Oleum Lini. U. S., Br. Linseed Oil.

Botanical name: 

Ol. Lini. [Oil of Flaxseed, Raw Linseed Oil]

Related entry: Linum

"A fixed oil obtained from Linseed. Preserve it in well-stoppered containers. Linseed Oil which has been 'boiled' must not be used nor dispensed." U. S. "Linseed Oil is the oil expressed from Linseed." Br.

Huile de Semence de Lin, Fr.; Oleum Lini, P. G.; Leinöl, Leinsamenöl, G.; Olio di lino, It.; Aceite de linaza, Sp.

This oil is obtained by expression from the seeds of Linum, usitatissimum, or common flax, which, according to Berjot, contain 34 per cent. (J. P. C., April, 1863. p. 277.) In its preparation on a large scale, the seeds are usually roasted before being pressed, in order to destroy the gummy matter contained in their coating. The oil is thus obtained more free from mucilage, but more highly colored and acrid than when procured by cold expression. For medicinal use, therefore, it should be prepared without heat, and, as it is apt to become rancid quickly on exposure, it should be used as soon after expression as possible. It may, however, be rendered sweet again by agitation with warm water, rest, and decantation. It is said to be obtained purer and in larger proportion by treating the crushed seeds with carbon disulphide than by expression. (A. J. P., xxvi, 265.)

Oil of flaxseed is u a yellowish, oily liquid, having a peculiar odor and a bland taste. When exposed to the air, it gradually thickens, darkens in color, and acquires a strong odor and taste. It is slightly soluble in alcohol, miscible with ether, chloroform, petroleum benzin, carbon di-sulphide, or oil of turpentine. Specific gravity: 0.925 to 0.935 at 25° C. (77° F.). It is not more than slightly acid to litmus paper which has previously been moistened with alcohol (free acid). Linseed Oil when spread in a thin layer on a glass plate and allowed to stand in a warm place is gradually converted into a hard, transparent resin (non-drying oils). To 10 mils of the Oil add 3 Gm. of potassium hydroxide, 10 mils of alcohol and 10 mils of distilled water, and heat the mixture on a water bath with frequent agitation, until a clear solution results. The addition of 100 mils of distilled water to this solution yields a clear liquid free from oily drops (mineral or rosin oils). Warm 2 mils of the Oil with frequent agitation in a test tube with an equal volume of glacial acetic acid, and, after cooling, add to the mixture 1 drop of sulphuric acid. A greenish color is produced (a violet color under these circumstances indicates the presence of rosin or rosin oils). Saponification value: not less than 187 nor more than 195. Iodine value: not less than 170." U. S.

"Yellowish-brown. Characteristic odor; taste bland. Specific gravity 0.930 to 0.940; saponification value 187 to 195; iodine value not less than 170; acid value not more than 3.0; unsaponfiable matter not more than 1.0 per cent.; refractive index at 40° C. (104° F.) 1.4725 to 1.4748. Does not congeal at temperatures higher than -20° C. (-4° F.). Gradually thickens on exposure to the air, forming, when spread in thin layers, a hard transparent varnish. A mixture of 2 millilitres of the Oil with an equal volume of acetic anhydride, warmed and shaken, and then cooled to 15.5° C. (60° F.), is not colored violet by the addition of 2 drops of a cooled mixture of 2 parts by weight of sulphuric acid and 1 part by weight of water (absence of resin and resin oils)." Br.

It has the property of drying or becoming solid on exposure to the air, acquiring during the process a strong odor and taste, and increasing as much as 12 per cent. of its weight, owing to the formation of linoxyn by atmospheric oxidation. The drying property resides in a constituent which, to distinguish it from the olein of the non-drying oils, is named linolein, and is the glyceride of linoleic acid. Linseed oil contains about 10 to 15 per cent. of glycerides of solid fatty acids, palmitic, myristic, and stearic, and 85 to 90 per cent. of liquid glycerides. Hazura (J. Soc. Chem. Ind., 1888, 506) states that the liquid fatty acids consist of about 5 per cent. of oleic acid, C18H34O2, 15 per cent. of linoleic acid, C18H32O2, 65 per cent. of isolinolenic acid, C18H30O2, and 15 per cent. of linolenic acid, C18H30O2. Boiled with litharge, red lead, manganese dioxide, and other so-called "driers," it absorbs oxygen still more rapidly, 'and gains 14 per cent. in weight. Its acridity is owing to the presence of a small proportion of an acrid oleoresin. From its drying property, it is useful in painting and in making printers' ink and in linoleum and oil cloth manufacture. The chief adulteration of linseed oil is with mineral oils and rosin oil. For their detection, see official tests already given.

It is said that crude cod liver oil has been used for the adulteration of the oil of flaxseed, especially where the latter is intended for preparing printers' ink. Aug. Morell detects tile adulteration by the following method. Take 10 parts by weight of the suspected oil, mix it in a small cylindrical glass tube with 3 parts of crude nitric acid, agitate the mixture well, and allow it to rest. If cod liver oil be present, the oily layer at top will assume a dark-brown to blackish-brown color, while the acid at bottom will vary from bright orange to orange or dark yellow. So little as 3 per cent. of cod liver oil may thus be detected. If the flaxseed oil be pure, it will become, during the agitation, first sea green, and afterwards dirty greenish-yellow, the acid being bright yellow. The prohibition of the use of boiled linseed oil for medicinal purposes has its origin in the fact that much of the boiled linseed oil of commerce contains a compound of lead or manganese as a drying agent. Instances are on record where lead-containing boiled linseed oils caused the death of cattle to which the oil had been administered;

Uses.—The oil is laxative in the dose of a fluidounce (30 mils), but, on account of its disagreeable taste, is seldom given internally. It has, however, been highly recommended as a cure for piles, in the dose of two fluidounces (60 mils) of the fresh oil, morning and evening. It is sometimes added to purgative enemata. Particular care must be observed not to use boiled linseed oil for any medicinal purposes, as the latter frequently contains compounds of lead which give it poisonous properties.

Dose, one to two fluidounces (30-60 mils).

Off. Prep.—Linimentum Calcis, U. S.; Ceratum Resinae Compositum, N. F.

The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.