Atmospheric Air and Oxygen Gas by Respiration. 2 6g 
It appears, at first sight, that 177.08 cubic inches of oxygen 
were missing, but great part of this may be accounted for, by 
adverting to the state of the lungs after the experiment. 
The addition of 110.08 cubic inches of azote, we consider as 
arising from that portion still retained in the lungs, notwith- 
standing the forced expiration at the beginning of the ex- 
periment, and considering that in the 14th and 15th experi- 
ment, where the same air was repeatedly breathed, the pro- 
portion 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 the 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 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 oxygen, 
and pretty deep inspirations of this gas having been made 
during 9'. 20", the azote must have been in great measure 
