STUFFY ROOMS 385 



At sea-level the pressure of oxygen in the pulmonary alveolar air 

 is about 100 mm. Hg. Exposed to only half this pressure the hemo- 

 globin is more than 80 per cent, saturated with oxygen. 



In noted health resorts of the Swiss mountains the barometer stands 

 at such a height that the concentration of oxygen is far less than in the 

 more ventilated room. On the high plateau of the Andes there are 

 great cities : Potosi with a hundred thousand inhabitants is at 4,165 

 meters, and the partial pressure of oxygen there is about 13 per cent. 

 of an atmosphere in place of 71 per cent, at sea-level; railways and 

 mines have been worked up to altitudes of 14,000 to 15,000 feet. At 

 Potosi girls dance half the night, and toreadors display their skill in 

 the ring. On the slopes of the Himalayas shepherds take their flocks 

 to altitudes of 18,000 feet. No disturbance is felt by the inhabitants 

 or those who reach these great altitudes slowly and by easy stages. 

 The only disability to a normal man is diminished power for severe 

 exertion, but a greater risk arises from want of oxygen to cases of heart 

 disease, pneumonia, and in chloroform anesthesia at these high alti- 

 tudes. The newcomer who is carried by the railway in a few hours to 

 the top of Pikes Peak or the Andes may surfer severely from mountain 

 sickness, especially on exertion, and the cause of this is want of oxygen. 

 Acclimatization is brought about in a few days' time. The pulmonary 

 ventilation increases, the bronchial tubes dilate, the circulation becomes 

 more rapid. The increased pulmonary ventilation lowers the partial 

 pressure of carbon dioxide in the blood and pulmonary air, and this 

 contributes to the maintenance of an adequate partial pressure of 

 oxygen. Haldane and Douglas say that the percentage of red cor- 

 puscles and total quantity of the hemoglobin increases, and maintain 

 that the oxygen is actively secreted by the lung into the blood, but the 

 C method by which their determinations have been made has not met 

 with unqualified acceptance. If waste products, which arise from 

 oxygen want, alter the combining power of hemoglobin, this alteration 

 may not persist in shed blood; for these products may disappear when 

 the blood is exposed to air. Owing to the combining power of hemo- 

 globin the respiratory exchange and metabolism of an animal within 

 wide limits is independent of the partial pressure of oxygen. On the 

 other hand, the process of combustion is dependent not on the pressure 

 but on the percentage of oxygen. Thus the aeroplanist may become 

 seized with altitude sickness from oxygen want, while his gas engine 

 continues to carry him to loftier heights. 



The partial pressure of oxygen in a mine at a depth of 3,000 feet 

 is considerably higher than at sea-level, and if the percentage is 

 reduced to 17, while the firing of fire-damp and coal dust is impossible, 

 there need be in the alveolar air of the lungs no lower pressure of 

 oxygen than at sea-level. Thus the simplest method of preventing 



