212 



quantity of photo-ketone = ^7 (1 — e^^^^') approaching to kl. 



1. ketone + lig'it = plioto-ketone ; 

 as this quantity is formed at the moment that tiie solution is illumi- 

 nated, it is as if with the velocit}' of light a plate of" a catalyst 

 slides on the light side of some vessel or other, in which the solu- 

 tion is put. 



Then the reaction lakes place the velocity of which regulates the 

 process: the meeting of liie alcohol molecules and those of the 

 photo-kelone : 



II. 2 phot.o-ketone -)- alcohol = (photo-kelone), alcohol. 



By this meeting two H-aloms of the alcohol are activated: 



IIT. ([)lioto-ketone), alcohol — > [(pholo-ketone), active alcohol]. 



This process, which prül)ably takes place with the velocity of 

 light, is the real cdtaJysis, the dislocation. 



The alcohol-molecules are enabled to react witli the oxygen accord- 

 ing to the scheme : 



IV. 2 [(photo-ketone) active alcoholj -[- 0^ = 



4 ketone + 2 aldehyde + 2H,0, 

 which last process also lakes place with great velocity. 



We see that the actual catalysis has to do with the formation of 

 the ternary compound only in so far as the photo-activity of the 

 C = 0-groups of the ketone can be transferied to the H-atoms of 

 the alcohol. Here the distinction of the catalysis and of the forma- 

 tion of the compound is, indeed, very clear, for the ternary compound 

 is also formed in the dark, and then there is no question of any 

 catalytic action. 



When the photo-ketone is thought replaced by an ordinacy cata- 

 lyst, e.g. a plate of paladium, it is clear that the combining of this 

 metal with the alcohol is not the essential part of the catalysis, but 

 what happens with the alcohol molecules at the moment that the 

 atoms Pd get into contact with them, through which two of the 

 H-atoms are activated. This the paladium can do by itself, without 

 being activated by a stimulus from outside. 



It appeared from the light-investigation that the oxidation of the 

 activated alcohol molecules took place very rapidly. This will as a 

 rule also be the case in the ordinary catalysis, but this velocity 

 can be different for each case. 



If, however, a catalyst in very small quantities is to accelerate 

 a given reaction considerably, every contact of its molecules with 

 those of the substance that is to be activated, must give rise to a 

 dislocation that sets in very rapidly. 



