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Acetylene

carbide, calcium and water

ACETYLENE (Formula C,II,).—An illuminating gas obtained from calcium carbide when brought into contact with water. The acetylene is evolved in accordance with the following equation : CaC, H,0 = C,H, CaO Calcium Carbide added to Water forms Acetylene and Quick Lime.

With this reaction great heat is evolved and the gas is often beyond the control of the experimentalist. The following arrangement has been devised by Mr. F. B. Grundy :* In the diagram (Fig. 13), A is a forty ounce flask containing the calcium carbide broken up into small pieces, the quantity of carbide placed in the flask being dependent, of course, upon _ I the quantity of gas required. is to be borne in mind that each pound of calcium carbide about five cubic feet of acetylene will be given off. B is a glass vessel, known to chemists as a sepa rating funnel, fitted with a stopcock, by means of which the water contained in the vessel can be allowed to drop on the carbide in the flask. The acetylene which is produced is led off from the generator by means of the tube C into the two necked bottle D containing water. This is to wash the gas, and also to prevent the steam which is formed from condensing in the pipes, and thus obstruct the free passage of the acetylene, which passes by the outlet tube E to the gasholder, in which it is to be stored.

Acetylene was discovered by Berthelot about 1845, but little was known about it owing to the expense of production. The recent discovery of S. L. Wilson and Prof. V. B. Lewes has enabled us to produce it from calcium carbide at a very small cost. Some experiments made by Professor Lewes show that its actinic power, compared with ordinary coal gas,was about 2.5 times as great. This property will render it a valuable illuminant for photographic purposes. The flame is so intense that small flat burners have to be employed. The light emitted has a remarkable actinicity.

Acetylene is soluble in water, alcohol, and .11 • • • '1 • most it can be condensed by pressure into a liquid. When diluted with twelve times its volume of air it is highly explosive, but this property is lost when the dilution exceeds twenty parts. It forms dangerously explosive compounds with gold, silver, copper, mercury, and several other metals.*