Notes on Patchouli.
BY J. CH. SAWER.
The identity of the plant furnishing this perfume has been the subject of articles in this journal since the year 1844 ("Phar. Journ.," [I], vol. iv., p. 80; vol. vi., p. 432; vol. viii., p. 574; vol. ix., p. 282, and iv. [3d series], p. 362), but the first mention of it in a pharmaceutical paper seems to be in the "Journal de Pharmacie," 1826, (vol. xii., p. 61). The first parcel of the leaf offered at public sale in London was in 1844, and it was bought in at 6s. per lb. Since that date the trade in these leaves and the oil has enormously increased, the number of bales imported into London during the last twelve months having been from 300 to 400 bales of 2 cwt. each. It is stated by Dr. Piesse that "its consumption in the perfumery trade of Europe is something beyond belief" ("Garden," Nov. 24th, 1877), and in the last edition of his work on perfumery he says that "were the otto cheaper its consumption could be increased tenfold." This book is dated 1879; the average price, first-hand, during that year was 3s. per oz. in London; it is now only 1s. 7d., and leaves have been sold at from 3.5d. to 9d. per lb., according to the quality.
The bulk of the enormous quantity of leaves harvested and of the oil goes direct from its place of production to Mecca, the Arabs believing in its health-giving properties and in its power of warding off fever and sickness. During the last five years China and Japan have adopted it for similar reasons. As a perfume it has much more popularity amongst Orientals than among Europeans; still, if the European consumption alone increases in the ratio predicted by Dr. Piesse, consumers will naturally inquire into the causes which influence so large a market, held in a few hands and based on the supply of a plant of which very little is known in Europe.
The generally accepted name, "Pogostemon patchouly," originated by Pelletier-Sautelet ("Mem. de la Soc. Roy. des Sciences d'Orleans," V. n. 6, 1845, and Benth. in De Cand. "Prodr.," xii., p. 153; also Hooker's "Journ of Bot. and Kew Mis.," i., pp. 22 and 328), and the minute botanical description of that plant given by him in vol. viii. of this Journal, may apply to a variety of the true plant yielding a somewhat similar perfume, but the plant as it grows wild in Province Wellesly does not flower; neither does the variety which is cultivated at Singapore. Still Bentham was of opinion that Pelletier's plant was identical, or not really specifically distinct from his Pogostemon intermedius ("Wal. Cat.," 2327), of Silhet, Penang and the opposite shore of the Malay peninsula, or from P. parviflorus of Silhet, Assam and Saharunpur, or even from P. Heyneanus of Ceylon, Java, etc., which Drury describes as "probably merely a variety with larger spikes and more drooping in habit," and says that it is found wild in the Concans, and that it is probably Rheede's synonym "cottam," ("Hort. Mal.," x., t. 77).
Apparently there are several varieties of this plant. It is found in many other places than those above named; in Ceylon, China, Java, Mauritius, etc. Its native locality may not have so wide a range, but it has most likely been introduced for cultivation at many of those places. The plant does not grow to any extent on the island of Penang, but a plant said to have been obtained from thence was introduced into the botanic garden at Calcutta, and during ten years showed no disposition to blossom. Other specimens flowered in the stoves at Kew and Orleans; others received from Louis Van Houtte of Ghent, and grown in the moist stove here, have not attempted to flower, although they otherwise throve exceedingly and agreed in the structure of leaf and stalk with the figure of the Kew plant. The only variety known to flower (if really it be a variety of the same plant) grows on one of the islands near Sourabaya, south-east of Sumatra; the leaf is odorous, though not so broadly ovate and with shorter pedicels, and it is grown simply for the flowers, which are sold in large quantities for medicinal purpose in the various markets of Java, and fetch a high price.
The difficulty of obtaining accurate botanical details of these plants is great, but there are no doubt many varieties, and all labiate plants, especially the mints, are apt to take a character and habit not true to the original plant, when transplanted to a climate or soil other than is natural to them; and under such conditions the development of odorous properties is as much changed as is the development of medicinal properties in many drug-yielding plants. To instance the former I may mention the lavender and the peppermint, and regarding the latter, Dr. Hooker observes, in the introductory essay to his "Flora Indica," that the most conspicuous Indian examples are presented by the opium poppy, mudar (Calotropis) and the Cannabis sativa or common hemp of England, which yields "bhang" and "chirris" in varying quantities and of different quality very much in proportion to the humidity of the soil and climate it grows in. The digitalis grown in the Himalaya is said to have proved almost inert, and so with other plants which have been cultivated for medicinal and economic purposes. The wood of the English-grown Lebanon cedars diners greatly in color, hardness and odor, and the wood of the English oak grown at the Cape of Good Hope is worthless. The patchouli plant cultivated at Singapore is of course not propagated by seed, as it never flowers. It may be a hybrid, and if its difference of odor be not attributable to this cause it may be to the drying, fermenting and distilling processes being carried on in a different way to that adopted in Province Wellesley. These reasons may also account in some measure for the differences observed in the Chinese oil of peppermint.
Inquiring into the causes which influence the price of any volatile oil, we find that besides supply and demand, quality is considered, depending on freedom from adulteration and careful manufacture, whether derived from stale or recent plants, and particularly on the variety of the plant from which it is produced. Whether in the case of patchouli there are plants differing specifically or not, it is certain that there are varieties, arising perhaps from hybridization, cultivation or climatic influence, and there are still greater differences in the aroma of the oil, arising either from method of production or adulteration. The bales which now arrive in London are mostly from Province Wellesley, and consist of leaves and woody stalks (too large a proportion of the latter) of the wild variety known as "Doun Tilâm Utan," Doun signifying leaf, Tilâm bed or mattress, also including the idea "health-giving," and outan "wild," meaning that the natives stuff their beds and pillows with the leaf and believe in its health-giving and life prolonging virtues. Now, even assuming that these bales consist of this plant alone, unadulterated with leaves of any other plant, that they really have been properly cured and dried, and do not turn mouldy or rancid in transit and arrive sound and un-sea-damaged, and that during the time they are stored in warehouse in London they escape dampness (which the leaf is remarkably apt to absorb), the oil which is afterwards distilled from these leaves differs in aroma from that distilled from the leaves on the spot immediately after the final drying process. The majority of the bales imported are re-shipped to a German port and the oil distilled from them is said to be often adulterated to the extent of even 60 per cent., with cheaper oils, mostly with those of cedar and cubebs. [It is remarkable that these have been selected as adulterants, as the camphor of patchouli is isomeric with that of cubebs and with the concrete oil of cedar.] ("Comptes Rendus," January 8, 1877.)
The method of cultivation of the plant and preparation of the oil, as practised by Mr. Fisher of Singapore, is as follows: The variety selected for cultivation is known locally as Tilâm Wangi (meaning "fragrant"), obtained from the island of Rhio, near Singapore, in the Straits Settlements. The soil most suitable is a rather stiff clay with only a small percentage of silica, and land of this description found near the coast (containing traces of marine deposits) is planted in rows about 4 or 5 feet apart. The plants are propagated by cuttings struck in the open air, which until rooted, are sheltered from the sun by pieces of cocoa-nut shell. The harvest is made in dry weather and when the sun has drawn up the dew from the leaves; the tops and green parts of the plant are broken off by hand, rejecting all yellow or decayed leaves and all the woody stems. The selected parts are then dried in the shade under large sheds (as the sun would draw out the perfume), and to ensure evenness in drying, they are spread on bamboo racks, allowing the air to penetrate from beneath. During this process they are frequently turned over, and when so far dried as to leave just sufficient moisture to permit a slight fermentation, they are piled in heaps and allowed to heat gently; after this they are again spread out and dried—but not to absolute dryness—and are immediately distilled. The addition of about 25 per cent. of the wild herb "Tilâm outan" is said to increase the fragrance of the distillate. The distillation is effected by passing steam generated in a boiler apart through the leaves in the stills. The pressure of steam is not allowed to rise above 30 lbs. The yield, under these conditions, being about 1/4 oz. per lb. of leaves; by high pressure steam the yield would be greater but more rank in quality. The stills are sometimes jacketted, and by passing a separate current of steam into the jacket condensation in the body of the still is avoided. Operating on specimens of leaf recently imported into London, I have observed that at the commencement of the distillation a small portion of pale colored oil passes over, lighter than water, and of a more delicate aroma than the heavy oil; but the heavy oil was rank. The Singapore oil is sent to London in cases of twelve bottles containing 22 ounces in each bottle, labeled with the manufacturers' name and guaranteed by him to be pure. From London it is sent to merchants and manufacturing perfumers in all parts. Obviously such oil is more likely to be pure and of better quality than an oil distilled in England, France or Germany from the baled leaves and without a reliable pedigree. The oil described as "French" oil has a different odor to the genuine leaf, and has not the peculiar olive-brown tint of the Singapore oil.
An examination of oil of patchouli was made in 1864, by Dr. Gladstone ("Journ. Chem. Soc.," series 2, vol. iii.), on a specimen obtained from Dr. Piesse, and believed to be quite genuine; also on a specimen obtained from India. Both specimens were brownish-yellow and slightly viscid. They began to boil at 257 °C., at which temperature nearly all distilled over, and was found to be a hydrocarbon analogous to that from cubebs, but towards the end the thermometer rose much higher, and the distillate became of a deep blue color, owing to the presence of an intensely blue matter termed "azulene" or "caerulein," which is also found in the oils of Calamus aromaticus, Matricaria chamomilla, Artemisia absinthium, Achillea millefolium, and in small quantity in the oils of bergamot and Ceylon lemon-grass. The analysis of this remarkable fluid shows its formula to be C16H13O (and not C12H13O, as stated by Piesse at page 58 of his last edition). Its boiling point is 576°F., and its sp. gr. .930. There are but few liquids which give a colored vapor when boiled, but azulene is one of them. Like itself its vapor is blue. It is soluble in and imparts its color to fatty and volatile oils, alcohol and many other liquids, but not water. It is very permanent, and bears a temperature of 700° to 800° F. in a sealed tube without alteration, and none but the strongest acids aided by heat will break up its constitution. It is most intensely blue, appearing almost black when in a concentrated state. It is not .decolorized by sulphurous acid, sulphuretted hydrogen, or bromine water. It does not attach itself to animal charcoal, nor does it dye wool, cotton or silk. It has been found to exist to the extent of 6 per cent. in the pure oil.
When left at rest oil of patchouli deposits a crystalline body, known as camphor of patchouli, in regular hexagonal and pyramidal prisms. The composition of this camphor has been stated as C30H28O2 by Gal ("Bul. de la Soc. Chim.," 1869, p. 304), but by Montgolfier ("Comptes Kendus," January 8, 1877, p. 88), as C36H28O2, which would constitute it an isomer of camphor of cubebs and of concrete essence of cedar. The conditions most favorable to the formation of this body are little known, but it has been remarked that it forms more rapidly in samples of oil which have been desiccated by chloride of calcium. This camphor not having any commercial value its formation is undesirable, but as it results from a simple molecular change it may be difficult to prevent it; however, it is possible that the presence of a small quantity of water in the oil may, at least retard it.
The difference of the boiling point of oil of patchouli from that of oil of cedar and of oil of cubebs may serve as a guide in testing a suspected sample; so also may the percentage of azulene.
Volatile oils exhibit great diversity in their action on polarized light, some being dextro-, others laevorotatory in various degrees. According to Gladstone ("Journ. Chem. Soc.," xvii., p. 3) the rotatory power (determined for a column of liquid 10 inches long) of the so-called "Penang" oil of patchouli is -120°, the same for cedar wood oil being +3°. The hydrocarbon of patchouli oil—patchoulene—deviates the polarized ray -90°; the rotatory power of cubebs is recorded as +55°.
The same authority gives the sp. gr. of the three sorts of commercial oil of patchouli as follows: Indian, .9554; Penang, .9592; French, 1.0119; all taken at 60°F., and for their hydrocarbons:
|Sp. gr. at 20°C.||Boiling point.|
Of course the addition of oil of turpentine would have the effect of lowering the sp. gr. and so counterbalance the adulteration of ol. copaibae, but the application of Professor Dragendorff's test should detect this ("Pharmaceutical Journal," [3d series], vi., p. 541).—Phar. Jour. and Trans., Nov. 20, p. 409.