RHU 



R.HOX, a word ufed by fome authors to exprefs the 

 tunica uvea of the eye. 



RHUBARB, Rhabarbarum, in Botany. See 

 Rheum. 



Rhubarb, Rheum Palmatum, in the Materia Medica. 

 The rhubarb, called the rhabarbarum officinale, was fup- 

 pofed, in the year 1732, to be fupplied by fome plants fent 

 from Ruffia, to Juffieu of Paris, Rand at Chelfea, and Lin- 

 nxus at Upfal. Accordingly thefe plants were adopted by 

 Linnaeus, in his firft edition of the Species Plantarum, un- 

 der the name of rheum rhabarbarum. This, however, was 

 not very generally received as the genuine rhubarb plant. 

 But in order to ascertain this matter more completely, Kauw 

 Boerhaave procured, from a Tartarian rhubarb merchant, 

 the feeds of thofe plants, which he annually fold, and which 

 were admitted at Peterfburgh to be the true rhubarb. 

 Thefe feeds were foon difcovered by de Gorter to produce 

 two diftindt fpecies ; viz. the R. rhabarbarum of Linnaeus, 

 or R. undulatum, as it has been fince called ; and another 

 fpecies, declared by Linnaeus to be a new one, and firft 

 mentioned in the fecond edition of the Species Plantarum, 

 in 1762, under the name of R. palmatum. But before this 

 time, de Gorter had repeatedly fent its feeds to Linnaeus, 

 and the young plants conftantly perilhed : at length he ob- 

 tained the frefh root, which fucceeded very well at Upfal, 

 and enabled the younger Linnaeus to defcribe this plant in 

 the year 1767. However, two years antecedent to this, Dr. 

 Hope's account of the rheum palmatum, as it grew in the 

 Botanic garden near Edinburgh, had been read before the 

 Royal Society at London ; and of the great eflimation in 

 which this plant was held by him we have the following 

 proof. " From the perfect fimilarity of this root with the 

 belt foreign rhubarb in tafte, fmell, colour, and purgative 

 qualities, we cannot doubt our being at lad pofTeffed of the 

 plant which produces the true rhubarb, and may reafonably 

 entertain the agreeable expectations of its proving a very im- 

 portant acquifition to Britain." (See Phil. Tranf. for the 

 year 1765.) But from the relation above given, it appears 

 that the leeds of both R. undulatum and R. palmatum were 

 tranfmitted to Peterfburgh as thofe of the true rhubarb : 

 we are therefore to conclude, that the former fpecies has an 

 equal claim to this importance with the latter ; and from 

 further inquiries made in Ruffia, there is the beft authority for 

 believing that the R. colnpadtum alfo affords this very ufeful 

 drug. Bergius fays, " Rheum palmatum producit rhabar- 

 barum in officinis Sibiricum appellatum : certe e feminibus a 

 Bucharis e montofis Tibeti in Ruffiam apportatis, et poitea 

 fatis hocce rheum palmatum enatum eft." (Vide Pallas 

 Reife, Sec. vol. iii. p. 157.) " Rhabarbarum vero Chinenfe 

 ex alia fpecie rhei defumptum effe videtur." (Vide Georgi 

 Reife, &c. vol. i. p. 211.) The feeds of the rheum pal- 

 matum were firft introduced into Britain in 1762, by Dr. 

 Mounfey, who fent them from Ruffia, and were fuppofed 

 to be a part of thofe already mentioned ; and fince their 

 profperous cultivation by the late profeffor of botany at 

 Edinburgh, the propagation of this plant has been gradually 

 extended to moft of our Englifh gardens, and with a degree 

 of fuccefs which promifes in time to fuperfede the importa- 

 tion of the foreign root. The R. rhaponticum is a different 

 fpecies from either of thefe. This is fuppofed to be the 

 rhabarbarum of the ancients. It is well known that the an- 

 cient rhubarb had net the purgative virtues of the modern. 

 Two farts of rhubarb are ufually imported into this country 

 for medical ufe, viz. the Chinefe and the Tartary rhubarb. 

 Mr. Bell informs us, in his travels, that the beft rhubarb 

 grows in that part of the Eaftern Tartary called Mongallia : 

 which ferves as a boundary between Ruffia and China ; or 



RHU 



on the chain of mountains in Tartary, which ftretches from 

 the Chinefe town Selin to the lake Kokonor, near Thibet. 

 This plant, he fays, does not run and fpread itfelf like 

 docks, but grows in tufts at uncertain diilances, as if the 

 feed had been dropped with deiign. As the Mongalls do 

 not think it worth cultivating, the marmots, which burrow 

 under the fhade of its fpreading leaves, and probably feed 

 on its leaves and roots, contribute to its increafe, partly by 

 the manure which their dung affords it, and principally by 

 calling up and loofening the earth, into which the ripe 

 feeds, blown by the wind, fall, and where they immediately 

 take root. After digging and gathering the rhubarb, the 

 Mongalls cut the large roots into fmall pieces, in order to 

 make them dry the more readily. The roots are taken up 

 in autumn, according to Mr. Bell's account ; but according 

 to Pallas, in April and May : ar.d after being cleaned, and 

 cut tranfverfely into pieces of a moderate fize, thefe pieces 

 are placed on tables, and turned three or fosr times a day 

 for five or fix days. In the middle of every piece they 

 fcoop a hole, through which a cord is drawn, in order to 

 fufpend them in a convenient place, but fheltered from the 

 fun, and expofed to the air and wind ; and by this practice 

 they deftroy fome of the beft part of the root. 



The proper exficcation of this root is certainly attended 

 with great difficulty, and the cultivators of rhubarb in this 

 country have not yet agreed as to the beft mode of accom- 

 plifhing it. The recent root, in this procefs, according to 

 the experiment of fir William Fordyce, lofes nearly nine- 

 tenths of its weight ; and as others fay, feven-eighlhs. In 

 China the roots are not dug up till winter; and the culti- 

 vators, after cleaning, fcrape off the bark, and cutting 

 them, dry the flices by frequently turning them on ftone 

 flabs, heated by a fire underneath ; after which, the drying 

 is completed by hanging them up in the air, expofed to the 

 greatelt heat of the fun. Part of the Tartarian rhubarb is 

 carried to Turkey through Natolia ; but the greateft part it 

 conveyed by the Bucharians to Kiachta, on the Ruffian 

 frontier, where it is examined by a Ruffian apothecary, and 

 the beft pieces only are fele&ed and fent .to Peterfburgh. 

 The Chinefe is conveyed to Canton, and there purchafed by 

 the agents of the Ealt India Company. 



Of the two forts of rhubarb above mentioned, the Chinefe 

 is chiefly obtained in the province of Xenfi or Shenfee, un- 

 der the name " Taihoung." It comes immediately from 

 the Eaft Indies, in oblong pieces, flattifh on one fide, and 

 convex on the other ; compact, hard, heavy, internally of a 

 dull red colour, variegated with yellow and white ; and 

 when recently powdered, appears yellow ; but on being 

 kept, becomes gradually redder. The fecond is the moft 

 valuable, and is brought to us from Turkey and Ruffia, in 

 roundifh pieces, with a large hole through the middle of 

 each ; it is more foft and friable than the former fort, and 

 exhibits, when broken, many itreaks of a bright red colour. 

 This fort, unlefs kept very dry, is apt to grow mouldy and 

 worm-eaten ; the other is lefs fubject to thefe inconveniences. 

 Some of the more indullrious artifts are faid to fill up the 

 worm-holes with certain mixtures, and to colour the outfide 

 of the damaged pieces with powder of the finer forts of rhu- 

 barb, and fometimes with cheaper materials. The marks 

 of the goodnefs of rhubarb are, the livelinefs of its colour 

 when cut, its being firm and folid, but not flinty or hard ; 

 its being eafily pulvei able, and appearing, when powdered, 

 of a fine bright yellow colour ; its imparting to the fpittle, 

 on being chewed, a deep faffron tinge, and not proving 

 flimy or mucilaginous in the mouth. Its tafte is fubacrid, 

 bitterifh, and fomewhat ftyptic ; the fmell is flightly aro- 

 matic. 



Turkey 



