form them.

MRS. B.

You might, indeed, almost confine that number to four; for barytes,
strontites, and the others of late discovery, act but so small a part in
this great theatre, that they cannot be reckoned as essential to the
general formation of the globe. And you must not confine your idea of
earths to the formation of soil; for rock, marble, chalk, slate, sand,
flint, and all kinds of stones, from the precious jewels to the
commonest pebbles; in a word, all the immense variety of mineral
products, may be referred to some of these earths, either in a simple
state, or combined the one with the other, or blended with other
ingredients.

CAROLINE.

Precious stones composed of earth! That seems very difficult to
conceive.

EMILY.

Is it more extraordinary than that the most precious of all jewels,
diamond, should be composed of carbon? But diamond forms an exception,
Mrs. B.; for, though a stone, it is not composed of earth.

MRS. B.

I did not specify the exception, as I knew you were so well acquainted
with it. Besides, I would call a diamond a mineral rather than a stone,
as the latter term always implies the presence of some earth.

CAROLINE.

I cannot conceive how such coarse materials can be converted into such
beautiful productions.

MRS. B.

We are very far from understanding all the secret resources of nature;
but I do not think the spontaneous formation of the crystals, which we
call precious stones, one of the most difficult phenomena to comprehend.

By the slow and regular work of ages, perhaps of hundreds of ages, these
earths may be gradually dissolved by water, and as gradually deposited
by their solvent in the undisturbed process of crystallisation. The
regular arrangement of their particles, during their reunion in a solid
mass, gives them that brilliancy, transparency, and beauty, for which
they are so much admired; and renders them in appearance so totally
different from their rude and primitive ingredients.

CAROLINE.

But how does it happen that they are spontaneously dissolved, and
afterwards crystallised?

MRS. B.

The scarcity of many kinds of crystals, as rubies, emeralds, topazes,
&c. shows that their formation is not an operation very easily carried
on in nature. But cannot you imagine that when water, holding in
solution some particles of earth, filters through the crevices of hills
or mountains, and at length dribbles into some cavern, each successive
drop may be