THE VALENCY RULE AND THE HOFMEISTER SERIES 87 



while ions of the same sign of charge and valency have similar 

 effects. In the second part of the book it will be shown that this 

 is due to the fact that the colloidal behavior is the expression of 

 the forces set up by the Donnan equilibrium and in the equation 



pH 6 



10 



11 



12 



FIG. 25. Curves representing relative viscosity of Na and Ba caseinate for 



different pH. 



for this equilibrium only the sign of charge and valency appear. 

 It is also obvious that it would have been impossible to arrive at 

 this valency rule without the proof of the stoichiometrical 

 character of the combination of proteins with acids or bases, 

 especially the proof that weak dibasic and tribasic acids combine 

 in the range of pH concerned in molecular proportions. 



