Haldane, John Scott (1860-1936)
Scottish physiologist whose studies of the exchange of gases during respiration led to an interest in the health hazards of coal mining and deep-sea diving. His aim was to bridge the gap between theoretical and applied science.

Haldane was born and educated in Edinburgh. He was director of the Mining Research Laboratory (first in Doncaster, then in Birmingham) 1913-28. He also lectured at various universities in the UK, the USA, and Ireland.
Haldane devised methods for studying respiration and the blood - the Haldane gas analyser and an apparatus for determining the blood gas content. Having investigated the danger to miners of suffocation, he turned to the toxicity of carbon monoxide, which is usually present in mines after an explosion, and showed that this gas binds to the haemoglobin in the blood in preference to oxygen.
In 1905, Haldane published his idea that breathing is controlled by the effect of the concentration of carbon dioxide in arterial blood on the respiratory centre of the brain. In 1907, he announced a technique of decompression by stages which allows a deep-sea diver to rise to the surface safely; it is still used today.
He also researched the reaction of the kidneys to the water content of the blood, and the physiology of sweating.