Rhubarb (FR., Bhubarbe ; GER., Rhabarber).—The root of several species of .Rheum is one of the commonest and most valuable purgatives, and is also used as a stomachic and tonic. The bulk of the commercial drug would seem to be afforded by two species, but this is a point on which botanists are not agreed. The rival species are B. offieinale and a variety of B. palmatum called R. Tanguticum. The first is a native of S.-E. Thibet, and of various parts of W. and N.-W. China, where it is in a measure cultivated. Supplies of the drug are received from these districts, and it is claimed for this plant that it is the only source of the true drug. The second species certainly furnishes considerable quantities of the drug, but opinions differ as to its genuineness. This plant is abundant near the sources 'of the Tatung and Etsina rivers, in the dense mountain forests. Its root is dug up by Tangutans and Chinese, in September and October ; the lateral shoots are cut off, the outer rind is removed by a knife, and the root is then cut transversely into segments, which are threaded on strings, and hung up to dry in the shade, where they are exposed to a draught, but not to the sun. The larger segments are also divided longitudinally, the pieces being known in commerce as "rounds" and " flats" respectively. The drug, locally worth about 2s, 2d. a lb., is sent to Si-ning. the chief central depOt, and is thence despatched (in winter, by land ; in summer, by boat) down the Hoanglio to Pekin, Tientsin, &c., where it fetches ten times the local price. The plant affects ravines with a rich loamy soil and N. aspect, and is seldom found on S. slopee, or on the bare mountain. In altitude it ascends to 10,000 ft. It is sometimes cultivated by means of seeds and young plants. Seed is sown in autumn or early spring, in a fine black mould. In the third year, the root is as thick as a man's fist ; in eight to ten years, it ie mature.
The drug-yielding species of the plant are very widely distributed : they extend over the four N. provinces of China, named Chihli, Shansi, Shensi, and Henan ; through the N.-W. province of Kansn, reaching to the frontiers of Thibet ; the Mongolian province of Taing-hai, including Lake Koko-nor, and the regions of Tangut, Sifan, and Turfan ; and the mountains of the W. province of Sechuan. The drug from the last-mentioned district is very inferior, owing, it is said, to the moist heat of the province, which interferes with the drying process, and necessitates the employment of direct heat, either from the sun, or by placing the sliced root on heated stones. The places of production, qualities, and comparative prices of the various grades of rhubarb furnished by the Chinese Empire may be thus stated :—Si-ning (Kansu province), average 80 tads (tael = 5s. 10 /.) a picul (1334 lb.); Liangchow (Kansu), 75 taels ; Mienchow (Sechuan), 55 t eels ; Kiaichow (Kansu), 40 tads; Kansu, and N.-W. border of Sechuan, best, 40 tads, common, 20 tads; Kuan Hien (Seelman), best, 30 taels, common, 20 taels ; Sechuan also yields some very common, value 5-8 teas. The Si-ning and Liangehow brands never come to Hankow, and probably go overland to Russian markets; very little even of the Mienchow quality reaches Hankow, and the demand is therefore supplied entirely from the lower grades. A different species is said to grow in the alpine region of the Kansu
mountains, but is unfit for medicine ; yet another is ascribed to the Ala-Shan mountains.
The very various names by which commercial rhubarb has been known at different times in this country are due solely to changes in the route by which the article, purchased from the pro ducers by Bokharian merchants, has reached Europe. The first route lies over the eteppes, by Yarkand, Kashgnr, Turkestan, and the Caspian, to Russia. In 1719, Urga was the great depot ; in 1728, the trade was transferred to Kiachta and Maimatchin. The drug was subjected to special control by Russia, and officials were appointed to inspect it, and reject all spurious pieces, and to improve and protect it by trimming, paring, boring, drying, and packing it in chests, sewn up in linen, pitched, and then covered with hide. This article constituted " Russian," "Muscovite," or " Crown " rhubarb, whose uniformly good quality gave it pre-eminence. Since 1860, it has dis appeared from commerce ; the severity of the Russian monopolists drove it to seek another outlet. The second route is by the Indus or Persian Gulf to the Red Sea and Alexandria, or by Persia to Syria and Asia Minor. From the Levant ports of Aleppo, Tripoli, Alexandria, and Smyrna, it reached Europe, and got known as " Turkey " rhubarb. This did not long survive the competition of the Russian route ; and as the imports in this direction ceased, the name was commonly and confusedly (in England only) applied to the drug brought through Russia. The third line is by way of Chinese seaports, the route now traversed by all the supplies coming to W. Europe, and only developed since about 1860, whence the drug is called "China," "Canton," or "East Indian" rhubarb, generally the first-named. It is chiefly purchased at Haukow, sent down to Shanghai, and thence shipped to Europe. The exports from Hankow, in 1878, were :—Shansi drug, 2697 piculs (of 133* lb.), value about 32,000/. ; Sechuan drug, 3245 piculs, value about 11,0001. Tien tsin, in 1877, exported 959 piculs. Minor quantities are occasionally despatched from Amoy, Foochow, and Ningpo. Our imports of the drug in 1870 (since which date no returnlbas been issued) were over 153 tons, valued at more than 60,0001.
Its commercial value is now about 3-4s. a lb., for good and fine ; 6d.-2s. 6d. for middling and ordinary. In 1657, when it came overland, its price was I6s. a lb. As now imported from China, the drug consists of portions of a massive root, varying in form according to the treatment under gone, and often trimmed to resemble the old Russian drug. The pieces are commonly 3 in. long, and 2 in. wide, but sometimes much larger, usually pierced by a bole, and coated with a bright brownish-yellow powder. This last characteristic is considered much more in England than on the Continent ; to imitate the Russian or Crown rhubarb, it is cut or filed, by a workman wearing leather gloves, and is then known as " Turkey trimmed "; the terminal portions of these are called " stick" rhubarb, and sold at a low price. The fracture must show no sign of decay, stain, or sponginess. The root feels gritty in the month, from the presence of orystals of oxalate of lime, and has a bittor, astringent, nauseous flavour ; and a peouliar odour.