432 Scientific Intelligence. — Physiology. 



that, as the proportions between the oxygen and carbonic acid 

 are invariably the same, these results may be regarded as sa- 

 tisfactory. With regard to the theory of respiration, all 

 experimentalists agree as to the reciprocal proportions be- 

 tween the carbonic acid expired and the oxygen absorbed ; 

 while, however, some of them are of opinion that those quan- 

 tities are always equal, as must happen if the oxygen gas were 

 employed merely in the formation of carbonic acid in the lungs. 

 There are chemists whose results shew- that more oxygen is 

 inspired than carbonic acid expired. Messrs Allen and Pepys 

 observed that this was constantly the case where the same air 

 was repeatedly respired. M. Magnus adds, that this fact, so in- 

 explicable by other theories, is an immediate consequence of the 

 hypothesis founded on the law, that a liquid holding a gas in so- 

 lution parts with it when it comes in contact with another gas. 

 Another circumstance noticed by Messrs Allen and Pepys, is as 

 inexplicable as the preceding, namely, that by the respiration of 

 oxygen, or of a mixture of oxygen and hydrogen, azotic gas 

 is constantly expired, the volume of which is proportional to the 

 bulk of the animal ; this proves that it cannot at all be attribu- 

 ted to the air. It now remains to be shewn that the carbonic acid 

 extracted from the blood is in sufficient quantity to account for 

 that which the lungs expire. The results obtained on this sub- 

 ject are discordant ; those of Messrs Allen and Pepys evidently 

 exceed what they should be ; for Berzelius has shewn that if cor- 

 rect, it would require six pounds and a quarter of solid nourish- 

 ment in twenty-four hours, to produce the quantity of carbon 

 consumed. Taking, then, the results by Davy as a mean of those 

 of Lavoisier, and Allen and Pepys, although perhaps a little 

 too high, we shall have thirteen cubic inches as the quantity of 

 carbonic acid gas expired by a man. If it be further admitted, 

 that at each pulsation of the heart an ounce of blood arrives at 

 the lungs, seventy-five pulsations in a minute would convey five 

 pounds of blood in the same time. This is the minimum quan- 

 tity which can be admitted; for it is very probable that five 

 pounds of blood pass through these organs every minute ; these 

 five pounds produce thirteen cubic inches. It has been already 

 mentioned that the blood contains at least one-fifth of its vo- 

 lume of carbonic acid ; and as a pound is equal to twenty-five 



