THE PURIFICATION OF THE BLOOD, ETC. 37 



perhaps to become combined with carbon 

 during its progress through the system. 



According to the experiments of Dr. Prout, 

 the generation and expiration of carbonic acid 

 gas vary according to different conditions of 

 the system, and also according to the hours of 

 the day. For example, the lungs give out 

 more carbonic acid during those of sunlight 

 than those of darkness. The increase com- 

 mences at daybreak, and at noon arrives at its 

 maximum, decreasing as the shades of evening 

 approach. With respect to the azote of the 

 atmospheric air, it is returned unchanged, but 

 generally diminished in volume, a portion of it 

 having been absorbed into the system. With 

 the carbonic acid and azote expired from the 

 lungs, a large quantity of watery vapour is also 

 thrown off, which appears, in a great measure, 

 to be derived from the chyle which has recently 

 been admitted into the venous system, and to 

 constitute a means of its perfect purification. 

 It is thus that the essential oil of various sub- 

 stances taken as aliment, and useless to the 

 blood, although mixed with the chyle, is thrown 

 out. For example, onions, garlic, rum, etc., 

 impart their peculiar odour to the breath, and 

 in indigestion, and during various diseases, the 

 blood becoming loaded with deleterious parti- 

 cles, really poisonous, thus gets rid of them by 

 a self-purifying process. The quantity of car- 

 bon thrown off from the lungs of a man during 

 the twenty-lour hours of the total day, has been 

 estimated at about eleven ounces — a quantity, 



