us substance
as might suffice for the formation of bituminous strata, no difficulty
would be left in explaining the original of fossil coal. But tho'
sufficient quantity of this fuliginous matter might not be found for the
explanation of natural appearances, yet there cannot be a doubt that
more or less of this matter must be produced in the mineral operations
of the globe, and be found precisely in that place where it is required
for the forming of those strata of coal.

In order to conceive this, we are to consider, that there are actually
great quantities of coal strata in a charred state, which indicates
that all their more volatile oleaginous or fuliginous matter had been
separated by force of subterranean heat; and, we are to suppose that
this had been transacted at the bottom of the ocean: Consequently, a
subtile oleaginous, bituminous, or fuliginous substance, must have been
diffused in that ocean; and this bituminous matter would be employed in
forming other strata, which were then deposited at the bottom of the
waters.

But besides this quantity of bituminous matter which is necessarily
formed in the mineral operations of the earth, and with regard to the
quantity of which we can never form a proper estimate, there must enter
into this same calculation all the fuliginous matter that is formed in
burning bodies upon the surface of this earth. This bituminous matter of
smoke is first delivered into the atmosphere, but ultimately it must
be settled at the bottom of the sea. Hence though, compared with the
quantity that we think required, each revolution of the globe produces
but a little in our estimation, yet the progress of time, in reforming
worlds, may produce all that is necessary in the formation of our
strata.

There now remains to explain the other way in which bituminous matter
may be obtained from vegetable bodies, that is, by means of water. For
this purpose we must begin with a part of natural history that will
throw some light upon the subject.

All the rivers in Scotland run into the sea tinged with a brown
substance; this is most evident in some of them after a flood, and while
yet the river is swelled; but, in travelling to the north of Scotland
in the summer season, without any rain, I saw all the rivers, without
exception, of a brown colour, compared with a river of more clear water.
This colour proceeds from the moss water, as it is called, which runs
into the rivers, or the infusion of th