Monday, June 30, 2008

A Chemical Curiosity


Carbide of Calcium and Water Produce a Brilliant Illuminating Gas.

Decidedly the most interesting and curious of recent chemical products is calcium carbide, or calcium acetylide, as it might be called from a theoretical chemical point of view. It was first described by Wohler, who made it by strongly heating an alloy of zinc and calcium with charcoal, but it is now turned out on a considerable scale by heating a mixture of dry lime and coal dust in an electric furnace. In other words an immense electric current, such as is used in the production of aluminium, for example, is passed through the mixture, whereupon a part of the carbon takes the oxygen from the lime and carries it off as carbon monoxide gas, while another part of the carbon combines with the calcium thus set free. Analogous bodies, all of which are explosive, are formed with copper, silver, sodium and potassium. The noteworthy feature of the new compound, which is of a greenish gray color and somewhat resembles the mineral serpentine, is that, on contact with water, it develops acetylene, the hydrogen of the water combining with the carbon to form this gas, while the oxygen of the water forms lime by combination with the calcium.

From information kindly given by Dr. Henry Morton of Stevens institute it appears that the calcium carbide is claimed to be obtainable at a cost of £3 or £4 a ton. If this be so, the compound would promise well as a source of illuminating gas, since acetylene gas burns with a very luminous flame. In a country house, for example, it would be necessary only to have a closed vessel, charged with the calcium carbide and provided with an automatic stopcock, which would allow water to flow in as required. Then, the piping of the house being connected with the closed vessel, and with a small gas holder to regulate pressure, the light supply would be complete and automatic. A piece of carbide of calcium may be held in the hand and sprinkled with a few drops of water. A gas will then be developed which may be lighted with a match and will continue to burn as long as a few drops of water are sprinkled on the substance from time to time. — Cassier's Magazine.

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