608 



COLLOIDAL BEHAVIOR OF EDESTIN 



The effect of the hydrogen ion concentration on the p.d. was deter- 

 mined by using 1 per cent solutions of edestin in varying concentrations 

 of HCl without the addition of salt. The results of such an experi- 

 ment are given in Table VI and Fig. 5. 



n 1_LX_L11.1X11 

 ^ 20^ 1024 512 256 I2& 64 3^ 16 8 4 



Concentreition of salt, ecj^uivalents per liter 



Fig. 4. Effect of different chlorides on p.d. observed with 0.45 per cent edestin 

 chloride at pH 3. 



It will be noticed that the observed and calculated values for p.d. 

 agree fairly well up to pH 4.0. The results therefore show that Don- 

 nan's theory does apply quantitatively to edestin chloride solutions 

 between pH 1.5 and 4.0. 



