ties, and then made solid, after pyrites
had been introduced into those cavities of the agate, and, as our author
expresses it, _parsemee pour toute la substance?_ Here are suppositions
which are not only perfectly gratuitous, but are also inconsistent with
any thing that we understand. This is not explaining nature; it is only
feigning causes[39].

[Note 39: The description of those insulated siliceous bodies,
containing in their closed cavities all the usual concretions of
calcedony and crystals, as well as full of small pyrites floating in the
solid flint, are extremely interesting to a mineral system, or such a
geological theory as should explain the present state of things in those
strata that had been formed by deposits of known materials at the bottom
of the sea; they are indeed such appearances as may be found, more or
less, in all consolidated strata. But it is this author's explanation of
that petrifaction which is our present object to consider; and, as he is
so particular in giving us his theory upon the subject, it is easy to
detect the error of his reasoning. Were those naturalists who explain
things only in general, by saying that water is the agent, and
infiltration the means employed by nature;--were these naturalists, I
say, to give us as particular a description of their process, it would
appear as inconsistent with the nature of things as that which we have
from this author, who examines nature very minutely, and who sees
distinctly that the infiltrating theory is inapplicable for the
explanation of those petrifactions.]

The third section has for title, "_Generation du Silex et Quartz de la
Pierre Puante_." Here we find an example worthy of being recorded,
as contributing to throw great light upon those mineral operations;
however, the opinion of our author and mine, upon this subject, differ
widely. He proceeds thus:

"Cette pierre n'est, comme chacun le scait, qu'une pierre calcaire
contenant du bitume.

"Nos montagnes n'en contiennent seulement pas de simples couches, mais
il y en a meme de grandes bancs fort epais.

"Le caillou, ou silex qui s'y genere, forme, tantot de gros blocs
informes, qui occupent des cavites dans l'interieure des montagnes,
tantot, enfin, en forme de filons.

"J'ai remarque cette metamorphose sur trois endroits differens, dans
chacun des quels la nature a autrement opere.

"Sur l'un, la pierre puante fait un banc horizontal dans une montagne de
pierre calcaire cr