Oil

a well known substance with a greasy, sticky feel. Oils are composed of the same chemical elements as sugar and alcohol-namely, charcoal and water. All oils are lighter than water, and are insoluble in it. There are several hundred oils, divisible into three general classes: mineral oils, fatty or fixed oils, and essential or volatile oils. The mineral or rock oils are petroleum and its various products, as kerosene, gasoline, naphtha, and the like. When reduced, they produce paraffin, vaseline, and various lubricating oils used for machinery. The fatty or fixed oils leave a permanent greasy stain on paper. They are derived from animal and vegetable sources. They differ from fats chiefly in being liquid at ordinary temperature.

Some fixed oils dry out on exposure to the air, leaving a film or varnish. These are called drying oils, and are much used in varnishes and paints. Linseed oil, derived from the seed of the flax plant, may be described as a fixed vegetable drying oil. Flaxseed yields about thirty per cent of its own weight of linseed oil. Hemp oil is pressed from the seeds of the common hemp. It is used in soapmaking, and is an adulterant for linseed oil. The seeds of the common poppy yield about forty-five per cent of their own weight of a thin, colorless, odorless oil, used in the preparation of salads and as an adulterant of olive oil, but chiefly in the preparation of the finer class of artist's colors. Sunflower oil is obtained from the seeds of the common sunflower. It is used in making soap, as an oily finish for woodwork, and also in adulterating olive oil. Cotton-seed oil is obtained from the kernels of cotton seed. It is used in soap making, as an adulterant of olive oil, and in the manufacture of axle-grease, cottolene, butterine, and oleomargarine. Sesame is an oil obtained from the seeds of an East Indian plant. It is much used as a substitute for olive oil and butter, in lamps, and in making high grade soap. Castor oil, well known in medicine and in the making of soap, is prepared from the seeds of castor oil plants.

A number of non-drying fixed oils are obtained from various vegetable and animal sources. All may be used for soapmaking. Peanut oil is pressed from peanuts. Olive oil, obtained from the fruit of the olive tree, is an important article of food in semitropical countries. Its chief use is in salads. Users also dip bread in it, using it as we do syrup and molasses. Fish oils are obtained by boiling the entire body of the fish. Cod liver oil, of particular value as a cure for consumption, is obtained from the liver of the codfish by a process of rendering by steam. Whale oil or train oil is rendered from the blubber of the Greenland or right whale. It is obtained by boiling in water. It is a valuable oil in dressing leather and in tempering steel. It was much used formerly for illuminating purposes. Sperm oil is obtained from the blubber and head cavity of the sperm whale. It is one of the most valuable lubricating oils and is used also for tempering steel. Neat's foot oil, a valuable lubricator and dressing for leather, is obtained by boiling the feet and shin bones of cattle in water. Lard oil is a liquid pressed out of cold lard. Of the fats, lard is, of course, prepared from the fat of the hog, and tallow from the solid fat of the sheep or ox. Palm oil is prepared from the fruit of several varieties of palms found chiefly on the west coast of Africa. It is much used for candles and soap, also as a lubricant.

Volatile oils are so called because they evaporate readily at ordinary heat. They leave no stain. They are called essential oils also. When absorbed by alcohol they make the essences or perfumes; as essence of peppermint, essence of wintergreen, etc. A brief description of the essential oils would occupy 300 pages of this volume. They are all alike in at least one respect,--that molecules or fine particles escape freely into the air until the oil has evaporated. It is this quality of volatility or easy evaporation which enables the rose or other flower to spread its odor abroad. The volatile oils of commerce are obtained chiefly by distilling a portion of the plant. This may be the root, the wood, the inner bark, the outer bark, the leaves, the bud, the petals, the entire flower, the seed pod, seed kernel, or the entire plant. Their preparation gives employment to many thousands of people. A catalog of these oils includes sixty-one families of plants from which volatile, that is to say, aromatic oils are obtained.

Some of the prominent volatile oils are fern oil, obtained from the stems of various ferns; oil of turpentine, from the pines and firs; oil of cypress, from the wood of the cypress; sequoia oil, from the needles of the California giant; and hemlock oil, from the needles and twigs of the hemlock. Juniper berries, juniper wood, red cedar wood, cedar leaves, and the wood of the Lebanon cedar yield oils of the name. A number of grasses belonging to the genus Andropogon yield the ginger-grass, lemon-grass, cardamon-grass, and citronella oils of the druggist. Palmetto oil is obtained from the berries of the saw-palmetto. The aloe plant, garlic, leek, onion, saffron, and orris or iris yield characteristic oils. Ginger oil, cardamon oil, black pepper oil, oil of cubebs, oil of betel leaves, bayberry oil, and sweetbirch oil are obtained from the plants of that name. Oil of hops, of hemp, of ginger, of anise leaves, of mace, of nutmeg, of camphor, of cinnamon, of cassia, of cloves, of sassafras, of laurel, of mustard, of watercress, of mignonette, of bitter almond, of wild cherry, of tolu, of rose-geranium, of rue, of lemon, of sweet orange, of bitter orange, of bergamot, of myrrh, of sandalwood, of senega root, of tea, of pimento, of bay, of cloves, of eucalyptus, of celery, of parsley, of caraway, of fennel, of asafoetida, of dill, of Labrador tea, of wintergreen, of jasmine, of verbena, of rosemary, of lavender, of spike, of catnip, of sage, of pennyroyal, of hyssop, of sweet marjoram, of thyme, of peppermint, of spearmint, of elder, of valerian, of camomile, of tansy, of feverfew, of wormseed, of wormwood, and of arnica, are only a few of the many essential oils derived from vegetable sources. As stated before, they are composed of carbon, hydrogen, and oxygen, each with some peculiar property of its own. The mint family is remarkable for its oils. The frankincense of the Orientals and attar-of-roses are well known volatile oils. The delightful fragrance of peach and apple blossoms, of new mown hay, of corn-fodder, of sweet clover, and of the plant world in general is due to the escape of essential oils. Many of the essential oils may now be produced in the laboratory of the chemist. The flavor of pineapple may be obtained from rancid butter and alcohol.

See Petroleum; Perfume; Paint; Distillation; Flax