The English localities where peppermint is cultivated are Mitcham, in Surrey (500 acres in 1850, 219 in 1864); Wisbeach, in Cambridgeshire ; Market Deeping, in Lincolnshire (150 acres in 1871); and Hitchin, in Herts. At Mitcham, two varieties are distinguished : "black," having purple stems, hardier, more prolific, but inferior product ; and "white," with green stems, a much more delicate and valued product. The chief French peppermint-gardens seem to he at Sena (department of Yonne), on the flats at the confluence of the Yonne and the Vanne. In Germany, Ciilleda, near Leipzig, is the centre of a production of 40,000 cwt. of the herb annually. The cultivation in the American States of S. Michigan, W. New York, and Ohio, exceeds all the European localities combined. Michigan has 2100 acres under this crop, 2000 of which are in St. Joseph county, which possesses 100 distilleries, turning out 15,000-30,000 lb. of oil yearly. New York and Ohio total about 1000 acres between them. The annual crop of peppermint-oil for the whole world is estimated at 90,000 lb. One dealer despatched 57,365 lb. from America in 1870 ; and the receipts at Hamburg in 1876 were 25,840 lb. from America, and 14,890 lb. from England. Its commercial value varies widely, Mitcham oil bringing twice or thrice the price of the best American ; and even the Mitcham oil itself is by no means constant. A fertile source of deprecia tion is the presence of weeds among the herbs, necessitating laborious care when preparing the plant for distillation ; sometimes other species of Mentha usurp the ground, and ruin the fragrance of the product. The American oil is frequently adulterated with castor-oil and alcohol.
Peppermint-oil is colourless, yellowish, or greenish ; of peculiar odour ; burning, camphor aceo us, then cooling flavour ; sp. gr. 0 . 84-0 92 ; boils at 188°-193° (374-3791° F.) ; dissolves readily in alcohol ; cooled to —4° (25° F.), sometimes deposits menthol or peppermint-camphor. It is used in medicine (p. 819), confectionery, perfumery (less in England than on the Continent), and largely by sanitary engineers for testing joints and traps.
Other oils afforded by Mentha spp. are as follows :—M. Pulegium (pennyroyal), sp. gr. boils at 183°–] 88° (364°-370i° F.). M. viridis (spearmint), see p. 1431. Al. australis, resembles 2nd quality peppermint-oil. M. gracilis, with an odour of peppermint and pennyroyal, sp. gr. 0.914. M. laxijlora, sp. gr. 0.924, coarse odour ; fiery, bitter, nauseous flavour. Much more important than these, is a peppermint of China and Japan, which E. M. Holmes considers most like M. canad,ensis. This plant is distilled at Canton, whence an export of 800 lb. of the oil, valued at Ns. a lb., was specified in 1872 ; there are also large plantations of it in Japan, and the oil (frequently adulterated) is shipped from Bingo and Osaka. These Chinese and Japanese oils afford much more menthol than other kinds. Seeds of the plant and quantities of the camphor (menthol) yielded by it are imported into this country by T. Christy and Co., 155 Fenchurch
St., London.
Petit-grain-oil.—The oil or essence of petit-grain is produced on a large scale by distillation of the leaves and young shoots of both the bitter and sweet varieties of orange (see p. 1025), the former being far the more fragrant and valuable. The leaves of the bitter orange are obtained in the Mediterranean lemon-districts, where lemons are mostly grafted on orange-stocks ; the latter put forth shoots during the summer, which are often allowed to grow to a length of some feet, and are then cut off, bound in bundles, and conveyed to the distillery. The oil is very extensively employed in perfumery. Other Citrus-oils are described under Bergamot, Cedrat, Lemon, Neroli, and Orange (pp. 1417, 1419, 1423, 1425).
Pimento.—See Allspice, p. 1416.
Pine-oils.—An essential oil is distilled at Reichenhall, in Bavaria, and other places, from the leaves and twigs of Pinus Pumilio, which is much esteemed in medicine by the Germans. That from P. sylvestris is also recommended in certain throat diseases. (Sec also Turpentine-oil, p. 1431).
Poplar-oil.—The leaf-buds of Populus nigra, and other species, by aqueous distillation, give a colourless oil, of pleasant, balsamic odour.
Pyrethrum-oil.—The flowering herb of Chrysanthemum [Pyrethrum] Parthenium, subjected to aqueous distillation, affords a greenish oil, depositing stearoptene by keeping.
Rose-oil, or Otto [Attar] of Roses (Fa., Essence de Roses ; GER., Rosenol).—This celebrated perfume is the volatile essential oil distilled from the flowers of some varieties of rose. The botany of roses appears to be in a transition and somewhat unsatisfactory state. Thus the otto-yielding rose is variously styled .Rosa damascena, R. sempervirens, R. moschata, R. gallica, R. centifolia, R. pro vincialis. It is pretty generally agreed that the kind grown for its otto in Bulgaria is the damask rose (R. damascena), a variety induced by long cultivation, as it is not to be found wild. It forms a bush, usually 3-4 ft., but sometimes 6 ft. high ; its flowers are of moderate size, semi-double, and arranged several on a branch, though not in clusters or bunches. In colour, they are mostly light red ; some few are white, and said to be less productive of otto.
The utilization of the delicious perfume of the rose was attempted, with more or less success, long prior to the comparatively modern process of distilling its essential oil. The early methods chiefly in vogue were the distillation of rose-water, and the infusion of roses in olive-oil, the latter flourishing in Europe generally down to the last century, and surviving at the present day in S. France. The butyraceous oil produced by the distillation of roses for making rose-water in this country is valueless as a perfume ; and the real otto was scarcely known in British commerce before the present century.