CAL 
CAL 
pstallecl i nectary five-leaved ; capsule five- 
celled. There is but one species, viz. C. 
capensc, which is an evergreen. Flowers 
in terininating panicles, or opposite one 
flowered peduncles. Native of the Cape. 
CALOMEL, in the materia medica, a 
name given to mercurius dulcis. See Mer- 
cury. 
CALOPHYLLUM, in botany, a genus 
of the Polyandria Monogynia class and 
order. Essential character: calyx foin- 
leaved, coloured ; corolla four-petalled ; 
drupe globular. There are two species; 
viz, C. inophyllum and C. calaba, both na- 
tives of the East and West Indies. They 
are both lofty trees, ninety feet in height, 
and twelve in thickness : leaves like those 
of the water lily. In Java they plant these 
trees about their houses, for the elegance of 
the shade and the sweetness of the flowers. 
CALOPUS, in natural history, a genus of 
insects of the order Coleoptera. Generic 
character: antenn® filiform; four feelers, 
the fore ones clavate, the hind ones fili- 
form ; thorax gibbous ; shells linear. There 
are three species; viz. the serraticornis, 
hispicoruis, and pygm®us. 
CALORIC, in chernistry, a word used to 
signify that substance or property by which 
the phenomena of heat are produced. Con- 
cerning the nature of caloric there are two 
opinions, which have divided philosophers 
ever since they turned their attention to the 
subject, Some suppose that caloric, like 
gravity, is merely a property of matter, and 
that it consists in a peculiar vibration of its 
particles; others, on the contrary, flunk 
that it is a distinct substance. Each of 
these opinions has been supported by the 
greatest philosophers; and till lately the 
obscurity of the subject has been such, that 
both sides have been able to produce ex- 
ceedingly plausible and forcible arguments. 
The recent improvements, however, in this 
branch of chemistry have gradually render- 
ed the latter opinion much more probable 
than the former : and a recent discovery, 
made by Dr. Herschel, has at last nearly 
put an end to the dispute, by demonstrating 
that caloric is not a property, but a peculiar 
substance; or at least, that we have the 
same reason for considering it to be a sub- 
stance as we have for believing that light 
is material. Dr. Herschel had been em- 
ployed in making obseiwations on the sun, 
by means of telescopes. To prevent the 
incoiwenience arising from the heat, he 
used coloured glasses; but these glasses, 
w'hen they were deep enough coloured to 
intercept the light, very soon cracked, and 
broke in pieces. This circumstance induced 
him to examine the heating power of the 
different coloured rays. He made each of 
them in its turn fall upon the bulb of a ther- 
mometer, near which two other thermome- 
ter's were placed to serve as a standard. The 
number of degrees which the thermometer 
exposed to the coloured ray rose above the 
other two thermometers indicated the heat- 
ing power of that ray. He found that the 
most refrangible rays have the least heating 
power, and that the heating power gradually 
increases as the refrangibility diminishes. 
The violet ray therefore has the smallest 
heating power, and the red ray the greatest. 
Dr. Herschel found, that flie heating power 
of the violet, green, and red rays, are to 
each other as the following numbers : 
Violet =16. 
Green = 22.4 
Red = 53. 
It struck Dr. Herschel as remaikable, 
that the illuminating power and the heating 
power of the rays follow such different laws. 
The first exists in greatest perfection in the 
middle of the spectrum, and diminishes as 
we approach either extremity; but the 
second increases constantly from the violet 
end, and is greatest at the red end. This 
led him to suspect that perhaps the heating 
power does not stop at the end of the visible 
spectrum, but is continued beyond it. He 
placed the thermometer completely beyond 
the boundai-y of flie red ray, but still in the 
line of the spectrum, and it rose still higher 
than it had done when exposed to the red 
ray. On shifting the thermometer still far- 
ther it continued to rise, and the rise did 
not reach its maximum till the thermometer 
was half an inch beyond the utmost extre- 
mity of the red ray. When shifted still far- 
ther, it sunk a little ; but the power of heat- 
ing was sensible at the distance of li inch 
from the red ray. These important experi- 
ments have been lately repeated and fully 
confirmed by Sir Henry Englefield, in the 
presence of some very good judges. 
From these it follows, that there are rays 
emitted from the sun which produce heat, 
but have not the power of illuminating ; and 
that these are the rays which produce the 
greatest quantity of heat. Consequently 
caloric is emitted from the sun in rays, and 
the rays of caloric are not the same with 
the rays of light. On examihing the other 
extremity of the spectrum. Dr. Herschel 
ascertained that no rays of caloric can be 
