Decreased Pressure 997 



and 26 cm. wide, and weighing with the Denayrouze regulator only 

 13 kilograms. The volume of the cylinders being 11 liters, one 

 would have at 30 atmospheres, a pressure which presents no dan- 

 gers, 330 liters of oxygen, 24 which one would evidently have to 

 take as pure as possible, that is, in practice, at 95%. But since the 

 respiration of pure oxygen is not at all necessary, I had a tube 

 made in the form of a Y, which serves to mix in proper proportions 

 the oxygen of the receiver with the outer air; one of the branches, 

 which opens out, is free; the other, which communicates with the 

 cylinders, has a graduated bolt, by means of which its caliber is 

 narrowed more or less, according to specifications calculated in 

 advance, so as to maintain the oxygen tension at a sufficient degree. 



Supposing that one breathes, on the average, air with 45% of 

 oxygen, the volume available would become 660 liters, which could 

 suffice for the continuous respiration of a man for more than one 

 hour. But in practice it would not be necessary to breathe super- 

 oxygenated air constantly. On Mont Blanc, the mountain in Europe 

 where these symptoms are at the maximum, this provision would 

 be enough for the most susceptible of travellers, and on the average 

 could guard two or three travellers from what is sometimes so 

 painful in mountain sickness; they would only have to come from 

 time to time, in difficult places, to breathe some whiffs of this 

 gaseous cordial, to drink some gulps of oxygen, according to the 

 picturesque expression of Sivel. But we see that the use of this 

 means would be rather difficult and inconvenient in very lofty 

 regions, where superoxygenated breathing should be almost con- 

 tinuous, and even, we must confess, dangerous, if a violent fall of 

 the man carrying it should break the apparatus. 



It certainly would be much better to be able to produce oxygen 

 from time to time, at necessary halts, to meet the needs, instead of 

 storing it up in little bags. But I do not now know any chemical 

 reaction which can be managed easily without the transportation 

 of fragile or heavy instruments, or, in a word, in conditions practi- 

 cal for ordinary ascents. But scientific expeditions of long duration, 

 like those which sojourned for weeks in the lofty regions of Thibet, 

 Ladak, and Pamir, could and even should carry with them the 

 equipment necessary to procure oxygen under given circumstances. 

 It is rare, no doubt, that anyone dies exclusively from the effects of 

 rarefied air, although we have mentioned examples of this kind of 

 death; but its fearful influence increases rapidly the dangers of all 

 the maladies which jeopardize the oxidation of the blood. I am 



