6 



consequently the longer exposed to the process of bitumi- 

 nization, the more perfect is the conversion. Some pieces 

 are found to have nearly lost their ligneous appearance, 

 their respective lines and markings having been molten 

 down in different degrees during their bituminization ; 

 whilst others, in which the nature of the substance is also 

 entirely altered, are found still to retain almost all their 

 characteristic markings. This substance has long been 

 known by the designation of bituminous wood. 



Wood of a very different character, called Moss Fir, is 

 also frequently found in the peat mosses or bogs. It much 

 resembles, in its colour and general external appearance, 

 ordinary decayed fir-wood ; but on examination it appears 

 that the fibre of the wood is strongly imbued with resin, 

 and that all its interstices are filled with resinous matter. 

 It is so highly inflammable, as to be employed, by the poor 

 of the districts in which it is found, not only as fuel, but 

 as torches. 



As the real nature of this substance is not perhaps 

 known, it would be very desirable that further inquiries 

 might be made respecting it : it might then be determined 

 whether the opinion which is here offered be correct or not. 

 From its retaining the colour and appearance of decayed 

 wood, it is conjectured to be fir -wood which, by exposure to 

 the atmosphere, had sustained the abstraction of all its con- 

 stituent parts, except the resin and ligneous fibre impreg- 

 nated therewith ; and from its having been thus rendered 

 almost an entirely resinous mass, it has not been affected by 

 the bituminizating process. 



Subterranean collections of bituminized wood and other 

 vegetable matter are found at various depths in different 

 parts of the world. The substance thus found is generally 

 a compact, light, glossy, combustible substance ; of a dark 

 brown colour, and frequently almost black ; splitting longi- 

 tudinally into plates of various thicknesses, breaking trans- 



