Creosote

Creosote, Creasote or Kreasote (from Gr. κρέας, flesh, and σώζειν, to preserve), a product of the distillation of coal, bone oil, shale oil, and wood-tar (more especially that made from beech-wood). The creosote is extracted from the distillate by means of alkali, separated from the filtered alkaline solution by sulphuric acid, and then distilled with dilute alkali; the distillate is again treated with alkali and acid, till its purification is effected; it is then redistilled at 200° C., and dried by means of calcium chloride. It is a highly refractive, colourless, oily liquid, and was first obtained in 1832 by K. Reichenbach from beech-wood tar. It consists mainly of a mixture of phenol, cresol, guaiacol, creosol, xylenol, dimethyl guaiacol, ethyl guaiacol, and various methyl ethers of pyrogallol. Creosote has a strong odour and hot taste, and burns with a smoky flame. It dissolves sulphur, phosphorus, resins, and many acids and colouring matters; and is soluble in alcohol, ether, and carbon disulphide, and in 80 parts by volume of water. It is distinguished from carbolic acid by the following properties:—it rotates the plane of polarized light to the right, forms with collodion a transparent fluid, and is nearly insoluble in glycerin; whereas carbolic acid has no effect on polarized light, gives with about two-thirds of its volume of collodion a gelatinous mass, and is soluble in all proportions in glycerin; further, alcohol and ferric chloride produce with creosote a green solution, turned brown by water, with carbolic acid a brown, and on the addition of water a blue solution. Creosote, like carbolic acid, is a powerful antiseptic, and readily coagulates albuminous matter; wood-smoke and pyroligneous acid or wood-vinegar owe to its presence their efficacy in preserving animal and vegetable substances from putrefaction.

Creosote oil is the name generally applied to the fraction of the coal tar distillate which boils between 200° and 300° C. (see Coal Tar). It is a greenish-yellow fluorescent liquid, usually containing phenol, cresol, naphthalene, anthracene, pyridine, quinoline, acridine and other substances. Its chief use is for the preservation of timber.

Pharmacology and Therapeutics.—Creosote derived from wood-tar is given medicinally in doses of from one to five minims, either suspended in mucilage, or in capsules. It should always be administered after a meal, when the gastric contents dilute it and prevent irritation. Creosote and carbolic acid (q.v.) have a very similar pharmacology; but there is one conspicuous exception. Beech-wood creosote alone should be used in medicine, as its composition renders it much more valuable than other creosotes. Its constituents circulate unchanged in the blood and are excreted by the lungs. Although carbolic acid has no value in phthisis (pulmonary tuberculosis) or in any other bacterial condition of the lungs, creosote, having volatile constituents which are excreted in the expired air and which are powerfully antiseptic, may well be of much value in these conditions. In phthisis creosote is now superseded by both its carbonate (creosotal)—given in the same doses—which causes less gastric disturbance, and by guaiacol itself, which may be given in doses up to thirty minims in capsules. The phosphate (phosote or phosphote), phosphite (phosphotal), and valerianate (eosote) also find application. Similarly the carbonate of guaiacol may be given in doses even as large as a drachm. Creosote may also be used as an inhalation with a steam atomizer. It is applicable not only in phthisis but in bronchiectasis, bronchitis, broncho-pneumonia, lobar pneumonia and all other bacterial lung diseases. Like carbolic acid, creosote may be used in toothache, and the local antiseptic and anaesthetic action which it shares with that substance is often of value in relieving gastric pain due to simple ulcer or cancer, and in those forms of vomiting which are due to gastric irritation.