764 Experiments 



We may conclude that variations are in a general way very slight. 

 This point, which had not been clearly determined by the authors 

 who preceded me, is of great importance, as we shall show later. 



Finally, my experiments show, as all observers had already noted, 

 a considerable increase of the maximum pulmonary capacity (Col- 

 umns 4, 8, 12) . On the average, the strongest expiration which I can 

 make rose from 3.75 liters to 3.99 liters; this is an increase of 240 cc. 

 that is, 6.9%. In M. Regnard it was 450 cc, or 11%. After the de- 

 compression I rapidly returned to the normal state. 



Circulation. The average pulse rate decreased considerably dur- 

 ing the stay in compressed air; from 76 at the beginning, it became 

 73 at the maximum of the compression and 62 when I left the cylin- 

 der. 



But I must say that the apparent clearness of this result is de- 

 cidedly lessened by the fact that at normal pressure my pulse, when 

 taken at the same hours, that is, at the same time after lunch and 

 after a seated rest of several hours, gave variations which were ab- 

 solutely of the same order. 



Metabolism. My experiments are very few; but they have been 

 conducted with the greatest physiological precautions. The analysis 

 of the air expired quietly for 10 minutes gives me (Experiment 

 CCCXXII) for one hour at normal pressure 15.858 liters of carbonic 

 acid; at the maximum of the compression (56 cm.), it gave 16.260 

 liters, an increase of 0.418 liters, or 26%. 



The production of urea (Experiment CCCXXIII) gave a more 

 interesting result; under the influence of compressed air, it in- 

 creased considerably (from 20.15 gm. it rose to 24.72 gm., then to 

 26.04 gm.) to fall again under normal pressure to amounts near its 

 original rate (21.18 gm.; 20.80 gm.; 22.50 gm.). So that, on the aver- 

 age, at normal pressure it was 21.9 gm. and rose to 25.3 gm. in air 

 compressed to -4- 53 cm. 



I shall take the opportunity, in the third part of this book, to 

 compare these figures with those obtained by M. G. Liebig and 

 M. Pravaz in recent investigations. 



B. Production of Urea: Experiments on Dogs. 



I tried again to measure the modifications caused in the produc- 

 tion of urea by experimenting on dogs. I kept them, of course, on a 

 strict diet; the urine was collected by catheterization once every 

 24 hours and added to what the animal voided spontaneously. 



Here are the results of one of these experiments, which no 

 accident hindered. 



