constituent Parts of astrhigejit Fegefahles. 73 



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

 coacknsed m small ciystals in the neck ot the retoit,) and 

 a yellowish fluid, which had the strong smell and tasie of 

 this volatile salt. Alter the process oi distillation, the solid 

 matter remaining was found of a dark bio\Mi colour ; a part 

 of it rcadi'y disaolved in cold water, and the solution acted 

 on gelatine. 



I'he rt;^idua] fluid of the portions of the infusion which 

 had been acted on by , the carbonates of soda and of animo- 

 iria, as in the instance of the carbonate of potash, gave no 

 precipitate with gtlatine, till they were saturated wuh aa 

 acid ; so that in all these cases the changes are strictly 

 analogous. 



The infusion of galls, as appears from the analysis, con- 

 tains in its. primitive state calcareous matter. Hy the action 

 pf the mild alkalis, this substance is preciptaled in union 

 with a portion of the vegetable matter, in the tbrm of an 

 insoluble compound. The alkalis ihemselvcs at the same 

 time enter into actual combination with tlie reniaining 

 tannin and gallic acid ; and a part of the compound formed 

 is precipitated, whilst another part remains m solution. 



\V hen the att.ficial carbonates ot lime, magnesia, and 

 barytes, were separately boiled with the portions of infu- 

 sion of galls for some hours, they conrbined with the tan- 

 nin contained in it so as to form with it insoluble com- 

 pounds ; and in each case a deep green fluid was obtained, 

 whieh gave no precipitate to gekitine even when an acid 

 was added, but which produced a deep black colour in the 

 solutions of the salts of iron. 



Sulphate of lime, when finely divided, whether natural 

 cr artilicial, alter having been long heated with a small 

 quantity of the infusion, was found lo have combined with 

 the tannin of it, and to have gained a faint tinge of light 

 brown. The liquid became of a blue-green c-olour, and 

 acted upon the salts of iron, but not upon gelatine ; and 

 there is every reason to suppose that it held lu solution a 

 triple compound, of gallic acid, sulphuric acid, and fmc. 



We owe to Mr. Proust the discovery that diflerent solu- 

 tions ot the neutral salts precipitate the inhision of galls; 

 and he supposes that the pucipiiatiou is owing to'their 

 combining with a portion of the water which held the ve- 

 getable niaiter in solution. In exa;nining the solid matters 

 thrown down from the infusion by sulphate of alumine, 

 liltrate of potash, acetite of potash, muriate of soda, and 

 uiiiiiate ot barytes, I found ihein solubicj to a certain ex- 

 tent. 



