We now pass to the _volatile_ or _essential oils_. These form the basis of all the vegetable perfumes, and are contained, more or less, in every part of the plant excepting the seed; they are, at least, never found in that part of the seed which contains the embrio plant. EMILY. The smell of flowers, then, proceeds from volatile oil? MRS. B. Certainly; but this oil is often most abundant in the rind of fruits, as in oranges, lemons, &c. from which it may be extracted by the slightest pressure; it is found also in the leaves of plants, and even in the wood. CAROLINE. Is it not very plentiful in the leaves of mint, and of thyme, and all the sweet-smelling herbs? MRS. B. Yes, remarkably so; and in geranium leaves also, which have a much more powerful odour than the flowers. The perfume of sandal fans is an instance of its existence in wood. In short, all vegetable odours or perfumes are produced by the evaporation of particles of these volatile oils. EMILY. They are, I suppose, very light, and of very thin consistence, since they are so volatile? MRS. B. They vary very much in this respect, some of them being as thick as butter, whilst others are as fluid as water. In order to be prepared for perfumes, or essences, these oils are first properly purified, and then either distilled with spirit of wine, as in the case with lavender water, or simply mixed with a large proportion of water, as is often done with regard to peppermint. Frequently, also, these odoriferous waters are prepared merely by soaking the plants in water, and distilling. The water then comes over impregnated with the volatile oil. CAROLINE. Such waters are frequently used to take spots of grease out of cloth, or silk; how do they produce that effect? MRS. B. By combining with the substance that forms these stains; for volatile oils, and likewise the spirit in which they are distilled, will dissolve wax, tallow, spermaceti, and resins; if, therefore, the spot proceeds from any of these substances, it will remove it. Insects of every kind have a great aversion to perfumes, so that volatile oils are employed with success in museums for the preservation of stuffed birds and other species of animals. CAROLINE. Pray does not the powerful smell of camphor proceed from a volatile oil? MRS. B.