employed for the absorption of carbonic acid, and then a solution of
green sulphate of iron, saturated with nitrous gas, to determine the
quantity of oxygen that remained.
In the sixth experiment there were found 9 carbonic acid, and 9 oxygen; together 18.
In the seventh experiment there were found 8 carbonic acid, 10—;- oxygen; together 18%.
In the eighth experiment there were found 6% carbonic acid, and 12% oxygen; together 19.
In the ninth experiment there were found 7 carbonic acid, and 11 oxygen; together 18.
So that as one measure of carbonic acid contains just an equal measure of oxygen, the apparent diminution of oxygen in these experiments is 2½ per cent.
In the subsequent experiments two mercurial gasometers were em- ployed, so that the hurry of measuring the gas, and inconvenience of retaining the breath, were avoided, and the respiration was consequently more natural throughout the whole of each experiment.
Nevertheless, the result of the ten experiments still showed an apparent diminution of l per cent. But the eleventh experiment showed no diminution, and is considered by the authors as a standard experiment. From this the quantity of oxygen consumed, and of car- bonic acid formed in a minute, is calculated to be 26% inches, and hence the quantity of solid carbon given ofl“ by the lungs, in twenty-four hours, is computed at 10¾ ounces troy.
The person who made these experiments breathes about nineteen times in a. minute, and takes about 16½cubic inches of air at each natural inspiration.
In the twelfth experiment the same quantity of air was breathed from one of the mercurial gasometers to the other repeatedly during three minutes, and was then found to contain 9% carbonic acid, 55 oxygen, and 85 azote per cent. ; so that six parts, in 100 of oxygen, seemed to have disappeared, and some other gas, not absorbed by water, was apparently given off from the lungs.
The results of the fourteenth experiment were similar, and more remarkable, as the respiration of the same air was continued for a greater length of time : 100 parts contained 10 carbonic acid, 4 oxygen, and 86 azote; so that in this instance there appeared a loss of 7 oxygen, and an equal increase of azote, or of some other gas not absorbable by water. By careful examination, the authors are satisfied that no other gas is present in the residuum but azote; that the azote itself, though apparently in greater proportion, is in fact unaltered; and that the difl'erence arises solely from diminution of oxygen when respiration is painfully protracted.
By the respiration of another person, whose chest was of greater capacity, the same quantity of air as by the former was taken in just one half the time; but nevertheless very nearly the same proportion of it was found converted into carbonic acid.
In the succeeding experiment nearly 10,000 cubic inches of air
