This section is from the "A Practical Treatise On Materia Medica And Therapeutics" book, by Roberts Bartholow. Also available from Amazon: A Practical Treatise On Materia Medica And Therapeutics
A stearopten (having the character of a secondary alcohol) obtained from the official oil of peppermint (from Mentha piperita, Smith) or from Japanese or Chinese oil of peppermint (from Mentha arvensis, Linné, var. piperascens, Holmes, and Mentha Canadensis, Linné, var. glabrata, Holmes; Nat. Ord. Labiatae, [U. S. P.]).
"Colorless, acicular or prismatic crystals, having a strong and pure odor of peppermint, and a warm, aromatic taste, followed by a sensation of cold when air is drawn into the mouth.
"Menthol is only slightly soluble in water, but imparts to the latter its odor and taste. It is freely soluble in alcohol, ether, chloroform, carbon disulphide, or glacial acetic acid. When triturated with about an equal weight of camphor, thymol, or chloral hydrate, it becomes liquid."
The oil of peppermint has long been known to have carminative and anodyne properties in flatulent colic and gastralgia, and in gastric and intestinal catarrh. It has been much used in domestic practice for these purposes. Since the discovery of menthol, a much wider range has been given to its applications. To the taste it is pungent, a little bitter, and the local effect is extended into a cooling sensation when air is drawn in. The sense of coolness is due to an impression on the sensory nerves of the part. Applied to the skin it causes some heat, and the superficial vessels dilate, causing redness. It lowers the sensibility both of the motor and sensory nerves. The circulation is first excited, then depressed by it, and the heart is finally paralyzed.
That menthol allays the sensibility of painful nerves a multitude of facts show. For hemicrania, neuralgia of the face, and toothache, it is a sovereign remedy. To give relief in these cases, the solid stick or cake is rubbed on until the pain is relieved or the skin becomes red and sensitive. An excellent combination for the relief of local neuralgias is a mixture of menthol, thymol, chloral hydrate, rubbed up together until liquefied, and then morphine, atropine, or cocaine, or all, dissolved in the mixture. Rx Menthol, thymol, chloral hydrat., āā 3 ij; adde morphinae sulph., gr. ij; atropinae sulph., gr. 1/8; vel. cocainae hy-drochlor., gr. j. M. Or a solution of the three in ether or chloroform may be painted over a painful or inflamed part. There is little doubt that menthol applied freely may arrest a beginning boil or abscess in accessible places. To an inflamed joint the combination above mentioned is an effective application. This is true of rheumatic or gonorrhceal inflammation. Internally menthol is applicable to the treatment of spasmodic cough, asthma, and singultus. In some instances it has appeared to do good in phthisis.