744 ELECTRIFICATION AND DIFFUSION OF WATER 



diffusion under the influence of these forces, which may be elec- 

 trostatic in character. 



It follows from the data of Table VIII that the balancing concen- 

 trations given in Table V are the maximal values for e for each of the 



electrolytes mentioned and that it is not necessary to deduct tt 



from this value. The real deduction to be made is so small that it 

 falls within the limits of error of the determination of the balancing 

 concentration and the latter may therefore be taken as the rough 

 expression for the value of the electrical forces. 



SUMMARY. 



1. When pure water is separated by a coUodion membrane from a 

 watery solution of an electrolyte the rate of diffusion of water is 

 influenced not only by the forces of gas pressure but also by electrical 

 forces. 



2. Water is in this case attracted by the solute as if the molecules 

 of water were charged electrically, the sign of the charge of the water 

 particles as well as the strength of the attractive force finding expres- 

 sion in the following two rules, {a) Solutions of neutral salts possess- 

 ing a univalent or bivalent cation influence the rate of diffusion of 

 water through a coUodion membrane, as if the water particles were 

 charged positively and were attracted by the anion and repelled by the 

 cation of the electrolyte; the attractive and repulsive action in- 

 creasing with the number of charges of the ion and diminishing in- 

 versely with a quantity which we will designate arbitrarily as the 

 "radius" of the ion. The same rule appHes to solutions of alkalies. 

 (6) Solutions of neutral or acid salts possessing a trivalent or tetra- 

 valent cation influence the rate of diffusion of water through a collo- 

 dion membrane as if the particles of water were charged negatively 

 and were attracted by the cation and repelled by the anion of the 

 electrolyte. Solutions of acids obey the same rule, the high elec- 

 trostatic effect of the hydrogen ion being probably due to its small 

 "ionic radius." 



3. The correctness of the assumption made in these rules concern- 

 ing the sign of the charge of the water particles is proved by experi- 

 ments on electrical osmose. 



