[405] 



not entirely extradled, though freHi fpirits were five times 

 poured on the refidua, as it retained a dark colour to tlie 

 laft. The tenacity of the refiduum of No. I. and No. II- 

 and the brittlenefs and fhining refinous appearance of the 

 Turkey and Eaft-Indian refidua, arc ftrong proofs of tlie 

 two latter containing a larger proportion of refm. 



It is highly probable, that the refin facintates the folution 

 of gum or mucilage in fpirits, much as gum renders oils 

 or refins foluble in water. The folubility of fome of the 

 gum rclins, as aloes, afafoetida, gum ammoniacum, &c. either 

 in water or fpirits, is a ftrong prefumption in favour of this 

 opinion. At any rate, thefe experiments rather tend to 

 fhew the fuperiority of the foreign rhubarbs, as ftomachick 

 and aftringent remedies ; but I am not clear, if the larger 

 proportion of mucilage witli which the refinous part of the 

 Engljfh rhubarb is combined, may not render its operation 

 as a purgative more eafy. The refin of jalap, which is fo 

 irritating when given alone, is rendered a fafe and eafy 

 cathartick, by combining it with mucilaginous bodies.* 



The fifth and fixth experiments fhew the different pro- 

 portions of refin contained in the feveral kinds of rhubarb. 

 No. I. in this refpedl is far fuperipr to No. II. and the 

 foreign rhubarbs are ftill more abundant. It fliould be 

 obfervcd, that the peculiar flavour and tafte of the rhubarb 

 does not refide in the rchnous parts, but probably in fome 

 eflential oil ftill more fubtile. Though refins and eflential 

 oils refemble each oiher very ftrongly, yet they are often 

 found feparate. The peculiar flavour of the clove is con- 

 tained init§ eflential oilj its acrimony in the refii>.ous part.t 



The fevcnth experiment is made with brandy, in the 

 fame proportion with that ufed in the London pharma- 



• Lewis's Mat. Mei). Art, Jalaplum.— NcwDifpcnfatory, p. 410^ 

 t Lewii's Difpcnfatory, p. 360. 



copeeia. 



