EXPERIMENTS ON ASTRINGENT VEGETABLES, 263 



mine; fo that its properties approached to thofe of extractive 

 matter ; and it probably contained oxalic acid, as it rendered 

 turbid a folution of muriate of lime. 



When a very weak folution of nitric acid was mixed with Weak nitric acid 

 the infufion, a permanent precipitate was formed, and the re_ th/othe^ acids, 

 fidual liquor, examined by the folution of gelatine, was found 

 to contain tannin. 



A folution of pure potafh was poured into a portion of the Pure potafh 

 infufion. At firft, a faint turbid appearance was percefved ; c ^^ ne ^ w i^k 

 but, by agitation, the fluid became clear, and its colour changed the tannin, 

 from yellow brown to brown red ; and this laft tint was moft which did not 



J ' 4 * . then Separate 



vivid on the furface, where the folution was expofed to the t, y geiacine till 

 atmofphere. The folution of ifinglafs-did not aft upon the an acid had takqp 



the a:kali. 



in fu(i on modified by the alkali, till an acid was added in excefs, 

 when a copious precipitation was occasioned. 



The compound of potafh and folution of galls, when eva- The alkaline 

 porated, appeared in the form of an olive-coloured mafs, which ra^bTevapo-" 

 had a faint alkaline tafte, and which ilowly deliquefced when ration, 

 expofed to the air. 



Soda acted upon the infufion in the fame manner as potafh ; Soda acted like 

 and a fluid was formed, of a red-brown colour, which gave no pota * 

 precipitate to gelatine. • . 



Solution of ammonia produced the fame colour as potafh and Ammonia, 

 foda, and formed fo perfect an union with the tannin of the 

 infufion, that it was not acted upon by gelatine. When the 

 compound liquor was expofed to the heat of boiling water, a 

 part of the ammonia flew off, and another part reacted upon 

 the infufion, fo as to effect a material change in its properties. 

 A considerable quantity of infoluble matter was formed ; and 

 the remaining liquor contained little tannin and gallic acid, but 

 a considerable portion of a fubftance that precipitated muriate 

 of tin, and the falts of al umine. 



When the experiment on the ebullition of the compound of 

 the infufion and ammonia was made in clofe veffels, the liquor 

 that came over was strongly impregnated with ammonia ; 

 its colour was light yellow, and, when fatiirated with an acid, 

 it was very little altered by the falts of iron. The refidual 

 fluid, after the procefs had been continued for fome time, as 

 in the oiher cafe, precipitated gelatine flightly, but the falts 

 of alumine copioufly ; and it gave a tinge of red to litmus 

 paper. 



When 



