EXPERIMENTS ON ASTRINGENT VEGETABLES; C 2Q\ 



agents. By incineration of the products obtained from the 

 evaporation of aftringent infufions, I have ufually procure'd car- 

 bonate of lime and carbonate of potato. 



In the different analyfes, as will be feen from the refults T he practical 

 given in the following fections, I have attended chiefly to the precipitatlo/ 

 proportions of the tanning principle, and of the principles pre- with gelatine and 

 cipitable by the falts of iron, as being mod connected with Jj£ falt3 of 

 practical applications. 



With regard to the knowledge of the nature of the different 



fubftances, as they exift in the primitive aftringent infufion, 



we can gain, by our artificial methods of examination, pnly 



very imperfect approximations. In acting upon them by re- Though ftri£r 



agents, we probably, in many cafes alter their nature; and "* ly ( [?L ,s !? erC , 



very few of them only can be obtained in an uncombined ftate. yet the experi- 



The comparifon, however, of the products of different expe- **J t ! ,ead i to 

 . . ufeful conalu- 



riments with each other, is always connected with fome ufeful f lon s. 



conclufions ; and the accumulation of facts with regard to the 



fubject, muft finally tend to elucidate this obfcure but moft 



interefting part of chemiftry. 



II. EXPERIMENTS ON THE INFUSIONS OF GUIS. 



I have been very much affifted in my inquiries concerning 

 the properties of the infufions of galls, by the able Memoir of 

 M. Deyeux, on galls. * 



The ftrongeft infufion of galls that I could obtain, at 56° Go1<1 Infufion of 



Fahrenheit, by repeatedly pouring diftilled water upon the J°i^"y" S J^ 



beft Aleppo galls broken into fmall pieces, and fuffering it to grains of folid 



remain in contact with them till the faturation was complete, matte r> which 



■'•■■• T ' was nine parts 

 was of the fpecific gravity 1.068. Four hundred grains of it tannin and one 



produced, by evaporation at a temperature below 200?, fifty- 8 allic acid# 



three grains of fold matter; which, as well as I could eftimate, 



by the methods of analyfis that have been juft defcribed, con- 



$(ted of about -j% of tannin, or matter precipitable by gelatine, 



and -j 1 ^ of gallic acid, united to a minute portion of extra&ive 



matter. 



100 grains of the folid matter obtained from the infufion, The infufion 



left, after incineration, nearly 4| grains ofafhes; which were j£S« «£?' 



chiefly calcareous matter, mixed with a fmall portfon of fixed left byinciaera- 



. tipn al ne i-2oth» 



* Annates de Chimie, "Tome XVII. page 1. . «,. J^ c&n 



alkali, alkali. 



