EMILY.
There is, however, one very considerable class of elements, which seems to be confined to the mineral kingdom: I mean metals.
MRS. B.
Not entirely; they are found, though in very minute quantities, both in the vegetable and animal kingdoms. A small portion of earths and sulphur enters also into the composition of organised bodies. Phosphorus, however, is almost entirely confined to the animal kingdom; and nitrogen, but with few exceptions, is extremely scarce in vegetables.
Let us now proceed to examine the nature of the three principal materials of the animal system.
Gelatine, or jelly, is the chief ingredient of skin, and of all the membranous parts of animals. It may be obtained from these substances, by means of boiling water, under the forms of glue, size, isinglass, and transparent jelly.
CAROLINE.
But these are of a very different nature; they cannot therefore be all pure gelatine.
MRS. B.
Not entirely, but very nearly so. Glue is extracted from the skin of animals. Size is obtained either from skin in its natural state, or from leather. Isinglass is gelatine procured from a particular species of fish; it is, you know, of this substance that the finest jelly is made, and this is done by merely dissolving the isinglass in boiling water, and allowing the solution to congeal.