210 THE CHEMISTEY OF ESSENTIAL OILS
No. 2.Fraction.Per Cent.
1.. .10
2 3 4 5 6 7 8Residue10
10
10
10
10
10
10
20
•
Specific Gravity.0-874
0-878
0-879
0-883
0-886
0-891
0-896
0-909
—
Rotation.- 12° 30'
- 13°
- 13° 30'
- 12° 20'
- 11° 20'
- 10° 30'
- 8° 30'
- 5° 30'
—
Refractive
Index.1-4660
1-4670
1-4670
1-4670
1-4670
1-4670
1-4678
1-4702
1-4859
No. 3.Fraction.1 2 3 4 5 6 7 8
ResiduePerCent.. 10
10
10
10
10
10
10
10
20
Specific Gravity.0-885
0-888
0-891
0-896
0-900
0-909
0-921
0-938
Rotation.10°
10°
9° 20'
7° 70'
6° 70'
4° 50'
1°
• 2°
Refractive
Index.Partially crystallised1-4660
1-4680
1-4685
1 -4686
1-4686
1-4686
1-4686
1-4697
It is therefore quite clear that the borneol is derived principally, if
not entirely, from the leaves, and a genuine laevo-rotatory oil containing
a comparatively low percentage of borneol may be assumed to have been
-distilled from the leaves and stalks, since the leaves alone yield an oil
which has a finer odour and higher borneol-content.
According to Gutkind,^1 the optical rotation of Spanish rosemary oil
is very variable, even when the plants are grown in the same locality.
He states that the rosemary on one hill-side frequently yields an oil of
an opposite rotation to that on another hill-side, although, as a rule, the
^optical rotation is constant for each particular hill-side. In this respect,
therefore, it differs from the observations made by Henderson on the
oils of rosemary distilled at Hitchin, which he found in some instances
to be dextro-rotatory and in others laevo-rotatory.
J. C. Umney
2
gives the following particulars of a sample adulterated
with camphor oil, and compares it with pure French oil. Where, how-
ever, camphor oil is used as an adulterant, it is usually the light variety,
free from safrol, which lowers the specific gravity and greatly diminishes
the solubility.
The oil appeared to smell slightly of safrol, and was found to have
a somewhat high specific gravity, -916 being high for a natural French
oil of rosemary. The oil, submitted to fractional distillation, afforded
the following figures :—
1
Private Communication from J. C. Umney.
2
P. and E.O.R., April, 1913, 271.