RHOXOLANI, a Sarmatian tribe defeated in the Crimea by Diophantus, general of Mithradates, c. I00 B.C., and by the Romans on the lower Danube c. A.D. 6o, and also under M. Aurelius. They seem to have finally succumbed to the Goths. RHUBARB. This name is applied both to a drug and to a vegetable.
I. The drug has been used in medicine from very early times, being described in the Chinese herbal Pen-king, which is believed to date from 2700 B.C. It is still produced in the four northern provinces of China. In England the culture of rhubarb for medic inal purposes began in 1777 at Banbury in Oxfordshire and is still carried on there. Later it extended to France and other parts of Europe.
The botanical origin of Chinese rhubarb is uncertain. Rheum palmatum, R. officinale, R. palmatum, var. tanguticum, R. colini anum and R. Franzenbachii have been variously stated to be the source of it, but the roots produced by these species under cultiva tion in Europe do not present the characteristic network of white veins exhibited by the best specimens of the Chinese drug. The Banbury rhubarb appears to be a hybrid between R. rhaponticum and R. undulatum—the root, according to E. Colin, not presenting the typical microscopic structure of the former. More recently very good rhubarb has been grown at Banbury from Rheum officinale, but these two varieties are not equal in medicinal strength to the Chinese article, yielding less extract—Chinese rhubarb affording, according to H. Seer, 58%, English rhubarb 21 % and R. officinale 17%.
Two varieties of the drug are known, viz., kiln-dried and sun dried. So-called "Turkey" rhubarb was the Chinese drug which reached Europe from Aleppo and Smyrna, having travelled to Asia Minor by way of Persia and the Caspian.
oxalate, which gives it the characteristic grittiness. There is also present rheotannic acid, which is of some practical importance. There are numerous other constituents, such as emodin, mucilage, resins, rheumic acid, aporrhetin, etc.
The dose of rhubarb is from 2 up to 3o grains, according to the action which is desired. The Pulvis Rhei Compositus of the British Pharmacopoeia, or Gregory's powder, is composed of 2 parts of rhubarb, 6 of heavy or light magnesia and i of ginger. The dose is 20 to 6o gr.
Rhubarb in small doses-4 to 2gr.—is an astringent tonic, since it stimulates all the functions of the upper part of the alimentary canal. Its more characteristic action, however, is purgation, which it causes in doses of i 5gr. and upwards. The action occurs within seven or eight hours, a soft, yellow motion being produced. Rhubarb also increases the amount of bile formed by the liver. The drug is apt to cause colic, and should therefore never be given alone. Purgation is succeeded by definite constipation, hence rhubarb is obviously worse than useless in the treatment of chronic constipation, which it only aggravates. On the other hand, it is valuable when diarrhoea has been caused by unsuitable food. The drug removes the indigestible residue and then gives the bowel rest.
Some chrysarobin is absorbed and is excreted in the urine, which it slightly increases and colours a reddish brown. The colour is discharged by the addition of a little dilute hydrochloric acid to the urine.
2. The rhubarb used as a vegetable consists of the leaf stalks of R. rhaponticum and its varieties, and R. undulatum. It is known in America as pie-plant. Several other species, such as R. palmatum, R. officinale, R. nobile and others, are cultivated for their fine foliage and handsome inflorescence, especially in wild gardens, margins of shrubberies and similar places.