EXHALATION AND ABSORPTION THROUGH THE LUNGS. 533 



the crude fluid which has been newly introduced into the circulating current 

 by the process of nutritive absorption. But there is strong evidence that Hydro- 

 gen as well as carbon undergoes combustion in the system ; and that a portion 

 of the exhaled aqueous vapor is the product of that combustion. For of the 

 hydrogen which the food contains, not more than from l-8th to l-10th passes 

 off by the other excretions, the remaining 7-8ths Or 9-10ths being exhaled in 

 the condition of watery vapor from the lungs. A portion of the oxygen which 

 this vapor contains, is supplied by the food ; but there is a considerable surplus 

 of hydrogen ; and this can only be converted into water, at the expense of oxy- 

 n derived from the atmosphere. Upon this point the experiments of M. Barral 

 loc. cit.) gave the following results. 



Difference. 

 321.1 grs. 



252.8 " 

 95.3 " 



187.9 

 E 3140.5 392.5 643.8 251.3 " 



Thus it appears that, of the Hydrogen exhaled from the lungs and skin of M. 

 Barral, in the condition of watery vapor, not less than 321.1 grs. in winter, 

 and 252.8 grains in summer, must have been converted into water by oxygen 

 derived from the air ; and this calculation would give 2889.9 grs. (6 oz. troy) 

 for the winter, and 2275.2 grs. (4.7 oz. troy) for the summer, as the amount of 

 water thus generated in the combustive process. This, however, can only be 

 regarded as an approximation to the truth ; since there are many circumstances 

 not taken into account in the computation, by which the estimate may be 

 affected. 



570. The fluid thrown of from the lungs is not pure Water. It holds in 

 solution, as might have been expected, a considerable amount of carbonic acid, 

 and also some animal matter ; the exact nature of the latter, which according to 

 Collard de Martigny (op. cit.) constitutes about 3 parts in 1000, has not been 

 ascertained ; but from the recent inquiries of Mr. R. A. Smith, 1 it would appear 

 to be an albuminous substance in a state of decomposition. If the fluid be kept 

 in a closed vessel, and be exposed to an elevated temperature, a very evident 

 putrid odor is exhaled by it. Every one knows that the breath itself has occa- 

 sionally in some persons, and constantly in others, a fetid taint ; when this does 

 not proceed from carious teeth, ulcerations in the air-passages, disease in the 

 lungs, or other similar causes, it must result from the excretion of the odorous 

 matter, in combination with watery vapor, from the pulmonary surface. That 

 this is the true account of it seems evident, from the analogous phenomenon of 

 the excretion of turpentine, camphor, alcohol, and other odorous substances, 

 which have been introduced into the venous system, either by natural absorption 

 or by direct injection ; and also from the suddenness with which it often mani- 

 fests itself, when the digestive apparatus is slightly disordered, apparently in 

 consequence of the entrance of some mal-assimilated matter into the blood. 

 Among the substances occasionally thrown of by the lungs, phosphorus deserves 

 a special mention, on account of the peculiarity of the form under which it is 

 eliminated : for it has been found that if phosphorus be mixed with oil, and be 

 injected into the bloodvessels, it partly escapes in an unoxidized state from the 

 lungs, rendering the breath luminous. 3 And this luminous breath has also 

 been observed in spirit-drinkers j in whom the oxidation of the effete matters 

 of the system is impeded, in consequence of the demand set up by the alcohol 

 ingested for the oxygen introduced ( 564, Ti). 



1 "Philosophical Magazine," vol. xxx. p. 478. 



2 "Casper's Wochenschrift," 1849, band 15. 



