By PROF. FLÜCKIGER.
According to a notice contained in the American Journal of Pharmacy, May, 1871, p. 223, (See Pharm. Journ., No. 26, 1870, p. 426.) the Chinese, when suffering with facial neuralgia, use oil of peppermint, which they lightly apply with a camel-hair pencil. This application has now found its way to the opposite shore of the Pacific, where the immigration of Chinese people is very considerable. The American journal, indeed, states that Chinese pharmaceutists in San Francisco, as well as in New York, sell the said remedy for neuralgia, and that it has already gained some repute. The oil for this purpose is put up in small phials containing about half a drachm.
I had the opportunity, some weeks ago, of a conversation with a Swiss merchant, coming from San Francisco, who not only corroborated the above information, but showed me a phial containing the "Chinese medicine," which he had bought there himself in a Chinese pharmaceutical shop. The owner of the phial had frequently used it, and spoke in high terms of the good effects of the oil. The phial contained, I think, even less than half a drachm (price one dollar !), and was labelled, Fook Chang Yong, wholesale and retail druggist and chemist, 744 Sacramento street, corner Dupont, San Francisco.
I was suspicious enough to suppose the oil to be common peppermint oil, of American or English origin, procured, perhaps, by the Chinese in San Francisco, although the said merchant firmly believed, for good reasons, as he thought, it was directly imported from China.
Having pointed out the magnificent fluorescence which nitric acid imparts to peppermint oil, (See Pharm. Journ., Feb., 1871, p. 682, and Aug., 1871, p. 714; also Amer. Journ. of Pharm. 1871, p. 164.) I found that the above Chinese oil partakes not at all of this reaction; it is not colored by nitric acid (1-20 sp. gr.), even when gently warmed with it.
A few drops of the oil exposed for some hours only on a glass slide yielded abundantly crystals of a camphor, reminding me in every respect of the solid Japanese peppermint oil, which during the past few years has been met with in European trade.
In both the above respects the Chinese peppermint oil is consequently different, at least, to most of the specimens of European and American oil at my command, although it has the same agreeable flavor. Does it, that is to say its solid part, which appears to be prevailing, agree with the Japanese drug? I have ascertained that the latter is not altered by the treatment with nitric acid; it may, therefore, very likely be identical with the crystallizable part of Chinese oil. I have also been informed by the said Swiss gentleman that the "Chinese medicine" in cold weather solidifies even in California.
I should be happy if my fragmentary observations could induce some resident in China or Japan to devote some investigation to the mother-plant of the Eastern soils under notice, and to the production of the latter. Is the solid Japanese oil obtained by means of cooling from a liquid similar to the Chinese oil? Chinese oil is said to be distilled at Canton. (Hanbury, Pharm. Journ., Sept., 1871, p. 244.)
As to the former, I beg to remind that it has been shown by Oppenheim and by Gorup-Besanez (Comptes Rendus, liii, 379, 483; Journ, Chem. Soc., xv, 24; Jahresbericht der Chemie, von Kopp und Will., 1861, 683.) to agree with the formula C10H18+H2O, and to possess the nature of an alcohol. This so-called Menthol appears to be identical with peppermint-camphor, which sometimes in cold separates from peppermint oil; their identity, however, is not quite satisfactorily proved. Camphor obtained from peppermint oil has been analyzed by Dumas, by Blanchet and Sell, and also by Walter. (Gmelin, Org. Chemistry, viii, 450.) Its percentage composition is the same as that of menthol. Pharm. Journ., Lond., Oct. 21, 1871.