198 



ELECTROCHEMISTRY 



To all the solutions employed a small amount of KCl was added. 

 This is necessitated in the preparation of the casein solutions 

 by technical difficulties of which an account will be found in the 

 appendix, but it serves also to confer upon the solutions a higher 

 conductivity and thus to render more easy the detection of the 

 zero point upon the potentiometer bridge wire by means of a 

 galvanometer. So far as the solutions of casein in KOH are 

 concerned, the presence of KCl in the concentrations employed 

 evidently did not appreciably affect the combining capacity of 

 the protein for the base, since, as the tables reveal, in solutions 

 of very different KCl-content (0.015 N to 0.030 N) the combining 

 capacity at absolute neutrality proved to be the same. In the 

 tables the total amount of potassium present in the solvent as 

 KOH or KCl, is designated by the symbol r. 



All of these determinations were made at 30° C. 



0.5 PER CENT CASEIN DISSOLVED IN KOH SOLUTIONS 



(r = 0.020) 



1.0 PER CENT CASEIN IN KOH SOLUTIONS (FIRST SERIES) 



