8140 COLCHICUM. 
and which usually contain thirty-six bushels of 
coal, A door serves the common purpose of in- 
troducing the coal and admitting air, and a 
chimney is built to carry off smoke and promote 
a circulation of air through the oven while the 
coal is burning; and as soon as the burning has 
been carried to a sufficient extent, the door and 
chimney are both closed, and luted with moist 
clay, so that no more air can enter, and in this 
state the oven is left some hours for cooling, 
when the coke is drawn out by a large wide iron 
shovel called a peel, which is supported by a 
chain from a small swinging crane or gibbet. 
Water is thrown on the coke after it is dis- 
charged, to prevent its rekindling, and it is like- 
wise said to harden and improve it. After the 
coke is withdrawn, the oven will retain sufficient 
heat to re-kindle the next charge of coals, which 
is immediately introduced, and each charge of 
36 bushels generally requires 24 hours for its 
coking, so that the oven may be charged daily 
and kept at constant work. Coke swells so much 
in its formation, that 36 bushels of coal will pro- 
duce from 45 to 48 bushels of coke; and when it 
is good and well burnt it becomes very hard, has 
a shining and almost metallic lustre, and is very 
sonorous. Notwithstanding that coke is better 
and more economically made in a close oven than 
in any other way, yet such ovens are too tedious 
and expensive for large iron works at which the 
coke is constantly made on the open ground. 
The coal is piled up in long heaps, and after 
being ignited and suffered to burn a sufficient 
time, earth is dug and thrown upon them until 
the air is thought to be quite excluded, and the 
heaps are then watered through the earth, and 
are not opened until the coke becomes quite cold. 
—Mullington. 
COLCHICUM. A genus of ornamental, bulb- 
ous rooted plants, of the melanthium tribe. The 
autumnal or meadow-saffron species, C. autum- 
nale, grows wild in the meadows of many parts of 
Britain, and is particularly abundant in Suffolk 
and Hssex. Its bulb is solidand egg-shaped, and 
covered with a brown, membranous skin; its 
leaves are radical, lanceolate, and about five 
inches in length and half an inch in extreme 
breadth,—and they appear in spring, and wither 
wholly away before the end of summer ; and its 
flowers spring direct from the offsets of the 
bulb whose leaves have decayed,—they comprise 
a segmented tubular corolla, of about five inches 
in length, two-thirds of which are below the 
ground, and subulate yellow-anther-bearing fila- 
ments of half the length of the segments of the 
corolla,—and they have a pale pinkish lilac col- 
our, and appear in September and October. The 
bulbs have strongly acrid, narcotic, poisonous 
properties; and figure among the materia medica 
of the British pharmacopeias. An instance is 
recorded of their having been accidentally boiled 
with potatoes, and in consequence poisoning a 
whole family. So small a quantity as from three 
‘diseases for which it is prescribed are dropsy, 
COLD. 
to nine grains of the dried bulbs is a full medi- 
cinal dose; so that this drug is vastly too active 
to be played with by quacks and empirics. The 
humoral asthma, gout, rheumatism, and various 
disorders of the gall-duct and the nerves. A 
milky-looking acrid juice exudes from a trans- 
versely-cut, fresh bulb; and this, when treated 
with alcoholic solution of guiacum, produces a 
beautiful coerulean blue colour. A peculiar alka- 
line principle, variously called colchicia and ve- 
ratrine, is obtainable from the bulbs, and seems 
to comprise all their medicinal and narcotic pow- 
er; it takes the form of a white powder, and is 
easily soluble in alcohol; and it consists of 66°75 
per cent. of carbon, 19°6 of oxygen, 8°54 of hydro- 
gen, and 5:04 of nitrogen. The other constitu- 
ents of the bulbs are lignin, inulin, starch, gum, 
malic acid, fatty matter, and a yellow colouring 
matter. The petals, the leaves, the seed-vessels, 
and the seeds all more or less partake of the 
active principles of the bulbs, and ought, as much 
as possible, to be kept out of the way of children, 
and even of cattle. A French veterinary journal 
relates a case of twelve cows, which were sud- | 
denly seized with very alarming symptoms, in 
consequence of eating the leaves and the seed- 
vessels, and states that they were restored in the 
course of two or three days by the use of strong 
decoctions of linseed.—Six varieties of the autum- 
nal colchicum are grown in British gardens as 
ornaments of the parterre,—the white-flowered, 
the double-flowered, the striped double-flowered, 
the variegated-leaved, the purple-striped, and 
the dark purple; and nine other species, all 
hardy, and principally purple-flowered, have been 
introduced from the Crimea, the Levant, Chio, 
Hungary, and the south of Europe. | 
COLD. A peculiar sensation excited in ani- | 
mals, when substances at an inferior temperature 
are applied to their organs of feeling. It is also 
used to denote a certain principle or power resid- | 
ing in bodies, by the operation of which the sensa- | 
tion is produced. It was long considered doubtful 
whether this principle ought to be regarded asa | 
distinct condition of matter, or as a mere modi- | 
fication of caloric; though almost all men of 
science are now disposed to consider it in the 
latter point of view. 
The means, with which we are acquainted, of 
reducing the temperature of bodies, are much 
more limited in their effects, than those of in- 
creasing it. But many important facts connected 
with the production of cold have already been 
discovered; and though we can scarcely expect 
ever to acquire the same extensive command 
over the lower, as we already possess over, the 
higher temperatures, we have reason to hope, 
that since we know the circumstances upon 
which refrigeration depends, processes of cooling 
may yet be discovered still more effectual than 
any that have hitherto been employed. The 
various methods of producing cold, which are at 
