This section is from the book "Welding And Cutting Metals By Aid Of Gases Or Electricity", by L. A. Groth. Also available from Amazon: Welding and cutting metals by aid of gases or electricity.
In its number for May, 1908, Acetylene, The Lighting Journal, states that The Acetylene Illuminating Company, Limited, were the founders of the acetylene industry in the United Kingdom, by introducing the manufacture of carbide of calcium in this country in 1895. For this purpose the Wilson patents were acquired by the company, and an experimental plant was started in Leeds. As the result of the successful experiments, a permanent plant was laid down at the Falls of Foyers, Scotland, which started turning out carbide on a commercial scale in 1896. In 1902, however, it was found necessary to cease carbide manufacture, owing to the power being required for the manufacture of aluminium and the company's lease for power having terminated.
In 1901 the Acetylene Illuminating Company, Limited, acquired the patents for the manufacture of dissolved acetylene (acetylene-dissous) in Great Britain, the British Colonies and Dependencies.
Carbide of Calcium is a dark grey slag made by fusing together coke and lime in the intense heat of an electric furnace.
The following formula denotes the chemical reaction which produces acetylene:
CaC2 / Calcium carbide + 2H20 / water =
C2H2 / Acetylene + CaOH2 O / Lime
To put it simply :
Carbide of calcium consists of one atom of calcium combined with two atoms of carbon.
When brought into contact,
The carbon of the carbide of calcium combines with the hydrogen of the water to form acetylene.
The calcium of the carbide of calcium combines with the oxygen of the water to form lime.
After acetylene has been produced the residuum is a lime which may be used in the garden as a fertilizer.
The average quality of carbide of calcium will yield 4.7 cubic feet of gas per pound of carbide.
Carbide of calcium attracts moisture from the atmosphere so rapidly that it must always be stored in an air-tight and damp-proof receptacle to avoid generation of gas or crumbling of the carbide with consequent deterioration and waste.
Carbide of calcium in itself is not an explosive, and cannot be made to explode even if exposed to the highest degree of heat, but when water is added to it, or if it be kept exposed in a damp atmosphere, the carbide of calcium is attacked and acetylene gas evolved. But even with unpacked carbide of calcium, in a damp atmosphere the evolution is slow, as a hydrate of lime forms on the lumps and protects them, to a great extent, from atmospheric influence. If gas be evolved and allowed to accumulate, and a light be applied, it will of course fire and explode in the same way as coal gas. Its escape is easily detected owing to its pungent odour.