LECT. VI. 



GASEOUS ENDOSMOSE. 



131 



their density.* According to the recent researches of 

 Valentin and Brunner, this law is verified in the pheno- 

 menon of respiration.f 



Some facts obtained from experimental physiology, and 

 which I have yet to notice, furnish evidence of the strongest 

 kind in favour of our conclusions. Spallanzani, Nysten, 

 Martigny, and Edwards, removed the air from the lungs of 

 some frogs, by making pressure on the breast and abdomen. 

 In this condition, some of the animals were put into hydro- 

 gen, and some into azote. Dogs, rabbits, and a great 

 number of other animals, were likewise submitted to these 



* In the French edition of Matteucci's lectures, Graham's law is erro- 

 neously stated. I have, therefore, corrected the text in the English trans- 

 lation. 



Graham's law may be thus expressed mathematically : 



Diffusiveness = . / 



V sp. gr. 



The following Table shows the specific gravities, the squaie- roots of the 

 specific gravities, and the diffusiveness of several gaseous substances. 



t According to Graham's law of the diffusion of gases, when they are 

 separated by an animal membrane and are under equal pressure, they be- 

 come mixed inversely as the square roots of their densities; consequntly 

 1-17585 volume of oxygen is absorbed for one volume of expired carbonic 

 acid. Comparison of the figures shows us that the mixture of the two 

 gases in respiration takes place entirely according to the law of diffusion 

 of gases j for a method of experimenting, as accurate as possible, gave re 

 suits in which the figures obtained for the carbonic acid and absorbed oay- 



