idified, it will
never return to its fluid state.

Sulphuric acid and alcohol are each of them capable of coagulating
albumen in the same manner as heat, as I am going to show you.

EMILY.

Exactly so. --Pray, Mrs. B., what kind of action is there between
albumen and silver? I have sometimes observed, that if the spoon with
which I eat an egg happens to be wetted, it becomes tarnished.

MRS. B.

It is because the white of egg (and, indeed, albumen in general)
contains a little sulphur, which, at the temperature of an egg just
boiled, will decompose the drop of water that wets the spoon, and
produce sulphurated hydrogen gas, which has the property of tarnishing
silver.

We may now proceed to _fibrine_. This is an insipid and inodorous
substance, having somewhat the appearance of fine white threads adhering
together; it is the essential constituent of muscles or flesh, in which
it is mixed with and softened by gelatine. It is insoluble both in water
and alcohol, but sulphuric acid converts it into a substance very
analogous to gelatine.

These are the essential and general ingredients of animal matter; but
there are other substances, which, though not peculiar to the animal
system, usually enter into its composition, such as oils, acids,
salts, &c.

_Animal oil_ is the chief constituent of fat; it is contained in
abundance in the cream of milk, whence it is obtained in the form of
butter.

EMILY.

Is animal oil the same in its composition as vegetable oils?

MRS. B.

Not the same, but very analogous. The chief difference is that animal
oil contains nitrogen, a principle which seldom enters into the
composition of vegetable oils, and never in so large a proportion.

There are a few animal acids, that is to say, acids peculiar to animal
matter, from which they are almost exclusively obtained.

The animal acids have triple bases of hydrogen, carbon, and nitrogen.
Some of them are found native in animal matter; others are produced
during its decomposition.

Those that we find ready formed are:

The _bombic acid_, which is obtained from silk-worms.

The _formic acid_, from ants.

The _lactic acid_, from the whey of milk.

The _sebacic_, from oil or fat.

Those produced during the decomposition of animal substances by heat,
are the _prussic_ and _zoonic_ acids. This last is produced by the
roasting of meat, and gives it a brisk flavour.

CAROLINE.

The class of animal acids is not very extensiv