SALEP.

Radix Salep, Radix Satyrii; Salep; F. Salep; G. Salepknollen.

Botanical Origin—Most, if not all, species of Orchis found in Europe and Northern Asia are provided with tubers which, when duly prepared, are capable of furnishing salep. Of those actually so used, the following are the more important, namely—Orchis mascula L., O. Morio L., O. militaris L., O. ustulata L., O. pyramidalis L., O. coriophora L., and O. longicruris Link. These species which have the tubers entire are natives of the greater part of Central and Southern Europe, Turkey, the Caucasus and Asia Minor.[2436]

The following species with palmate or lobed tubers have a geographical area no less extensive, namely O. maculata L., O. saccifera Brongn., O. conopsea L., and O. latifolia L. The last named reaches North-Western India and Tibet; and O. conopsea occurs in Amurland in the extreme east of Asia.

The salep of the Indian bazaars, known as Sālib misrī, for fine qualities of which the most extravagant prices are paid by wealthy orientals, is derived from certain species of Eulophia, as E. campestris Lindl., E. herbacea Lindl., and probably others.[2437]

History—Under the superstitious influence of the so-called doctrine of signatures,[2438] salep[2439] has had for ages a reputation in Eastern countries as a stimulant of the generative powers; and many Europeans who have lived in India, although not prepared to admit the extravagant virtues ascribed to it by Hindus and Mahommedans, yet regard it as a valuable nutrient in the sick-room.

The drug was known to Dioscorides and the Arabians, as well as to the herbalists and physicians of the middle ages, by whom it was mostly prescribed in the fresh state. Gerarde (1636) has given excellent figures of the various orchids whose tubers, says he, “our age useth.”

Geoffroy[2440] having recognized the salep imported from the Levant to be the tubers of an orchis, pointed out in 1740 how it might be prepared from the species indigenous to France.

Collection—The tubers are dug up after the plant has flowered, and the shrivelled ones having been thrown aside, those which are plump are washed, strung on threads and scalded. By this process their vitality is destroyed, and the drying is easily effected by exposure to the sun or to a gentle artificial heat. Though white and juicy when fresh, they become by drying hard and horny, and lose their bitterish taste and peculiar odour.

Salep is largely collected near Melassa (Milas) and Mughla (or Moola), south-east of Smyrna, and also brought there from Mersina, opposite the north-eastern cape (Andrea) of Cyprus. The drug found in English trade is mostly imported from Smyrna. That sold in Germany is partly obtained from plants growing wild in the Taunus mountains, Westerwald, Rhön, the Odenwald, and in Franconia. Salep is also collected in Greece, and used in that country and Turkey in the form of decoction, which is sweetened with honey and taken as an early morning drink.[2441] The salep of India is produced on the hills of Afghanistan, Beluchistan, Kabul and Bokhara;[2442] the Neilgherry Hills in the south, and even Ceylon are said likewise to afford it.

Description—Levant salep, such as is found in the English market, consists of tubers half an inch to an inch in length, of ovoid or oblong form, often pointed at the lower end, and rounded at the upper where is a depressed scar left by the stem; palmate tubers are unfrequent. They are generally shrunken and contorted, covered with a roughly granular skin, pale brown, translucent, very hard and horny, with but little odour and a slight not unpleasant taste. After maceration in water for several hours, they regain their original form and volume. German salep is more translucent and gummy-looking, and has the aspect of being more trimmed and prepared.

Microscopic Structure—The fresh tuber exhibits on transverse section a few outer rows of thin-walled cells rich in starch. These are followed by parenchyme of elongated colourless cells likewise containing starch, and isolated bundles of acicular crystals of oxalate of calcium. In this parenchyme, there are numerous larger cells filled with homogenous mucilage. Small vascular bundles are irregularly scattered throughout the tuber. In Orchis mascula and O. latifolia the starch grains are nearly globular, and about 25 mkm. in diameter. In dried salep the cell-walls are distorted and the starch grains agglomerated.

Chemical Composition—The most important constituent of salep is a sort of mucilage, the proportions of which according to Dragendorff (1865) amounts to 48 per cent.; but it is doubtless subject to great variation. Salep yields this mucilage to cold water, forming a solution which is turned blue by iodine, and mixes clearly with neutral acetate of lead like gum arabic. On addition of ammonia, an abundant precipitate is formed. Mucilage of salep precipitated by alcohol and then dried, is coloured violet or blue, if moistened with a solution of iodine in iodide of potassium. The dry mucilage is readily soluble in ammoniacal solution of oxide of copper; when boiled with nitric acid, oxalic, but not mucic acid is produced. In these two respects, the mucilage of salep agrees with cellulose, rather than with gum arabic. In the large cells in which it is contained, it does not exhibit any stratification, so that its formation does not appear due to a metamorphosis of the cell-wall itself. Mucilage of salep contains some nitrogen and inorganic matter, of which it is with difficulty deprived by repeated precipitation by alcohol.

It is to the mucilage just described that salep chiefly owes its power of forming with even 40 parts of water a thick jelly, which becomes still thicker on addition of magnesia or borax. The starch however assists in the formation of this jelly; yet its amount is very small, or even nil in the tuber bearing the flowering stem, whereas the young lateral tuber abounds in it. The starch so deposited is evidently consumed in the subsequent period of vegetation, thus explaining the fact that tubers are found, the decoction of which is not rendered blue by iodine. Salep contains also sugar and albumin, and when fresh, a trace of volatile oil. Dried at 110° C., it yields 2 per cent. of ash, consisting chiefly of phosphates and chlorides of potassium and calcium (Dragendorff).

Commerce—The shipments of salep from Smyrna are about 5000 okkas (one okka equal to 283·2 lb. avdp. = 128·5 kilogrammes) annually.

Uses—Salep possesses no medicinal powers; but from its property of forming a jelly with a large proportion of water, it has come to be regarded as highly nutritious,—a popular notion in which we do not concur. A decoction flavoured with sugar and spice, or wine, is an agreeable drink for invalids, but is not much used in England.[2443]

VANILLA.

Vanilla;[2444] F. and G. Vanille.

Botanical Origin—Vanilla planifolia Andrews—Indigenous to the hot regions (tierra caliente) of Eastern Mexico, diffused by cultivation through other tropical countries. The plant, which is rather fleshy and has large greenish inodorous flowers,[2445] grows in moist, shady forests, climbing the trees by means of its aërial roots.

History—The Spaniards found vanilla in use in Mexico as a condiment to chocolate, and by them it was brought to Europe; but it must have long remained very scarce, for Clusius, who received a specimen in 1602 from Morgan, apothecary to Queen Elizabeth, described it as Lobus oblongus aromaticus, without being in the least aware of its native country or uses.[2446] In the Thesaurus of Hernandez there is a figure and account of the plant under the name of Araco aromatico.[2447]

In the time of Pomet (1694) vanilla was imported by way of Spain, and was much used in France for flavouring chocolate and scenting tobacco. It had a place in the materia medica of the London Pharmacopœia of 1721, and was well known to the druggists of the first half of the 18th century, after which it seems to have gradually disappeared from the shops. Of late times it has been imported in great abundance, and is now plentifully used, not only by the chocolate manufacturer, but also by the cook and confectioner.

Cultivation—The culture of vanilla is very simple. Shoots about three feet long having been fastened to trees, and scarcely touching the ground, soon strike roots on to the bark, and form plants which commence to produce fruit in three years, and remain productive for thirty to forty.

The fertilization of the flower is naturally brought about by insect agency. This was practised as early as 1830 by Neumann in the Jardin des Plantes at Paris, and in 1837 by Morren,[2448] the director of the Botanical Garden of Liège, since which the production of the pods has been successfully carried on in all tropical countries[2449] without the aid of insects. Even in European forcing houses the plant produces fruits of full size, which for aroma bear comparison with those of Mexico.

In vanilla plantations the pods are not allowed to arrive at complete maturity, but are gathered when their green colour begins to change. According to the statements of De Vriese,[2450] they are dried by a rather circuitous process, namely by exposing them to heat alternately uncovered, and wrapped in woollen cloths, whereby they are artificially ripened, and acquire their ultimate aroma and dark hue. They are then tied together into small bundles.

In Réunion the drying of the pods is performed since 1857 by dipping them previously in boiling water.

Description—The fruit when fresh is of the thickness of the little finger, obscurely triquetrous, opening longitudinally by two unequal valves. It is fleshy, firm, smooth, and plump; when cut transversely it exudes an inodorous slimy juice, abounding in spiculæ of oxalate of calcium.[2451] It is one-celled, with a three-sided cavity, from each wall of which projects a two-branched placenta, each branch subdividing into two backward-curling lobes. There are thus in all 12 ridges, which traverse the fruit lengthwise, and bear the seeds. Fine hair-like papillæ line as a thick fringe the three angles of the cavity, and secrete the odorous matter, which after drying is diffused through the whole pod. The papillæ likewise contain drops of oil, which is freely absorbed by the paper in which a pod is wrapped. That the odorous matter is not resident in the fleshy exterior mass we have ascertained by slicing off this portion of a fresh fruit and drying it separately; the interior alone proved to be fragrant.

The vanilla of commerce occurs in the form of fleshy, flexible, stick-like pods, 3 to 8 inches long, and ³/₁₀ to ⁴/₁₀ of an inch wide, of a compressed cylindrical form, attenuated and hooked at the stalk end. The surface is finely furrowed lengthwise, shining, unctuous, and often beset with an efflorescence of minute colourless crystals. The pod splits lengthwise into two unequal valves, revealing a multitude of minute, shining, hard, black seeds of lenticular form, imbedded in a viscid aromatic juice.

The finest vanilla is the Mexican. Bourbon Vanilla, which is the more plentiful, is generally shorter and less intense in colour, and commands a lower price.

Microscopic Structure—The inner half of the pericarp contains about 20 vascular bundles, arranged in a diffuse ring. The epidermis is formed of a row of tabular thick-walled cells, containing a granular brown substance. The middle layer of the pericarp is composed of large thin-walled cells, the outer of which are axially extended, while those towards the centre have a cubic or spherical form. All contain drops of yellowish fat and brown granular masses, which do not decidedly exhibit the reaction of tannin. The tissue further encloses needles of oxalate of calcium and prisms of vanillin.

On the walls of the outer cells of the pericarp[2452] are deposited spiral fibres, which occur still more conspicuously in the aërial roots and in the parenchyme of the leaves of other orchids. The placentæ are coated with delicate, thin-walled cells.

Chemical Composition—Vanilla owes the fragrance for which it is remarkable to Vanillin, which is found in a crystalline state in the interior or on the surface of the fruit, or dissolved in the viscid oily liquid surrounding the seeds. It was formerly regarded as cinnamic or benzoic acid, and then as cumarin, until Gobley (1858) demonstrated its peculiar nature.

The admirable researches of Tiemann and Haarmann performed in Hofmann’s laboratory at Berlin (1874-1876) have shown that vanillin is constituted according to the formula

It is the aldehyde. It is the aldehyde of methyl-protocatechuic acid, and like other aldehydes yields a crystallized compound with the bisulphites of alkalis. This is obtained by shaking an ethereal extract (e) of vanilla, with a saturated solution of bisulphite of sodium. The vanillin compound remaining in aqueous solution is mixed with sulphuric acid and ether; the latter on evaporation affords crystals of vanillin. They melt at 81°, and may be sublimed by cautiously heating them. Vanillin is but sparingly soluble in cold water, and requires about 11 parts of it at 100° C. for solution; it strikes a fine dark violet with perchloride of iron.

The said chemists have further demonstrated that vanillin may be formed artificially. In the sapwood of pines there occurs a substance called Coniferin, C₁₆H₂₂O₈ + 2 H₂O, first observed in 1861 by Hartig. By means of emulsin coniferin taking up H₂O, can be resolved into sugar and another crystallizable substance:—C₁₆H₂₂O₈ + H₂O = C₆H₁₂O₆ + C₁₀H₁₂O₃. The second substance thus derived may be collected by means of ether, which dissolves neither coniferin nor sugar. By oxidizing it, or coniferin itself, by bichromate of potassium and sulphuric acid, Vanillin is obtained. The latter has been for sometime manufactured in that way by Tiemann, but now eugenol (see p. 285) is used for that purpose. Another source for vanillin is benzoin (p. 409).

The amount of vanillin was stated by Haarmann and Tiemann to be 1·69 per cent. in Mexican vanillin, from 1·9 to 2·48 in the Bourbon variety, and 2·75 in that from Java. The so-called Vanillon affords only 0·4 to 0·7 per cent. of vanillin.

From the above-mentioned ethereal solution (e), after it has been deprived of vanillin, vanillate of sodium may be removed by a dilute solution of carbonate of sodium. On acidulating the aqueous solution crystals of vanillic acid,

are precipitated. If the ether of the solution (e), after it has been treated with carbonate of sodium, is allowed to evaporate, a mixture of fatty substances and a resin are obtained. The latter has a peculiar odour, somewhat suggestive of castoreum; vanillic acid is almost inodorous.

Leutner (1872) also found in vanilla fatty and waxy matter 11·8, resin 4·0, gum and sugar 16·5 per cent.; and obtained by incineration of the drug 4·6 per cent. of ash.

Production and Commerce—The chief seats of vanilla-production in Mexico are the slopes of the Cordilleras, north-west of Vera Cruz, the centre of the culture being Jicaltepec, in the vicinity of Nautla.[2453] The finest specimens were contributed in 1878 to the Paris Exhibition from Agapito, Fonticilla, Misantla, Papantla, also from Teziutlan, province of Puebla. There are likewise “Baynillales,” plantations of vanilla, on the western declivity of the Cordilleras in the State of Oaxaca, and in lesser quantity in those of Tabasco, Chiapas, and Yucatan. The eastern parts of Mexico exported in 1864, by way of Vera Cruz and Tampico, about 20,000 kilo. of vanilla, chiefly to Bordeaux. Since then the production seems to have much declined, the importation into France having been only 6,896 kilo. in 1871, and 1,938 in 1872.[2454]

The cultivation of vanilla in the small French colony of Réunion or Bourbon (40 miles long by 27 miles broad), introduced by Marchant in 1817 from Mauritius, has of late been very successful, notwithstanding many difficulties occasioned by the severe cyclones which sweep periodically over the island, and by microscopic fungi which greatly injured the plant. In 1849 the export of vanilla from Réunion was 3 kilogrammes, in 1877 it reached 30,973 kilogrammes. The neighbouring island of Mauritius also produces vanilla, of which it shipped in 1872 7,139 lbs., in 1877 the quantity was 20,481 lbs. There is likewise a very extensive cultivation of vanilla in Java.

Vanilla comes into the market chiefly by way of France, which country, according to the official statistics, imported in 1871, 29,914 kilo. (65,981 lbs.); in 1872, 26,587 (58,643 lbs.); in 1874 that quantity amounted to 34,906 kilo.

Uses—Vanilla has long ceased to be used in medicine, at least in this country, but is often sold by druggists for flavouring chocolate, ices, creams, and confectionery.