The test for the carbonic acid was, as before, in all cases, lime-water. He also found that the skin absorbed oxygen much more readily than most other gases. One remarkable experiment we will notice, to show how laborious all these investigations were, and for the interesting nature of the result. He placed his hand alternately in vessels containing each twenty-four ounces, by measure, of nitrogen and oxygen gases. After eight hours' exposure in each, two-thirds of the oxygen had disappeared, whereas only _one twentieth_ of the nitrogen was absorbed. Indeed, there is no one feature of these experiments perhaps more interesting than those which suggest the stronger aptitude of the skin to absorb oxygen in comparison with other gases. For example, Abernethy found that the skin absorbed, by measure, Ozs. Of oxygen gas, in eight hours 8 Of nitrous gas, in five hours 3 Of hydrogen, in five hours 1-1/2 Of nitrogen, in eight hours 1 Mr. Abernethy then made some experiments on his own lungs, after the manner that Mr. Cruikshank had done, to find the quantity of _water_ exhaled, by breathing into glass jars filled with and inverted in quicksilver, and by other methods, and also to ascertain the change produced in the air by respiration. These are all interesting; but we can only give general results, referring to the work itself, as full of material for thought and future observation. He considered that, on the whole, the change in the air was, that in one hundred parts, consisting of Parts. Nitrogen 80 Oxygen 18 Carbonic acid 2 about _three_ parts of the oxygen were absorbed, whilst about _twelve_ parts of carbonic acid were exhaled, the nitrogen being little altered, or even receiving some small addition. The quantity of _inspired_ oxygen which disappeared varied in different experiments, probably depending on the depths of the inspiration, and the duration between it and the following expiration—the time, in fact, during which it was retained in the lungs. The smallest quantity which disappeared was one-twelfth; the largest, one-sixth. The moisture (water) exhaled, he found to be about three drachms in an hour. These experiments, for the particulars of which we must refer to the book itself, contain a calculation of the extent of surface of the body, which he estimates at about two thousand seven hundred square inches—that is, about thirty-eight times that of the hand and wrist, on which he experimented. Thus, if we multiply any of the results he obtained by thirty-eight, we shall obtain some idea of the prodigious power of this wonderful organ, and of the vast influence which its various conditions must exert on the whole animal economy. The whole of the experiments in the paper are just as interesting as ever, and would, we are well persuaded, be found amply to repay further investigation.