artshorn shavings, and of calves' feet; do
these substances contain gelatine?

MRS. B.

Yes. Gelatine may be obtained from almost any animal substance, as it
enters more or less into the composition of all of them. The process for
obtaining it is extremely simple, as it consists merely in boiling the
substance that contains it with water. The gelatine dissolves in water,
and may be attained of any degree of consistence or strength, by
evaporating this solution. Bones in particular produce it very
plentifully, as they consist of phosphat of lime combined or cemented by
gelatine. Horns, which are a species of bone, will yield abundance of
gelatine. The horns of the hart are reckoned to produce gelatine of the
finest quality; they are reduced to the state of shavings in order that
the jelly may be more easily extracted by the water. It is of hartshorn
shavings that the jellies for invalids are usually made, as they are of
very easy digestion.

CAROLINE.

It appears singular that hartshorn, which yields such a powerful
ingredient as ammonia, should at the same time produce so mild and
insipid a substance as jelly?

MRS. B.

And (what is more surprising) it is from the gelatine of bones that
ammonia is produced. You must observe, however, that the processes by
which these two substances are obtained from bones are very different.
By the simple action of water and heat, the gelatine is separated; but
in order to procure the ammonia, or what is commonly called hartshorn,
the bones must be distilled, by which means the gelatine is decomposed,
and hydrogen and nitrogen combined in the form of ammonia. So that the
first operation is a mere separation of ingredients, whilst the second
requires a chemical decomposition.

CAROLINE.

But when jelly is made from hartshorn shavings, what becomes of the
phosphat of lime which constitutes the other part of bones?

MRS. B.

It is easily separated by straining. But the jelly is afterwards more
perfectly purified, and rendered transparent, by adding white of egg,
which being coagulated by heat, rises to the surface along with any
impurities.

EMILY.

I wonder that bones are not used by the common people to make jelly;
a great deal of wholesome nourishment, might, I should suppose, be
procured from them, though the jelly would perhaps not be quite so good
as if made from hartshorn shavings?

MRS. B.

There is a prejudice among the poor against a species of food that is