224 Mr POWER'S THEORY OF 



21. If the pore be circular, let ^ be its diameter, then 



c = 2'7r.-, and to = tt . — : 

 2 4t 



€ 4 



•'. - = -J ;. 



CO 



the sustaining force is therefore inversely proportional to the diameter 

 of the pore, as in ordinary capillary attraction. 



Hence we see how the membrane^s delicacy of texture contributes 

 to the intensity of the sustaining force. 



22. It is now easy enough to see in what manner the process is 

 effected. The residual force cA{p — r) + cB{p'^ — r"), which would result 

 if the ends of the tube communicated with fluid of the densities 

 r and p, being greater than the altitudinal pressure upon the section w, 

 would cause the fluid within the tube to move as a mass into the 

 endosmometer, thus bringing fluid more and more diluted to the 

 issuing orifice; this will continue until the residual force is weakened 

 to such a degree as exactly to counterbalance the altitudinal pressure. 

 Contemporaneously with the former motion, the mixing process will 

 transfer the two fluids in opposite directions, the current from the 

 endosmometer towards the water producing the exosmose, and the 

 opposite current supplying the deficiency caused by the exosmose, and 

 therefore not contributing to the endosmose. The diluted fluid which 

 was carried into the endosmometer by the residual force, will gradually 

 mix with the treacle within, whether that mixture be carried on near 

 the orifice of the tube, or whether the diluted fluid be raised by its 

 specific levity higher up in the endosmometer. The extremely small 

 portion of diluted fluid which has thus been transmitted, and the 

 viscosity of the treacle, render it most* probable that it would not be 



* This probability amounts nearly to certainty when we consider that the denser fluid 

 has no access to the lower part of the transmitted fluid. It is only when a lighter body 

 is insulated, or partially insulated^ in a denser that it rises by its specific levity. 



