470 Historical 



Here also therefore, on reaching the maximum pressure, after a 

 half-hour in compressed air, there is an increase of the quantity of 

 carbonic acid exhaled, similar to that observed in me. This increase 

 was 0.0453 grams, that is, 1/5.53. The absolute maximum in Dr. 

 Lange, at normal pressure, was 0.3770 grams, and in compressed air 

 0.4345 grams. But we find here, after an hour of maximum pressure 

 a decrease of 0.0295 grams in the carbonic acid exhaled. 



However the figure obtained in the last place is doubtful, as was 

 evidenced by tests made later, and that is explained by the fact that a 

 part of the expired air was lost, because the rubber tubes had not 

 been hermetically closed. Tests made afterwards by Dr. Lange gave 

 the following figures, as the total quantity of carbonic acid exhaled 

 in two ordinary expirations (of about 3000 to 4000 cubic centimeters) 

 and also as the quantity of carbon eliminated: 



Observer Lange 



At normal 

 pressure 



On reaching maxi- 

 mum pressure 

 (after a half hour) 



After an hour 



at maximum 



pressure (after 



V,A hours) 



Carbonic acid | 0.2460 gm. j 0.2910 gm. | 0.2920 gm. 



Carbon | 0.06709 gm. 1 0.07936 gm. 1 0.07964 gm. 



Which agrees with the results which I had obtained myself as 

 increase in the quantity of carbonic acid exhaled in compressed air. 



If now I compare the figures obtained from several persons, I find 

 as the excess of the carbonic acid exhaled in compressed air, in com- 

 parison with the total quantity: 



1 



In myself _ =22.99% 



4.35 

 1 



In M. H . . . t =24.75% 



4.04 

 1 



In Mile. B. : =23 20% 



4.31 



In Dr. Lange . = 18.08% 



5.53 



1 



Average =22.26% 



4.50 



We should note here that the excess of carbonic acid expired in 

 compressed air cannot be attributed to an increase in the quantity of 

 carbonic acid which might have been contained in the pneumatic 

 apparatus. A test of the air in the apparatus made by Dr. Lange after 

 three persons had stayed there for two hours gave as an average of 

 4 experiments on 3,500 cc. of air 0.0391 grams of carbonic acid. The 

 air of the waiting-room, where the spirometer was placed and where 

 the tests described above of the carbonic acid expired under normal 

 pressure were made, likewise gave, as an average of 4 tests on 3,500 

 cc. of air, 0.0392 grams of carbonic acid, that is, exactly the same 

 quantity. 



