JACQUES LOEB 



569 



of the ion. Fig. 3 represents the influence of different concentrations 

 of electrolytes (with hydrogen ion concentration above 10"* n) upon 

 the rate of diffusion of water through the membrane. It increases 

 with the valency of the cation and diminishes with the valency of the 

 anion, the curves in the case of Na2S04 or NaH2P04 showing no rise. 

 The curves for CaCU and NaCl show a rise and then a drop, the turn- 

 ing point, however, lying at higher concentrations than for neutral 

 solutions. The rise and drop find their explanation on the assump- 

 tion that the influence of the cation on the charge of the membrane 



^ mm'mm z^ m M % 

 Concentration 



Fig. 4. Electrical endosmose. Effect of acidulated salt solutions on electrical 

 endosmose. Inside and outside the bag indentical solutions. Similarity of 

 curves of transport in Fig. 4 and Fig. 3. 



increases at first more rapidly with increasing concentrations than 

 the depressing effect of the anion upon this charge, while at concen- 

 trations above a certain point the reverse happens. 



This conception is supported by experiments on electrical endosmose 

 as represented in Fig. 4. The solutions of Na2S04, NaCl, CaCU, and 

 CeCla were made up in m/ 1,024 HNO3 and the hydrogen ion concen- 

 tration was in the neighborhood of 10"' n. The ThCU solution was 

 sufficiently acid on account of hydrolysis (its pH varying between 

 3.5 and 1.9 according to concentration). The watery phase was nega- 

 tively charged and it was necessary to put the anode into the glass 



