248 THE CHEMISTRY OF ESSENTIAL OILS
service for identifying the plant unless the name of the botanical
authority follows the name of the plant, e.g. Origanum Creticum Lin-
naeus ; Origanum Creticum Schousboe ; or Origanum Creticum Sieber.
" When these are given it is possible for any botanist to understand
which species is meant, and so far the course is clear. But the matter
is further complicated when two different plants are used in the same
locality, at different times, or are mixed before distillation. Failure of
the crop, or the exhaustion of the wild plant from careless collection,
may lead at any time to substitution of the nearest plant having a some-
what similar odour or similar appearance, and then the identification of
the botanical sourca of the oil can only be settled by the botanical ex-
amination of a specimen of the plant actually employed for distillation.
"I, is now known that the character and percentage of the phenols
carvacrol and thymols differ in different species, and may possibly do
so in the same species under different conditions, and that as a rule they
do not both occur in the same species. But with the aid of botanical
descriptions and illustrations it should be possible to select and cultivate
experimentally those species which give the highest yield, and to
determine the conditions of soil, or the use of particular manure under
which the largest yield may be obtained. Until this is done there is
little hope of obtaining anything approaching a uniform oil in commerce.
" The principal species from which the oil has actually been distilled
and examined are the following:—
Origanum majoranoides Willd.
Origanum onites Linn.
Origanum maru Linn.
Origanum hirtum Link."
The oil of Origanum majorana, or sweet marjoram, is produced
principally in Spain, where the fresh herb yields 0
- 3 to 04 per cent, of
oil. This oil has the following characters :—
Specific gravity.. 0895 to 0 910
Optical rotation
Refractive index
Acid value
Ester „
The oil is soluble in 2 volumes of 80 per cent, alcohol.
These properties may vary somewhat, and three samples, two dis-
tilled in Cyprus and one in London from material obtained from
Cyprus, were found to have the following characters :—l
Cyprus. Cyprus. London.
Specific gravity .... 0-899 0912 0-888
Optical rotation.... + 14° 2' +3° 45' + 13° 15'
Saponification value ... 6-4 8'25 12 S
Solubility in 80 per cent, alcohol. 1 in 1-3 1 in 1 1 in 8 to 9
This oil contains about 40 per cent, of terpenes, principally terpinene,
terpineol, terpinenol-4, and small quantities of esters. Possibly borneol
and camphor are present in traces.
The oil from Origanum majoranoides from Cyprus has been ex-
amined by Pickles^2 who gives the following results :—
Carvacrol, about 840 per cent.; another phenol with a creosote-like
odour, 02 per cent.; a hydrocarbon origanene C 10 H 16 , about 25 per
cent.; cymene and terpenes, boiling-point 170° to 180°, about 8 per
(^1) Bull. Imp. Inst., 11 (1913), 50. a Trans. Chem. Soc. (1908), 876.