of some of the Principles of Vegetables into Bitumen , &c. 391 
apparent properties of charcoal, still retained a Small portion of 
some of the other principles of the original vegetable. 
My suspicion was excited, partly by the odour produced 
during combustion, which rather more resembled that of wood 
than that of charcoal, and partly by the brawn solution 
formed by digesting the powder of the unburned schistus in 
boiling distilled water ; for, by various tests I ascertained, that 
the substance thus dissolved was not of a mineral nature. In 
order, however, fully to satisfy myself in this respect, I digested 
2 5° grains of the pulverized schistus with six ounces of water. 
The liquor was, as before, of a dark brown colour. 
It had but little flavour. 
Prussiate of potash, muriate of barytes, and solution of 
isinglass, did not produce any effect ; nitrate of silver formed a 
very faint cloud ; sulphate of iron was slowly precipitated, of a 
dark brownish colour; and muriate of tin produced a white 
precipitate. 
A portion of the solution, by long exposure to the air, was 
partially decomposed ; and a quantity of a brown substance was 
deposited, which could not again be dissolved in water. 
Another portion was also evaporated to dryness, and afforded 
a similar brown substance, which was only partially soluble in 
water ; and the residuum, in both of the above cases, was found 
to be insoluble in alcohol, and in ether. 
When burned, it emitted smoke, with the odour of vegetable 
matter. 
250 grains of the schistus, afforded about three grains of fhe 
above substance; and, when the properties of the aqueous 
solution are considefed, such as its partial decomposition, and 
the deposit which it yielded by exposure to air, and by evapora- 
mdccciv. 3 E 
