33 



air, which was increased to 10 p. c. if the same 

 air was repeatedly respired ; but it never ex- 

 ceeded this quantity however long the respiration 

 of the same air was continued* Again, on those 

 occasions, where the respiration was performed 

 \vith some difficulty, more oxygene was absorbed, 

 than carbonic acid gas produced. These Gentle- 

 men had the kindness to send me a copy of their 

 essay, inserted in thePhilosophical Transactions for 

 1808; in consequence of which, I took the liberty 

 to propose to them some farther experiments ; for 

 although it was easy to explain the loss of nitro- 

 gen e gas in DAVY'S experiments, and there was 

 consequently no reason to doubt the correctness 

 of their observation, that no nitrogene disappears 

 during respiration, yet I had, for some time 

 back, entertained the idea, that nitrogene might 

 possibly be absorbed by the blood of herbivorous 

 animals, whereby their bodies became provided 

 with the nitrogene, which was wanting in their 

 food, and I therefore proposed to Messrs. ALLEN 

 and PEPYS to examine also the respiration of 

 herbivorous animals, with respect to the absorption 

 of the nitrogene. They executed this experiment, 

 and obtained altogether unexpected results. They 

 made use of guinea pigs, which were placed in a 

 gasometer, and kept there for about an hour, 



D 



