gas, which was readily ignited and burned with its characteristic sooty flame.
Regarding the illuminating power of acetylene, a proper burner using five cubic feet per hour will give from two hundred to two hundred and forty candle power. Five cubic feet of ordinary gas give from fifteen to thirty candle power; that is, a cubic foot of acetylene will give about eight times as much light as the same amount of coal or water gas. Indeed, it is claimed by Prof. Lewes and others that the formation of acetylene in the ordinary gas flame accounts for the latter's luminosity, and it has been proposed to enrich water gas by the addition of a small amount of acetylene; but so much of the latter was found necessary to produce any appreciable result as to render the process impracticable. Acetylene requires a much larger amount of air for complete combustion than does ordinary gas. This is a distinct disadvantage, as the large amount of air cools the flame, and thus diminishes its luminosity. The temperature of the acetylene flame is about 1000° C, that of an ordinary flat coal-gas flame being 1360° C.
The present rise into prominence of acetylene, which up to 1888 was simply a laboratory product, is due to the discovery of the formation of calcium carbide in the electric furnace. There is some controversy as to who first made this discovery, but the honors seem to belong to Mr. T. L. Wilson, of the Wilson Aluminum Works. In 1888 Mr. Wilson began a series of experiments with the electric furnace for reducing refractory ores; during one of these a curious, dark-brown, dense mass was formed, whose immersion in water produced a violent evolution of gas, which upon investigation proved to be acetylene. A French chemist, Moissan, independently discovered the process, and reported it at the meeting of the French Academy, in December, 1892. But as Mr. Wilson sent samples of the carbide to Lord Kelvin in the summer of 1892, for examination, he seems to have preceded Moissan, at any rate in announcing his discovery. All the alkaline earths form carbides in a similar way, which, when treated with water, give off acetylene. It may be interesting to note, in passing, that by means of the electric furnace, a carbide of silicon has recently been obtained, which under the name of carborundum is coming to be used extensively as a polishing and grinding material. It is extremely hard (scratching rubies) and is said to wear well. Another interesting product is the carbide of titanium, the hardness of which is sufficient to scratch the diamond. This discovery of the ready formation of carbides under the great heat of the electric furnace is of special interest to the geologist, as bearing on the theory that these carbides are present in large quantities in the interior regions, to which water must occasionally penetrate; the resulting generation of gases
