HUTTONIAN THEORY. 



35 



) 



i 



gree, fo that the latter, though they could not 

 efcape, may have been forced from one part of 

 a ftratum, or body of itrata, to another. 



31. In confirmation of this it muft be obferved, 

 that, as the fixed part of coal is thus found in 

 the bowels of the earth, feparate from the vola- 

 tile or bituminous, fo, in the neighbourhood of 

 coal ftrata, the latter is fometimes found with- 

 out any mixture of the former. The fountains 

 of naphtha and petroleum are well known ; and 

 Dr Hutton has defcribed a ftratum of limeftone. 



lying 



in 



th 



centre 



f 



coal country, which 



matter 



is pervaded and tinged by bituminous 

 through its whole mafs, and has, at the fame 

 time, many clofe cavities in the heart of it, lined 

 with calcareous fpar, and containing foilil pitch. 



fometi 



ge pieces, fometime 



hem 



^ 



fpherical drops, fcattered over the furface of the 



cavities. This comb 



feded by a part of 

 the beds of coal u 

 by heat, ai 



ould only be 



flammable 



m 



derneath, being d 



ef- 



of 



off 



d made to p 



th 



ft 



while it was yet foft and pervious to heated 



P 



urs *. 



32. Hitherto we have enumerated thofe fpf 



fils that are 'either not at 

 foluble 



y fparingly 



in water. 



There are, however, fal 



C2 



* Note IX 



bodies 



