“…2 (Forbes, Sargent, and Roughton, 1945;Henderson et al, 1921Drinker, 1938 (Haldane and Priestley, 1935;Asmussen and Chiodi, 1941 ;Apthorp et al, 1958); but, as Haldane emphasized, such exposures may be followed by tiresome headaches coming on some hours later. At saturations between 40 and 50% there is impairment of mental function and ataxia, and collapse may occur on exertion.…”