3 i6 THE POPULAR SCIENCE MONTHLY 



The writer's shortness of breath became more and more distressing as he 

 rose; all were more affected than at any time before, but none of the others in 

 this acute way. The fits of panting became more frequent and more violent; at 

 such times everything would turn black before his eyes and he would choke and 

 seem unable to recover his breath at all. Yet a few moments' rest recovered 

 him as completely as ever, to struggle on another twenty or thirty paces, and to 

 sink gasping on the snow again. . . . With keen excitement we pushed on. . . . 

 The last man on the rope, in his enthusiasm and excitement somewhat overpass- 

 ing his narrow wind margin, had almost to be hauled up the few final feet, and 

 lost consciousnes for a moment as he fell upon the floor of the little basin that 

 occupies the summit. 



Various experimental researches, and especially the latest and very 

 careful investigation by Haldane, Douglas, Henderson and Schneider 

 on Pike's Peak, have proved beyond a doubt that that formerly mys- 

 terious disease, mountain sickness, is due solely to the greatly dimin- 

 ished pressure of oxygen existing at all considerable heights. That won- 

 derful power of adaptation to unusual conditions, however, of which the 

 human body is so generously possessed, is here demonstrated in the fact 

 that on reaching the unusual height the quantity of hemoglobin, which 

 gives the red color to the blood and enables it to carry oxygen to our 

 tissues, begins to increase, and a few days of life at the high altitude 

 renders us capable of continuing to live there under the diminished 

 oxygen pressure without further danger to life. 



Within a crowded assembly the proportion of oxygen may fall to 

 one twentieth of its usual amount in the outdoor air, probably never 

 more except in the most extreme experimental conditions. Experimen- 

 tation has apparently shown that the evil effects of such indoor air are 

 not due in any respect to this slightly lesened quantity of the gas. It 

 has even been diminished to less than seventeen per cent, in experimental 

 chambers without apparent detriment to persons confined therein. Hill 

 says of a group of his students whom he confined in a narrow air-tight 

 room : " We have watched them trying to light a cigarette (to relieve the 

 monotony of the experiment) and puzzled by their matches going out, 

 borrowing others, only in vain. They had not sensed the percentage of 

 the diminution of oxygen, which fell below seventeen." The ventilation 

 of coal mines by air containing only seventeen per cent, of oxygen has 

 indeed been suggested as a preventive of explosions. On the other 

 hand, a " sand hog " working in a caisson at a depth of one hundred 

 feet must be subjected to a pressure of oxygen four times that found in 

 the usual atmosphere. Here he can work for several hours with im- 

 punity; a longer time would give an opportunity for the excess of this 

 gas to manifest its toxic action on his tissues. Because of this poisonous 

 action too, a man can breathe pure oxygen when in excess for a limited 

 period only. The administration of oxygen in extreme illnesses thus 

 has its limitations. 



