were breathed. The quantity of carbonic acid was in this case 8,
the remaining oxygen 13, and the azote 79 per cent., as before in-
spiration. The average consumption of oxygen, and formation of
carbonic acid, being 32'3 inches in a minute.
The deficiency in the quantity expired was so small, that the au- thors were satisfied that none was absorbed. But in the two fol- lowing experiments, which were each performed on upwards of 3000 inches of arygen gas, the deficiency was much greater, and there did appear to have been absorption of 58 in one experiment, and of 67 in the other.
The formation of carbonic acid was, in these cases, far more rapid, being at the rate of 37% inches in a minute. From the quantity of air which had necessarily remained in the lungs before the experi- ments, a quantity of azote was unavoidably mixed with the inspired oxygen, and emitted with it, in the preportion at first of 25 per cent., but varying in the successive portions, removed for trial, till the pro- portion was at last reduced to 5—;— per cent.
From these data, the authors endeavour to estimate the quantity of air that had been in the lungs at the beginning of each experiment.
By estimation from the former experiment on oxygen, the residue in the lungs appeared to have been 140%; but in the second, it was found that as much as 177 of mere azote had been expired, and hence that the lungs, in this instance, had contained as much as 226 inches of air, unless the proportion of azote in the residual gas was greater than usual, in consequence of previous fatigue.
The inferences drawn by the authors from these experiments are,
1. That the quantity of carbonic acid emitted is equal in bulk to the oxygen consumed, and consequently that no water is formed in respiration by union of oxygen and hydrogen.
2. That carbonic acid, in expired air, varies from 8 to 10 per cent.
3. That about 1800 inches of carbonic acid are formed in twenty- four hours, containing about 10% ounces troy of solid carbon.
4. That when air is breathed several times over, a portion of oxygen is absorbed.
5. More carbonic acid is formed from respiration of oxygen, than in breathing atmospheric air.
6. That the subject of these experiments takes about 17 inches at each inspiration. and makes about 19 inspirations in a minute.
7. No hydrogen or other gas appears to be evolved during respi- ration.
8. There appears to be no alteration in the quantity of azote, since ' the average diminution of six parts in 1000 is more likely to arise from incomplete exhaustion of the lungs after the experiment.
9. The residual gas in the lungs, after forced expiration, appears about 140 cubic inches.
