The American Cyclopædia (1879)/Turpentine, Oil of

TURPENTINE, Oil of, called also spirits of turpentine, the volatile oil distilled from turpentine, and naturally contained in the wood, bark, and leaves of the trees from which it is obtained. It is prepared by distilling the crude turpentine either alone or with water. It was formerly supposed that all the oils thus obtained, which have the formula C₁₀H₁₆, had the same properties; but recent investigations, particularly by Berthelot, show that the oils obtained from different sources possess different physical (particularly optical) properties, and that they are generally mixtures of two or more isomeric or polymeric hydrocarbons; and furthermore, that the modifications are often produced hy heat and chemical reagents during the distillation or purification of the oil. But they all belong to the class of terpenes, of which the volatile oils of aurantiaceous plants, as the orange and lemon, are members, as well as the oils of caraway, juniper, and lavender, which are isomeric; also the oils of copaiba and cubebs, which are polymeric (C₂₀H₃₂). These terpenes are members of a large group, designated by Berthelot as camphenes, which also have the formula C₁₀H₁₆. The several varieties of turpentine oil, when purified by repeated rectification with water, are colorless mobile liquids having a peculiar aromatic odor. They are insoluble in water, slightly soluble in aqueous alcohol, but dissolve in all proportions in absolute alcohol, ether, and bisulphide of carbon. They dissolve iodine, sulphur, and phosphorus, and also fixed oils and resins, on which account they are used for mixing with paints and for making varnishes. The oils of different origin vary slightly as to specific gravity and boiling point, but more particularly in regard to their optical rotatory power; but many of them are derived from several sources, and as before remarked vary when of the same origin on account of different modes of preparation. French turpentine oil, obtained from French or Bordeaux turpentine, consists of a hydrocarbon, C₁₀H₁₆, called by Berthelot terebenthene. It cannot be readily obtained from the commercial oil, which is too much contaminated with products of transformation, but may be obtained pure by treating French turpentine with an alkaline carbonate, and distilling it first over a water bath and then in a vacuum, by which transformation by heat or reagents is avoided. Terebenthene obtained in this way has a constant specific gravity of 0.864, a boiling point of 321.8° F., and a rotatory power of -43.3°. (See Light, Optics, and saccharimetry in the article Sugar.) This oil also contains an isomeric hydrocarbon, terepentilene, boiling below 356° F., and also a polymeric oil, parterebenthene, which boils at about 482°. The principal oil contained in English turpentine is australene, or austraterebenthene, having the same specific gravity and boiling point as the French oil terebenthene, but an optical rotatory power of +21.5°. The English oil also contains, according to Berthelot, an isomeric body called australene. Both the English and French oils, before their constituents are separated, possess rather less rotatory power. Venetian oil of turpentine has a rotatory power of -5.2°. All these oils possess the common property of absorbing oxygen from the air and ultimately becoming resinous, at the same time producing carbonic, acetic, and formic acids. In this gradual oxidation ozone is produced, as it is more rapidly by dipping a warm glass rod in a jar filled with vapor of turpentine; and turpentine oil exposed for some time to the sun's rays contains oxygen and ozone in solution. A paper soaked in oil of turpentine and immersed in a jar of chlorine takes fire, producing a dense black smoke and white fumes of hydrochloric acid. When treated with excess of iodine the combination takes place explosively. Turpentine oil is violently acted upon by nitric acid, often taking fire, producing nitro-benzene.—Oil of turpentine, besides being used in making varnishes, is, on account of its solvent action generally on oils and resins insoluble in water, used for discharging such substances from cloth, rags, &c. It is one of the most energetic of volatile oils. Its vapor is quickly destructive to plants and to many insects. It acts more powerfully on the lower animals than on man, easily blistering the skin of the horse. It is used in medicine as a diuretic and anthelmintic, and as a stimulant to the mucous membranes of the bowels and genito-urinary organs. It is often of great benefit in the ulcerated condition of the small intestines consequent upon typhoid fever, and also in diarrhœas. It also possesses many interesting chemical characteristics, the study of which has been of great advantage to the progress of theoretical chemistry.