Sugar may be decomposed by a red heat, and, like all other vegetable substances, resolved into carbonic acid and hydrogen. The formation and the decomposition of sugar afford many very interesting particulars, which we shall fully examine, after having gone through the other materials of vegetables. We shall find that there is reason to suppose that sugar is not, like the other materials, secreted from the sap by appropriate organs; but that it is formed by a peculiar process with which you are not yet acquainted. CAROLINE. Pray, is not honey of the same nature as sugar? MRS. B. Honey is a mixture of saccharine matter and gum. EMILY. I thought that honey was in some measure an animal substance, as it is prepared by the bees. MRS. B. It is rather collected by them from flowers, and conveyed to their store-houses, the hives. It is the wax only that undergoes a real alteration in the body of the bee, and is thence converted into an animal substance. Manna is another kind of sugar, which is united with a nauseous extractive matter, to which it owes its peculiar taste and colour. It exudes like gum from various trees in hot climates, some of which have their leaves glazed by it. The next of the vegetable materials is _fecula_; this is the general name given to the farinaceous substance contained in all seeds, and in some roots, as the potatoe, parsnip, &c. It is intended by nature for the first aliment of the young vegetable; but that of one particular grain is become a favourite and most common food of a large part of mankind. EMILY. You allude, I suppose, to bread, which is made of wheat-flower? MRS. B. Yes. The fecula of wheat contains also another vegetable substance which seems peculiar to that seed, or at least has not as yet been obtained from any other. This is _gluten_, which is of a sticky, ropy, elastic nature; and it is supposed to be owing to the viscous qualities of this substance, that wheat-flour forms a much better paste than any other. EMILY. Gluten, by your description, must be very like gum? MRS. B. In their sticky nature they certainly have some resemblance; but gluten is essentially different from gum in other points, and especially in its being insoluble in water, whilst gum, you know, is extremely soluble. The _oils_ contained in vegetables all consist of hydrogen and carbon in various proportions. They are of two kinds, _fixed_ and _volatile_, both of which we formerly mentioned. Do you remember in what the difference between fixed and volatile oil consists? EMILY. If I recollect rightly, the former are decomposed by heat, whilst the latter are merely volatilised by it. MRS. B.