722 



ACTIVITY COEFFICIENT OF THE HYDROGEN ION 



velocity of hydrolysis of the gelatin under different conditions it 

 was first necessary to determine some value to be used as a standard. 

 Two gelatin solutions were therefore prepared, one containing 0.75 

 N NaOH and the other 4.5 n HCl. These solutions were then placed 

 at 65°C. and the increase in the fonnol titration followed. The 

 results are shown in Fig. 1. The curves fall off more rapidly than 

 the predicted rate of a monomolecular reaction, as is shown by 

 Fig. 2, in which the logarithm of the quantity of gelatin remaining 

 is plotted against the time, which in the case of a monomolecular 





Z|2 

 8 



1 



a 



.2 



DaysO 



I 



Fig. 1. Increase, with time, in fonnol titration in strongly alkaline and strongly 

 add solutions. 



reaction gives a straight line. It is obvious from the figure that 

 the reaction is monoir olecular for the first 30 or 40 per cent but than 

 becomes too slow. This cannot be ascribed to changes in the Ch 

 or CoH since no measureable change in these values could be detected. 

 This rreans presuniably that the simpler decomposition products 

 are more resistant to hydrolysis than is the gelatin itself. Schroeder^^ 



" von Schroeder, P., Z. physik. Clicm., 1903, xlv, 75. Taylor (Taylor, A. E., 

 l/niv. California Pub., Path., 1907, i, 239) states that the Jiydrolysis of protamine 

 bv acid is monomolecular. 



