402 



CAUSE OF INFLUENCE OF IONS. 



We notice, however, that the rate of endosmotic transport to the 

 anode increases in acid solutions with the increase in the valency of 

 the cation and diminishes with the increase in the valency of the anion. 

 Electrolytes influence, therefore, the transport of liquid in acid solu- 

 tions in the same sense in the case of free and of electrical osmosis. 

 The influence is in both cases an additive effect of the oppositely 

 charged ions of the electrolyte. The watery phase of the electrical 

 double layer is negatively charged in acid solutions of the hydrogen 

 ion concentration used in this case; namely, 10~^ n. 



TABLE IV. 



Relative Transport of Liquid in Electrical Endosmose to the Anode in Acid Solutions, 



pH = 3.0. 40 Volts. 



M/512NaCl 



m/512 CaCU 



M/512BaCl2 



m/512 CeCla 



m/512 ThCU 



m/512 Na2S04.... 

 m/512 Naj oxalate 

 m/512 NaHjPOi.. 



If we summarize all three cases we may state that in both 

 free and electrical osmosis, the transport of liquid is accelerated by 

 that ion of an electrolyte which has the opposite sign of charge as 

 the watery phase of the double layer (or the same sign of charge as 

 the collodion membrane) and retarded by that ion which has the same 

 sign of charge as the watery phase of the double layer (or the opposite 

 sign of charge as the collodion membrane); and that both the accel- 

 erating and the retarding effect of ions increase with their valency 

 and a second constitutional quantity of the ion which is still to be 

 defined and for which the high transport number of several salts in 

 Table III may serve as an example. 



The writer has made a number of experiments on electrical endos- 

 mose with different concentrations of electrolytes. The curves repre- 



