in the process of Respiration. 53 



the present time the opinion is generally maintained that the nitrogen 

 is entirely passive, or at least that its only use is to neutralize the en- 

 ergetic properties of the oxygen. This view which has retarded, 

 nay almost stopped the progress of eriquiry, has however, been sha- 

 ken by the recent and well conducted experiments of Dr. Edwards. 

 In examining these experiments, it occurred to me that nitrogen per- 

 formed other offices which have not to my knowledge been assigned 

 to it. These views I now present for publication, in the hope that 

 even if they are ultimately found to be incorrect, they may open a 

 new subject for chemical and physiological enquiry. 



That acute physiologist Dr. Edwards, has shown that the quan- 

 tity of nitrogen given out by the same animal during respiration is ve- 

 ry variable, being at one time increased, at another diminished, and 

 at a third remaining wholly unchanged.* These phenomena he has 

 traced to the influence of the seasons and to other causes. It has 

 also been shown by Mess. Allen and Pepys, that when animals are 

 confined in vessels of oxygen gas, or in an atmosphere composed of 

 twenty one measures of oxygen and seventy nine of hydrogen, the 

 residual air contains a large quantity of nitrogen, and in the latter 

 case a portion of hydrogen was consumed. Mess. Dulong and Des- 

 pretz inferred from their experiments that the proportion of nitrogen 

 is in all cases greater in expired air than in that which is inspired. 



It does not appear then to admit of a doubt, that nitrogen is con- 

 stantly exhaled or given out by the lungs. The accurate experi- 

 ments of Priestley and of Davy show that nitrogen is also absorbed 

 or consumed during respiration. 



Having premised these observations, the position which I shall ad- 

 vance is, — That nitrogen as well as oxygen is absorbed by the blood, 

 that during its passage through that fluid, it combines with carbon, 

 and forms cyanogen^ and that this last uniting with iron exists in the 

 blood in the form of a cyanide of Iron. 



In favor of this view I offer the following facts and reasonings. 



1. It has been satisfactorily shewn that many, if not all, the gases 

 may be taken into the circulation. It is also known that a large pro- 

 portion of carbon exists in the blood. If then nitrogen is absorbed 

 during respiration, there is no greater difficulty in supposing that it 

 combines with a portion of carbon, than that oxygen should do so, 

 which appears to be quite generally admitted. 



* Do I'Infliicnce dcs Agens Physiques sur la Vie, 



