The pepper vine (Piper nigrum) is a perennial plant, with a round, smooth, woody, articulated stem, swelling near the joints, branched, and from eight to twelve feet or more in length. The leaves are entire, broad-ovate, acuminate, five- to nine-nerved, coriaceous, very smooth, of a dark green color, and attached by strong sheath-like petioles to the joints of the branches. The flowers are small, whitish, sessile, covering thickly a cylindrical pendulous spike, and succeeded by globular sessile drupes which are red when ripe.

The plant is a native of southern India and grows wild in Cochin-China and various parts of India. It is cultivated on the coast of Malabar, in the peninsula of Malacca, in Siam, Sumatra, Singapore, Johore, Borneo, the Philippines, Japan and many other places in the East; also to some extent in the West Indies. The chief commercial supplies now come from Singapore. The plant is propagated by cuttings, and is supported by props, or trees planted for the purpose, upon which it is trained. In three or four years from the period of planting, it begins to bear fruit. The plant sometimes begins to bear as early as the first year after planting, increases in its yield to the fifth or sixth year, when it produces eight or ten pounds, and begins to lose its productiveness about the fifteenth year. The fruits are gathered while green and dried in the sun or above fires, when they become black and wrinkled. The fire-dried fruits possess a smoky odor and taste and are the most esteemed.

The greatest production is in Sumatra, and the ports of export are principally Singapore and Penang, the Malabar pepper coming from Tellicherry. In England, at least, it is customary to mix peppers of different origin in grinding, taking Malabar for weight, Penang for strength, and Sumatra for color. Owing to the widespread cultivation of pepper a large number of varieties exist; these receive their names from the place of their production or their ports of shipment, as Singapore, Acheen, Penang, Siam, Tellicherry, Trang, Lampong, etc. For a description of the most important of these varieties with the percentage of active constituents contained in each, see J. W. Gladhill, A. J. P., Feb., 1904; Kraemer and Sindall, A. J. P., 1908, p. 1; also Blyth, Foods: Their Composition and Analysis.

White pepper is the nearly ripe drupe, deprived of the outer part of its pericarp by maceration in water and subsequent friction, and afterwards dried in the sun. It occurs as yellowish more or less broken grains with a smooth shiny surface from which the epicarp or outer layer of the fruit has been removed. It is sold in the market either as a whole white pepper or as broken white pepper; the whole peppers are very likely to have some of the epicarp or hull remaining. The removed hull is sold separately under the name of " pepper hulls "; it forms a light to dark brown powder, with a very pungent odor and taste and contains large amounts of the oleoresin of pepper, but according to Gladhill, no piperine. The hulls are sometimes sold mixed with broken white pepper. This mixture contains more oleoresin and less piperine than does the pure pepper; the percentage of the two active constituents varying according to the percentage of drugs in the mixture. White pepper is much less pungent but more aromatic than black pepper.

Long Pepper is obtained from Piper offlcinarum Casimir DC., and P. longum L., the former species yielding the principal commercial supplies and being grown in Java, India, and the Philippines. The plants are distinguished in having their flowers in dense, short terminal, and nearly cylindrical spikes and their fruits, consisting of very small one-seeded drupes, embedded in a pulpy matter. The fruit is green when immature, and becomes red as it ripens. It is gathered in the former state, as it is then hotter than when perfectly ripe. The whole spike is taken from the plant, and dried in the sun. The fruit of the P. offieinarum is cylindrical, 2 to 6 cm. long and 4 to 7 mm. in diameter, indented on its surface, of a dark-gray color, a weak aromatic odor, and a pungent fiery taste. The fruits of P. longum are shorter and thicker. Dulong found its chemical composition to be closely analogous to that of black pepper.

West African or Ashantee Pepper is the fruit of P. Clussii, C. DC., which grows abundantly in tropical Africa. It does not come into Western commerce, although much used in Africa. The berry is described as resembling cubeb, but less rugose, and with a more slender pedicel and having the odor and taste of black pepper. Stenhouse found piperine in this variety of pepper.

Kissi Pepper is a fruit yielded by the Piper Famechoni, Heckel, of Upper Guinea. The berries, which grow in cylindrical clusters, are small, blackish-brown, ovoidal, with a cubeb-like pedicel at their base. Their powder is very aromatic, with an especially pleasant taste. They have been found by A. Barille to contain 4.5 per cent, of volatile oil and 3.7 per cent, of piperine. (J. P. C., 1903,106.)

Description and Physical Properties. � Unground Pepper.� Nearly globular, from 3.5 to 6 mm. in diameter, epicarp very thin, easily separable from the sarcocarp; externally blackish brown or grayish black, coarsely reticulate; unilocular, 1-seeded; seed nearly white, hollow, adhering to the pericarp. Odor aromatic, slightly empyreumatic; taste aromatic and very pungent.

Powdered Pepper. � The powder is a mixture of blackish brown fragments of the pericarp and nearly white fragments of the perisperm and embryo; starch grains spherical or somewhat angular, from 0.001 to 0.003 mm. in diameter, mostly in the polygonal cells of the perisperm; stone cells of the epiearp varying from nearly isodiametric or palisade-like to long tapering or somewhat irregular in shape, with thick porous walls and large lumina frequently containing a reddish brown pigment; stone cells of the endocarp unevenly thickened, the outer walls being usually rather thin, and the lumina usually filled with a reddish brown substance; oil cells with suberized walls and containing a yellowish oil, from which monoclinic prisms of piperine occasionally separate. Pepper yields not less than 6 per cent, of non-volatile extract, soluble in ether. It contains not less than 25 per cent, of starch." N. F.

For information on the pharmacognosy of pepper, see Winton and Moeller in the " Microscopy of Vegetable Foods;" Spaeth, Ztehr. f. Unters. d. Nahr. u. Genussm., 1908, xv, p. 472; Kraemer and Sindall, A. J. P., 1908, lxxx,-p. 1; Collin in Ann. des. Falsifications, 1910, iii, p. 272; Wallis, Chem. News, cxi, 143.

Constituents. � Pepper contains three important ingredients, a volatile oil, a resin and piperine. The volatile oil is composed of terpenes, chiefly Iaevo-phellandrene. It is colorless or slightly yellow Iaevo-rotatory with a specific gravity of 0.880 and 0.905. It is not pungent but represents the characteristic aromatic flavor of the pepper. The resin, sometimes called chavicin, is a soft greenish substance, extremely pungent but without odor. Its pungency is by many attributed to the presence of piperine. A mixture of the volatile oil and resin which was made by extracting with ether, was formerly official under the name of Oleoresina Piperis. The process for this was as follows:

"Pepper, in No. 40 powder, five hundred grammes; Ether, a sufficient quantity. Place the pepper in a cylindrical glass percolator, provided with a stop-cock, and arranged with a cover and a receptacle for volatile liquids. Pack the powder firmly, and percolate slowly with ether, added in successive portions, until the drug is exhausted. Recover the greater part of the ether from the percolate by distillation on a water bath, and, having transferred the residue to a dish, set this aside in a warm place until the remaining ether has evaporated, and the deposition of piperine has ceased. Lastly, separate the Oleoresin from the piperine by straining through purified cotton. Keep the Oleoresin in a well-stoppered bottle." U. S. IX.

Piperine, C₁₇O₁₉O₃N, which may be regarded as the true active principle of black pepper was defined by the U.S. VIII as "a feebly basic substance [CH₂O_2.C₆H₃.CH:CH.:CH.: CH.CON.- C₅H₃₀] obtained from Pepper and other plants of the Piperaceae." U.S. VIII.

It was officially described as " colorless or pale yellowish, glistening, monoclinie crystals, odorless, permanent in the air, and containing no water of crystallization. When put into the mouth, it is at first tasteless, but on prolonged contact it develops a sharp, biting taste. It is optically inactive. Insoluble in water; soluble in 15 parts of alcohol, 36 parts of ether, and in 1.7 parts of chloroform at 25� C., soluble in 4.4 parts of alcohol at 60� C. It melts at 130� C. Upon ignition, it emits alkaline vapors, and is completely consumed. Its alcoholic solution is neutral to litmus paper. Sulphuric acid dissolves Pipeline with the formation of a blood-red color, which disappears on dilution with water. On heating Piperine with alcoholic potassium hydroxide, it is converted into piperinic acid and piperidine, the latter recognizable by its alkaline, pepper-like odor, and the former by its melting point, 215� C. On adding a crystal of Piperine to sulphuric acid containing about half its volume of solution of formaldehyde, a permanently green liquid is formed. On adding a crystal of Piperine to sulphuric acid containing a fragment of potassium dichromate, it at once acquires a purple color, and, on stirring, dissolves, forming a reddish-brown solution, which becomes greenish on adding water to it. On adding a crystal of Piperine to sulphuric acid containing a trace of selenous acid, it turns brown, changing at once to violet, and dissolves, forming a brown solution changing to green. When heated with nitric acid, Piperine is colored at first orange, then red, and the acid acquires a yellow color, deepening to reddish as the crystals dissolve. On adding to this solution an excess of potassium hydroxide T.S., the color is at first yellow, but upon boiling, it becomes blood-red." U.S. VIII.

Piperine has such feebly basic properties that its salts are immediately decomposed by solution. By boiling with an alcoholic solution of potassium hydroxide, it is split up into a strongly basic substance, piperidine, and piperic acid, C₁₂H₉O₃. Piperidine, which probably occurs naturally in small quantities in pepper, is a volatile, liquid alkaloid with a boiling point of 106� C., soluble in either alcohol or water and forming crystalline salts. It is of great chemical interest as being a simple derivative of pyridine, which seems to underlie the molecular structure of so many alkaloids. Piperidine is hexahydropyridine, C₅H₁₁N, and can be easily obtained from pyridine by the action of tin and hydrochloric acid, or when sodium acts upon the alcoholic solution. Conversely, piperidine can be changed into pyridine when sulphuric acid at 300� C. or gentle oxidizing agents act upon it. Coniine, it will be remembered (see Conium), has been shown synthetically to be a normal propyl-piperidine. For a paper on commercial peppers, by J. W. Gladhill, see A. J. P., 1904, 71.

Adulterations. � On account of its extensive use as a condiment pepper has been largely adulterated, especially when sold in the form of a powder. Chief of the adulterants are pepper-hulls, ground olive pits, wheat middlings, and roasted cereals. Among the other substances sometimes used have been ground beans or peas, corn starch, flaxseed, mustard hulls, and coffee hulls. The adulterated articles are usually fortified with the addition of Cayenne pepper. At the present time, by virtue of the National and State Food Laws, black pepper is seldom adulterated. Adulterations can be detected by the microscope with more or less ease (see P. J., Ixxi, 269; P. J., June, 1890; Bull. U. 8. Dept. of Agriculture, No. 13, Part II, pp. 183, 1887; A. J. P., 1887,146); but when pepper has been adulterated to the amount of 10 per cent, the discovery of the fraud is best made by determining the proportion of ash, of ether extract and of piperine present. The ash should never be above 6.5 per cent, for black and 3 per cent. for white pepper; the ether extract should be between 7.5 and 10 per cent, for black and 6 to 9 per cent, for white pepper, the U. S. standard being not less than 6 per cent, in which not less than 3.25 per cent, nitrogen shall be present. Piperine should be present in from 5.5 to 9 per cent, in good black pepper.

The amount of oleoresin in any pepper can readily be determined by subtracting the weight of piperine from that of the mixture. Penang pepper is sometimes made to resemble the higher priced white peppers by coating the grains with an earthy matter (lime or clay). According to A. Mennechet, the fruits of Myrsine africana and of Embelia Ribes may sometimes be detected in the powder of pepper by extracting with ether and adding a little water, followed by a few drops of ammonia, when after shaking, a deep lilac-red color will appear in the aqueous layer. (/. P. C., xiv, 587.)

Uses. � Black pepper is a warm carminative stimulant, capable of producing general arterial excitement, but acting with greater proportional energy on the part to which it is applied. From the time of Hippocrates it has been used as a condiment and in medicine. Its chief medicinal application is to excite the languid stomach and correct flatulence. In the early part of the 19th century piperine enjoyed a considerable popularity as a remedy for malarial fever. Although the evidence seems strong that it does really possess some antiperiodic powers, it is not comparable to the preparations of cinchona and has almost completely passed out of use except as an ingredient in Warburg's tincture and similar preparations. Some have attempted to explain its synergism with cinchona on the ground that its action on the stomach improves the absorption of quinine, but there is on the one hand no evidence that it does improve the absorption of quinine, and on the other hand considerable evidence that it possesses intrinsic anti-malarial powers (for evidence on this see Husemann, Die Pflanzenstoffe, 1882, p. 491).