864 



TABLE X. 



the active I'ays ai'e siluated for the greater part at 407.8 and 404.7 fc/.j '). 



Th(' action of li(/hf on ni/'.rf/n-cs of ki'toiii's. 



The pheiionieiia observed by us dining the exposure to Hglit of 

 ketone mixtures in absolute alcohol divulged a very strong mutual 

 inlluence. 



In order to better understand these observations, the following 

 should precede: 



We have noticed that the chemically active light comprises a very 

 limited part of the .spectrum, yet. therein ai-e rays of different 

 frequency and intensity. 



A. We can now suppose that each of the ketones present wants 

 its own active rays witiiout absorbing rays intended foi" the other 

 ketone ; then — as the pinacone formation is independent of the 

 concentration — there will have formed in the tube with the mixture 

 the sum of the quantities of pinacone that are formed in the separate 

 tubes under the same conditions. 



Those quantities within certain limils must also be independent 

 of the propoition of the concentrations of the ketones in the tube 

 containing the mixture. - 



1) Presumably, the action is in a high degree selective, as a layer of 3 dm 4% 

 benzophenone in absolute alcohol certainly caused a very distinct fading of these two 

 mercuiy lines, whereas nothing could be noticed of a curtailing or fading at the 

 violet side of the arc lamp spectrum through that same liquid layer. We attach, 

 moreover, not much value to this subjective observation, for only an accurate 

 spectrophotometric investigation of the absorption spf^clra of the ketones can 

 properly determine the connexion between absorption and chemical action. 



