(3Q history of the gallic acib, . 



being formed ; and it will have lost its astringent taste, but bt 

 acid. On leaving the liquor at rest five weeks longer, a prcci-r 

 pitate will be formed two fingers thick, and a mumous pellicle 

 above it. The liquor is now to be filtered again, and left anew 

 exposed to the air. At the expiration of some months, the 

 greater part of the liquor will be evaporated : all the precipi<* 

 tates are to be added together, and cold water is to be poured 

 on them ; when the liquor has stood to settle, what is clear is 

 to be decanted off: as much hot water as is necessary for the 

 | solution is poured on ; and by evaporating with a gentle heat 



yellow crystals will be obtained. 



Mr. Rartholdi 's process. 



JSarthuldi's. A tincture of galls in alcohol is -to be evaporated ; the rcsi« 



duum is to be dissolved in distilled water; and sulphuric acid 

 is to be added to the solution, till the mixture is decidely acid 

 to the taste. In the course of a few hours the extractive mat- 

 ter will fall clown, and the supernatant fluid, freed from sulphu- 

 ric acid by barytes, will yield, according to the author, pure 

 gallic acid. ■ 



This process by no means gives this result. It is in general 

 very difficult to seize the moment when all the sulphuric acid 

 is removed by the barytes, since it combines with the gallic 

 acid likewise : and after the liquor is evaporated nothing 

 remains but an acerb matter, containing a great deal of tannin,, 

 and insusceptible of crystallization. 



Process of Mr. Deijeux. 



Deycux. This chemist discovered, that, by heating bruised nutgalls 



slowly, and cautiously, in a glass retort, a pretty considerable 

 quantity of lamellated, shining, and silvery crystals was sub- 

 limed. 



Mr. Richter's process. 



Nutgalls reduced fo a fine powder are to be macerated in 

 mid water, shaking the mixture frequently. After some time 

 the liquor is to be strained off through a cloth: the residuums 

 i! 10 \)o taacerate'd in a Fresh portion of water, and after it has 



beffn 



