101 
LETTER XL 
BITUMINOUS WOOD SURTURBRAND OF ICELAND BOVEY COAL 
OF ENGLAND. 
Previously to ofFering, for examination, the opinion which I en- 
tertain, respecting the nature and the formation of peat, it will be 
proper to call your attention to some other substances, the origin of 
wLich has hitherto appeared to be equally doubtful. The necessity 
of furnishing you with the most material facts which have been 
noticed, respecting these substances, before I attempt to communicate 
my ideas respecting the nature and the formation of peat, will, I 
trust, plainly appear, when I show you the connexion which appears 
to exist between it and those several substances ; and when I also 
endeavour to demonstrate, on what principle the formation of all 
these substances depends. 
The substance, with whose nature and properties I shall next 
endeavour to make you acquainted, is that which in Iceland is called 
surturhrand, and which, in this country, is chiefly known by the 
name of Bovey Coal. 
The ligniform appearances, which bituminous substances some- 
times bear, have been long known, and even the particular kind 
which we are now about to examine, has been noticed by some ot 
the early writers in natural history. This substance, although pos- 
sessing all the properties of bitumen, bears the distinctive marks of 
wood, but generally in the form of splinters or chips ; or, if in larger 
masses, these are very capable of being divided into such fragments, 
even with a very slight force. 
Theophrastus states, that there is found, in the mines of Scap- ^ 
tesylas, a stone, in its external appearance something resembling 
