Discovery of his Theory of Colors. 263 
3. “Tn light produced by the combustion 
of terrestrial substances, the spectrum 
VIOLET is still more interrupted ; thus, the bluish 
light of the lower part of the flame of 
a candle is separated by refraction into 
five parcels of various colours; the light 
of burning spirits, which appears per- 
fectly blue, is chiefly composed of green 
and violet rays; and the light of a can- 
GREEN dle into which salt is thrown abounds 
A narrow With a pure yellow, inclining to green, but 
line of Yel. not separable by refraction. The electric 
: spark furnishes alsoa light which is differ- 
ently divided in different circumstances. 
“Tf the breadth of the aperture viewed through a prism is 
somewhat increased, the space occupied by each variety of light 
in the spectrum is augmented in the same proportion, and eac 
portion encroaches on the neighboring colours, and is mixed with 
them; so that the red is succeeded by orange, yellow, and yel- 
lowish green, and the blue is mixed on the one side with the 
green, and on the other with the violet; and it is in this state 
that the prismatic spectrum is commonly exhibited. 
Fig. 4. “The appearance of a circular aperture, 
4. gla" pp ss 
- (~\ moderately large, viewed through a prism. fs 
aan. 
RED 
A ieee notwithstanding the omission of some of 
the rays naturally belonging to white light. Thus, if 
we intercept one-half of each of the a por- 
’ 
wo H 
Y the appearance of whiteness; so that it is probable 
about two parts red, four green, and one violet, with respect 
to the quantity or intensity of the sensations produ 
