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. EMILY. The wine, lemon, and spices, are, I suppose, added only to flavour the jelly? MRS. B. Exactly so. CAROLINE. But jelly is often made of hartshorn 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.