Chemistry of Essential Oils

268 THE CHBMISTEY OF ESSENTIAL OILS

It contains 22 per cent, of menthol of which about 3 per cent, is
present in the form of esters. A small amount of a ketone is also
present.
The oil of Nepeta Nepetella has an odour of peppermint and has the
following characters :—

Specific gravity 1-0398 at 20°
Optical rotation + 15° 12'
Acid value 45*5
Ester„245-7
„ „ (after acetylation) 314'5
It consists largely of the caprylic and valerianic esters of menthol or
an allied alcohol.

OIL OF PBOSTANTHBBA CINEOLIFEEA.

Baker and Smith

l

have examined the oil distilled from the leaves

and stalks of this Labiate plant. The yield was 0*71 per cent, and the

oil had an odour of eucalyptol, with the following characters :—

Specific gravity 0-9204

Refractive index 1-4711 at 22°

The oil contains about 3 per cent, of geranyl acetate, pinene, cymene,

free geraniol, eucalyptol, traces of phenol (carvacrol ?), and an aldehyde

which is probably cuminic aldehyde.

OIL OF BYSTBOPOGON MOLLIS.

Bystropogon mollis, known as Argentine mint, yields about 0*4 per

cent, of essential oil, which has been examined by Doering.^2 It is a

clear liquid of specific gravity 0*918 to 0'920, which on cooling to 12°

does not separate any menthol. It boils principally at 210°. The oil

contains 2*5 per cent, of furfurol, but no other constituent has been

identified.

OIL OF MERIANDBA.

The oil of Meriandra benghalensis (M. dianthera) has been distilled
in the Italian Colony of Eritrea, and is described as " sage-oil ". It has
been examined by Schimmel & Co.
3
A sample distilled from the herb
by these chemists (yield 1-5 per cent.) had the following characters:—

Specific gravity 0*9513

Optical rotation - 2° 5'

Refractive index 1-4790

Acid value 3*7

Ester , 14-8

On freezing, camphor separates from the oil.

The two oils distilled in Eritrea had the following characters: —

1. d15o 0-9464; aD - 0° 30'; nD20» 1-47176; acid value 1-0 ; ester
   value 11*8 ; soluble in 2 volumes 70 per cent, alcohol.


2. d 1 6o 0-9526; .aD - 1°; WD 20
   O
   1-47548; acid value 5'6; ester value
   9-3 ; soluble in T8 volumes 70 per cent, alcohol.
   Neither sample possessed its full camphor-content, for in the pre-
   paration of No. 1 part of the camphor had separated out during distilla-

1

Jour, and Proc. Roy. Soc. N.S. W., xlvi. (1912), 103.

*Bol. Acad. Nac. Cienc. Cordoha, 19 (1913), 379.

» Bericht, October, 1911, 106.