ON THE ELECTRICAL CHARGE OF PROTEIN. 143 



tests, in which the effect of concentration and other con- 

 ditions was also determined quantitatively, may be thus 

 summarized : 



1. A protein which has been carefully freed from 

 electrolytes shows no recognizable electrical charge and 

 does not wander toward one of the two electrodes, even 

 when subjected to an electric current for twenty-four 

 hours. 



2. Each of the albuminous constituents of the serum 

 serum albumin, pseudoglobulin, euglobulin shows no 

 electrical charge in the absence of electrolytes. 



3. The addition of neutral salts of the alkalies or the 

 alkaline earths does not impart an electrical charge to 

 the uncharged protein. 



4. Traces of acids impart a positive charge to protein 

 through their positively charged hydrogen ions; alkalies 

 a negative charge through their hydroxyl ions. 



5. Salts with an alkaline reaction toward litmus, such 

 as carbonates and the secondary and tertiary phosphates 

 of the alkali metals, render protein electronegative; acid 

 salts give it a positive charge. 



6. This charge is independent of the end reaction of 

 the medium. A proper mixture of protein and sodium 

 bicarbonate is faintly acid toward phenolphthalein, neutral 

 toward litmus; the protein has, however, a strongly 

 negative charge. 



III. 



Let us consider, first of all, the fact that our salt-free 

 protein carries no electrical charge. How does it behave 

 toward the salts of the heavy metals, such as Cu, Fe, Zn, 

 Pb, Hg, which are all regarded as general precipitants of 



