should
rather think that water and caloric unite their efforts to dissolve a
body, and that the difficulty or facility of effecting this, depend both
on the degree of attraction of aggregation to be overcome, and on the
arrangement of the particles which are more or less disposed to be
divided and penetrated by the solvent.

EMILY.

But have not all liquids the same solvent power as water?

MRS. B.

The solvent power of other liquids varies according to their nature, and
that of the substances submitted to their action. Most of these
solvents, indeed, differ essentially from water, as they do not merely
separate the integrant particles of the bodies which they dissolve, but
attack their constituent principles by the power of chemical attraction,
thus producing a true decomposition. These more complicated operations
we must consider in another place, and confine our attention at present
to the solutions by water and caloric.

CAROLINE.

But there are a variety of substances which, when dissolved in water,
make it thick and muddy, and destroy its transparency.

MRS. B.

In this case it is not a solution, but simply a mixture. I shall show
you the difference between a solution and a mixture, by putting some
common salt into one glass of water, and some powder of chalk into
another; both these substances are white, but their effect on the water
will be very different.

CAROLINE.

Very different indeed! The salt entirely disappears and leaves the water
transparent, whilst the chalk changes it into an opaque liquid like
milk.

EMILY.

And would lumps of chalk and salt produce similar effects on water?

MRS. B.

Yes, but not so rapidly; salt is, indeed, soon melted though in a lump;
but chalk, which does not mix so readily with water, would require a
much greater length of time; I therefore preferred showing you the
experiment with both substances reduced to powder, which does not in any
respect alter their nature, but facilitates the operation merely by
presenting a greater quantity of surface to the water.

I must not forget to mention a very curious circumstance respecting
solutions, which is, that a fluid is not nearly so much increased in
bulk by holding a body in solution, as it would by mere mixture with the
body.

CAROLINE.

That seems impossible; for two bodies cannot exist together in the same
space.

MRS. B.

Two bodies may, by condensation, occupy less space when in union than
when se