the portions first consolidated must have been
shattered by considerable violence. But, where no such fragments exist,
the unequal diffusion of components at first uniformly mixed, and even
the formation of nodules differing in proportions from the paste which
surrounds them, may perhaps admit of explanation, by some process
analogous to what takes place in the preparation of the compound of which
the ordinary earthenware is manufactured; where, though the ingredients
are divided by mechanical attrition only, a sort of chemical action
produces, under certain circumstances, a new arrangement of the parts.*
And this explanation may, probably, be extended to those nodular
concretions, generally considered as contemporaneous with the paste in
which they are enveloped, the distinction of which, from conglomerates of
mechanical origin, forms, in many cases, a difficulty in geology. What
the degree may be, of subdivision required to dispose the particles to
act thus upon each other, or of fluidity to admit of their action,
remains still to be determined.

(*Footnote. The clay and pulverized flints are combined for the use of
the potter, by being first separately diffused in water to the
consistence of thick cream, and when mixed in due proportion are reduced
to a proper consistence by evaporation. During this process, if the
evaporation be not rapid and immediate, or if the ingredients are left to
act on each other, even for twenty-four hours, the flinty particles unite
into sandy grains, and the mass becomes unfit for the purposes of the
manufacturer. I am indebted for this interesting fact, which, I believe,
is well known in some of the potteries, to my friend Mr. Arthur Aikin.
And Mr. Herschel informs me, that a similar change takes place in
recently precipitated carbonate of copper; which, if left long moist,
concretes into hard gritty grains, of a green colour, much more
difficultly soluble in ammonia than the original precipitate.)

6. As the superficial extent of Australia is more than three-fourths of
that of Europe, and the interior may be regarded as unknown,* any
theoretic inferences, from the slight geological information hitherto
obtained respecting this great island, are very likely to be deceitful;
but among the few facts already ascertained respecting the northern
portion of it, there are some which appear to afford a glimpse of general
structure.

Captain Flinders, in describing the position of the chains o