| cub. in. | |
| Nitrogene | 128 |
| Oxygene | 29 |
| Carbonic acid | 14 |
Comparing these results with the former ones, we find the mean quantities of air respired in equal terms rather less; but the proportions of carbonic acid, nitrogene and oxygene in the respired air, nearly identical.
e. To ascertain the changes effected in a given quantity of atmospheric air by continued respirations, I breathed after a compleat expiration, at temperature 63°, 161 cubic inches of air for near a minute, making in this time, 19 deep inspirations. After the compleat expiration, which was very carefully made, the gas filled a space nearly equal to 152 cubic inches, so that 9 cubic inches of gas had disappeared.
The 152 cubic inches analised, were found to consist of
| cub. in. | |
| Nitrogene | 111,6 |
| Oxygene | 23, |
| Carbonic acid, | 17,4 |
The 161 cubic inches before inspiration, were composed of
| cub. in. | |
| Nitrogene | 117,0 |
| Oxygene | 42,4 |
| Carbonic acid | 1,6 |
But the residual gas in the lungs before the experiment, was of different composition from that remaining in the lungs after the experiment. Making corrections on account of this circumstance, as in section IV. it appears that about 5,1 of nitrogene were absorbed in respiration, 23,9 of oxygene consumed, and 12 of carbonic acid produced.
I repeated this experiment three times; in each experiment the diminution after respiration, was nearly the same; and the residual gas making the necessary allowances, of similar composition. So that supposing the existence of no source of error in the experiments from which the quantity and composition of the residual gas of the lungs were estimated in section IV. the absorption of nitrogene by the venous blood, appears almost demonstrated.
f. To compare the changes effected in atmospheric air by respiration of the smaller quadrupeds, with those in the experiments just detailed, I introduced into a jar of the capacity of 20 cubic inches filled with mercury in the mercurial trough, 15 cubic inches of atmospheric air which had been deprived of its carbonic acid by long exposure, to solution of potash.