Elements of chemistry : including the recent discoveries and doctrines of the science / by Edward Turner.

  • Turner, Edward, 1798-1837.
Date:
1828
Catalogue details

Licence: Public Domain Mark

Credit: Elements of chemistry : including the recent discoveries and doctrines of the science / by Edward Turner. Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

    848/948 (page 826)
    IlESPl RATION. the air-cells of the lungs. Messrs. Allen and Pcpys arrived at a similar conclusion ; and since the appearance of their Essay, the opinion has prevailed very generally among phy- siologists, that in respiration the nitrogen of the air is altogether passive. The facts ascertained by Dr. Edwards relative to this sub- ject are novel and of peculiar interest. This acute physio- logist has reconciled the discordant results of preceding experi- menters by showing that, during the respiration even of the same animal, the quantity of nitrogen may one while be in- creased, at another time diminished, and at a third wholly un- changed. He has traced these phenomena to the influence of the seasons; and he suspects, as indeed is most probable, that other causes, independently of season, have a share in their production. In nearly all the lower animals which were made the subjects of experiment, an augmentation of nitrogen was observable during summer. Sometimes, indeed, it was so slight that it might be disregarded. But in many other instances it was so great as to place the fact beyond the possi- bility of doubt; and on some occasions it almost equalled the whole bulk of the animal. Such continued to be the result of his inquiries until the close of October, when he observed a sensible diminution of nitrogen, and the same continued throughout the whole of winter and the beginning of spring. Thei'e are two modes of accounting for these phenomena. According to one view, the nitrogen which disappears is ascribed to the absorption of what was inhaled, and its increase to direct exhalation, the opposite processes of absorption and exhalation being supposed not to occur at the same moment. According to the other view, both these processes are always going on at the same time, and the result depends on the preponderance of one over the other. When absorption pre- vails, a smaller quantity of nitrogen is exhaled than was inspired; when exhalation exceeds absorption, increase of ni- trogen takes place; but when absorption and exhalation are equal, the bulk of the inspired air, so far as concerns nitrogen, is unchanged. The latter opinion, which is adopted by Dr. Edwards, is supported by two decisive experiments performed by Messrs. Allen and Pepys, in one of which a guinea-pig- was confined in a vessel of oxygen gas, and in the other in an