EFFECT OF CULTURE AND CLIMATE ON PEPPERMINT OIL. 5 



The results show that the yield of oil from the whole herb in the 

 budding and flowering stages is consistently lower than that from 

 the leaves and tops. In the fruiting stage, however, a slight devia- 

 tion is observed. The yield of oil from the fresh herb is slightly 

 higher in some instances than that from the leaves and tops. In 

 practically all cases, however, the average yield from the leaves and 

 tops during the three successive years is higher than the average 

 from the whole herb at the three stages of growth. 



From these results it is concluded that the largest portion of the 

 oil in the peppermint plant is found in the leaves. The flowering 

 tops contain slightly less than the leaves, and the stems are nearly 

 devoid of oil. This latter fact possibly accounts for the lower per- 

 centage of oil in the whole plant as compared with that from the 

 leaves and tops. 



PHYSICAL AND CHEMICAL PROPERTIES OF PEPPERMINT OIL FROM 

 FRESH AND FROM DRY PLANTS AT VARIOUS STAGES OF GROWTH. 



In order to make possible a comparison of the properties of the 

 various oils, a careful physical and chemical examination was made, 

 and the results are presented in Table IV. 



Table IV. — Physical properties and chemical composition of peppermint oil distilled 

 from the fresh and from the dry herb at various stages of growth during successive years. 





Physical properties. 



Chemical composition (per 

 cent). 



Year and descrip- 

 tion of material. 



Color , odor , and taste. 



Specific 

 gravity. 



Rota- 

 tion, 

 50 mm. 

 tube. 



Refrac- 

 tion. 



Solubil- 

 ity in 

 80 per 

 cent 



alcohol. 



Free 



acid 



(as 



acetic). 



Ester 

 (men- 

 thyl 

 ace- 

 tate). 



Menthol. 





Free. 



Total. 



1908. 



Fresh herb: 



Budding 



Flowering 



Fruiting 



1909. 



Fresh herb: 



Budding 



Flowering 



Fruiting 



Paleyellow; pleasant 

 menthol-like odor; 

 cooling taste. 



Pale yellowish green ; 

 pleasant esterlike 

 odor; very pun- 

 gent taste. 



Yellowish green; 

 pleasant m i n t y 

 odor; less pungent 

 and cooling taste. 



Golden yellow; pleas- 

 ant, faint odor; 

 slightly pungent 

 and cooling taste. 



Pale yellow; agree- 

 able menthol-like 

 odor; pungent, 

 minty taste. 



Straw colored; very 

 flowery odor; 

 minty, pungent, 

 taste. 



a0. 912 

 a. 924 



o.918 



d. 9158 

 d. 9203 

 d. 9151 



-15.8 

 -4.5 



-21 



-9.2 

 -10.6 

 -8.3 



61.4696 

 61.4728 



61. 4681 



«1. 4738 

 el. 4662 

 el. 4676 



Volumes. 

 cl.5 



c 1.25 

 c 1.5 



/l 

 9.1.2 



h.8 





 







.10 

 .21 

 .10 



9.55 

 14.50 



24.40 



6.72 



7.07 



12.37 



. 30. 56 

 23.97 



34.33 



30.1 

 46.5 

 33.8 



38.08 

 35.39 



53.55 



35.39 

 52.09 

 43.58 



« At 23° C. 

 6 At 24° C 

 e Clear solution. 



d At 22° C 

 e At 25° C 

 / Clear in excess. 



g Turbid in 2 volumes or more. 

 * Turbid in 1$ volumes or more. 



