806 



We notice that when one of llie ketones does not get reduced it 

 exerts a very powerful retarding action on the reduction of the 

 other ketone. 



This action, particularly with phenyl-«-naphtylketone is much 

 more important than we should expect even in the extreme case C; 

 besides the elimination of the chemically active rays, the molecules 

 of the naphtylketone must cause an impediment, which may, perhaps 

 be put on a par with the obstruction caused by oxygen in the 

 photo-halogenations. 



TABLE XII. 



From Table XII it appears that, in the case when both ketones 

 are reduced, we have demonstrated a considerably less impediment 

 than in the case that one of them is not reduced. Still, there is 

 always a negative intluence, we obtain in all cases a quantity less 

 than the sum of the quantities wdiich we should have obtained in 

 separate tubes; we are always dealing with case B. 



In this we notice the smallest mutual hindrance in the mixture 

 of benzophenone and o-chlorobenzophejione, yet we notice plainly 

 that the impediment increases w^hen one of the ketones is present 



