In 1920 Henderson and Haggard1 published the results of experimental treatments of dogs asphyxiated by carbon monoxid. The rate of fall of the carbon monoxid hemoglobin was studied in control dogs and in dogs treated with air containing 6 per cent. and 10 per cent, carbon dioxid and with oxygen containing 10 per cent. carbon dioxid. As a result of these experiments they advocated the use of a mixture of carbon dioxid in oxygen for carbon monoxid poisoning. In later papers2 the same workers have recommended the use of a mixture of 95 per cent. oxygen and 5 per cent. carbon dioxid for resuscitation from carbon monoxid asphyxia, from ether or alcohol intoxication and for respiratory failure due to other causes, such as morphin narcosis. In the discussion following the reading of one of these papers,3 Dr. R. R. Sayers, chief surgeon of the Bureau of Mines, stated that at