THE EXPIRED AIR. 33/5 



experiments of Regnault and Reiset, that the hydrogen and the 

 carhuretted hydrogen which they found in air which had served 

 for a prolonged time for the respiration of animals, were not 

 dependent solely upon the perspiration or the intestinal exhalation, 

 but that an appreciable quantity both of hydrogen and proto- 

 carburetted hydrogen was exhaled from the lungs when in a per- 

 fectly normal condition. 



We will now proceed to establish several absolute values which 

 the above-named investigators have obtained in reference to many 

 of these points. We possess very different statements regarding 

 the quantity of carbonic acid exhaled within a definite time by an 

 adult man. The cause of this diversity may readily be compre- 

 hended, when we consider the methods by which these numbers 

 have been obtained. With the exception of Scharling and 

 Vierordt, all other observers have contented themselves with col- 

 lecting the air of only a few respirations, and, after determining the 

 amount of carbonic acid, have calculated the quantity of this gas 

 for a definite period of time. We have already seen how easily we 

 may be led into error, from want of practice, by the determination 

 of individual respirations, and these errors augment in proportion 

 to the length of time (as, for instance, 1 hour or 24 hours) for 

 which we endeavour to establish the exhalation of carbonic acid. 

 We will therefore pass over the older results, which vary con- 

 siderably, merely observing that, according to Scharling, a very 

 powerful adult man exhales in 24 hours 867 grammes, or at 

 a temperature of 0, and the barometer at 336'" [29*84 inches,] 

 443,409 cubic centimetres [or about 27,058 cubic inches] of car- 

 bonic acid. Basing his calculations on Valentin's law, Vierordt 

 therefore calculates that the amount of oxygen absorbed by an 

 adult in 24 hours (and partly given off again with the carbonic acid 

 and the water, and partly remaining in the body) amounts to 

 746 grammes, or 520,601 cubic centimetres [or about 31,740 cubic 

 inches] ; consequently about 116 grammes of the absorbed oxygen 

 are retained in the organism. According to Boussingaulf s deter- 

 minations, about 8 grammes of nitrogen would be given off to the 

 atmosphere in the same period of time by the same individual, 

 whilst, according to Valentin, about 500 grammes of water are 

 exhaled on an average in equal intervals of time. The numerous 

 and carefully conducted experiments of Vierordt show that the 

 air exhaled by a healthy man in a state of rest contains on an 

 average 4'334-g- by volume of carbonic acid. 



