Camphene (a contraction of camphogen, from camphor and Gr. , to produce), a name commonly applied to purified oil of turpentine, but which is also the generic name for the volatile oils or hydrocarbons, isomeric or polymeric with oil of turpentine. Most of them are isomeric, consisting of C10H16, as oil of turpentine, oil of lemons, oil of juniper, the more volatile part of oil of bergamot,caoutehine, etc.; some, as colophine, appear to consist of C20H33. Many of the camphenes exist ready formed in plants, and are sometimes contained in natural oils associated with oxygenated compounds from which they may be separated by practical distillation. All the camphenes are liquid at ordinary temperatures, except Berthelot's, which melts at 114° F., with an average density of 0.8 to 0.9 ; oil of parsley, however, being slightly heavier than water. Their boiling points range from 311° to 329° F. A few boil at higher points, as oil of copaiba, 482°; petrolene, 536° ; and metate-rebene, at about 680°. Camphenes are distinguished from each other by their odors, some of which are very fragrant, while others are disagreeable; and also by their influence on polarized light, some turning the plane of polarization to the right, others to the left.
Oxygen is readily absorbed by the camphenes and converted into ozone. Chlorine, bromine, and iodine decompose them with evolution of heat, these bodies taking the place of a portion of the hydrogen, by which reaction the adulteration of other volatile oils with camphenes may be detected. A camphene may yield several isomeric modifications when treated with different acids, or by repeated treatment with the same acid. Such modifications are called camphenes of the second order, or campherenes. Another class are of the third order, called camphilenes, and are obtained by acting on the hydrochlorates of camphenes with lime or baryta at high temperatures. The following is a list of some of the principal camphenes: oil of bergamot, oil of lemon, oil of hops, neutral oil of cloves, oil of pepper, oil of savin, oil of parsley, oil of gomart, oil of copaiba, oil of elemi, petrolene, caoutchine, thymene, tolene, oil of turpentine. The purified oil of turpentine, or camphene of commerce, is obtained by distilling the oil over quicklime, which separates the resin. It has been much used for purposes of illumination, but its employment is attended with danger. For complete combustion it requires a large supply of air, because of the great proportion of carbon.
When burned in a properly constructed lamp it yields a brilliant light. Mixed with three times its volume of alcohol, it forms the " burning fluid " which at one time was extensively used in lamps having long safety tubes. Both of these preparations have been almost entirely superseded by kerosene or refined petroleum.