_Castor[624] Oil._
QUALITIES. _Form_, a viscid and colourless, or pale straw-coloured oil;
it is nearly inodorous, but on being swallowed, excites a slight
sensation of acrimony in the throat. It has all the chemical habitudes
of the other expressed oils, except those which relate to its solubility
in alcoholic and ethereal menstrua. MED. USES. It is mildly cathartic,
and is particularly eligible in cases where stimulating purgatives would
prove hurtful, but in obstinate constipation, where copious evacuations
are required, this oil cannot be trusted, it will insinuate itself
through the intestinal canal, bringing with it a small portion of the
more fluid contents, but leaving behind it the collection of indurated
fæces. FORMS OF EXHIBITION. The most efficacious mode of administering
it is by floating it upon tincture of senna, or peppermint water, or
some other similar vehicle; it is also sometimes given with success in
coffee or mutton broth, or suspended in water by the intervention of
mucilage, yelk of egg (_Form. 75_,) or by honey, which at the same time
contributes to its laxative operation: alkalies, although they form an
emulsion with it, convert it into a saponaceous compound, and impair its
cathartic force. DOSE, f℥ss to f℥iss. ADULTERATIONS. It is usually
adulterated with olive oil or poppy oil, and when to a considerable
extent, scammony is added to quicken its operation. There is however a
peculiarity in castor oil which serves to distinguish it from every
other fixed oil, viz. its great solubility in rectified spirit; for
instance, f℥iv of alcohol of ·820 will mix uniformly with any proportion
of castor oil, whereas it will not dissolve more than fʒj of _Linseed
Oil_; and a still less proportion of the expressed oils of almonds and
of olives; when the spirit is diluted, its action on all these oils is
equally diminished, so that _common spirit of wine_ has but little power
even over castor oil; but here chemistry again interposes its aid, for
by the addition of camphor, in the proportion of one part to eight of
spirit, spirit of ·840 is enabled to dissolve castor oil, whilst it has
no influence upon the other fixed oils; castor oil is also soluble in
any proportion, in sulphuric æther of the specific gravity ·7563, while
four fluid-ounces of the same liquid will only dissolve a fluid-ounce
and a quarter of the expressed oil of _Almonds_; a fluid-ounce and a
half of that of _Olives_; and two fluid-ounces and a half of _Linseed
oil_. Vogel introduced a composition as a substitute for this oil, which
some practitioners have greatly extolled; it consisted of nine grains of
the extract of Jalap, and three grains of Venetian soap, triturated in a
mortar with an ounce and a half of Olive oil.