101 



LETTER XL 



BITUMINOUS WOOD....SURTURBEAND OF ICELAND. . ...BXTt'JBYv COAL 



OF ENGLAND. 



/,./.-_. 



i REVIOUSLY 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 which has hitherto appeared to be equally doubtful. The neces- 

 sity of furnishing you with the most material facts, which have 

 been noticed, respecting these substances, before I attempt to com- 

 municate my ideas respecting the nature and the formation of peat, 

 will, I trust, plainly appear, when I shew you the connection 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 en- 

 deavour to make you acquainted, is that which in Iceland is called 

 surturbrand, 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 of 

 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 Scapte- 

 sylae, a stone, in its external appearance something resembling rot- 



