on the constituent Parts of astringent Vegetables , 267 
alkaline earths, and of the carbonated alkalis ; and they formed, 
with the caustic alkalis, fluids not precipitable by gelatine. 
An ounce of the bark of the elm, furnished 13 grains of 
tannin. 
The same quantity of the bark of the common willow, gave 
11 grains. 
The residual matter of the bark of the elm, contained a con- 
siderable portion of mucilage; and that of the bark of the 
willow, a small quantity of bitter principle. 
The strongest infusions of the sumachs from Sicily and 
Malaga, agree with the infusions of barks, in most of their pro- 
perties ; but they differ from all the other astringent infusions 
that have been mentioned, in one respect ; they give dense pre- 
cipitates with the caustic alkalis. Mr. Proust has shown, that 
sumach contains abundance of sulphate of lime ; and it is pro- 
bably to this substance that the peculiar effect is owing. 
From an ounce of Sicilian sumach, I obtained 165 grains of 
matter soluble in water, and, of this matter, 78 grains were 
tannin. 
An ounce of Malaga sumach, produced 156 grains of soluble 
matter, of which 79 appeared to be tannin. 
The infusion of Myrobalans* from the East Indies, differed 
from the other astringent infusions chiefly by this circumstance, 
that it effervesced with the carbonated alkalis ; and it gave with 
them a dense precipitate, that was almost immediately redis- 
solved. After the tannin had been precipitated from it by 
gelatine, it strongly reddened litmus-paper, and gave a bright 
black with the solutions of iron. I expected to be able to procure 
* The Myrobalans used in these experiments are the fruit of the Terminalia Che- 
bula. Retz. Obs. Botan. Fasc. V. p. 31. 
Mm2 
