INFLUENCE OF TEMPERATURE. 423 



nitrogen of the air plays an important part in the phenomena 

 of respiration by virtue of its degree of diffusibility. 



In view of the great variations in the consumption of 

 oxygen dependent on different physiological conditions, such 

 as digestion, exercise, temperature, etc., it is impossible to fix 

 upon any number which will represent, even approximatively, 

 the average quantity consumed per hour. The estimate 

 arrived at by Longet, 1 from a comparison of the results ob- 

 tained by different reliable observers, is perhaps as near the 

 truth as possible. This estimate puts the hourly consumption 

 at from 1,220 to 1,525 cubic inches, "in an adult male, during 

 repose and in normal conditions of health and temperature." 



In passing through the lungs, the air, beside losing a 

 proportion of its oxygen, undergoes the following changes : 



1. Increase in temperature. 



2. Gain of carbonic acid. 



3. Gain of watery vapor. 



4. Gain of ammonia. 



5. Gain of a small quantity of organic matter. 



6. Gain, and occasionally loss, of nitrogen. 



The elevation in temperature of the air which has passed 

 through the lungs has been carefully observed by Dr. Gre- 

 hant. 2 He found that with an external temperature of 72, 

 respiring IT times per minute, the air taken in by the nares 

 and expired by the mouth, through an apparatus containing 

 a thermometer carefully protected from external influences, 

 marked a temperature of 95*4. Taking in the air by the 

 mouth, the temperature of the expired air was 93. At the 

 commencement of the expiration, Dr. Grehant noted a tem- 

 perature of 94. After a prolonged expiration, the temper- 

 ature was 96. In these observations the temperature taken 

 beneath the tongue was 98. 



1 Op. dt., p. 531. 



a GREHANT, RechercJics PJiysiques sur la Respiration de VHomtne. Journal de 

 r Anatomic at de la Physiologic, 1864, tome i, p. 546. 



