HISTORY. Although it was shown by Fontana, in 1780, that a combustible gas could be formed by the reaction between steam and incandescent carbon at high temperatures, which is the basis of all water-gas manufacture, and between 1823 and 1858 many patents were taken out aim ing to take advantage of this reaction, the commercial development of the manufacture of water-gas and carbureted water-gas is of com paratively recent date. This development was made almost entirely in the United States, where both anthracite coal, a desirable source of carbon, and petroleum, for the manufacture of oil-gas, were plentiful and cheap. In the earlier forms of apparatus the water-gas was made from coal raised to incandescence in externally heated re torts, similar to coal-gas retorts, and the amount of fuel required proved too great for the success of the process. In 1871 Tessie du Motay erected in New York an apparatus for the manufacture of 'oxygen' gas, which, although it proved un successful, was later developed into the genera tor-retort form of carbureted water-gas appa ratus, and in 1873 Lowe erected, in Phenixville, Pa., the first apparatus of the generator-super heater type, covered by his patent taken out in 1872. In 1875 Mr. Lowe took out, as a result
of his experience in the construction of apparatus, another patent, which proved to be the basic patent for apparatus of this class.
When the proper temperature is reached, the blast is shut off, the outlet for the escape of the products of combustion closed, and steam is ad mitted to the fire, forming water-gas. The water gas is led from the generator into a small gas holder, called a relief holder. This is necessary, as the action of the generator is intermittent, because the production of water-gas rapidly cools the fire below the gas-making temperature, to which it must be brought back by again putting on the blast, while the gas must pass through the rest of the apparatus continuously and at a uniform rate. From the holder it is led above a series of steam-heated shelves, on which naph tha is vaporized, and the mixture of gas and vapor then passes through externally heated re torts, the vapor being converted by the heat into