The investigation of mine air : an account by several authors of the nature, significance, and practical methods of measurement of the impurities met with in the air of collieries and metalliferous mines / edited by Clement le Neve Foster and J.S. Haldane.

  • Foster, Clement le Neve, Sir, 1841-1904.
Date:
1905
Catalogue details

Licence: In copyright

Credit: The investigation of mine air : an account by several authors of the nature, significance, and practical methods of measurement of the impurities met with in the air of collieries and metalliferous mines / edited by Clement le Neve Foster and J.S. Haldane. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    complete combustion. It is nowhere found in nature,^ but it is produced wherever carbonaceous substances are burnt with an insuflicient quantity of air, or when carbonic acid comes in contact with red-hot coal, which takes from it one part of its oxygen. These two processes of formation take place according to the following chemical equations:— 2C +02 = 200. C02 + C = 2CO. The formation of carbonic oxide in the second way may be observed in every fireplace. The tongues of blue flame on the surface of the red-hot coal are due to burning carbonic oxide; the carbonic acid produced in the excess of air in the lower part of the fireplace is reduced to carbonic oxide as it passes through the upper layer of red-hot coal. It is likewise formed by the dry distillation of coal, and is consequently an integral constituent of illuminating gas, which may contain as much as 10 per cent, of it. It has never been proved with certainty that carbonic oxide is a normal constituent of mine gas. It is found, however, in the gases from underground fires, as indeed in all smoke, and its percentage increases in proportion as the amount of fresh air supplied to the fire decreases. It also forms a constituent of the after-damp produced by an explosion of fire-damp, when the per- centage of methane exceeds 9-5, because then the proportion of air no longer suffices for the complete combustion of the methane. Such explosions are very rare, and in spite of this carbonic oxide is an almost invariable constituent of after- damp, because coal dust has taken part in the explosion. In a case of this kind the carbonic oxide may have arisen either from the dry distillation of particles of coal, in consequence of the heat evolved by the combustion of the gas, or by the incomplete combustion of the distillation products so generated. Carbonic oxide is a colourless and inodorous gas with a specific gravity of 0-967; 1 litre of it under normal conditions weighs 1 -251 grammes. It is much less easily liquefied than carbonic acid. Its critical temperature is about -139'5°C., below which it is converted by pressure into a colourless liquid which boils at - 190°. If the temperature is lowered to - 207°, it solidifies into a transparent substance. Carbonic oxide will not support com- bustion, but itself burns with a pale blue flame to carbonic acid and with great development of heat. 200 + 0^ = 2002. 1 Cf. pp. 132, 170.