551 



The axioms which are more partiouhirlj applicable to the cata- 

 lysis are : 



"When... the one exerts an inflnence on the other, this latter... 

 is changed by the first . . . 



"If in the calcnlation of one of these the change may be neglected 

 we may speak of a one-sided intlnencing, which, however, as such .. . 

 may not be considered one-sidedly (dissertation p. 4 — 5). 



and snbsequently : 



"If we consider the possible relation of two snbstances (wliether 

 element or compound) three stages arc to be dis(ingnished therein". 



"J. The stage of the relative inertness. In this stadinm even 

 the catalytic influence is imperceptible, whilst there is no question 

 of a chemical compound. 



"2. The catalytic stage ^) in which occnrs also the mutual acti- 

 vation. In this stage the catalytic actions are enacted. 



"3. The reaction stage in which appears an intra- or extra- 

 molecular reaction". 



The catalytic stage forms the bridge between the inertness and 

 the chemical compound. In each chemical reaction all three stages 

 are gone throngh. 



By varying the conditions we can, however, cause the influencing 

 to be confined to the second stage". (Chem. Weekbl. 11, 475, 

 also Jonrn. f. pr. Chem. N. F. 89, 448 (1913). 



2. Prins starts from the general thesis that on interaction, there 

 takes place a change in two conditions, which will be least powerful 

 the moment it begins to reveal itself. 



This stage lies, chemically speaking, in the dissociation region 

 where the free energy of the entire system approaches to zero 

 and is called by Pkins the catalytic stage. 



In this catalytic stage thei'e is really no question of a catalyst 

 in the sense of Ostvvald ; we are dealing with a change of condition : 

 A ^ B "which taken by itself can take place more or less rapidly. 



Being in the catalytic stage does not at all imply, in my opinion, that the 

 changes must take place rapidly ; this depends on the nature of the change 

 (chemically speaking on the nature of the atoms or atomic groups which in the 

 transformation play a role in the first place). 



If, for convenience sake, we call A and B two molecules, one 

 of these molecules, in a reaction in which the other one (with its 



1) In order to prevent confusion it would be better to speak of the activating 

 stage. (Pkins also points out that the word "activator" expresses his ideas better 

 than catalyst). 



