JOHN H. NORTHROP 



727 



TABLE III. 



Influence of Concentration of Gelatin at 65° C. 



Gelatin Per Cent Concentration Noted + HCl to pH 2.0. 



//. The Influence of High Concentrations of Hydrogen and Hydroxyl 



Ions. 



It was shown above that the rate of the reaction decreased very 

 rapidly if the hydrogen ion concentration was allowed to decrease. 

 This in itself indicates that the rate is a function of the hydrogen 

 ion concentration and not of the total amount of acid present. The 

 fact that it is the hydrogen ion concentration and not the total acidity 



TABLE IV. 



Influence of Diferent Acids on Velocity of Hydrolysis. 

 2.5 Per Cent Gelatin at 65°C. with pH Measured at 25°C. 



is shown more clearly in Table IV which contains the results of an 

 experiment in which the gelatin was brought to the same pH with 

 different acids. The table shows that the velocity is the same in 

 all the solutions although the total concentration of citric acid was 

 more than 10 times that of the HCl. 



