Increased Pressure 



1019 



gm., and in the second case, from 6.481 gm. to 8.879 gm. The dif- 

 ference is much smaller and less constant for carbonic acid 

 (Column 7), if one considers only the averages; however, the 

 examination of the maxima and minima corroborates the idea of a 

 greater formation of carbonic acid in compressed air: at ordi- 

 nary pressure, indeed, the variations were from 5.747 gm. to 8.710 

 gm., and under pressure from 5.824 gm. to 8.737 gm. 



Table XXIII. 



3 4 



The numbers relating to pulmonary ventilation (Column 4) are 

 also very interesting. First, evidently, there passes through the 

 lungs, in a given time, less air, in volume, under increased pressure 

 than at normal pressure; the general average gives 110 and 118, 

 with deviations, in the first case, from 102.9 to 118.5, and in the 

 second, from 103.2 to 129.6. The number of respiratory movements 

 is also decreased in compressed air; on the average it falls from 

 16.5 to 15.9 per minute. It results from these two modifications 

 that the respiratory amplitude hardly changes, since it varies on 

 the average only from 0.48 liters (normal pressure) to 0.46 liters 

 (compressed air). Let us add that an attentive inspection of the 

 respiratory movements, holding a watch with a second-hand, would 

 have permitted G. Liebig to note that the respiratory rhythm itself 

 changes in compressed air, the inspiration becoming shorter and 

 the expiration longer: the ratio of duration between these two 

 phases in one of his observations would have passed from 2 : 3 

 to 1 : 2. He therefore agrees with what Vivenot had said (See 

 Figure 9), and contradicts Panum. 



