205 



The reaction constants of the catalysed reactions are recorded in 

 the following table: 



It is remarkable that the activity of the catalyst decreases allow 

 temperatures, and becomes about at 0°. At lower temperature the 

 catalyst is paralysed, to whicli we shall revert later on. The energy 

 increment can be calculated from two observations by the aid of 



the formula In 



k 



1 1. m 



T 



the calculation of the energy- 



E f 1 



increment of the catalysed reactions it should be borne in mind 

 that this must not be done in the usual way, if the measured reac- 

 tion is a combination of two or more reactions taking place side 

 by side '). The hypothesis according to which it is assumed that 

 with a small catalyst concentration, the number of collisions of the 

 kind as occur in the non-catalysed reaction, remains the same, and 

 that only another kind of collisions is added to them, is permissible 

 in ray opinion. In this case the measured constant of reaction 



Ï) Lacomblé, Diss. Leiden 1920, p. 80. 



