130 



. Together with this increase of oxygen gas 

 and carbonic acid, beyond what the residual air in 

 the lungs would supply, there was a considerable 

 increase also of nitrogen gas, which corresponds 

 with what takes place when this oxide is exposed to 

 blood out of the body ; for, besides the carbonic a- 

 cid produced, there are always present small por- 

 tions of nitrogen gas*. Since, therefore, the same 

 products are obtained when this oxide is breathed, 

 as when it is exposed to blood out of the body, it 

 may be inferred that they are effected by similar 

 means. These means cannot, in the latter case, be 

 absorption in the sense we apply that term to the li- 

 ving human body ; because the blood speedily be- 

 comes an inert mass> bearing no analogy in its pro- 

 perties to the absorbent function in the lungs : and, 

 even if chemical attraction were allowed to ope- 

 rate between this oxide and blood out of the body, 

 this will not apply to the circumstances hi which 

 they are respectively present in the lungs ; because 

 the intervention of cells and blood-vessels wholly 

 forbids that degree of actual contact, which is essen- 

 tial to chemical action. It is therefore only on the 

 supposition of a decotnfusititin taking place, that these 

 contradictory results can be reconciled. 



106. Against the idea of such decomposition in 

 the lungs, Mr Davy urges, that " it is difficult to 

 suppose how nitrous oxide, which requires the tem- 

 perature of ignition for its decomposition by the 

 most inflammable bodies, should be partially ab- 



* Researches, p. 387. 



