684 



DONNAN EQUILIBRIUM AND MEMBRANE POTENTIALS 



These experiments offer an excellent opportunity to test our theory 

 that the p.d. can be calculated with a fair degree of accuracy from 

 the values of pH inside minus pH outside on the basis of Nernst's 

 formula. Tables VIII, IX, and X show that this is true. The upper 



pH 1.8 2.0 22 24 2.6 2S 3.0 3.2 34 36 38 40 42 44 4.6 48 



Fig. 6. Influence of pH and valency of anion on p.d. of solutions of different 

 gelatin-acid salts. The curves in Fig. 6 are similar to (but not identical with) 

 those in Fig. 5. 



two horizontal rows give the pH inside and outside, the third hori- 

 zontal row gives the difference pH inside minus pH outside, and the 

 fourth row gives the p.d. calculated in millivolts by multiplying the 

 values pH inside minus pH outside by 59. The last horizontal row 



