Pulmonary Gases in the Respiration of Man. 



215 



In this table the first column of figures, on the left, shows the 

 volumes of air inspired, as measured in the bell- jar from which the 

 air was breathed ; the second column shows the corresponding 

 volumes of air expired as determined in the second receiver. The 

 third column gives the volumes of air inspired, calculated from the 

 assumption that the whole of the nitrogen exhaled is also inhaled. 



It will be observed that the mean of the volumes in the third 

 column is all but exactly the same as the mean of the volumes in the 

 first column, the difference being only by 3 c.c. ; hence the obvious 

 conclusion that nitrogen takes no appreciable part, or no part at all 

 in the interchange of the pulmonary gases. 



It follows from the harmony found to exist between the mean 

 volumes of air actually inspired and the mean volumes of air in- 

 spired determined by calculation, that the corresponding volumes of 

 nitrogen, of oxygen consumed, and oxygen absorbed and retained in 

 the blood, whether found or calculated, will also be practically the 

 same ; this is set forth clearly in the next table. 



These experiments show most satisfactorily that the method 

 adopted to obtain the volumes of air inspired by calculation can be 

 trusted as correct ; and, therefore, that not only the means obtained 

 by that method, but also every single experiment, may be accepted as 

 giving a reliable result. A certain amount of training was, however, 

 required before the results could be considered as fit for recording. 



The next point for consideration refers to the influence of changes 

 of temperature on the consumption of oxygen per minute, or, in other 

 words, on the carbonic acid produced and oxygen absorbed. These 

 experiments have been made on myself and Mr. Smith while under 

 the influence of food, and an additional number were made on 



