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 that vegetable substance which
forms combustible turf, called peat.
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