed with the highly car bureted gases formed by the action of the heated bricks on mineral oil, which is intro duced from abos e. This process is completed in the superheater, and the carbureted gas is then ready fur purification process in which the sulphureted hydrogen and carbon dioxide com ponents are removed. In the Wilkinson proc ess the operations of making the gas and car bureting arc separate. In the United States carbureted water-gas has largely replaced coal gas as an illuminant, partly because of its brighter light and partly because it can be more cheaply manufactured. Illuminating gas made from coal is often mixed with carbureted water gas in order to increase its illuminating power. The chief objection to the use of water-gas as an illuminant is the highly poisonous nature of one of its largest constituents, carbon monoxide. By keeping the percentage of this constituent down to 16 per cent of the total volume, the mixture is not more dangerous to inhale than ordinary coal-gas. See GAS, N AT? URAL.