46% 
consider it as an argillaceous schistus, 
impregnated with bitumen; which in- 
deed, may be the case with some species; 
which, however, ought rather to be 
called bituminous schistus, than coal; 
in the best kinds of which, there “is too 
little argillaceous matter, to consider it 
as an essential part of its composition, 
The most generally received opinion is, 
that vegetable matter is converted into 
coal; but we know no similar fact or ex- 
periment, from the analogy of which we 
can infer the possibility of such conver- 
sion. I believe, indeed, that in all or 
most coals the vestiges of vegetable 
fibres, like the charcoal of burnt leaves, 
are to be seen ; not however forming the 
whole substance of the cecal, but inter- 
spersed as thin laminew, between the 
thicker. and more shining bituminous 
layers of the coal. We know also, that 
m all coal mines, the superincumbent 
strata of clunch and rock contain 
abundance of vegetable impressions, 
ehiefly of reeds and broad leaves, like 
the stems and fuliage of aquatic plants. 
The substance or body of the reed is 
sometimes rock, and sometimes iron ore; 
and its surface only is covered with a 
thin coat of coal, asif the rocky, or fer- 
ruginous matter, which filled up the 
space which had been occupied by the 
decayed vegetable, had, by the contrac- - 
tion of drying, left an interval, which 
was afterwards filled up by a bitumen, 
whether that bitumen came in a liquid 
form, or in the state of a distilled and 
condensed vapour, or whether it was the . 
remaining oil and resin of the plant, 
hardened by age; that is, according to 
late experiments, by absorption of air. 
But in the coal mine, we do not find any 
forms of plants, or any vegetable trace, 
but those resemblances which I have 
mentioned to the formation of the fibres 
of charcoal, which cross each other in all 
directions ; and by their want of gloss, 
are distinguished trom the more bitumi- 
nous parts of the coal. These fibres 
are, however, not in quality real char- 
coal; but true fossil coal. How much 
then these vegetable matters, which 
originally formed the bed, which 1s now 
the coal, have contributed to the for- 
mation of this substance, is a question 
very dificult to determine; whether, by 
some Operation unknown to our che- 
mistry, they have been compressed into 
asubstance apparently so different -from 
them, or whether they have done little 
but furnish, by their decay, spaces into 
which the bitumen might be collected 
i 
Mineralogy of the South-West of Staffordshire. [Dec. 3, 
and dep. ‘hat might have beet 
raised or distitied from iaferior beds of 
vegetable J: animal matter, by subter- 
ranean heat; or which might have béen 
ejected from the bowels of the earth, in 
a fluid state, and insinuated itself into 
these spaces formed by decayed ve-= 
getables; as the same fluid bitumen has 
been seen by late observers to be thrown 
out of Vesuvius. Some kinds of ceal 
are entirely free from vegetable vestiges, 
and are an uniform compact bitumen. 
Such is that which is to be found in the 
cavities of calcareous rocks. According 
then to this opinion, which seems to me 
to be the most probable, the vegetables 
have done little more towards the for- 
mation of coal, than to farnish a more 
convenient space for the insinuation of 
this ejected, or distilled bitumen, than 
the more solid strata. ; 
But in whatever manner coal may 
have been formed, an important infer- 
ence may be drawn trom the uniformity 
of the several beds composing the ten- 
yard coal, in respect to their qualities, | 
thickness, and relative position, over an - 
extent of many square miles; viz. that 
the coal has been formed all over the 
country at the same time, and lkewise 
upon level ground; for, what but the 
greatest regularity of surface could have 
given such uniformity to the disposition 
of the vegetable matter, which either 
formed the coal, or gave occasion and 
place for its formation. But a level 
surface of great extent must be accom- 
panied with a marsh, from the want of 
defluxion to the waters; and from the 
great abundance of the iimpressiens of 
the stems and leaves of aquatic plants, 
it may be inferred, that such had actually 
been the state of the surface of the 
ground, when these beds were formed in 
which the coal afterwards existed. The 
formation of coal, must therefore be re- 
ferred to a very remote period, even in 
the history of the earth, as it must have 
preceded the existence >f mountains, 
and of those inequalities of surface, 
which are essential to the life of all but 
aquatic animals and vegetables. The 
shells of marine animals seem to have 
furnished the substance of those immense 
beds of lime-stone, which enveloped 
those strata, which were increased by 
the gradual accumulation of those ani- 
mal exuvie at the surface of the sea: 
Another important inference, which 
perfectly coincides with the former, may 
be drawn from the abrapt termination, 
or cropping out, of the coal, along the 
' lune-stone 
