Prop., &c. Colourless; sweet-tasted; agreeably fragrant, the odour approaching that of oil of caraway; slightly soluble in water; freely so in alcohol and ether; it sinks in water; boils at 180° Fahr.; burns with a smoky greenish flame; is unaffected by oil of vitriol; but decomposed by solution of caustic potassa. It combines with chlorine, forming new compounds. See Chlorides of Carbon (page 403).
OLEIC ACID. HC18H33O2. Syn. Elaic acid. One of the fatty acids discovered by Chevreul, and produced by saponifying oils, and then separating the base from the resulting soap by means of a dilute acid. It now forms an important secondary product in the manufacture of stearic acid. Perfectly pure oleic acid may be obtained as follows:—
1. By saponifying olein, as just noticed.
2. Pure almond or olive-oil soap is decomposed by a dilute acid, and the resulting oily acid is digested in a water bath with half its weight of litharge (in very fine powder) for some hours, constantly stirring; the mixture is then agitated with twice its volume of ether in a close vessel, and in 24 hours the clear ethereal solution is decanted, and decomposed with dilute hydrochloric acid; the oleic acid separates, and the ether mixed with it is expelled by evaporation. To render it colourless,
the acid is again saponified with caustic soda, and the soap thus retained is repeatedly dissolved in a solution of soda, and as often separated by adding common salt; this soap is, lastly, decomposed by dilute hydrochloric acid, as before.
3. (H. N. Fraser, pharmacist.) Oil of cotton seeds (‘winter oil’), deprived of most of its stearin by chilling and pressure, is first saponified with potassa, using a slight excess of the base. The soap is then treated with tartaric acid, or any other acid which will make a soluble salt with potassa, until the base is completely neutralised; the residue is washed until a mass is left about the consistence and colour of cerate, free from any of the salt; this is heated for several hours with nearly its weight of litharge, and three or four times its bulk of water; the resulting compound is shaken up while yet warm with ether, and allowed to stand until all the soluble matter separates.
This separates the stearate, and leaves a nearly pure oleate of lead. The clear liquor is decanted and briskly shaken with dilute muriatic acid for a few minutes to precipitate all the chloride of lead, the lighter liquid washed to remove traces of muriatic acid and filtered; the filtrate heated slowly in a water bath, and the ether distilled until the residue ceases to have an ethereal odour. The product is about 60 per cent. of the bulk of the oil.
Crude oleic acid may be purified as follows:—Expose it repeatedly to a temperature of about 45° F., and express the liquid portion. With this mix an equal bulk of solution of sulphurous acid, place the mixture in the light, and shake it frequently until no more colour is discharged. After separation the oleic acid is to be washed repeatedly with cold distilled water, and put into bottles, which should be kept filled up and in a cool place.
Prop., &c. A colourless oily acid, insoluble in water, soluble in alcohol, ether, and oil; with the bases it forms salts called oleates. The best kind of oleic acid is known as “pale cloth oil.”
O’LEIN. C57H104O6. Syn. Elain; Huile absolue, Fr. The liquid portion of the fixed oils and fats. By saponification it yields oleic acid.