£58 « t)n the Changes produced in Atmospheric Air 



The addition of 1 10*08 cubic inches of azote, we consider 

 as arising from that portion still retained in the lungs, not- 

 withstanding the forced expiration at the beginning of the 

 experiment, and considering that in the 14th and 15th ex- 

 periment, 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 residual air 

 contained in the lungs after a forced expiration may amount 

 in 100 parts, to not more than 16 oxygen and 84 azote : any 

 one who reflects upon the structure of (he lungs, and the 

 minute ramifications of the extremities of the bronchial ves- 

 sels ; and when he also considers that those parts of the 

 lungs with which the air comes in contact, if spread out, 

 would present a surface equal to that of the superficies of the 

 whole body ; and lastly, that this viscus 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 por- 

 tion 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 oxygen, but also that the residual quan- 

 tity of air in the lungs, after the most violent attempts at 

 expiration, may be very considerable. It is to this circum- 

 stance that we attribute the excess of azote in the experi- 

 ments upon oxygen, and pretty deep inspirations of this gas 

 having been made during Q'-QQ" ', the azote must have been 

 in great measure displaced. Admitting then that the air 

 contained in the lungs, before the experiment, consisted of 

 16 oxygen, 84 azote, and at the conclusion of the experi- 

 ment of 94 oxygen, 6 azote, then we have 

 ?lf! azote at the begining;, 



100 



6 — azote at the end. 

 too 



^ + no = 8 ^ 



100 (00 



110 = — — — or, S-U - 'OGx - -l%x. 



, 100 100 ' 





X 



. no or 141 cubic inches; 



Therefore upon this calculation it appears that 141 cubic 



inches 



