1891.] Formation of Carbonic Acid in Human Respiration. 67 



between O consumed and C0 2 produced is barely perceptible, 

 although exhibiting a slight tendency to fall while fasting. The pro- 

 portions of oxygen absorbed in 100 of air and oxygen inspired are 

 much the same under the influence of food and fasting. 



The main effect produced on Mr. Russell by the ingestion of food 

 and fasting is to be found in the weight of oxygen consumed per 

 hour, which falls from 28*66 grams under the influence of food to 

 23*30 when fasting, and per kilo, weight from 0*417 gram to 0*330 

 gram. There is also, when fasting, a considerable reduction of 

 weight of the CO 2 expired per minute (0'578 gram to 0*468 gram). 



The results obtained from the present investigation of the inter- 

 change of gases in the respiratory process of man may be summed up 

 as follows : > 



1. The percentage of C0 2 , O, and N in the air expired alters 



according to the person under experiment, but in every case 

 the proportions of each gas vary but slightly up to a period 

 of about four hours and a half after the mid-day meal, a result 

 I had formerly obtained for C0 2 . 



2. The ratio between the oxygen consumed and the carbonic acid 



produced exhibited a mean of 0*871 for two persons and 

 twenty-four experiments. This is nearly the same figure as 

 that obtained by Messrs. Jolyet, Bergonie, and Sigalas 0'868, 

 and a marked approximation to 0'90, the corresponding ratio 

 given for rabbits by Messrs. Chapman and Brubacker. 



3. The mean volume of oxygen absorbed per minute was very 



nearly the same for the two persons, and amounted to a total 

 mean of 34*3 c.c. on twenty-four experiments. This would be 

 equal to 2 '94 grams of oxygen absorbed per hour. 



4. The mean volume of oxygen absorbed in relation to the air 



inspired proved nearly the same in both persons submitted to 

 experiment, and amounted to 0'75 per cent. A similar remark 

 applies to the proportions of oxygen absorbed to the oxygen 

 inhaled ; the figures are 36'9 in one case, and 3*55 in the other, 

 with a mean of 3*63. 



5. The mean weight of oxygen consumed per hour varied with each 



person submitted to experiment, amounting to 20*8] grams in 

 the older and 26*09 in the younger man. The corresponding 

 figures per kilo, of body weight were 0'355 gram and 0*380 

 gram. 



6. The weight of carbonic acid expired per minute is notably 



higher in the younger man, and corresponds approximately to 

 proportionally increased amount of oxygen consumed. 



The elaborate investigation of Messrs. Hanriot and Richet calls for 

 a few remarks. 



F 2 - 



