54 CUBKENT FOKCE CHAP. IV. 



Force, which has since appeared in their Trans- 

 actions''. In this Paper Professor Geaham has shewn 

 that osmose is dependent upon chemical action, and 

 not, as it has been generally supposed, upon capiUary 

 attraction. Space will not allow me to enter upon 

 the facts brought forward in support of this opinion ; 

 and 1 must therefore refer my readers to the Paper 

 itself, which cannot be too strongly recommended. 



The conditions under which an osmotic experiment 

 is conducted, viz. the necessity of having two fluids, 

 one on each side of the septum, render it extremely 

 difficult to ascertain by means of the galvanometer 

 the exact mode of action which arises during osmose, 

 so as to compare it with that which takes place in 

 the animal body during secretion, in consequence of 

 the reaction of the two fluids upon each other pro- 

 ducing their own peculiar effects on the galvanometer; 

 and the changes upon which osmose depends take 

 place, according to Professor Gbaham, mthin the 

 substance of the porous diaphragm, where we cannot 

 apply the electrodes of the galvanometer. 



The fact of osmose depending upon chemical 

 action, shews however that the act itself must not be 

 considered as a mere transudation, a mere physical 

 separation, but that it depends upon other important 

 conditions; and if upon chemical action, they are 

 consequently polar in their nature. If this con- 

 clusion be arrived at in regard to osmotic phenomena, 

 we may with equal propriety consider the phenomena 



P Phil. Trans. 1854. 



