JACQUES LOEB 407 



(c) The relative influence of the oppositely charged ions, mentioned 

 in (&), is not the same for all concentrations of electrolytes. For lower 

 concentrations the influence of that ion usually prevails which has the 

 opposite sign of charge from that of the watery phase of the double 

 layer; while in higher concentrations the influence of that ion begins 

 to prevail which has the same sign of charge as that of the watery 

 phase of the double layer. For a number of solutions the turning 

 point lies at a molecular concentration of about m/256 or m/512. 

 In concentrations of m/8 or above the influence of the electrical charges 

 of ions mentioned in (6) or (c) seems to become less noticeable or to 

 disappear entirely. 



2. It is shown in this paper that in electrical endosmose through a 

 collodion membrane the influence of electrolytes on the rate of trans- 

 port of liquids is the same as in free osmosis. Since the influence 

 of electrolytes on the rate of transport in electrical endosmose must 

 be ascribed to their influence on the quantity of electrical charge on 

 the unit area of the membrane, we must conclude that the same 

 explanation holds for the influence of electrolytes on the rate of 

 transport of water into a solution through a collodion membrane in 

 the case of free osmosis. 



3. We may, therefore, conclude, that when pure water is separated 

 from a solution of an electrolyte by a collodion membrane, the rate of 

 diffusion of water into the solution by free osmosis is accelerated by 

 the ion with the opposite sign of charge as that of the watery phase of 

 the double layer, because this ion increases the quantity of charge 

 on the unit area on the solution side of the membrane; and that 

 the rate of diffusion of water is retarded by the ion with the same 

 sign of charge as that of the watery phase for the reason that this ion 

 diminishes the charge on the solution side of the membrane. When, 

 therefore, the ions of an electrolyte raise the charge on the unit 

 area of the membrane on the solution side above that on the side 

 of pure water, a flow of the oppositely charged Hquid must occur 

 through the interstices of the membrane from the side of the water 

 to the side of the solution (positive osmosis). When, however, the 

 ions of an electrolyte lower the charge on the unit area of the solu- 

 tion side of the membrane below that on the pure water side of the 

 membrane, liquid will diffuse from the solution into the pure water 

 (negative osmosis). 



