Oil of Almonds.
This fixed oil, whether procured from the sweet or bitter almond, has the same properties, for the bitter principle resides exclusively in combination with a peculiar volatile oil attached to the mucilage;[[579]] that from the latter keeps longer without rancidity. It is sometimes made from old Jordan almonds, by heat, in which case it very soon grows fetid. Nut oil, Oleum nucum Coryli, has been proposed as a substitute for that of almonds; in China it is drunk with tea, instead of cream. Medical Uses. For forming emulsions, in coughs, and other pulmonary complaints. Forms of Exhibition. It may be formed into an emulsion by the intermedium of mucilage, the yelk of an egg, or by that of an alkali.
1. By Mucilage. This is in general a more convenient medium than the yelk of an egg; one part of gum, made into mucilage, will be sufficient for the diffusion of four parts of oil, (see Mucilago Acaciæ) the oil and mucilage must be carefully triturated together, and the water then gradually added; the emulsion thus formed is permanent, and the addition of a moderate quantity of acid, spirit, or tincture, will not produce decomposition. See Form. 73.
2. By Alkalies. This oil, by uniting with alkalies and water, forms an elegant and grateful mixture, for which purpose the following proportions are to be observed, every fʒj of oil requires ♏︎viij of liquor potassæ, and f℥iss of distilled water. Incompatible Substances. Acids; oxymel; syrups of poppies and squills; tartrate and super-tartrate of potass; super-sulphate of potass; oxy-muriate of mercury; resins; hard water. See Form. 166, 167.
OLEUM AMYGDALÆ AMARÆ VOLATILE.
Qualities. Colour, pale yellow; Odour, fragrant and pungent, having the characteristic smell of prussic acid. Taste, pungent, bitter, and peculiar. Solubility. Like other essential oils, its sensible properties and medicinal effects are imparted to water; in alcohol it is very soluble.[[580]] Chemical Composition. A peculiar oil, combined with hydro-cyanic acid. M. Vogel of Munich has lately succeeded in separating these constituents, by agitating the whole in a concentrated solution of potass, and distilling to dryness; the oil volatilized together with water, while the residuum in the retort was found to contain Cyanide of Potassium. The volatile oil, thus purified, is without odour, and heavier than water. Its taste is extremely acrid and burning; by contact with air it crystallizes rapidly; it dissolves easily in alcohol and æther, but only in a very small proportion in water. The flame of its combustion is very brilliant, and accompanied with much smoke. In order to discover whether this oil, when freed from its hydro-cyanic acid, is still poisonous, M. Vogel put a drop of it on the tongue of a sparrow; when it died, after violent convulsions, in a few seconds; he also poisoned a dog, two months old, with four drops of it; whence he concludes that the volatile oil, divested of its hydro-cyanic acid, is still a poison, although less energetic than the oil that has not undergone such a change. Med: Uses. It has all the characteristic effects of prussic acid, but is so powerful and dangerous as to preclude its application. It is principally sold to perfumers and confectioners.
It is generally obtained by distilling the expressed cake of bitter almonds; the operation however requires considerable pharmaceutical address, and is, moreover, attended with unpleasant consequences.[[581]]
OLEUM OLIVÆ. L.E.D. Olive Oil.
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.
OLIBANUM. L.D.