t seen that they are the same in the
one case as in the other. Neither does time count for anything here,
since, according to accepted ideas, the burial having been longer, the
carbonization ought to have been more perfect, while the contrary is the
case.

If we admit (1) that vegetable remains alter more and more through
maceration in ordinary water and in certain mineral waters; (2) that,
beginning with their burial in sufficiently thick strata of clay and sand,
their chemical composition scarcely varies any further; and (3) that these
are important changes only as regards their physical properties, due to
loss of water and compression, we succeed quite easily in learning what
has occurred.

In fact, when, as a consequence of the aforesaid alteration, the vegetable
matter had taken the chemical composition that we find in the less
advanced coal of the pebbles, it was in the first place covered with sand
and protected against further destruction, and it gradually acquired the
physical properties that we now find in it. At the period that channels
were formed, the coal was torn from the beds in fragments, and these
latter were rolled about for a time, sometimes being broken, and then
covered anew, and this too at the same time as were the plants less
advanced in composition that we meet with at the same level. These latter,
being like them protected against ulterior alteration, we now find less
advanced in carbonization (notwithstanding their more ancient origin) than
the other vegetable fragments that were converted into coal after them,
but that were more thoroughly altered at the time of burial.

There are yet a few other important deductions to be made from the
foregoing facts: (1) the same coal basin may, at the same level, contain
fragments of coal of very different ages; (2) its contour may have been
much modified owing to the ravines made by the water which transported the
ancient parts into the lowest regions of the basin; and (3) finally, since
the most recent sandstones and schists of the same basin may contain coal
which is more ancient, but which is formed from the same species of plants
that we find at this more recent level, we must admit that the conversion
of the vegetable tissues into coal was relatively rapid, and far from
requiring an enormous length of time, as we are generally led to believe.

If, then, lignites have not become soft coal, and if the latter has not
become anthracite, it is not th