THE ALUMNI JOURNAL. 



225 



THE EFFECTS OF CLIHATE AND SOIL 

 ON OILS OF PEPPERHINT.* 



By Johx 



Umney, Ph. C, F. I. C. 



In the discussion following the paper on black 

 and white peppermint oils read at an evening 

 meeting of the Pharmaceutical Society in Feb- 

 ruary, 1896 {Ph. J., Iv., II, 123), I stated that I 

 was in correspondence with distillers in the 

 United States with a view to ascertain the 

 varieties chiefly cultivated there and to deter- 

 mine the effect of climate and soil on the essen- 

 tial oil of plants of the same varieties cultivated 

 in different countries. 



It will be remembered that the principal 

 difference found between black and white 

 Mitcham (England) oils was in the proportion 

 of esters of menthol present, the latter being as 

 high as 14 per cent., whilst the former usu- 

 ally does not exceed 7 per cent. I have since 

 had the opportunity of confirming these ester 

 percentages in other samples, and although 

 they may be to some extent modified by the 

 method of distillation, they appear to be dis- 

 tinctly characteristic of the two varieties. I 

 have not succeeded in obtaining an authentic 

 sample of oil distilled from white peppermint 

 in the United States, but I have obtained sam- 

 ples of oil distilled from plants grown in Amer- 

 ica from black Mitcham roots and Japanese 

 roots respectively. The samples of oil distilled 

 in the United States from black Mitcham 

 plants vary in ester percentage somewhat, but 

 the ester percentage in the Wayne county is 

 in each instance higher than the Michigan — the 

 other figures showing but slight variation. 







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The ester percentages of the American oils 

 are higher than usually found in black pepper- 

 mint oil from plants cultivated in this country, 

 but the physical characters and total menthol are 

 very similar. The plants grown from Japanese 

 roots {Mentha arvensis var. piperasccns) are 

 much cultivated on account of the larger pro- 

 portion of oil they yield per acre. The specific 

 gravity from .902 to .905, and the percentage of 

 esters of menthol present are low, one sample 

 yielding only 2.5 per cent., the lowest ester per 

 centage I have obtained in any peppermint oil. 





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* Read at meeting of British Pharmaceutical Confer- 

 ence. 



In the paper previously referred to mention 

 was made of the U. S. P. color reactions for 

 ])eppermint oils, as affording striking differ- 

 ences between oils of high and low ester value 

 — taking the white Mitcham oils as the one 

 extreme and Japanese oil as the other extreme 

 — and it has been noticed in continuing the ex- 

 amination of the.'^e freshly- distilled oils that 

 the intensity of the colorations produced by 

 acids follows the ester percentage without ex- 

 ception. The color reactions of peppermint 

 oil with various acids was first noticed by 

 Fliickiger {Ph. J. [3], i., 682) and was subse- 

 quently the subject of considerable experiment 

 by Frebault {Ph. J. [3].iv., 978), who regarded 

 the reaction as dependent upon the coloring 

 matter contained in the oil of peppermint — a 

 comparison being instituted between the be- 

 havior of these bodies and chlorophyll under 



