Coal Gas
a mixture of gases produced by the destructive distillation of coal at regulated temperatures. It is used in lighting streets, houses, etc., and for cooking and heating purposes. Coal gas is colorless and has a disagreeable smell. It is purified from H2S by ferric hydrate, which is moistened with FeSO. and H2SO, to remove ammonia. The carbon disulphide can be removed by passing it through an iron tube filled with iron turnings and heated to redness.
Coal gas consists of a mixture of hydrogen, 40 to 50 per cent., carbon-monoxide about 5 per cent., marsh gas (CH.) about 40 per cent., which contribute nothing to the illuminating power of the gas; it depends upon the presence of heavy hydro-carbons, principally C₂H. ethene, ordinary gas containing about 4 per cent., and cannel gas about 8 per cent. Coal gas also contains small quantities of acetylene, butylene, etc., and aromatic hydro-carbons, as benzine, etc.
The percentage of ge of nitrogen is very variable. When gas is burned a large large quantity of water is formed, hence, if a gas stove is used to dry a room there must be sufficient ventilation to carry off the COAL OIL aqueous vapor. The escape of coal gas from pipes into the soil is very injurious to the roots of trees and shrubs. The admixture of a very small quantity of air greatly impairs the illuminating power of coal gas. Three causes are capable of decreasing the luminosity of flame, viz.: (1) withdrawal of heat; (2) dilution; and (3) oxidation of luminous material.
See GAS.
Poisoning by coal gas, is known only as an accident. Occasionally sudden fatal consequences ensue among workmen from exposure to a sudden rush of undiluted gas from gasometers and mains. More commonly, slowly fatal cases result from the gas-tap in a bedroom being left open carelessly, from accidental extinction of the light, from blowing the gas out, or from leakage of the pipes in a house, or at a distance, the gas gaining entrance to the house in the latter case through cellars, walls, and more especially by means of drains and sewer-pipes.