Chemistry of Essential Oils

CONIFEB.E 39

+ i

26

60

Specific gravity 0-863 to 0'892
Optical rotation-f 2°
Ester value 0 ,
,, „ (after acetylation) 5
These figures have reference to samples of apparently authentic origin,
but it must be remembered that some admixture of the leaves of allied
species may have taken place before distillation. Most specimens of ab-
solutely authentic origin have a specific gravity below 0*875, an ester
value not exceeding 5, and ester value after acetylation below 20.

CEDAR-LEAF OIL.
The true cedar-leaf oil may be regarded as the distillate of the leaves
of Juniperus virginiana, the red cedar, but the confusion implied in the
name " cedar" is reflected in the enormous variations met with in com-
mercial samples of so-called cedar-leaf oils. No doubt the leaves of
Thuja occidentalis and Chamcecyparis spharoidea contribute largely to
the commercial oil. Brant, indeed, describes the oil as having a " pene-
trating, disagreeable odour," and as " therefore not suitable for perfumery
purposes". Cedar leaves yield about 0'2 per cent, of essential oil, of
pleasant aromatic odour, having the following characters :—
Specific gravity 0-883 to 0-900
Optical rotation ....... + 55° „ + ^62°
Saponification value 8 „ 14
„ „ (after acetylation)... 35 „ 45
It is not soluble in even 10 volumes of 80 per cent, alcohol.
The examination of a pure sample by Schimmell showed that it con-
tains a-pinene, limonene, cadinene, borneol, and bornyl esters, probably
including bornyl valerianate; other terpenes are also present. Com-
mercial oils have specific gravities of 0'860 to 0'920 and optical rotations
of - 3° to - 24°.
The true Juniperits virginiana leaf oil is more expensive than the
corresponding oil from cedar wood—being worth from three to five times
as much, in fact, and as the oils from thuja and other leaves are also less
costly, it is a matter of importance that the oil should be carefully ex-
amined. Six commercial samples and one pure sample, examined by
Schimmel & Co., gave the following results :—
Specific Optical Solubility in
Gravity. Rotation. 70 per Cent. Alcohol.
Pure oil
1 2 3 4 5 6

•887

•897

•886

•887

•920

•918

•905

59° 25'

12° 25'

3° 40'

24° 10'

• 10° 25'
  10° 55'
  10°

very insoluble,

insoluble.

soluble in 4 parts.

„ „ '5 parts,

insoluble.

SEQUOIA OIL.

Sequoia oil is obtained from the leaves of Sequoia \giganfea\ (Welling -

tonia gigantea, Lindl.), the Californian mammoth* tree. Lunge and

Steinkauler^2 obtained the oil from smaller ornamental trees grown in

Zurich. The first portion of the distillate contained a crystalline hydro-

carbon C 13 H 10 , melting at 105°, which these chemists termed sesquoiene.

The later distillate contained a dextro-rotatory terpene boiling at*155°, and

(^1) Bericht, April, 1898, 14. (^2) Ibid., 13 (1880), 1656 ; 14 (1881), 2202.