M. C. Lea—Influence of Color upon Reduction by Light. 207 
impression. A repetition of the experiment with a shorter 
exposure gave the same curious result, the most curious of all 
the results attained. 
Carthamus, red litmus and capsicum produced an exceptional 
insensitiveness to the red and orange rays. 
actly equal time on or in solutions of exactly equal strength. 
As papers when hun up to dry are always more strongly im- 
in the successive treatments which each paper received to dry it 
with the same end uppermost, and in the exposure to light, to 
keep all the papers with their least sensitive ends to the same 
end of the spectrum: without this last precaution no concord- 
ant or reliable results could have been obtained. 
Solutions of equal strength, we are sure that the papers are 
equally chart be tested. 
