Oil of Lavender. Syn. Essence of l.; Lavandulæ oleum (B. P.), Oleum lavandulæ (Ph. L.), O. l. veræ (Ph. E. & D.), O. l.
spicæ, O. l. essentiale, O. l. florum, L. The oil (Oleum lavandulæ Anglicum) distilled from the flowers of ‘Lavandula vera’ (Ph. L.). Very pale lemon-yellow; highly fragrant; taste, warm and not disagreeable; carminative, antispasmodic, and stimulant. Sp. gr. ·877 to ·905. According to Brande, the sp. gr. of the oil obtained from the flowers only is ·8960; that from the whole plant, ·9206. The lightest is esteemed the best. Prod. Flowers, 11⁄2 to 2% (nearly). The whole of the flowering herb is commonly distilled. According to Raybaud, the herb, after flowering (Sept.), yields the most oil.
Pur. Alcohol is the substance commonly used to adulterate this oil; but, occasionally, oil of bergamot is used for the same purpose. If the density is below ·87, there is reason to suspect adulteration. When pure—1. Sulphuric acid turns it reddish-brown, and the reaction is accompanied by strong inspissation.—2. It fulminates quickly and violently with iodine, and the thick syrupy residue possesses a pungent, acid, balsamic odour. The oils of the other labiate plants fulminate much less powerfully with iodine. The presence of alcohol weakens, but does not destroy, the action of this test, unless it is added in an equal volume, when only a lively effervescence and a disengagement of orange-coloured vapours are produced by the iodine, without fulmination.—3. Santaline is nearly insoluble in pure oil of lavender, and exerts no marked action on it, but is freely soluble in oil of lavender adulterated with alcohol or rectified spirit.
Obs. English oil of lavender possesses the purest fragrance; and of this, the variety known as “Mitcham oil of lavender,” from the place of its preparation, is esteemed the best. The foreign oil of lavender is inferior. This last is improved by rectification. See Oil of Spike.
Oil of Lem′ons. Syn. Essence of l.; Oleum limonis (B. P.), Oleum limonis, O. limonum (Ph. L. E. & D.). From the yellow portion of the rind, grated, placed in hair bags, and exposed to powerful pressure; also by distillation, but the product is then less agreeably fragrant and sweet, but keeps better. Nearly colourless; odour that of the fruit. Sp. gr. ·8752 to ·8785. Expressed oil, ·8517, distilled do., ·845, at 72° Fahr. (Ure.) Prod. 100 lemons yield, by expression, 13⁄4 to 2 oz. (nearly); by distillation 11⁄4 to 11⁄2.
Pur. Commonly adulterated with oil of turpentine, and occasionally with nut or poppy oil. These may be detected in the manner already explained. When pure, it is soluble in all proportions in absolute alcohol, but rectified spirit only dissolves 16% of it. It also boils at 148° Fahr., whereas oil of turpentine boils at 312°, and mixtures of the two at intermediate temperatures, depending on the proportions.
Oil of Le′mon Grass. Syn. Essence of l. g., Indian grass-oil, Oil of verbena. Probably from Andropogon citratum, the Indian lemon-grass. Pale yellow; powerfully fragrant. Citronelle oil is also the product of this or of an allied species of Andropogon.
Oil of Lemon Thyme. Syn. Oleum serpylli, L.; Huile de tain, Fr. From the fresh flowering herb of Thymus serpyllum, the lemon or wild thyme of our hills and pastures. Very fragrant, used to scent soaps &c. Sp. gr. ·867. Prod. 100 lbs. yield 21⁄2 to 51⁄2 oz. of oil. When pure, it is scarcely affected by iodine, but solution of chromate of potassa acts on it with energy.
Oil of Let′tuce. Syn. Oleum lactucæ virosæ, L. From Lactusa virosa (Linn.), or strong-scented wild lettuce. Closely resembles the odorous matter of opium.
Oil of Limes. Syn. Oleum limettæ, L. From the rind of the fruit of Citrus limetta, or lime, as oil of lemons, which it somewhat resembles. Prod. 100 limes yield 21⁄4 to 21⁄2 oz. of oil.