392 Mr. Hatchett’s Observations on the Change 
tion; the insolubility of this deposit when again digested with 
water, alcohol, or ether; the smoke and odour which it yielded 
when burned ; and the precipitates formed by the addition of 
sulphate of iron and muriate of tin to its solution ; when these 
properties, I say, are considered, there seems much reason to 
conclude, that the substance dissolved by water was vegetable 
extract, which had apparently suffered some degree of modifi- 
cation, but not sufficient to annul the more prominent charac- 
teristic properties of that substance. 
The powder of the schistus, which had been employed in the 
preceding experiment, was afterwards digested in alcohol during 
two days ; and a pale yellow tincture was thus formed, which, 
by evaporation, left about one grain of a yellow transparent 
substance, possessing the properties of resin. 
It appears, therefore, that a substance very analogous to 
vegetable extract, and a small portion of resin, remain inherent 
in the leaves of this remarkable schistus. 
As solution of isinglass did not produce any effect, there was 
reason to conclude, that the aqueous solution above-mentioned 
did not contain any tannin ; but, as the tannin might be com- 
bined with the alumina of the schistus, I digested a portion of it 
in muriatic acid, which, after filtration, was evaporated almost to 
dryness, leaving, however, the acid in a slight excess. This was 
diluted with water; and afforded a blue precipitate with prussiate 
of potash, a yellowish precipitate with ammonia, and a white 
precipitate with muriate of tin, but not any with solution of isin- 
glass. The tannin which might have been contained in the recent 
vegetable, appears therefore to have been dissipated or decom- 
posed, with the greater part of the other vegetable principles, 
excepting the woody fibre reduced to the state of an imperfect 
