JACQUES LOEB 269 



presentation of the facts. With this reservation our experiments 

 suggest that the apparent electrostatic effect of the hydrogen ions 

 upon the motion of the electrified particles of water is small if com- 

 pared with the effect of the trivalent cations; in fact it seems smaller 

 even than that of other monovalent cations. 



When acid is put into collodion bags not treated with gelatin, we 

 observe a rapid diffusion of water into the acid solution as if the 

 attraction of the positively charged water by the anion of the acid was 

 very strong while its repulsion by the H ion was weak. When we 

 put acids into collodion bags treated with gelatin we observe negative 

 osmosis; i.e., slight attraction of the negatively charged particles of 

 water by the positive hydrogen ion, and a powerful repulsion of the 

 water by the anion of the acid. In all these cases, the apparent 

 electrostatic effect of the hydrogen ion upon the charged particles of 

 water seems smaller than the electrostatic effect of any other ion. 

 When we compare the electrostatic effect of trivalent cations on the 

 rate of diffusion of water, we notice that it is much more powerful 

 than that of the hydrogen ion. When water is negatively charged, 

 it is attracted very powerfully by AI2CI6 as well as by AI2 (804)3 though 

 naturally more by the former than by the latter. While in the case 

 of acids the SO4 ion has a more powerful influence than the H ion, the 

 electrostatic effect of a trivalent cation cannot be overcome by the 

 effect of a bivalent anion. It can only be equalled by the influence 

 of a trivalent anion ; e.g., the citrate. This comparatively weak electro- 

 static effect of the H ion is responsible for the phenomenon of negative 

 osmosis observed in the case of acids. When we use membranes in 

 which the electrified water is negatively charged in the presence of 

 acid the attractive effect of the H ion is so small that the repulsive 

 eft"ect of the anion prevails in the critical range of concentrations, 

 where the drop in the curve occurs. As a consequence no water can 

 diffuse into the solution and the volume of the latter will diminish 

 on account of the diffusion of solute into the pure solvent. Since we 

 notice also negative osmosis in the case of Ba(0H)2 and Ca(0H)2, we 

 conclude that the electrostatic effect of the OH ion on the movable 

 stratum of the double layer is also small. 



