ggo Mr. Hatchett’s Observations on the Change 
§ HI- 
This schistus was found by Sir Joseph, in the course of his 
tour through Iceland, near Reykum, one of the great spouting 
hot springs, distant about twenty-four English miles from 
Hafnifiord ; but circumstances did not permit him to ascertain 
the extent of the stratum. 
The singularity of this substance is, that a great part of it 
consists of leaves, which are evidently those of the alder, inter- 
posed between the different lamellae. I do not mean mere 
impressions of leaves, such as are frequently found in many of 
the slates, but the real substance, in an apparently half charred 
state, retaining distinctly the form of the leaves, and the arrange- 
ment of the fibres. 
The schistus is light, brittle, of easy exfoliation, in the 
transverse fracture earthy, and of a pale brown colour ; but, 
when longitudinally divided, the whole surface constantly pre- 
sents a series of the leaves which have been mentioned, uniformly 
spread, and commonly of a light gray on the upper surface, 
and of a dark brown on the other ; the fibres on the light gray 
surface being generally of a blackish-brown, which is also the 
colour assumed by the schistus when reduced to powder. 
The leaves appeared to be in the state of charcoal, by being 
extremely brittle, by the blackish brown colour, by deflagrating 
with nitre, by the manner of burning, and by forming car- 
bonic acid. I was, however, soon convinced that the substance 
of these leaves was not complete charcoal, but might more 
properly be regarded as vegetable matter in an incipient state 
of carbonization, which, although possessed of many of the 
