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360° On the Refraction of Light. * 
ai intermediate refraction, and: must necessarily occupy, on the spec- 
trum, a position between the red and the yellow. ‘The violet rays, 
being most rare, penetrate the thickest part of the prism, and con- 
— being most refracted, must occupy the summit of the spec- 
trum. It would follow, from this theory, that a beam of white light, 
eipaternttion a double dies lens, would undergo analysis, and 
paint many ‘ spectra, .on a white surface at some distance from its focus, 
since the lens is of unequal thickness. Such is really the case, 
iene the colors produced cannot separ ately affect the retina, from 
thé circumstance of their being developed in so many points of 
the lens, and blending so intimately together as to make white light. 
But that light is decomposed by the Jens, may be proved thus? 
Attach to the back of the lens a disk of sheet lead having any num- 
ber of punctures, and let a beam of light, entering a dark chamber, 
strike on the lead; at some distance beyond the focus, hold a sheet 
of letter paper,» one the image of each hole in the disk will be seen 
occupied by a apeetont. glowing with the “primitive colors. The 
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caloric, per se, is not subject FY Ke laws of refraction. When united: with ht, 
in a combination which may be called chemical, it accompanies its rays, as & neces» 
sary and indispensable agent. The combination of caloric with the red'rays seems 
to be in a certain invariable ratio above the surrounding temperature, and that ame 
is drectly as the density of the colorific rays. 1t becomes thus, easy to pee 
different colors or | en we reflect that caloric is held, chemically ¢ a 
with the atoms of each color of igbt, as the more the colorific rays are eonilensed, 
the more sensibly will their eveloped. That heat should be found beneath 
the apparent base of the spectrum may seem at first paradoxical ; but when it's 
recollected, that the illuminating, or pro perly. lucific rays, through which alon @ ob- 
_ jects are visible, are totally Sistinns Feed the colorific rays, the anomaly iamedatel 
_wanishes. For the densest-rays may be colleeted where sensible caloric predomt 
with the illuminating rays. That.a fluid, like caloric, perfectly homogeneous in all 
its parts, and producing uniformly the same effects, should consist of differently te 
frangible ra rays, is an hypothesis, so diametrically Sepuiptalat to all philosop ical prin- 
ciples, that it is wonderful it should have received a moment’s consideration. 
