Failure on Everest: the oxygen equipment of the spring 1952 Swiss expedition.

The Swiss expedition to Everest (altitude 8,848 m) in the spring of 1952 very nearly attained the summit with two of the climbers reaching 8,595 m. This would have been the first ascent of Everest. One main reason for failure was the inadequate oxygen equipment which was modified from sets designed for mine rescue using potassium peroxide generators. Oxygen could not be inhaled while the mountaineers were climbing because of the rigid mouthpiece assembly and the high breathing resistance of the equipment. It was argued that breathing oxygen during rest periods would suffice, but this was a fallacy as had been demonstrated by Kellas 30 years before.