206 Mr POWER'S THEORY OF 



confesses himself compelled to resign it, though he does so with 

 manifest reluctance. That electricity, artificially excited, is capable of 

 accelerating the process, is indeed sufficiently established by the experi- 

 ments of Dutrochet; but it is equally certain that this agent is by no 

 means essential to the operation, since, in the natural process, the most 

 delicate galvanometer gives no indication of its existence. 



3. To me it appears unquestionable, that the phenomenon results 

 from the corpuscular attractions, which the particles constituting the 

 membrane and the fluids, exert upon each other : that electricity, 

 by heightening or modifying these attractions, should produce a sensible 

 effect upon the operation, is nothing more than its ordinary chemical 

 agency would lead us to expect. 



4. By corpuscular attractions are meant the forces which the 

 ultimate atoms of different materials, whether simple or compound, 

 exert upon each other. These forces are enormously great (though not 

 infinite) when the particles are in immediate contact, but diminish with 

 extreme rapidity, as the particles separate, becoming insensible at a 

 sensible distance. The effects of corpuscular attraction are different, 

 according as it is exerted between particle and particle, or between 

 mass and mass. In the former case it gives rise to the phenomena of 

 chemical affinity ; and in the latter, to those of cohesion, adhesion, and 

 capillary attraction, which may be regarded in general, as the mutual 

 attraction of contiguous masses, being the combined effect of the 

 corpuscular attractions of their integrant particles. It is under this 

 point of view that La Place has considered the subject of capillary 

 attraction, and his theory will be of the greatest use in the present 

 investigation. 



5. Although no pores can be detected in the membranous partition 

 by the help of the most powerful microscope, yet the fact that the 

 fluids are transmitted, is a certain proof that such pores exist. They 

 must indeed be extremely minute, and it will be seen that it is on 

 this very minuteness that the energy of the sustaining force depends. 

 These pores must be regarded as communicating with the opposite fluids 



