]£5 * 'CHANGES PRODUCED IK AIR BY RESPIRATION. 



The add -ion The addition of ]10 # 08 cubic inches of azote we consi- 

 Jrom^thTaTr in der as arisin S fro,n that portion still retained in the lungs, 

 the lungs. notwithstanding the forced expiration at the beginning of 

 the experiment: ;ind con dering that in the 14th and 15th 

 experiment, where the same air was repeatedly breathed, 

 the proportion of azote was in the one case 85, and in the 

 other 86 per cent; it seems fair to presume, that the resi- 

 dual air contained in the lungs after a forced expiration may 

 amount in 100 parts to not more than 16 oxigen and 94 

 azote. Any one who reflects upon the structure of the 

 lungs, and the minute ramifications of the extremities of 

 the bronchial vessels; when he also < ousiders, that those 

 parts of the lungs wih which the air comes into contact, if 

 spread our, would present a surface equal to that pf the su- 

 / periicies of the whole body; aud lastly, that this vkcus is 

 so exceedingly spongy and porous, that when once inflated, 

 it is ever after impossible by ordinary mechanical means to 

 expel the air completely ; he will easily perceive, not only 

 that a large portion of air must remain for a considerable 

 time in contact with the internal surface of the lungs, where 

 it is liable to lose a portion of its oxigen, but also that the 

 residual quantity of air in the lungs, after the most violent 

 attempts at expiration, may be very considerable. It is to 

 this circumstance, that we attribute the excess of azote in 

 the experiments upon oxigen, and pretty deep inspirations 

 of this gas having been made during o/<20", the azote must 

 have been in great measure displaced. Admitting then, 

 that the air contained in the lungs, before the experiment, 

 consisted of 16 oxigen, 84 azote, and at the conclusion of 

 the experiment of 94 oxigen, 6 azote, we have 



azote at the beginning, 



6 x 



• azote at the end. 



100 



6 x 84x 



+ 100 = » 



100 100 



A 84* 6x 



uo = I^-!b-o or ' 84x ^' o6 * = ^ 



110 ,. • 



?~ ;^T or 141 cubic inches; 

 y© 



Therefore 



