176 ELECTROCHEMISTRY 



bases and acids and the dissociation of the resultant salts take 

 place according to the following schemes: 



H 



I ++ 



-N.HOC- + NaOH = -N" + NaOC- 



I 

 OH 



H 



I ++ 



-N.HOC- + HCl = -N" + HOC- 



I ' 

 CI. 



or in accordance with modifications of these schemes arising out 

 of the participation of dicarboxylic- and diamino-radicals in the 

 reactions. 



In the succeeding pages the endeavor will be made to interpret 

 the electrochemical behavior of the proteins and their salts with 

 the aid of this hypothesis. 



2. The Electrolysis of Protein Salts. — It was shown by 

 Hardy (9) in 1899 that if a trace of acid be added to a solution 

 of dialysed white of egg, modified by dilution and boiling, on 

 passing a direct current through the solution the whole of the 

 protein finally moves over to the cathode, where it is precipitated. 

 If a trace of alkali is added, however, instead of acid, the whole 

 of the protein finally migrates, under the influence of the current, 

 to the anode. He later showed that serum-globulin in solution 

 behaves similarly (10). Under such circumstances, therefore, the 

 protein behaves like the anion or cation of a salt; like the cation 

 when combined with an acid; like the anion when combined 

 with a base. 



Here an apparent, but not a real difficulty confronts us in the 

 application of the hypothesis outlined above to the electrolysis 

 of protein solutions. On the basis of this hypothesis the protein 

 should migrate in both directions, the cation, when the protein 

 is combined with a base, and the anion, when the protein is com- 

 bined with an acid, carrying the inorganic constituent with it. 

 At first sight it might appear as if the protein should be deposited 

 at both electrodes, but not when we look more closely into the 

 matter. In both of the cases just cited the free, uncombined 



