Joseph Barcroft Experiments

British physiologist Joseph Barcroft known for his studies on blood oxygenation never hesitated to use himself as a test subject. He once gassed himself to an atmosphere of poisonous hydrogen cyanide for a full 10 minutes and survived. The dog with him lasted only 95 seconds before dying. To find the minimum oxygen level needed to survive, he lived in an oxygen level found at 4,900 meters for a week, causing his whole body to turn blue. He once locked himself in a refrigerated chamber to test the effects of freezing. He chose to stay until he became unconscious and had to be rescued. He discovered that at a certain point close to lethal hypothermia, the human body begins to feel warm rather than freezing cold.