54 



THEORY OF COLLOIDAL BEHAVIOR 



ascertained potentiometrically and the number of cubic centi- 

 meters of 0.1 N acid required to bring the 1 per cent casein solu- 



C 

 '3 



a 



o 



i 



.3 



o 



CO 



o 

 u 

 o 

 o 



B 



u 



40 

 38 

 36 

 34 

 32 

 30 

 28 

 26 

 24 

 22 

 20 

 18 

 16 

 14 

 12 

 10 

 8 

 6 

 4 

 2 



\ 



\ 



\ 



pH 1.4 1.6 1.8 2.0 2.2 24 2.6 2.8 3.0 3.2 34 3.6 3.8 



FIG. 9. Ordinates represent the c.c. of 0.1 N HC1 or H 3 PO 4 in 100 c.c. of 1 

 per cent casein solution. The abscissa are the pH of the solution. Approxi- 

 mately three times as many c.c. of 0.1 N HsPC^ as of 0.1 N HC1 are required to 

 bring 1 gm. of casein to the same pH. 



tion to the same pH were plotted over the final pH of the casein 

 solution as abscissae. The casein chloride or casein phosphate is 

 not completely soluble in a 1 per cent solution until the pH is 



