JACQUES LOEB 567 



concentration the quantity of electro-endosmotic transport falls. 

 The curves resemble those in Fig. 1 except that the maximum is a 

 little lower in the case of electrical endosmose. The writer is inclined 

 to explain this difference by the fact that in electrical endosmose the 

 concentration of the liquid is increased by the secondary chemical 

 reactions at the electrodes and that thereby in a m/512 solution of 

 K2SO4 or KCl the concentration of the solution rises gradually as a 

 consequence of electrolysis and secondary chemical reactions at the 

 electrodes and approaches m/256. 



It is, moreover, obvious that the electrical transport (Fig. 2) of the 

 positively charged liquid increases with the valency of the anion as in 

 free osmosis (Fig. 1) and that it diminishes with the increasing valency 

 of the cation as shown by the flat curve for CaClg. The curves for 

 MgCl2 and BaCl2 are like those for CaCU in the case of free osmosis 

 as well as in the case of electrical endosmose. 



We have inferred in the preceding paper^ that the rate of transport 

 of liquid in electrical endosmose varies, if the other conditions remain 

 equal, with the value of the charge e on the unit area of membrane. 

 If this inference is correct then it follows from the nature of the curves 

 in Fig. 2 that beginning with the lowest concentrations the influ- 

 ence of the anion on the density of charge of the membrane increases 

 at first more rapidly with increasing concentration than the depres- 

 sing effect of the cation upon the density of this charge, while later the 

 reverse occurs. The turning point seems to lie for the solutions 

 mentioned between m/512 and m/256, where it also lies for free 

 osmosis. 



n. 



When we separate solutions of electrolytes with a hydrogen ion 

 concentration of 10~* n or above from pure water by collodion mem- 

 branes which have been treated with a protein, the watery phase of 

 the double layer is negatively and the membrane positively charged.^** 

 In the preceding paper^ it was shown that in such a case the charge of 

 the membrane is increased by the cation and diminished by the anion 

 of an electrolyte in solution, both effects increasing with the valency 



^ Loeb, J., J. Gen. Physiol, 1918-19, i, 717. 



