266 fcXPKRlMKNTS ON ASTRINGENT VEGETABLES. 



Its folution acts very little upon gelatine, till it is faturated 

 with an acid ; and it is not poflefled of the property of tanning 

 fkin. 



In various cafes, in which the greateft care was taken to ufe 

 no excefs, either of the aftringent infufion or of the alkaline 

 folution, I have found the folid matter obtained poflefled of 



Jt contains analogous properties: and it has always given, by incinera- 

 * tion, a confiderable portion of carbonate of potato, and a fmall 



quantity of carbonate of lime. 



The remaining The fluid remaining after the feparation of the precipitate, 



alkali, was °^ a dark-brown colour, and became green at the fur face, 



when it wasexpofed to the air. It gave no precipitate to folu- 

 tion of gelatine ; and afforded only an olive-coloured precipi- 

 tate with the falts of iron. 



exhibited tanin When muriatic acid was poured into the clear fluid, a violent 



,when t e a ai e ff erve f cence was produced ; the fluid became turbid ; a pre- 

 was facu rated r ' 



with mur. acid, ci pi tate was depofited ; and the refidual liquor acled upon 



gelatine and the falts of iron, in a manner fimilar to the pri- 

 mitive infufion. 

 Cryftals of gallic M. Deyeux, in diftilling the precipitate from infufion of galls 

 from^he^re- by carbonate of potato, obtained cryftals of gallic acid. In 

 cipitate. following bis procefs, I had fimilar refults j and a fluid came 



over, which reddened Htmus-paper, and precipitated the falts 

 of iron black, but did not a& upon gelatine. 

 The precip. was When the precipitate by carbonate of potato was a61ed upon 

 warm water i ^9 warm water > applied in large quantities, a confiderable 

 portion of it was diflblved ; but a part remained, which could 

 not in any way be made to enter into folution ; and its pro- 

 perties were very different from thofe of the entire precipitate. 

 It was not at all affected by alcohol : it was acled on by mu- 

 riatic acid, and partially diflblved; and the folution pre- 

 cipitated gelatine and the falts of iron. It afforded, by in- 

 cineration, a confiderable portion of lime, but no alkali. 

 Hence the In comparing thefe fads, it would feem, that the precipitate 



|wecip. wastaninf rom infufion of galls, confifts partly of tannin and .gallic acid 

 with a little united to a fmall quantity of alkali, and partly of thefe vegeta- 

 alkali, and a!fo ble matters combined with calcareous earth ; and it will appear 

 lime '""both car- P r °bable, when the fads hereafter detailed are examined, that 

 bonated. both the potato and the lime are contained in thefe compounds 



in a Irate of union with carbonic acid. 



The 



