on the constituent Parts of astringent Vegetables „ , 2 53 
communicate this tinge to paper ; they slightly redden litmus- 
paper; their taste is highly astringent, and they have no per- 
ceptible smell. 
The strongest infusions that I could obtain from the two 
kinds of catechu, at 48° Fahrenheit, were of the same specific 
gravity, 1.057. But, by long decoction, I procured solutions of 
1.102, which gave, by evaporation, more than of their weight 
of solid matter. 
Five hundred grains of the strongest infusion of catechu from 
Bombay, furnished only 41 grains of solid matter; which, 
from analysis, appeared to consist of 34 grains of tannin, or 
matter precipitable by gelatine, and 7 grains that were chiefly 
a peculiar extractive matter, the properties of which will be 
hereafter described. The quantity of solid matter given by the 
strongest infusion of the Bengal catechu, was the same, and 
there was no sensible difference in its composition. Portions 
of these solid matters, when incinerated, left a residuum which 
seemed to be calcareous ; but it was too small in quantity to be 
accurately examined, and it could not have amounted to more 
than — g of their original weights. 
The strongest infusions of catechu acted upon the acids and 
pure alkalis in a manner analogous to the infusion of galls. 
With the concentrated sulphuric and muriatic acids, they gave 
dense light fawn coloured precipitates. With strong nitrous 
acid they effervesced ; and lost their power of precipitating the 
solutions of isinglass, and the salts of iron. The pure alkalis 
entered into union with their tannin, so as to prevent it from 
being acted upon by gelatine. 
When the solutions of lime, of strontia, or of barytes, were 
