C 406 3 



copoeia. The foreign rhubarbs feem in this, as well as ia 

 the foregoing experiments, to contain the largeft propor- 

 tion of active foluble matter. 



The eightli, ninth, and tenth experiments, afford a more 

 accurate examination of the colour of the rhubarbs in in- 

 fufion and tincture. The Turkey feems to poffels the 

 largeft quantity of the colouring ingredient (which is cer- 

 tainly the refinous part) foluble in water or brandy; and 

 the Eaft-Indian rhubarb, moft of what is foluble in rec- 

 titied fpirits. Na II. was, in thefe as in the other experi- 

 ments, the weakeft of any. 



Experiments XI. and XII. are intended to (hew the 

 various degrees of aftringency poffefied by the feveral rhu- 

 barbs, of which quality the precipitation of iron from an 

 acid menrtruum in fonn of ink, is thought to be an accu- 

 rate teft.* The Kaft-Indian rhubarb poffefled this quality 

 moft ftrongly in the watery infufion; No. I. and the 

 Turkey were nearly alike; and No. II. the weakeft. In 

 the fpirituous tinfhire, the Turkey was the ftrongeft; next 

 the Eaft-Indian ; next No, I. ; and No. II. the weakeft. 



The experiments tried with the rhubarbs at the Bath 

 Hofpital ftiew, that both the portions of Englifti rhubarb 

 poflefs both the purgative and aftringent qualities of the 

 foreign. Their purgative qualities feem to be fcarcely fo 

 ftrong as thofe of the Turkey, or even of the Eaft-Indian; 

 but the difference is not great. Some perfons in the pro- 

 feffion, with whom I have converfed, feem to think, that 

 about three parts of the Turkey, or four of the Eaft- 



* Th; aftringent and colouring principles are not the fame; for the latter ap- 

 pears ftrongly to impregnate the urine of thofe who take the different kinds of 

 rhubarb; luit urine fo tinged docs not acquire a dark colour on being mixed with 

 1 fol'.it'on of iron. 



Indian, 



