160 THE CHEMISTEY OF ESSENTIAL OILS
understood to be the highest boiling portion of the oil, rich in safroP
and containing sesquiterpenes and a small amount of phenols. Its speci-
fic gravity usually lies between I'OOO and 1-040.
- Light camphor oil is the lowest boiling portion of the oil, and con-
sists principally of terpenes. Its specific gravity usually lies between
0-870 and 0*885, rarely up to 0'910. It is water white and resembles,
turpentine in general characters.
- The very high boiling fractions, rendered nearly colourless by re-
distillation, of specific gravity from 1060 to 1075, are sold as " artificial
sassafras oil". Ibuu
These details show that camphor oil must be bought for what it is-
worth. No definite standards can be laid down, and only a complete
analysis will show the value of a given sample.
The following figures, however, will be of assistance to the analyst..
The oil is always dextro-rotary, varying from + 12° in high gravity
samples to + 20° to + 32° in lighter oils. Light camphor oil, of speci-
fic gravity 0870 to 0910, will usually yield the following fractions on
distillation:•—
175° to 180° about 25 per cent, to 35 per cent.
180° „ 185 30 „ „ 45
185° „ 190° 10 „ „ 15 „
Camphor oil has an exceedingly complex composition. The earliest
scientific investigation of this oil was by Beckett and Wright,
1
but the
only conclusions they came to were that it was a complex mixture prob-
ably containing a hydrocarbon of the terpene series, a body having the
composition C 10 H 18 O, a liquid containing less hydrogen than camphor,
and much ordinary camphor. Oishi^2 described it as a crude oil, of
specific gravity 959, which yielded about 25 per cent, of camphor.
The rectified oil was a colourless liquid of specific gravity '895. He
concluded that the oil was a mixture of terpenes, camphors, and some
of the oxidised hydrocarbons. Yoshida
3
separated the oil into four
chief portions, which appeared to be (1) laevo-a-pinene boiling at 150°;
(2) a terpene (limonene) boiling at 172°; (3) camphor; (4) an oxygen-
ated body which he termed camphorogenol. A sample examined by
Trimble and Schroeter^4 was separated into ten fractions, each of which
the authors claimed to- be pure compounds, but which were clearly
mixtures in several cases. No fewer than five terpenes were given, and
five oxygenated bodies. Bertram and Walbaum
5
and Schimmel & Co/
have examined the oil since, and to them is due the discovery of the
presence of safrol, which is now manufactured on an enormous scale.
They also showed that Yoshida's camphorogenol had no existence.
The result of their researches shows that the following bodies are
present in the oil: /3-pinene, phellandrene, camphene, dipentene, dextro-
fenchene, dextro-limonene, and bisabolene, cineol, camphor, safrol,
eugenol, terpineol, citronellol, cumic alcohol, borneol, a-terpineol, and
cadinene, with traces of carvacrol, aldehydes and acids, including cap-
rylic acid, and one of the oleic series, with the formula C 9 H 16 O 2 , has
been isolated.
The latest investigation of camphor oil is that of Semmler and Kosen-
1
3 Jour. Chem. Soc. (1876), 7. *Chem. News, L, 275.
5 Jour. Chem. Soc. (1885), 782. - Pharm. Jour., xx., 145.
Jour, prakt. Chem., ii., 49 (1894), 19.
6
Reports, passim.
