consolidated and raised as land,
and then submerged in order to be again fused and elevated.

_II.--The Nature of Mineral Coal_

Mineral, or fossil, coal is a species of stratum distinguished by its
inflammable and combustible nature. We find that it differs in respect
to its purity, and also in respect to its inflammability. As is well
known, some coals have almost no earthy ash, some a great deal; and,
again, some coals burn with much smoke and fire, while others burn like
coke. Where, then, did coal come from, and how can we account for its
different species?

A substance proper for the formation of coaly matter is found in
vegetable bodies. But how did it become mixed with earthy matter?

Vegetable bodies may be resolved into bituminous or coaly matter either
by means of fire or by means of water. Both may be used by nature in
the formation of coal.

By the force of subterranean heat vegetable matter may have been charred
at the bottom of the sea, and the oleaginous, bituminous, and fuliginous
substances diffused through the sea as a result of the burning may have
been deposited at the bottom of the sea as coal. Further, the bituminous
matter from the smoke of vegetable substances burned on land would
ultimately be deposited from the atmosphere and settle at the bottom of
the sea.

Many of the rivers contain in solution an immense quantity of
inflammable vegetable substance, and this is carried into the sea, and
precipitated there.

From these two sources, then, the sea gets bituminous material, and this
material, condensed and consolidated by compression and by heat, at the
bottom of the sea, would form a black body of a most uniform structure,
breaking with a polished surface, and burning with more or less smoke or
flame in proportion as it be distilled less or more by subterranean
heat. And such a body exactly represents our purest fossil coal, which
gives the most heat and leaves the least ash.

In some cases the bituminous material in suspension in the sea would be
mixed more or less with argillaceous, calcareous, and other earthy
substances; and these being precipitated along with the bituminous
matter would form layers of impure coal with a considerable amount of
ash.

But there is still a third source of coal. Vegetable bodies macerated in
water, and consolidated by compression, form a body almost
indistinguishable from some species of coal, as is seen in peat
compressed under a great load of e