268 Mr. Davy’s Experiments and Observations 
gallic acid, by distillation, from the Myrobalans ; but in this 
I was mistaken ; they furnished only a pale yellow fluid, which 
gave merely a slight olive tinge to solution of sulphate of 
iron. 
Skin was speedily tanned in the infusion of the Myrobalans ; 
and the appearance of the leather was similar to the appearance 
of that from galls. 
The strongest infusions of the teas are very similar, in their 
agencies upon chemical tests, to the infusions of catechu. 
An ounce of Souchong tea, produced 48 grains of tannin. 
The same quantity of green tea, gave 41 grains. 
Dr. Maton has observed, that very little tannin is found in 
cinchona, or in the other barks supposed to be possessed of 
febrifuge properties. My experiments tend to confirm the ob- 
servation. None of the infusions of the strongly bitter vegetable 
substances that I have examined, give any precipitate to gelatine. 
And the infusions of quassia, of gentian, of hops, and of cha- 
momile, are scarcely affected by' muriate of tin ; so that they 
likewise contain very little extractive matter. 
In all substances possessed of the astringent taste, there is 
great reason to suspect the presence of tannin ; it even exists in 
substances which contain sugar and vegetable acids. I have 
found it in abundance in the juice of sloes; and my friend Mr. 
Poole, of Stowey, has detected it in port wine. 
V. GENERAL OBSERVATIONS, 
Mr. Proust has supposed, in his Paper upon Tannin and 
its Species,* that there exist different species of the tanning 
principle, possessed of different properties, and different powers 
* Annates de Cbimie, Tome XLI. p. 332. 
