ESSENTIAL OILS OR ESSENCES

ESSENTIAL OILS OR ESSENCES.—These are all of vegetable origin, usually of a pale yellow colour; lighter than water, and nearly all liquid at the ordinary temperature. They appear to constitute the odorous and sapid principles of plants. They are slightly soluble in water, perfectly so in alcohol or ether; and they evaporate so readily that their adulteration by any of the fixed oils may be readily detected by a drop of the oil being applied to white paper. The greasy spot will entirely disappear if held before the fire, provided the essential oil be unmixed; but if a fixed oil has been added, the greasy stain will remain. They are obtained chiefly by distillation from various parts of plants, as the wood, bark, leaves, flowers, fruits, and seeds. Some, however, are obtained by expression and other means. The essential oils or essences, as they are frequently called, are arranged by chemists under the three following divisions:—

1st. Pure Hydrocarbons, the principal of which are:—Oil of Turpentine, yielded by several trees of the Nat. Ord. Coniferae, the principal of which are Pinus taeda, Linn., Pinus palustris, H. K., and Abies excelsa, Poir. It is obtained by making holes in the base of the stem, from which a very large quantity of the fluid substance called turpentine flows and is

collected in casks. This is of a light yellow colour, and of the consistency of thin honey; but soon gets hard, by the evaporation of its essential oil. Turpentine, when distilled, yields about 25 per cent. of a thin, colourless essential oil, known as spirit or oil of turpentine, which is chiefly manufactured in this country from turpentine imported from the United States; but a considerable quantity is also sent from America. Oil of Orange Peel, from the yellow part (flavedo) of the rind, is imported from Sicily, and is used in perfumery. Oil of Orange Flowers, or Oil of Neroli, from the petals of the flowers, is used in perfumery, and is imported from Italy. Oil of Orange Leaves, or Oil of Petit-grain, from the leaves and the immature fruit which falls off soon after the flowers, is used in perfumery. It is imported from Italy and France. Oil of Lemon, from the yellow portion (flavedo) of the peel of the fruit, is used largely in perfumery; and imported principally from Sicily. Oil of Bergamotte, from the rind (flavedo) of the Bergamotte orange, is used in perfumery, and is imported from Sicily. Oil of Cloves, from the spice called cloves, is used in confectionary and perfumery; and is chiefly distilled in England. Oil of Pimento, from the spice called Jamaica pepper, allspice, or pimento, is used in perfumery and confectionary; it is chiefly made in England. Oil of Caraway, from caraway seeds (the fruit of Carum Carui, L., Nat. Ord. Umbelliferae), is distilled chiefly in this country for perfumery and confectionary. Oil of Camomile, from the dried flowers of the camomile (Anthemis nobilis, L., Nat. Ord. Compositae), is prepared in England; it is used only in medicine. Oil of Juniper, from the berries of Juniperus communis, L., (Nat. Ord. Coniferae), usually imported from Holland, is used principally in veterinary medicine. Oil of Thyme, from the whole plant of Origanum vulgare, L. (Nat. Ord. Labiatae), is used in veterinary medicine; and is both made in England and imported from the continental parts. Oil of Peppermint, from the whole plant of Mentha piperita, L. (Nat. Ord. Labiatae), is used chiefly in confectionary. It is imported in considerable quantities from the United States and from the European parts; but the best is that manufactured in England, at Mitcham, in Surrey, where the cultivation of plants yielding essential oils is extensively carried on; and the distillation of the oils carried to so high a degree of perfection, that the prices realized are often nearly double that of the foreign ones.

Attar, or Otto of Roses, is procured from the leaves of the rose (Rosa centifolia, L., Nat. Ord. Rosaceae). This most delicate perfume is only made in India and Persia. The chief manufacture is at Ghazipore, on the Ganges, where thousands of acres of roses are cultivated. The petals of the flower are distilled with water, which comes over highly perfumed. This water is then set aside in basins, carefully covered over to prevent impurities being blown in; and each morning the film of oil which has risen to the surface during the cool hours of night is carefully skimmed off with a feather, and placed in small glass bottles. When pure, it is extremely valuable; the present price in this country being about 80s. per ounce. It is too generally adulterated either with the odourless fixed oil of almonds or gingly, or the sweet-scented oil of Andropogon calamus-aromaticus, a grass which yields an abundance of rose-scented essential oil. Sometimes it consists almost entirely of this sophistication; but it is coarse and disagreeable to the practised perfumer, and can easily be detected; besides which, it remains liquid at the ordinary temperature, whereas pure otto of roses is solid at 83°F. The Persian is chiefly received from Turkey, and is generally considered the best. Oil of Birch is distilled in Russia from the bark of the common birch (Betula alba, L., Nat. Ord. Betulaceae). It has a sweet cedar-like odour, and is used in dressing Russia leather, to which it communicates its peculiar smell. Lately small quantities have been imported for preparing leather in a similar manner.

2d. Oxidized Essential Oils.—Oil of Mint, distilled from the whole plant of common mint (Mentha sativa, L., Nat. Ord. Labiatae), is chiefly made in England; and used only in pharmacy. Oil of Penny Royal, distilled from the whole plant of Mentha Pulegium, L. (Nat. Ord. Labiatae), is made in England for medicinal purposes. Oil of Cassia, distilled from the bark of Cinnamomum Cassia, Blume (Nat. Ord. Lauraceae), is manufactured in China, and imported in considerable quantities, usually in chests like those used for tea, each containing four tin canisters filled with the oil. It is used in perfumery. Oil of Cinnamon, distilled from cinnamon or

Oils
Oise. the bark of Cinnamomum zeylanicum, Nuts (Nat. Ord. Lauraceæ), possesses, when pure, all the delicious flavour and pungency of the spice, and is used for similar purposes. Small quantities only are imported from Ceylon. It is frequently adulterated with oil of cassia. The essential Oil of Almonds is usually distilled from bitter almonds, although it can also be obtained from the sweet varieties quite as easily; but for economy the cake of the former, from which the fixed oil has been expressed, is chosen. When first distilled, this oil contains hydrocyanic or prussic acid, and is consequently a dangerous poison; but when purified by mixing with lime, and the proto-chloride of iron, and re-distilling, it becomes quite innocuous. Oil of Lavander, distilled from the flowers of Lavandula vera, De Cand. (Nat. Ord. Labiatae), is only used in perfumery. The best is made at Mitcham; but considerable quantities are imported from France and Italy. An inferior kind is made from the flowers of L. spica, and is known in commerce as oil of spike. Oil of Rosemary, distilled from the leaves and flowers of Rosmarinus officinalis, L. (Nat. Ord. Labiatae). It resembles oil of lavender, and is chiefly

made in England and France. Oil of Aniseed, is distilled both from the seeds of Pimpinella Anisum, L. (Nat. Ord. Umbelliferae); and from those of Illicium anisatum, L. (Nat. Ord. Magnoliaceæ). It is imported in the same manner as oil of cassia, in considerable quantities from China; and is used in medicine, perfumery, and the manufacture of liqueurs. The oils distilled from different species of the genus Andropogon (Nat. Ord. Graminaceæ) are imported from Ceylon, and used in perfumery. Oil of Citronelle, from A. citratus, De Cand., has a lemon odour. Oil of Verbena, from A. Schenanthus, Linn., resembles the perfumed verbena (Aloysia citriodora). Oil of Rose-scented Geranium (from A. Calamus-aromaticus, Royle) is also produced abundantly in India, where the native medical practitioners use it as a rubefacient for rheumatism. It is also used in perfumery, and particularly to adulterate the otto of roses.

3d. Essential Oils containing Sulphur.—This division embraces only a few chemical oils, such as oils of mustard, garlic, horse-radish, and some others of no general importance.

(T. C. A.)