John Scott Haldane - Coal and Metal Mines

Coal and Metal Mines

He investigated the principle of action of many different gases. He investigated numerous mine disasters, especially the toxic gases which killed most miners after firedamp and coal dust explosions. The toxic mixtures of gases found in mines included afterdamp, blackdamp and whitedamp. His description of the way a flame safety lamp can be used to detect firedamp by the increase in height of the flame, and chokedamp by the dying of the flame, is a classic exposition in his textbook, Respiration. Although electronic gas detectors are now used widely in all coal mines, flame lamps are still used extensively for their ease and simplicity of operation. Electronic gas detectors rely on a catalytic chip which can be poisoned by atmopsheric impurities.

He identified carbon monoxide as the lethal constituent of afterdamp, the gas created by combustion, after examining many bodies of miners killed in pit explosions. Their skin was coloured cherry-pink from carboxyhaemoglobin, the stable compound formed in the blood by reaction with the gas. It effectively displaces oxygen, and so the victim dies of asphyxia. As a result of his research, he was able to design respirators for rescue workers. He tested the effect of carbon monoxide on his own body in a closed chamber, describing the results of his slow poisoning. In the late 1890s, he introduced the use of small animals for miners to detect dangerous levels of carbon monoxide underground, either white mice or canaries. With a faster metabolism, they showed the effects of poisoning before gas levels became critical for the workers, and so gave an early warning of the problem. The canary in British pits was replaced in 1986 by the electronic gas detector.