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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8/ 



2, comparative observations of visible radiation limited on the short 

 wave-length side to different portions of the spectrum with a view to 

 detecting the effects on photochemical reactions which differ as to 

 threshold ; 3, observations of the effects of monochromatic light in 

 the visible and ultra-violet, first alone and second supplementary to 

 other illumination. 



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