HERBA MENTHiE PIPERITA. 48:3 



colourless, pale yellow, or greenish liquid, of sp. gr. varying from 084 to 

 092. We learn from information kindly supplied by ^lessrs. Schimmel 

 and Co., Leipzig, that the best peppermint grown in Germany, carefully 

 dried, affords from 1 to l2o per cent, of oil. It has a strong and agree- 

 able odour, with a powerful aromatic taiste, followed by a sensation of 

 cold when air is drawn into the mouth. We find that the Mitcham oil 

 examined b}^ polarized light in a column 50 mm. long, deviates from 

 14°-2 to 10'-7 to the left, American oil 4°-3. 



When oil of peppermint is cooled to -4° C, it sometimes deposits 

 colourless hexagonal crystals oi Peppei^iint Camphor, (y'W^O^, called 

 also Menthol. We have never observed it, nor are we aware that 

 menthol has been noticed in America, but it is largely afforded by 

 eastern mints, and found in commerce under the name of Chinese or 

 Japanese Oil of Peppei'niint} either liquid, and easily depositing the 

 camphor, or also forming a crystalline mass impregnated with the liquid 

 oil. 



Pure menthol has the exquisite odour and taste of peppermint; it 

 forms hexagonal crystals, melting at 42" C, and boiling at 212° C By 

 distilling menthol with P-0^ it yields menthene, C^"H'*, a levogyratc 

 liquid, boiling at 163°, the peculiar odour of which reminds of pepper- 

 mint.- The Chinese crystallized oil of peppermint has sometimes a 

 bitterish after-taste and an odour similar to that of spearmint, but by 

 recrj^stallization it assumes the pure flavour. 



The liquid part of the oil of peppermint has not yet been thoroughly 

 investigated; it appears to consist chieflj' of the compound C"H''*0. 

 Upon the liquid portions depend the remarkable colorations which 

 the oil of peppermint is capable of assuming. If 50 to 70 drops of the 

 crude oil are shaken with one drop of nitric acid, sp. gr. about 12, the 

 mixture changes from faintly yellowish to brownish, and, after an hour 

 or two, exhibits a bluish, violet or greenish colour; in reflected light, it 

 appeal's reddish and not ti'ansparent. The colour thus produced lasts a 

 fortnight. We have thus examined the various samples of peppermint 

 oil at our command, and may state that the finest among them assume 

 the most beautiful coloration and fluorescence, which, however, shows 

 -very appreciable differences. An inferior oil of American origin was 

 not coloured; and a very old sample of an originally excellent English 

 oil was likewise not coloured by the test. Menthol is not altered when 

 similarly treated.^ The nitric acid test is not capable of revealing 

 adultei'ations of peppermint oil, for the coloration takes place with 

 an oil to which a considerable quantity of oil of turpentine has been 

 added. 



Remarkable colorations of a different hue are also displayed by 

 the various kinds of oil of peppermint if other chemical agents are 

 mixed with it. Thus green or brownish tints are produced by means of 

 wnJiydrous chloral; the oil becomes bluish or greenish or rose-coloured 



^ The Chinese oil is distilled at Canton, Osaka, but frequently adulterated. Mr. 



and was exported from Canton in 1872 Holmes informed me (1879) that he found 



to the extent of 800 lbs. ; it was valued at the mother plant coming nearest to Mentha 



about 30s. per lb. — See also Fluckiger in canadensis. — F. A. F. 



Pharm. Journ. Oct. 14, 1871. 321. As to - On Japanese Peppermint Camphor see 



Japan we are informed that there are large Beckett and Alder Wright, Yearbook of 



plantations of peppermint ; the oil "Haka- Pharm. 1875. 605. 



no Abura " is exported from Hiogo and ' Pharm. Journ. Feb. 25, 1871. 682. 



