EXHALATION OF NITROGEN. 451 



Exhalation of Nitrogen. The latest and most accurate 

 direct experiments, particularly those of Regnault and Reiset, 

 show that the exhalation of a small quantity of nitrogen is a 

 pretty constant respiratory phenomenon. From a large num- 

 ber of experiments on dogs, rabbits, fowls, and birds, these ob- 

 servers came to the conclusion that when animals are subject- 

 ed to their habitual regimen, they exhale a quantity of nitrogen 

 equal in weight to from yi-g- to T V of the weight of oxygen 

 consumed. In birds, during inanition, they sometimes observ- 

 ed an absorption of nitrogen, but this was rarely seen in mam- 

 mals. 1 Boussingault, by the indirect method, estimating the 

 nitrogen taken into the body and comparing it with the en- 

 tire quantity discharged, arrived at the same results in ex- 

 periments upon a cow. 2 Barral, by the same method, con- 

 firmed these observations by experiments on the human 

 subject. 3 



In spite of the conflicting testimony of the older physi- 

 ologists, there can now be no doubt that, under ordinary 

 physiological conditions, there is an exhalation by the lungs 

 of a small quantity of nitrogen. 



1 REGNAULT and REJSET, op. tit., Annales de Chimie et de Physique, 3me 

 serie, tome xxvi., pp. 510, 511. 



2 BOUSSINGAULT, Memoires de Chimie Agricole et de Physiologic, Paris, 1854, 

 pp. 1-24. 



3 LONGET, Physiologic, Paris, 1861, tome i., p. 543. 



