JACQUES LOEB 389 



What we designated in this statement as electrified particles of 

 water is the watery phase or the mobile stratum of the electrical 

 double layer (in the sense of Helmholtz) formed at the boundary of 

 membrane and water or solution. The other stratum of this double 

 layer, the membrane phase, must be considered as immobile in the 

 experiments on osmosis. The influence of electrolytes on the double 

 layer at the boundary of water and membrane will be assumed to be 

 responsible for the phenomena of abnormal osmosis. 



It follows from our previous publications that we must discrimi- 

 nate between two effects of electrolytes on the double layer. The 

 one effect is the influence of certain ions on the sign of the electrifi- 

 cation of the water or the solution phase of the double layer. Water 

 .in contact with a membrane is generally positively charged and 

 only in the case of certain types of membranes, e.g. collodion mem- 

 branes treated with proteins, can the sign of the charge be reversed 

 by two kinds of ions; namely (a) hydrogen ions, or (b) simple {i.e. 

 non-complex) cations whose valency is three or more.^ All elec- 

 trolytes which can lower the hydrogen ion concentration by a chemical 

 action, e.g. alkalies, can restore the original positive electrification of 

 the water stratum of the double layer. Some authors have drav/n 

 from this the conclusion that the OH ions act as directly as the H ions 

 upon the sign of the electrification of the membrane (e.g. by trans- 

 ferring their negative charge to it). It seems to the writer that it is 

 more in harmony with the facts to assume that the alkalies act merely 

 by the diminution of the hydrogen ion concentration through neutrali- 

 zation of acid. The special effect of the two classes of positive ions — ■ 

 H ions and simple cations with a valency of three or above^ — on the 

 sign of the electrification of the water stratum of the double layer 

 will be discussed in another paper. 



In addition to this specific influence of certain ions on the sign of 

 the electrification of water at the boundary of the membrane there 

 exists a second, more general effect of electrolytes on the rate of 

 diffusion of water which was described in terms of electrostatic 

 attraction and repulsion of the electrified stratum of water by the 

 ions of the electrolyte in the previous papers, since this way of describ- 

 ing the results had the advantage of simplifying the presentation of 

 the facts. It was not, however, intended to serve as a theoretical 



