some of the Principles of P'egehi'uies into Bitumen. 45 

 aqueous solution are considered, such as its partial decom- 

 position, and the deposit \\ liich it yielded by exposure to 

 air, and by evaporation; the insolubility oP this dtposa 

 when again digested with water, aleohol, or ether; the 

 smoke and odour whieh it yielded when burned ; ai/d the 

 precipitates formed by the addition of sulphate of iron and 

 muriate of tin to its solution ; when these properties, I sav 

 are considered, there seems much reason to conclude, that 

 llie substance dissolved by water \v;as vejietablc extract 

 whicli had apparently suffered some degree of modiJicati'on* 

 but not sufficient to annul the more prominent characteristic 

 properties of that substance. 



The powder of the schistus which had been employed in 

 the preceding experiment, was afterwards di^^csted 'in d- 

 cohol during two days ; and a pale yellow tincture u as thurj 

 Jornied, wlucii, by evaporation, left about one orain of a yel- 

 low transparent substance, possessing the properties of relin. 



It appears, therefore, that a substance very analoc-ous to 

 vegetable extract, and a small portion of resin, remain in- 

 herent in the leaves of this remarkable schistus. 



As solution of isinglass did not produce any effect, there 

 was rea.son to conclude that the aqueous solution above- 

 mentioned did not contain anv tannin ; but, as the tannin 

 might be combmed with the alumina of the seiiistus, I di- 

 gested a portion of it in muriatic acid, which, after filtra- 

 tion, was evaporated almost to drvness, leavino-, however 

 the acid in a slight excess. This was diluted with water' 

 and afforded a blue precipitate with prussiate of potash L 

 yellowish precipitate with ammonia, and a white precipitltc 

 with muriate of tin, but not any with solution of isin-dasii 

 The tanmn which might have been contained in the recent 

 vegetable appears therefore to have been dissipated or de- 

 composed, with the greater part of the other vegetable 

 principles, excepting the woody fibre reduced to the state of 

 an imperfect coal, and the small portions of extract and 

 reshi \i hich have been mentioned. 



Previous to having made the analysis, I had an idea that 

 this schistus might be a lamellated incrustation, formed by 

 tii«- tufa of the hot springs ; but, according to Mr. Klap- 

 iuth's analysis*, the tufa of Geyser is composed of. 

 Silica - - - 



Alumina 

 iron - - - 



* Sii'/riije; Zzi.fi Ur banJ, p. io_,, 



Xt 



