Professor John Scott Haldane CH FRS (2 May 1860 – 14/15 March 1936), brother of Viscount Haldane, was a British physician, physiologist and philosopher, famous for intrepid self-experimentation which led to many important discoveries about the human body and the nature of gases. He also experimented on his son, the celebrated and polymathic biologist John Burdon Sanderson Haldane. Haldane locked himself in sealed chambers breathing potentially lethal cocktails of gases while recording their effect on his mind and body.
Haldane visited the scenes of many mining disasters and investigated their causes. When the Germans used poison gas in World War I, Haldane went to the front at the request of Lord Kitchener and attempted to identify the gases being used. One outcome of this was his invention of a respirator, known as the black veil.
Haldane's investigations into decompression sickness resulted in the concept of staged decompression, and the first reasonably reliable decompression tables, and his mathematical model is still used in highly modified forms for computing decompression schedules.
See Wikipedia entry, from which the above information was condensed (3/11/2023).