92 



THEORY OF COLLOIDAL BEHAVIOR 



of with NaCl, at first a rise occurs which is followed by a drop 

 when the concentration of the Cl ion is a little above N/ 1,000. 

 In Fig. 26 the drop appears at a concentration of about N/256 HC1, 

 but the reader must remember that on account of the fact that 



\ 





\ 



'\ 



Xk 



28 

 2.7 

 26 

 25 

 24 

 23 

 2.2 



Z1 

 20 



1.9 



"> 



1-7 



1.6 



15 

 1.4 

 1.3 

 12 

 1.1 



Concentotion 



FIG. 27. The relative viscosity of 0.8 per cent solution of gelatin chloride 

 of pH 3.0 is depressed almost equally by the Cl ion of HC1 as of NaCl. The 

 augmenting effect of the H ion in the case of HC1 is no longer noticeable. 



part of the acid combined with the gelatin the pH of the solution 

 was about 3.0. In other words, while the addition of H ions 

 increases the viscosity of a solution of gelatin chloride of pH 4.0, 

 the addition of Na ions does not have such an effect, but the Cl 

 ion depresses the viscosity in both cases, no matter whether 

 NaCl or HC1 is added to the gelatin solution; and the depressing 

 action of the Cl ion increases with its concentration. Moreover, 



