QUALITIES. _Colour_, pale yellow, somewhat inclining to green; _Taste_,
bland; _Odour_, none; it ought to congeal at 38° _Fah_. With the
exception of the oil of Almonds, it is the lightest of the fat oils, its
specific gravity being only ·915. According to the recent observations
of Dr. Clarke of Cambridge, this oil crystallizes in rectangular
four-sided prisms with square bases. USES. Although much less laxative
than Castor oil, it is a useful aperient. It was long regarded, but
erroneously, as possessing antidotal powers against the bites of
venemous snakes and insects; and it has been confidently recommended, in
the form of liniment, as a remedy against the Plague. OFFICINAL
PREPARATIONS. _Linimentum Ammoniæ Fortius_. L. ADULTERATIONS. It is not
unfrequently mixed with the oil of poppy seeds, (see _Papaveris
Capsulæ_), a fraud which may be easily discovered by exposing a sample
to the freezing temperature, when the olive oil will congeal, while that
of poppies will remain fluid; and since those oils which freeze with
most difficulty are most susceptible of rancidity, the admixture of
poppy oil must be regarded as injurious: it also deserves notice that
the peculiar habitudes of _Oil of Olives_, with the _Pernitrate of
Mercury_, offer a distinguishing character, by which the adulteration of
the oil may be satisfactorily detected; for if the _pernitrate_, made by
dissolving 6 parts of the metal in 7·5 of nitric acid, of sp. grav.
1·36, at a common temperature, be mixed with olive oil, the mixture, if
kept cold, will in the course of a few hours become solid, whereas if it
has any admixture of the oil of grains, it will not undergo such a
change. The contamination derived from lead, which is frequently
immersed in the oil for the purpose of removing its rancidity, may be
detected by shaking one part of the suspected sample with three parts of
water, impregnated with sulphuretted hydrogen, in a stopped phial.