500 POLYGONACE.E 



r 



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

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



dorff. 



4. Phcvoretin, C^'^H^^Os 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 Dragendorft' (1878) wuicilacjinoiis ^matters 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 pedose 

 among the constituents of the dru^;. 



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 largo 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 ap]-)ropriately 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 

 purgatives ; 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 ot 

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

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

 drug prodnced has often been of good appearance, it has ftiiled to gam 

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

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

 of view is 



English 



English Efmbarb—So early as 1585, Andrew Boorde, an t^nga' 

 Carthusian monk and practitioner of medicine, obtained seeds 

 rhubarb, which he sent as "a qrett iremre" to Sir Thomas Cfomwe ■ 



Secretary of State to Henry VIIL; but as he says they ''comeoivtt''^ 

 harharyr we must be allowed to hold their genuineness as donbttuL ^ 

 In the following century, namely about the year K508, ^J?^y^^ 

 Alpinus of Padua cultivated as the True Rhubarb a plant ^nici 

 now known as Rheum Rhn-povticvm L., a native of Southern Si^' 

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

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

 ±'arkmson,3 who raised plants from them. 



r,rini''7l'^^'f/"^^"^'^""''«" ^"^^ ^y'^'^V^ ^^- ' Prosper Alpinus, De Bhapontko, lugA 



?87o L y *^^ ^""'^^ ^°sHsh Text Society. B..t. 1718. , . , . yf,. 



