nd it certainly helps us to believe that a thing has been
done, if we are shown that it can be done.

This fact explains, also, why in mines of wood-coal carbonic acid,
i.e. choke-damp, alone is given off. For in the wood-coal a great
deal of the hydrogen still remains. In mines of true coal, not only
is choke-damp given off, but that more terrible pest of the miners,
fire-damp, or explosive carburetted hydrogen and olefiant gases. Now
the occurrence of that fire-damp in mines proves that changes are
still going on in the coal: that it is getting rid of its hydrogen,
and so progressing toward the state of anthracite or culm--stone-coal
as it is sometimes called. In the Pennsylvanian coal-fields some of
the coal has actually done this, under the disturbing force of
earthquakes; for the coal, which is bituminous, like our common coal,
to the westward where the strata are horizontal, becomes gradually
anthracite as it is tossed and torn by the earthquake faults of the
Alleghany and Appalachian mountains.

And is a further transformation possible? Yes; and more than one.
If we conceive the anthracite cleared of all but its last atoms of
oxygen, hydrogen, and nitrogen, till it has become all but pure
carbon, it would become--as it has become in certain rocks of immense
antiquity, graphite--what we miscall black-lead. And, after that, it
might go through one transformation more, and that the most startling
of all. It would need only perfect purification and crystallisation
to become--a diamond; nothing less. We may consider the coal upon
the fire as the middle term of a series, of which the first is live
wood, and the last diamond; and indulge safely in the fancy that
every diamond in the world has probably, at some remote epoch, formed
part of a growing plant.

A strange transformation; which will look to us more strange, more
truly poetical, the more steadily we consider it.

The coal on the fire; the table at which I write--what are they made
of? Gas and sunbeams; with a small percentage of ash, or earthy
salts, which need hardly be taken into account.

Gas and sunbeams. Strange, but true.

The life of the growing plant--and what that life is who can tell?--
laid hold of the gases in the air and in the soil; of the carbonic
acid, the atmospheric air, the water--for that too is gas. It drank
them in through its rootlets: it breathed them in through its leaf-
pores, that it