}0 Experiments and Olscrvaticns on the 



When solution of lime, of strontia, or of barytcs, was 

 poured in excess into a portion of the infusion, a copious 

 olive-coloured precipitate was formed, and the solution be- 

 came almost clear, and of a reddish tiiit. In this case the 

 tannin, the gg.llic acid, and the extractive matter, seemed 

 to be almost wholly carried do'vn in the precipitates ; as the 

 residual fluids, when saturated by an acid, gave no precipi- 

 tate to gelatine, and only a very slight tint of purple to oxy- 

 genated sulphate of iron. 



When the solutions of the alkaline earths were used only 

 in small quantities, the infusion beii:ig in excess, a smaller 

 quantity of precipitate was formed, and the residual liquor 

 was of an olive-gi een colour ; the tint being darkest in the 

 experiment with the barytes, and lightest in that with the 

 lime. This fluid, when examined, was found to hold in 

 solution a compound of gallic acid and alkalii:ie earth. It 

 became turbid when acted on by a little sulphuric acid ; 

 and, after being filtrated, gave a black colour with the solu- 

 tions of iron, but was not acted upon by gelatine. 



When a large proportion of lime was heated for some 

 time with the infusion, it combined with all its constituent 

 principles, and gave, by washing, a fluid which had the 

 taste of lime water, and which held in solution only a very 

 Small quantity of vegetable matter. Its colour was pale 

 yellow; and, when saturated with muriatic acid, it did not 

 precipitate gelatine, and gave only a slight purple tinge to 

 the solutions of tlic salts of iron. The lime in combination 

 with the solid matter of the infusion was of a fawn colour. 

 It became green at its surface, where it was exposed to the 

 air ; and, when washed with large quanties of water, it con- 

 tinued to give, even to the last portions, a pale yellow tinge. 



Magnesia was boiled in one portion of the irifusion for a 

 few hours ; and mixed in excess with another portion, which 

 was suft'ered to remain cold. In both cases a deep green 

 fluid was obtained, which precipitated the salts of iron but 

 not the solutions of gelatine ; and the magnesia had acquired 

 a grayish-green tint. Water poured upon it became green, 

 and acquired the properties of the fluid at first obtained. 

 After long washing the colour of the magnesia changed tq 

 dirty ypllow; and the last portions of water made to act 

 upon it were pale yellpw, and altered very little the solu- 

 tions qf iron. 



When the magnesia was dissolved in miiriatic acid, a 

 brownish and turbid fluid was obtained, which precipitated 

 gelatine and the oxygenated salts of iron. So that there is 

 every reason to believe that the earthy in acting on the 



astrinsient 



