378 RESPIRATION 



insane confidence that he is all right. At very high altitudes in 

 balloons or aeroplanes it is imperative that oxygen should be 

 breathed continuously. 



For about twenty years after the accident just described no 

 further very high ascents in balloons seem to have been attempted. 

 The next high ascents were made in Germany, starting with an 

 ascent by Berson and Gross to 26,000 feet in 1894. Berson alone 

 then reached a height of 30,000 feet; and finally in 1901 Berson 

 and Siiring reached about 36,000 feet (n,ooo meters), with a 

 barometric pressure of 1 80 mm. In all these ascents oxygen was 

 used, without which they would have been quite impossible ; but 

 at the end of the last ascent both Berson and Siiring became un- 

 conscious, though fortunately not before the former had pulled 

 the valve rope and thus turned the balloon downwards. Berson 

 had the cooperation of the Austrian physiologist, von Schrotter, 

 and the latter in his book describes not only the ascents, but 

 various preliminary experiments in a steel chamber and experi- 

 mental ascents in which he made physiological observations. Von 

 Schrotter had thoroughly grasped Paul Bert's work and was not 

 misled by the mistaken opposition of some physiologists to the 

 oxygen theory. 16 



Berson and Siiring used steel oxygen cylinders from which a 

 constant stream of oxygen came to them through a tube which 

 they could hold in the mouth. The cylinders were a great improve- 

 ment on the bags used by Croce-Spinelli and his companions, but 

 in other respects the arrangement was very imperfect, as von 

 Schrotter pointed out. With any increase of breathing the volume 

 of oxygen supplied became insufficient, so that only a mixture of 

 air and oxygen was breathed, the air being taken in through the 

 nose or by opening the mouth. Moreover it required constant 

 attention to inspire through the mouth, even if the supply of 

 oxygen was adequate. It was no wonder, therefore, that first 

 Siiring and then Berson was overcome. 



In one of the ascents by Berson and von Schrotter liquid air 

 was tried for the first time. It failed, partly because there was 

 no proper means of gasifying as much of the liquid as they re- 

 quired, and partly because the oxygen percentage in the gasified 

 liquid air was not high enough. Cailletet had, however, already 

 indicated a method of controlling the gasification, and this method 

 in an improved form was extensively used by the Germans during 



18 Von Schrotter, Der Sauerstoft in cLer Prophylaxte und Therapie der Luft- 

 druckerkrankungen, 1906. 





