which would be beneficial to it. The well-informed,
though by no means exempt from error, have an unquestionable advantage
over the illiterate, in judging what is likely or not to prove
serviceable; and therefore we find the former more ready to adopt such
discoveries as promise to be really advantageous, than the latter, who
having no other test of the value of a novelty but time and experience,
at first oppose its introduction. The well-informed, however, are
frequently disappointed in their most sanguine expectations, and the
prejudices of the vulgar, though they often retard the progress of
knowledge, yet sometimes, it must be admitted, prevent the propagation
of error. --But we are deviating from our subject.

We have converted steam into water, and are now to change water into
ice, in order to render the latent heat sensible, as it escapes from the
water on its becoming solid. For this purpose we must produce a degree
of cold that will make water freeze.

CAROLINE.

That must be very difficult to accomplish in this warm room.

MRS. B.

Not so much as you think. There are certain chemical mixtures which
produce a rapid change from the solid to the fluid state, or the
reverse, in the substances combined, in consequence of which change
latent heat is either extricated or absorbed.

EMILY.

I do not quite understand you.

MRS. B.

This snow and salt, which you see me mix together, are melting rapidly;
heat, therefore, must be absorbed by the mixture, and cold produced.

CAROLINE.

It feels even colder than ice, and yet the snow is melted. This is very
extraordinary.

MRS. B.

The cause of the intense cold of the mixture is to be attributed to the
change from a solid to a fluid state. The union of the snow and salt
produces a new arrangement of their particles, in consequence of which
they become liquid; and the quantity of caloric, required to effect this
change, is seized upon by the mixture wherever it can be obtained. This
eagerness of the mixture for caloric, during its liquefaction, is such,
that it converts part of its own free caloric into latent heat, and it
is thus that its temperature is lowered.

EMILY.

Whatever you put in this mixture, therefore, would freeze?

MRS. B.

Yes; at least any fluid that is susceptible of freezing at that
temperature. I have prepared this mixture of salt and snow for the
purpose of freezing the water from which you are desirous of seeing the
latent hea