Theories and Experiments 



469 



This result evidently proves that one expiration in compressed 

 air contains from 0.0440 to 0.0570 grams, on the average 0.050 grams, 

 that is, 1/4.352 of carbonic acid more than at normal pressure. 



The figures obtained for normal pressure (with the exception of 

 the observation made at eight o'clock), the average of which is 0.2176 

 grams, show remarkable agreement; however, we cannot disregard a 

 slight progressive decrease of carbonic acid from eleven o'clock, that 

 is, after return to normal pressure, until noon or one o'clock. The 

 maximum quantity of carbonic acid found in my case under normal 

 pressure rose to 0.2890, and in compressed air to 0.3215 grams. 



The data obtained from other persons gave similar results. In 

 M. H . . . t, an expiration of 3,000 cc. under ordinary pressure con- 

 tained an average of 0.1305 grams of carbonic acid, but in compressed 

 air 0.1735, with an excess of 0.0430 grams, that is, 1/4.04 of the total 

 and normal quantity of carbonic acid. In Mile. B., a single experiment 

 made under normal pressure gave 0.138 grams for 3,000 cc. of air 

 expired at normal pressure, and in compressed air 0.170 of carbonic 

 acid, that is, an increase of 0.0320, or 1/4.31. 



Starting with the idea that at the beginning of the stay in com- 

 pressed air there was perhaps a greater quantity of oxygen absorbed 

 than towards the end of the stay, as if the blood was saturated with 

 oxygen, Dr. Lange made experiments upon himself, and modified my 

 own method of experimentation. He determined the content of car- 

 bonic acid in his respiration immediately before the treatment, then 

 he made another test after half an hour in the compressed air, that 

 is, when the pressure was reaching its maximum, then after an hour 

 of the continuous effect of this maximum pressure, that is, after a 

 stay of an hour and a half in compressed air. For a quantity of 3950 

 cc. of expired air, he obtained the following results: 



Observer, I 



Lange 



Quantity of carbonic acid 

 contained in one expiration | 

 expressed in grams. 



Quantity of carbon in one 

 expiration, expressed in 

 grams. 



Under increased pressure 



Under normal I On reaching I After an hour" 



pressure I maximum pres- I of maximum 



I sure (after a I pressure (that 



I half-hour). I is, after VA hrs.] 



0.2506 



0.06827 



0.2959 



0.08070 



0.2211 



0.06300 



