EXPERIMENTS ON ASTRINGENT VEGETABLES. 2^7 



The folutions of carbonate of foda and of carbonate of Habitudes of 

 ammonia, both precipitated the infufion of galls in a manner ammonL^nearl^ 

 fimilar to the carbonate of potafli ; and each of the precipitates, as thofe of pot- 

 when afted on by boiling water, left a fmall quantity of infolu- ilflx, 

 ble matter, which feemed to confift chiefly of tanpin and car- 

 bonate of lime. 



The entire precipitate by carbonate of foda produced, when Particular detail, 

 incinerated, carbonate of foda and carbonate of lime. The T * e ? rcCl JP lCate: 

 precipitate by carbonate of ammonia, when expofed to a heat 

 fufficient to boil water, in a retort having a receiver attached 

 to it, gave out carbonate of ammonia, (which was condenfed 

 in fmall cryfials in the neck of the retort,) and a yellowith 

 fluid, which had the ftrong fmell and tafte of this volatile fait. 

 After the procefs of difiillation, the folid matter remaining was 

 found of a dark brown colour ; a part of it readily diiTolved 

 in cold water, and the folution a£ted on gelatine. 



The refidual fluid of the portions of the infufion which had The refidual 

 been acled on by the carbonates of foda and of ammonia, as in U1 ' 

 the inftance of the carbonate of potafli, gave no precipitate 

 with gelatine, till they were faturated with an acid j fo that, 

 in all thefe cafes, the changes are frriclly analogous. 



The infufion of galls, as appears from the analyfis, contains Infufion of 

 jn its primitive ftate calcareous matter. By the a&ion of the J.J * * ontain * 

 mild alkalis, this fubftance is precipitated in union with a por- matter, 

 tion of the vegetable matter, in the form of an infoluble com- • 

 pound. The alkalis themfelves, at the fame time, enter into 

 actual combination with the remaining tannin and gallic acid ; 

 and a part of the compound formed is precipitated, whilif. 

 another part remains in folution. 



When the artificial carbonates of lime, . magnefia, and Carbonates of 

 barytes, were feparately boiled with portions of the infufion of aikall ? c earths 

 galls for fome hours, they combined with the tannin contain- c ip. 

 ed in it, fo as to form with it infoluble compounds; and, in 

 each cafe, a deep green fluid was obtained, which gave no The fluid fhevr- 

 precipitate to gelatine, even when an acid was added, but ed no tanin, \ 

 which produced a deep black colour in the folutions of the 

 falts of iron. 



Sulphate of lime, when finely divided, whether natural or Sulphate of 

 artificial, after having been long heated with a fmall quantity "me feized the 

 of the infufion, was found to havecoinbined with the tannin of j*"| n y 

 it, and to have gained a faint tinge of light brown. The liquid 



became 



