HERBA MENTHA PIPERITiE. 



483 



colourless, pale yellow, or greenish liquid, of sp. gr. varying from O'Sl to 

 0-92. We learn from information kindly supplied by JMessrs. Schimmel 

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

 dried, affords from 1 to 1-25 per cent, of oil. It has a strong and agree- 

 able odour, Yvdth a powerful aromatic taste, followed by a sensation of 

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

 examined by polarized light in a column 50 mm. lono-, deviates from 

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



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

 colourless hexagonal crystals oi Peppermint Camphor, C^^'H^OH, 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 

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

 Japanese Oil of Peppermint^ either liquid, and easily depositing the 

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



1 are menthol has the exquisite odour and taste of peppermint; it 

 forms hexagonal cry.stals, melting at 42" C, and boiling at 212° C. '^ 

 distilling nienthol with P^O^ it yields menthene, C"H'', a levogyrat*e 

 liquid, boiling at 1G3°, the peculiar odour of which reminds of pepper- 

 i^int. ^ The Chinese crystallized oil of peppermint has sometimes a 

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

 I'ecrystallization it assumes the pure flavour. 



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

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

 L-pori the liquid portions depend the remarkable colorations which 

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

 crude oil are shaken with one drop of nitric acid, sp. gr. about V2, 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 

 appears reddish and not transparent. The colour thus produced lasts a 

 wrtnight. We have thus examined the various samples of peppermint 

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

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

 very appreciable differences. An inferior oil of American origin wa^ 

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

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

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

 adulterations of peppermint oil, for the coloration takes place with 

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

 added. ^ 



Remarkable colorations of a different hue are also displayed by 



ai,1 Chinese oil is distilloJ at Cautoii, 

 "^ wag exported from Canton in 1S72 



ajL 7 ^^'^^"t of SOO lbs. ; it was valued at 

 awut 30.J. per lb.— See also Fluckiger in 



•pan we are informed that there are large 



^J;"j*"0"s^ of peppermint ; the oil "Haka- 



-abiira " ia exported from Hiogo and 



Osaka, but frequently adulterated. Mr 

 Holmes informed me (1S79) that he found 

 the mother plant coming nearest to Meulha 



canadensis. — F. A. F. 



2 On Japanese Feppermnit Camphor see 

 Beckett and Ahlcr \Vrisht, Yearbook oj 



Phartn. 1873. 605. 



3 Pharm. Jonm. Feb. 25, 1871. 682. 



