of some of the Principles of Vegetables into Bitumen , &c. 393 
coal, and the small portions of extract and resin which have 
been mentioned. 
Previous to having made the analysis, I had an idea, that this 
schistus might be a lamellated incrustation, formed by the tufa 
of the hot springs ; but, according to Mr. Klaproth’s analysis,* 
the tufa of Geyser is composed of, 
Silica - 98 
Alumina - - 1.50 
Iron 30 
100. 
It is therefore very different from the schistus, the component 
ingredients of which were ascertained by the following analysis. 
ANALYSIS OF THE SCHISTUS FROM ICELAND. 'f' 
A. 250 grains, by distillation, yielded water, which, in the 
latter part of the process, became slightly acid and turbid, 
= 42.50 grains. 
B. The heat was gradually increased, until the bulb of the 
retort was completely red-hot. During the increase of the heat, 
a thick brown oily bitumen came over, which weighed 7.50 
grains ; it was attended with a copious production of hydrogen, 
carbonated hydrogen, and carbonic acid, the whole of which 
may be estimated at 23.75 grains. 
C. The residuum was black, like charcoal, and weighed 
176.25 grains ; but, being exposed to a strong red heat in a 
crucible of platina, it burned with a faint lambent flame, and 
was at length reduced to a pale brown earthy powder, which 
weighed 122 grains; so that 54.25 grains were consumed. 
• Beitriige ; Zweiter band, p. 109. 
f The remaining specimens are now in the British Museum, and in the collection 
of the Right Honourable Charles Greville. 
3 E 2 
