466 ELECTRICAL CHARGES AND ANOMALOUS OSMOSIS 



the hydrogen ion concentration the experiments to be given in this 

 paper differ from those of previous workers. 



Fig. 1 represents the transport curves for different concentrations of 

 CeCla, CaClz, NaCl, Na2S04, and cane-sugar, all of pH 3.0 (HCl 

 having been added). The outside solution was an HCl solution 

 also of pH 3.0 (approximately n/ 1,000 HCl), but containing no salt. 

 The abscissae are the concentrations, the ordinates the level in mm. to 

 which the liquid had risen in the manometer after 20 minutes. The 

 results of these experiments corroborate similar experiments already 

 published.^ 



The curves for the first three salts, CeCls, CaCl2, and NaCl, rise 

 at first until the concentration is about m/32, then fall and then rise 

 again at a concentration of about m/4. The curves for cane-sugar 

 and Na2S04 commence to rise at a concentration of about m/32 or 

 m/8 respectively. The transport of water therefore increases with 

 the valency of the cation and inversely with the valency of the anion 

 and the question arises how to account for these curves. 



According to Helmholtz's formula modified by Perrin, the transport 

 of liquid through a capillary under the influence of a direct current is 



q-cE-D 



V = 



4 IT- If L 



where v is the quantity of liquid carried electroosmotically, q the 

 cross section of the capillary, e is the potential difference between the 

 two strata of the double layer inside the capillary, E the external 

 electromotive force (acting at right angles to the electrical double 

 layer in the capillary), D the dielectric constant of the medium, 

 77 the coefficient of internal friction, and L the distance of the external 

 electrodes. 



In the experiments on anomalous osmosis the driving force, E, 

 is not furnished by an external p.D. but by a p.d. across the membrane, 

 which has its origin in the difference between the solutions on the 

 opposite sides of the membrane and which acts only through the ex- 

 tremely small distance of the thickness of the membrane, e is the p.d. 

 between the liquid inside the pores and the wall of the gelatin film. At 

 pH 3.0, gelatin exists in the form of gelatin-acid salts, e.g. gelatin 



5 Loeb, J., /. Gen. Physiol, 1919-20, ii, 387, 563, 577, 659, 673. 



