Expressed Oil.—Specific gravity at 15° C., 0.870-0.885; optical rotation, +38° to +50°. Its most important constituent is citral.
Distilled Oil.—This is entirely different in character to the expressed oil. Its specific gravity at 15° C. is 0.854-0.870; optical rotation, +38° to +54°; soluble in 5-8 volumes of 90 per cent. alcohol.
Linaloe oil, distilled from the wood of trees of the Burseraceæ family, and obtained from Mexico. Specific gravity at 15° C., 0.876-0.892; optical rotation, usually lævo-rotatory, -3° to -13°, but occasionally dextro-rotatory up to +5° 30'; esters, calculated as linalyl acetate, 1-8 per cent.; total alcohols as linalol, determined by acetylation, 54-66 per cent.; soluble in 1-2 volumes of 70 per cent. alcohol.
This oil consists mainly of linalol, together with small quantities of methyl heptenone, geraniol, and d-terpineol.
Marjoram oil, distilled from Origanum majoranoides, and obtained entirely from Cyprus. Specific gravity at 15° C., 0.966; phenols, chiefly carvacrol, estimated by absorption with 5 per cent. caustic potash solution, 80-82 per cent.; soluble in 2-3 volumes of 70 per cent. alcohol.
This oil is used in soap occasionally in place of red thyme oil.
Neroli Bigarade oil, distilled from the fresh blossoms of the bitter orange, Citrus bigaradia. Specific gravity at 15° C., 0.875-0.882; optical rotation, +0° 40' to +10°, and occasionally much higher; refractive index at 20° C., 1.468-1.470; esters, calculated as linalyl acetate, 10-18 per cent.; soluble in 0.75-1.75 volumes of 80 per cent. alcohol, becoming turbid on further addition of alcohol.
The chief constituents of the oil are limonene, linalol, linalyl acetate, geraniol, methyl anthranilate, indol, and neroli camphor.
Orange (sweet) oil, expressed from the peel of Citrus aurantium. Specific gravity at 15° C., 0.849-0.852; optical rotation, +95° to +99°; refractive index at 20° C., 1.4726-1.4732.
The oil contains some 90 per cent. limonene, together with nonyl alcohol, d-linalol, d-terpineol, citral, citronellal, decyl aldehyde, and methyl anthranilate.