Dey CHE, 
CHEMICAL CHANGE OF COLORATION IN BUTTERFLIES’ WINGS. 
BY WILLIAM HENRY 
EDWARDS AND JOSEPH MARTIN WILSON. 
In Letters to the Editors of Psycne. 
In coloring a proof plate for the Butter- 
flies of N. A., the insect is enclosed in a 
tight shallow box, the flat sides of which 
are glass. When delivering the examples 
of Limenitis arthemis to the colorist, last 
summer, Mrs. Peart fastened in the box a 
bit of cotton on which was dropped a little 
undiluted carbolic acid (as sold by the 
druggists). When the colored plate was 
sent me for inspection, it appeared that a 
rich purple had been applied at every point 
which in the insect is metallic blue or 
green, and I wrote the colorist to ask for 
an explanation. She replied that she cop- 
ied the colors of the examples furnished 
her. Shortly afterward, I was in Phila- 
delphia, called on the colorist, and found 
that she was right. The insects were 
wholly changed wherever these two colors 
had been present, and I had to furnish 
other examples for copy. Of course I took 
care that no acid was now present. 
I brought the purple examples home, and 
several weeks later was surprised at finding 
that all trace of purple had passed away 
and the usual colors were restored. I 
should be pleased to see an explanation of 
this. W: H: Edwards. 
Coalburgh, W. Va., 50 April 1880. 
About the first of May you sent me the 
enclosed letter from W: H: Edwards, ask- 
jng for an explanation of the phenomenon 
described therein. 
At the Detroit meeting of the Ameri- 
can Association for the Advancement of 
Science, in 1875, Mr. George Dimmock 
read a paper which conclusively proved 
that the colors in.the wings of insects are 
pigments. It is also well known that cer- 
tain animal and vegetable coloring matters, 
eé. g., litmus, cochineal and others, are red 
or blue according to the character of the 
solution in which they are; that is, red in 
acid solution, blue in alkaline solution. My 
opinion is that the blue and green colors of 
the wings of L. arthemis are similarly af- 
fected ; experiments confirm this partly but 
not entirely, inasmuch as strong acids turn 
the colors reddish and alkalies partially but 
not entirely restore the blue color, so that 
there is possibly a decomposition of the 
coloring matter as well as a change in 
color effected by the acid. Carbolic being 
a comparatively weak acid, is more easily 
neutralized ; moreover, being volatile, its 
effects are more transient than those of the 
stronger acids. 
I was in hopes that I might isolate the 
