Rosemary oil (oleum rosemarini or ol. anthos) is obtained in Southern Europe, especially in Southern France, Dalmatia and Northern Italy, by distillation from the flowering rosemary, Rosmarinus officinalis, natural order Labiatæ. It is, when fresh, limpid, colorless, or yellowish, of a penetrating, camphor-like odor and taste, and specific gravity 0.880 to 0.915. By age it becomes darker and thickly-fluid. The French rosemary oil is the best and most expensive. It is distinguished from the Italian oil by its much more pleasant odor. Pure French rosemary oil dissolves in an equal part of 90 per cent. alcohol, while the Italian product requires 2 to 3 parts. The cheaper rosemary oils are generally adulterated with oil of turpentine, which is recognized by the oil not dissolving in the above-mentioned proportion in alcohol, as well as by the iodine test. Rosemary oil does not detonate with iodine, but simply dissolves with heating and perhaps the emission of vapors.
The French rosemary oil forms one of the ingredients of eau de Cologne and is used in other perfumery.
Rosewood oil or rhodium oil (oleum ligni rhodii), is obtained by distillation from the wood of the root and lower trunk of Convolvulus scopiarius and C. floridas, L., two plants indigenous to the Canaries. The waste falling off in the manufacture of rosewood beads is chiefly used for the purpose. The oil is of a pale yellow color becoming brown by age. It has a pleasant odor resembling in some slight degree the fragrance of the rose. It is sometimes used in cheap perfumery as a substitute for rose oil.
Sandal-wood oil (oleum ligni sandali) is distilled from the white West Indian or dark yellow East Indian sandal-wood (Santalum myrtifolium). For the purpose of distillation the wood is rasped as finely as possible. The oil obtained from the East Indian wood is the better and more valuable. It has a dark yellow to brown color and a pleasant intense, rose-like odor, while the West Indian oil is pale yellow and of a less agreeable odor. Both oils are very thickly-fluid. The quality and value of sandal-wood oil are best judged by the odor, an adulteration with cedar oil being readily detected thereby.
Sassafras oil (oleum ligni sassafras), from the bruised root of the sassafras tree, Sassafras officinale, natural order Lauraceæ. Sassafras is one of the most widely distributed trees of North America, being found in Canada, in all of the United States, east of the prairies, beyond the Mississippi, and in Mexico. The largest amount of oil distilled is within sixty miles of Baltimore, Md., which is the principal depot for its commerce.
Oil of sassafras varies in color from colorless to yellow and red. Its taste is pungent and aromatic, being agreeable to most persons. It has a pleasant odor resembling that of fennel, and is heavier than water, its specific gravity being 1.08 to 1.09. It is soluble in 4 to 5 parts of alcohol of 0.85 specific gravity, and consists of a mixture of various oils, among which is safrene (C10H16), a dextrorotatory terpene which boils between 311° and 314.6° F. By strongly cooling in a cold mixture, safrol, a crystallizing stearoptene of the composition C10H10O2, is separated. Safrol is the chief constituent of sassafras oil. It is obtained in abundance by cooling, at a temperature of 13° F., the portion boiling between 442.4° and 455° F. It melts at 46.4° F., and at a medium temperature forms a colorless clear oil of pungent taste, characteristic odor, and specific gravity 1.104. When the crystals have been heated to above 158° F., they congeal only after remaining for weeks at a temperature below 32° F., but on being melted at 68° F., the fluid mass again congeals readily on cooling. The safrol is neutral, optically inactive, boils at 449.6° F., and is soluble in alcohol and ether. Sassafras oil is said to be frequently adulterated with oil of turpentine, which is, however, readily detected by the energetic reaction and by distilling a sample of the suspected oil.
Safrol is very suitable for perfuming ordinary soaps. It has in a still higher degree than camphor oil the property of removing the disagreeable odor of some fats, while at the same time it imparts to the soaps an aromatic, refreshing odor. As a rule 8 to 11 ozs. are used for 220 lbs. of soap; but if it shall at the same time serve for removing the disagreeable odor of low quality fats, especially those extracted with bisulphide of carbon or benzine, it is advisable to take 2.2 lbs., or still better, 4.4 lbs. for 220 lbs. of soap. In this case the safrol should be added to the fat after melting and before saponification and thoroughly mixed with it by stirring. An excellent perfume for ordinary soaps is a mixture of safrol and citronella oil, it being at any rate preferable to oil of mirbane.
The standard of value for safrol is its specific gravity, which should not be below 1.104 at 59° F. Specifically lighter kinds contain camphor oil and other impurities.
Thyme oil is obtained in Southern France and Spain by distillation from the flowering thyme, Thymus vulgaris, L. It is greenish-yellow to red (red thyme oil, oleum thymi rubrum), but by rectification becomes colorless (white thyme oil, oleum thymi album). Both oils are quite limpid and possess a strong thyme odor. The specific gravity of the red oil is 0.91 to 0.94, and that of the rectified oil 0.87 to 0.89. The oil prepared from the fresh plant shows, as a rule, a higher specific gravity than that from the dried plant. Thyme oil consists essentially of thymene (C10H16) besides some cymene (C10H14) and thymol (C10H14O), the latter forming an essential constitutent of the oil. Oils from which the thymol has been withdrawn occur in commerce. Pure thyme oil dissolves clear in every proportion in 90 per cent. alcohol; if such is not the case, adulteration with oil of turpentine is probable.