EFFECT OF CULTUKE 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. 
Flota- 
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. 
Pale yellow; pleasant 
menthol-like odor; 
cooling taste. 
Pale yellowish green; 
pleasant esterlike 
odor; very pun- 
gent taste. 
Yellowish green; 
pleasant minty 
odor; less pungent 
and cooling taste. 
a0.912 
a. 924 
a. 918 
-15.8 
- 4.5 
-21 
61. 4696 
61. 4728 
61.4681 
Volumes. 
cl.5 
cl.25 
cl.5 



9.55 
14.50 
24.40 
30.56 
23.97 
34. 33 
38.08 
35.39 
53.55 
Fresh herb: 
Budding 
Golden yellow; pleas- 
ant, faint odor; 
slightly pungent 
and cooling taste. 
Pale yellow; agree- 
able menthol-like 
odor; pungent, 
minty taste. 
Straw colored; very 
fl owery odor; 
minty, pungent, 
taste. 
d. 9158 
-9.2 
el. 4738 
/l 
.10 
6.72 
30.1 
35.39 
Flowering 
d. 9203 
-10.6 
el. 4662 
gl.2 
.21 
7.07 
46.5 
52.09 
Fruiting 
d. 9151 
-8.3 
el. 4676 
h.8 
.10 
12.37 
33.8 
43.58 
a At 23° C. 
6 At 24° C 
« Clear solution. 
d At 22° C 
* At 25° C. 
/ Clear in excess. 
g Turbid in 2 volumes or more. 
h Turbid in li volumes or more. 
