206 M. C. Lea—Influence of Color upon Reduction by Light. 
Substances which conferred the greatest Substances which conferred the greatest, 
sensibility to the more refrangible half sensibility to the less refrangible half 
of the spectrum. of the spectrum, 
Infusion of tea leaves, Salicine, 
alicine, 
Red litmus, Plain bromide, 
Coralline, 
Aniline blue, Aniline green, 
Mauveine, 
Plain bromide, Aniline blue, 
— Aurine, 
Anil. green, Infusion of tea leaves, 
Mauveine, Coralline, 
Auri Infusion of capsicum 
urine. ? 
Cold infusion of safflower, Cold infusion of safflower (car- 
Infusion of capsicum. thamus). 
The substances above the “ plain bromide” increased its sen- 
sitiveness, those below it diminished it, and in all cases to an 
extent corresponding with the order of rank in the respective 
columns. 
In the above lists it will be noticed that there are not only 
verified ; no substance tried exerted a more powerful diserim- 
to the red ray as to the green. 
Generally speaking, the substances enumerated above exerted 
very much the same effect on the different colors at each end 
of the spectrum, that is, those that heightened or impaired the 
ness to the green ; 
Salicine confer on silver bromide a remarkable sensitive- 
ness to the red and orange rays, so that the whole of the Jess 
‘Yefrangible rays from green to red produced about an equal 
