CORRECTNESS OF THE CHEMICAL VIEWPOINT 



49 



TABLE II. CUBIC CENTIMETERS OF 0.1 N ACID IN COMBINATION WITH 



1 GM. OF ORIGINALLY ISOELECTRIC CRYSTALLINE EGG ALBUMIN IN 



100 c.c. SOLUTION 



sequence of the failure of the workers to consider the hydrogen 

 ion concentration of their solutions. Had this been done, nobody 

 would have thought of suggesting that acids combine with pro- 

 teins according to the adsorption formula. 



These titration experiments are of especial value for the reason 

 that crystalline egg albumin is for the present probably the 

 purest protein available. 



The same proof can be furnished in the case of other proteins, 

 e.g., gelatin. A stock solution of isoelectric gelatin was used for 

 the experiment. The isoelectric gelatin was prepared by putting 

 the powdered gelatin of pH 7.0 into M/128 acetic acid (100 c.c. of 

 11/128 acid for 1 gm. of gelatin) for 1 hour at 15C., and then 

 washing four or five times with cold water (5C.). An 8 per cent 

 stock solution was prepared ; the concentration of the gelatin was 

 ascertained by a determination of the dry weight. To 50 c.c. of a 

 2 per cent solution of isoelectric gelatin were added different 

 quantities of acid and the volume made up to 100 c.c. by adding 

 enough H 2 0, usually of a pH of about 5.6. It was ascertained 

 how many cubic centimeters of 0.1 N different acids were required 

 to bring 1 gm. of isoelectric gelatin in a 1 per cent solution to the 

 same pH. 



4 



