500 POLYGONACE^. 



no name has yet been given to it. A " white crystalline resin " (and 

 a dark brown crystalline resin) has been isolated in 1878 by Dragen- 

 dorfF. 



4. Phceoretin, C^'^H^^O'', agreeing with the substance thus named by 

 Schlossberger and Dopping. It is a brown powder, soluble in alcohol 

 or in acetic acid, but not in ether, chloroform or water. 



5. Chrysophan, described above. 



According to Dragendorff (1878) inucilaginons Tnatters occur in the 

 different varieties of rhubarb to the amount of from 11 to 17 per cent. 

 He states them to consist of mucilage (properly so called), arable acid, 

 metarabic acid and pararabin, and moreover enumerates also pectose 

 among the constituents of the drug-. 



Small quantities of albuminoid substances, malic acid, fat and sugar 

 have also been met with in rhubarb. As to its mineral constituents, 

 their amount is exceedingly variable. Two samples of good China 

 Rhubarb dried at 100° C. and incinerated, yielded us respectively 129 

 and 13"87 per cent, of ash. Another sample, which we had particularly 

 selected on account of its pale tint, afforded no less than 43"27 per cent, 

 of ash. The ash consists of carbonates of calcium and potassium. 

 English rhubarb from Banbury (portions of a large specimen) left after 

 incineration 10"90 per cent of ash. 



From a practical point of view the chemical history of rhubarb is 

 far from satisfactory, for we are still ignorant to what principle the 

 drug owes its therapeutic value, or what are the pharmaceutical prepara- 

 tions in which the active matter may be most a])propriately exhibited. 

 Chrysophan is said to act as a purgative, but less powerfully than 

 rhubarb itself 



Uses — Rhubarb is one of the commonest and most valuable 

 pvirgatives ; it is also taken as a stomachic and tonic. 



Substitutes — These are found in the roots of the various species of 

 Rheum cultivated in Europe. In most countries, the cultivation of 

 rhubarb for medicinal use has at some time been attempted. Yet in 

 but few instances has it been persistently carried on ; und though the 

 drug produced has often been of good appearance, it has failed to gain 

 the confidence of medical men, and to acquire much importance in the 

 drug-market. The European rhubarb most interesting from our point 

 of view is 



English Rhubarb — So early as 1535, Andrew Boorde, an English 

 Carthusian monk and practitioner of medicine, obtained seeds of 

 rhubarb, which he sent as " a grett tresure" to Sir Thomas Cromwell, 

 Secretary of State to Henry VIII.; but as he says they "come oivtt of 

 barbary," we must be allowed to hold their genuineness as doubtful.^ 



In the following century, namely about the year 1(508, Prosper 

 Alpinus of Padua cultivated as the True Rhubarb a plant which is 

 now known as Rheum Rhaponticuon L., a native of Southern Siberia 

 and the regions of the Volga.^ From this stock, Sir Matthew Lister, 

 physician to Charles I., procured seeds when in Italy, and gave them to 

 Parkinson,^ who raised plants from them. 



' Boorde's Introduction and Dyetary, re- - Prosper Alpinus, De Rhapontico, Lugd. 



printed by the Early English Text Society, Bat. 1718. 

 1870. 56. ^ Tkcatrum Botanicum, 1640. 157. 



