Creosote, an oily, colorless liquid, of a burning and bitter taste, and a peculiar smoky odor. It was first obtained by Reichenbach in 1830, among the products of the distillation of wood, and named from the Greek flesh, and to preserve, in reference to its peculiar antiseptic properties. It possesses neither acid nor alkaline reaction. It boils at the temperature of 397°, and does not freeze at 17° below zero. At 68° its specific gravity is 1.037. It evaporates without residue, leaving upon paper a temporary greasy stain, and upon the skin a white spot. In concentrated form it acts as a caustic. It may be inflamed from a candle, and then burns with much smoke. It is but partially soluble in, water, but is itself a powerful solvent of the resins, fats, indigo, camphor, etc. Its composition is variously stated. According to Ettling, it consists of carbon 77.42, hydrogen 8.12, and oxygen 14.46. Its most remarkable quality is that for which it was named. Meats are preserved by soaking them in a dilute solution of creosote for a quarter of an hour, and then draining off the water and drying. Hams and tongues acquire a very delicate flavor after being immersed for 24 hours in a mixture of 1 part of pure creosote with 100 of water or brine. A process has been patented in England for impregnating salt with the volatile products of wood tar; meats prepared with it are both smoked and salted.
It is the creosote in pyro-ligneous acid and in the smoke from wood that gives to these the property of curing meat. Either crude pyroligneous acid or wood tar may be used to furnish creosote. The liquid distilled off the latter divides into three layers, the lowest containing the creosote. The acetic acid also present in it is removed, after separating this layer from the other, by means of carbonate of potash. The oil which after some time collects upon the liquid is distilled, producing a heavy liquid, with other lighter fluids. , The latter is agitated with phosphoric acid, and again distilled to remove ammonia. It is then mixed with solution of caustic potash of specific gravity 1.12, which dissolves the creosote, but leaves the eupione insoluble. This is decanted off. The liquid is then left for some time exposed to the air till it acquires a brown color. Sulphuric acid is then added, which sets the creosote free, so that it may be decanted; but it requires to be again treated with caustic potash and sulphuric acid, and the process repeated until the creosote, on exposure for some time to the air, ceases to turn brown. It still requires, after thorough washing with water, to be distilled from hydrate of potash, or from a strong solution of caustic potash.
The first portions that come over are water, and are rejected. Creosote is known to be impure by turning brown on exposure to the air; strong acetic acid also detects its usual impurities, dissolving with the creosote, and leaving them floating on the surface. - As a medicine, creosote has been much used, but has recently been replaced to a great extent by carbolic acid. When undiluted it is an irritant and escharotic. In a weaker form it is an antiseptic of great efficacy, as shown above, and may be locally used as such in a great variety of diseases. When introduced into the cavity of an aching tooth, it relieves the pain by benumbing and to a limited depth destroying the nerve. In the dose of a fraction of a drop frequently repeated, it often proves useful in relieving nausea and vomiting, especially during pregnancy. It may also be applied as a haemostatic. In an overdose it is a poison, giving rise, in addition to the symptoms dependent upon gastro-intestinal irritation, to giddiness, depressed action of the heart, convulsions, and coma, indicating a direct action upon the nervous centres. No antidote is known, and the only treatment is evacuation of the stomach and the use of stimulants.
The poisonous action may arise from either its internal or external application.