MODIFIED ty COMPRESSION. 155 
trace could be difcovered of the original organization. In 
others, the vegetable fibres were ftill vifible, and are forced afun- 
der by large and fhining air-bubbles. » 
Since the publication of the fketch of my experiments, I 
have had the pleafure to read Mr Hatcuerr’s very interefting 
account of various natural fubftances, nearly allied to coal ; 
and I could not help being ftruck with the refemblance which 
my refults bear to them, through all their varieties, as brought 
into view by that able chemift; that refemblance affording a 
prefumption, that the changes which, with true fcientific mo- 
defty; he afcribes to an unknown caufe, may have refulted from 
various heats acting under preflure of various force. The 
fubftance to which he has given the name of Retina/phaltum, 
feems to agree very nearly with what I have obtained from 
animal fubftance, when the barrel was opened by means of low 
heat. And the fpecimen of wood entering into fufion, but ftill 
retaining the form of its fibres, feems very fimilar to the in- 
termediate fubftance of Bovey-coal and Surturbrand, which Mr 
Hatcuetr has aflimilated to each other. It is well known, 
that the furturbrand of Iceland, confifts of the ftems of large 
- trees, flattened to thin plates, by fome operation of nature hi- 
therto unexplained. But the laft-mentioned experiment feems 
to afford a plaufible folution of this puzzling phenomenon. 
In all parts of the globe, we find proofs of flips, and various 
relative motions, having taken place amongft great mafles 
of rock, whilft they were foft in a certain degree, and which 
have left unequivocal traces behind them, both in the derange- 
ment of the beds of ftrata, and in a fmooth and fhining fur- 
face, called flickenfide, produced by the direct fri@tion of one 
- mafs on another. During the action of fubterranean heat, were 
a fingle ftratum to occur, containing trees intermixed with 
animal fubftances, fhell- fith, &c. thefe trees would be reduced, 
to a foft and unctuous ftate, fimilar to that of the piece of wood 
(ae ies in 
