on the constituent Parts of astringent Vegetables. 241 
This last substance, as is well known, is thrown down from its 
solutions by sulphuric acid ; and I found, in distilling the pre- 
cipitate from galls by sulphuric acid, at a heat above 212 0 , that 
a fluid came over, of a light yellow colour, which was ren- 
dered black by oxygenated sulphate of iron ; but which was not 
altered by gelatine. 
Muriatic acid produced, in the infusion, effects analogous to 
those produced by sulphuric acid ; and two compounds of the 
acid and the vegetable substances were formed : the one united 
to excess of acid, which remained in solution ; the other con- 
taining a. considerable quantity of tannin, 1 which was precipi- 
tated in the solid form. 
When concentrated nitric acid was made to act upon the 
infusion, it was rendered turbid; but the solid matter formed was 
immediately dissolved with effervescence, and the liquor then be- 
came clear, and of an orange colour. On examining it, it was 
found that both the tannin and the gallic acid were destroyed ; 
for it gave no precipitate, either with gelatine or the salts of iron, 
even after the residual nitric acid was saturated by an alkali. 
By evaporation of a portion of the fluid, a soft substance was 
obtained, of a yellowish-brown colour, and of a slightly sourish 
taste. It was soluble in water, and precipitated the nitro-muriate 
of tin, and the nitrate ofalumine; so that its properties approached 
to those of extractive matter ; and it probably contained oxalic 
acid, as it rendered turbid a solution of muriate of lime. 
When a very weak solution of nitric acid was mixed with the 
infusion, a permanent precipitate was formed ; and the residual 
liquor, examined by the solution of gelatine, was found to con- 
tain tannin. 
A solution of pure potash was poured into a portion of the 
mdccciii. I i 
