Chemistry and Physics. O71 
Héive gy ha y 
rer hel, epipolized, To explain this remarkable appearance, Stokes 
that in the process of internal dispersion the refrangibility of 
is mode 
of explanation beyond all doubt. A pure solar spectrum was formed 
mn al manner, and a glass vessel containing a weak solution of 
sulphate of quinine placed ji The rays belonging to the greater 
been water. But from a point about half-way between the fix 
lines Gand H to far beyond the visible extreme violet, the incident 
Tays gave rise to light of a sky blue color which emanated in all direc- 
ons from the portion of the fluid under the influence of the incident 
tays. ‘The anterior surface of the blue space coincided of course with 
the inner Surface of the glass in which the fluid was contained; the 
The fixed lines belonging to the violet and the-invisible region bey 
Whe eautifully represented by dark planes interrupting the blue space. 
hen the eye was properly placed, these planes were projected into 
lites, "and Professor Stokes indentified these with the fixed lines in 
Becquerel’s map of the chemical spectrum. The blue dispersed light 
> 1s not 
ps neous, but consists of rays having a wide range of refrangibility, 
Sst Passing beyond the limits of refrangibility of the spectrum visi- 
he ne to do with the phenomenon of true internal dispersion. 
Iternal dispersion proves to be almost universal in solutions 
directly from different parts of vegetables. ‘The tint of the dis 
Persed: light and the part of the spectrum at which dispersion begins, 
on iterent in-different cases. In a decoction of madder in a solution 
bong the dispersion begins above the fixed line D and continues 
low penence far beyond the extreme violet; the dispersed light is yel- 
oF yellowish orange. In studying these phenomena it is not ne- 
ae to use either fluids or clear solids, but washed papers produce, 
ach pe oPerly examined, the same effect. ‘Turmeric paper and paper 
anility appears to be rare among inorganic compounds, but glass 
: peroxyd of uranium and solutions of the salts of this oxyd 
tions. 
“re remarkable excep) 
