Oil of lavender is a mobile liquid having a specific gravity from 0.85 to 0.89. Its chief constituents are linalool acetate, which also occurs in oil of bergamot, and linalool, C10H17OH, an alcohol derived by oxidation from myrcene, C10H16, which is one of the terpenes. The dose is ½-3 minims. The British pharmacopeia contains a spiritus lavandulae, dose 5-20 minims: and a compound tincture, dose ½-1 drachm. This is contained in liquor arsenicalis, and its characteristic odour may thus be of great practical importance, medico-legally and otherwise. The pharmacology of oil of lavender is simply that of an exceptionally pleasant and mild volatile oil. It is largely used as a carminative and as a colouring and flavouring agent. Its adulteration with alcohol may be detected by chloride of calcium dissolving in it and forming a separate layer of liquid at the bottom of the vessel. Glycerine acts in the same way. If it contain turpentine it will not dissolve in three volumes of alcohol, in which quantity the pure oil is perfectly soluble.
Lavender flowers were formerly considered good for "all disorders of the head and nerves"; a spirit prepared with them was known under the name of palsy drops.
Lavender water consists of a solution of the volatile oil in spirit of wine with the addition of the essences of musk, rose, bergamot and ambergris, but is very rarely prepared by distillation of the flowers with spirit.
In the climate of New York lavender is scarcely hardy, but in the vicinity of Philadelphia considerable quantities are grown for the market. In American gardens sweet basil (_Ocimum basilicum_) is frequently called lavender.
_Lavandula Spica_, a species which differs from _L. vera_ chiefly in its smaller size, more crowded leaves and linear bracts, is also used for the distillation of an essential oil, which is known in England as oil of spike and in France under the name of _essence d'aspic_. It is used in painting on porcelain and in veterinary medicine. The oil as met with in commerce is less fragrant than that of _L. vera_--probably because the whole plant is distilled, for the flowers of the two species are scarcely distinguishable in fragrance. _L. Spica_ does not extend so far north, nor ascend the mountains beyond 2000 ft. It cannot be cultivated in Britain except in sheltered situations. A nearly allied species, _L. lanata_, a native of Spain, with broader leaves, is also very fragrant, but does not appear to be distilled for oil.