412 CHEMICAL DYNAMICS 



lead to deviation from regularity in the relationship between 

 the degree and the time of hydrolysis which is experimentally 

 observed. Nevertheless, if the degree of alkalinity be sufficient, 

 this is not the case. Thus in Taylor's experiments upon the 

 hydrolysis of protamin sulphate the alkalinity of the system 

 changed markedly with the progress of hydrolysis, yet he ob- 

 tained results in satisfactory accord with the monomolecular law. 

 The reason for this fact is very clearly revealed by the experi- 

 ments of Robertson and Schmidt (113). We measured the rate 

 of change in the alkalinity of tryptic digests of sodium caseinate 

 and of protamin sulphate (dissolved in dilute alkali) by means 

 of the gas chain. The progressive change in hydroxyl-concen- 

 trations of these digests, it was found, can be expressed by a 

 monomolecular formula when the total OH' concentration is 

 greater than 10~^, but thereafter, or when the OH' concentration 

 initially is less than this, the progressive change in alkalinity 

 is no longer to be expressed by a monomolecular formula, but 

 is represented by the formula 



X 



kt = 



B{B - x)2 



(where t is the time since the gas-electrodes first came into equi- 

 librium with the solution and B is the OH' concentration when 

 t = 0), which is characteristic of a himolecular reaction. For a 

 short range of intermediate alkalinities the order of the reaction 

 is indeterminate. These facts are illustrated by the tables on 

 the following page. 



The point at which the order of the reaction changed is indi- 

 cated by an asterisk. It will be seen that it corresponds tolerably 

 closely with Coh' = 10~^; and it will also be observed that it is 

 the same for substrates so very different as casein and protamin 

 sulphate. This indicates that the change in the order of the 

 reaction at a certain OH' concentration depends upon an alter- 

 ation in some relationship between the alkali and the ferment 

 and not upon the alteration of such a relationship between 

 the substrate and the ferment. 



The most probable interpretation to be placed upon these 

 results is that the active agent in bringing about the hydrolysis 

 is not uncombined trypsin but a compound of trypsin with the 

 base which the solution contains. The efficiency of bases in 



