COA 
box, and four on the roof of the coach, oh 
the penalty of 5s. for each passenger at 
every turnpike-gate. 
COADUNATiE, in botany; the 52d or- 
der of plants in Linnaeus’ “ Fragments of a 
Natural Method,” so named from the general 
appearance of the seed-vessels, which are 
numerous, and being slightly attached be- 
low, fonn altogether a single fruit in the 
shape of a sphere or cone, the parts of 
which are easily separated from one an- 
other. 
(COAGULATION, is tlie property of 
certain liquids becoming solid without eva- 
poration, and without their assuming a crys- 
talline form. The hardening of the white of 
an egg, by mere heat, is an example of this 
kind : the characteristic properties of the 
substance are completely changed. In their 
first state it is soluble in water; but co- 
agulated, water neither hot nor cold has any 
power over it. See Albumen. 
COAL, in mineralogy, a most important 
genus of mineral inflammables, in which is 
included the carbonaceous, and carbono- 
bituminous fossils. In the excellent dicti- 
onary by Messrs. A. and C. Aikin, this 
genus is divided into the families of brown 
coal, black coal, and mineral carbon. The 
first, or brown coal, is imperfectly bitumi- 
nous, of a brown colour and vegetable 
texture : of this there are four species. 
The second, or black coal, is perfectly bi- 
tuminous, of a black colour, and contains 
three species, of which one is the slate 
coal, which is soft and easily frangible : 
specific gravity 1.2 to 1.24; it contains 
from 57 to 64 of carbon, and from 33 to 43 
of bitumen, being a mixture of maltha 
and asphalt, and from 3 to 6 of earth and 
oxide of iron. Most of our common coals 
belong to this species, and from the differ- 
ent phenomena which they exhibit during 
combustion, a great number of varieties 
are known in the market. The canal coal 
is of this family. See Ampehtes. The 
third sor t, or mineral carbon, is destitute of 
bitumen, and consists of charcoal with va- 
rious proportions of earth and iron. There 
ore three species, of which one is plum- 
bago, or black-lead. See Black-lead. 
Coal, of all the substances which natu- 
ralists have arranged in the class of inflam- 
mables, is by far the most serviceable to 
mankind. Nature has dealt it to us with 
an unsparing hand, and has provided mines 
of this mineral which seem to defy the 
power of man to exhaust. England and 
France, where tire different branches of 
COA 
manufacture are carried to a greater extent 
and perfection than in the other countries 
of Europe, are, at the same time, the 
most abundantljf provided with mines of 
coal, as if nature was determined to second 
the exertions of an industrious people by 
giving them the best possible assistance. 
Coal is always found ih masses, sometimes 
in a heap, most frequently in beds ; but 
rarely in veins. The beds are disposed 
within the earth with different degrees of 
inclination, and in almost eveiy possible 
direction. These beds of coal are sup- 
posed by most naturalists to be a deposit 
formed by the waters of the ocean; which 
once covered our continent. They are ne- 
ver found single, but generally disposed in 
strata one above another. The beds of 
coal are separated by layers of stone, which 
are nearly of the same nature in all coal 
mines. Those which form the side and the 
top of a stratum of coal are a sort of fria- 
ble slate, containing more or less of bitu- 
men, while the bottom is generally more 
compacted and mixed with micaceous sand. 
It is remarkable that this slaty kind of 
stone, which so generally accompanies the 
coal, should frequently contain the impres- 
sions of plants, and particularly ferns, some 
of which are met with in the finest state of 
preservation. 
In Scotland, the mines of Carron, of 
Edinburgh,, and of Glasgow, are chiefly 
distinguished for their produce. There are 
three beds of coal at Carron, the first of 
which is about 40 fathoms below the surface, 
the second 50, and the third 65. Only two 
beds are worked at Edinburgh, and one of 
them is remarkable for its situation, the 
opening of the mine being hardly forty ft- 
thorns from the sea, and only three fathoms 
above high water mark. The mines of 
Glasgow stretch from the north-east to the 
south-west, andoccupy a considerable space 
of ground. Here are several beds of coal, 
placed on each other and continued 
nearly from the surface of the ground to the 
depth of three hundred feet ; but of these 
beds there are only two or three that are 
worth the trouble of working. 
The principal mines of tliis useful mine- 
ral in England are those of Newcastle and 
Whitehaven. The town of Newcastle ab- 
solutely stands on beds of coals, which ex- 
tend to a considerable distance round the 
place. There are seven or eight beds of 
this mineral, one above the other, and all 
inclined in a south-east direction ; the low- 
est is a hundred fathoms from the surface OT 
