ay thus receive some illustration.

Sandstone, coal, and their accompanying strata, are thought to be
destitute of calcareous marine productions, although many vestiges of
plants or vegetable productions are there perceived. But this general
opinion is neither accurate nor true; for though it be true that in the
coal and sandstone strata it is most common to find marks of vegetable
production, and rarely those calcareous bodies which are so frequent in
the limestone, yet it is not unusual for coal to be accompanied
with limestone formed of shells and corals, and also with ironstone
containing many of those marine objects as well as wood. Besides,
sandstone frequently contains objects which have been organised bodies,
but which do not belong to the vegetable kingdom, at least to no plant
which grows upon the land, but would seem to have been some species of
zoophite perhaps unknown.

I have also frequently seen the vestige of shells in sandstone, although
in these strata the calcareous bodies are in general not perceived.
The reason of this is evident. When there is a small proportion of the
calcareous matter in the mass of sand which is pervious to steam and to
the percolation of water, the calcareous bodies may be easily dissolved,
and either carried away or dispersed in the mass; or even without being
thus dispersed by means of solution, the calcareous matter may be
absorbed by the siliceous substance of the stratum by means of fusion,
or by heat and cementation. The fact is, that I have seen in sandstone
the empty mould of marine shells with some siliceous crystallization,
so far as I remember, which corresponded perfectly with that idea. The
place I saw this was in a fine white sandstone accompanying the coal,
upon the sea side at Brora in Sutherland.

Mineralogy is much indebted to Mr Pallas for the valuable observations
which he has given of countries so distant from the habitations of
learned men. The physiology of the globe has also been enriched with
some interesting observations from the labours of this learned traveller.
But besides giving us facts, Mr Pallas has also reasoned upon the
subject, and thus entered deep into the science of Cosmogeny; here it
is that I am afraid he has introduced some confusion into the natural
history of the earth, in not properly distinguishing the mineral
operations of the globe, and those again which belong entirely to the
surface of the earth; perhaps also in confounding th