374 



carbonate of lime from waters holding it in solution may therefore 

 result from two opposite causes ; an absorption of carbonic acid, 

 from the atmosphere, or for some subterranean source ; and the 

 loss of that part of it, which exists in excess, and which may be 

 driven off by heat, or forced into other combinations, by the com- 

 bined agency off different affinities. A farther investigation of the 

 circumstances on which these 'depositions depend, does not appear 

 to be necessary, it seeming to be sufficient to have ascertained that 

 water, saturated with carbonate of lime, is not only flowing over 

 various parts of the earth's surface, but is also transuding its sub- 

 stance in almost every direction. That it should therefore impreg- 

 nate with its earthy particles, any substance, which like bitumi- 

 nized wood, or Ay decaying organic substance, might be fitted to 

 receive it, appears to be highly probable ; and that calcareous fossil 

 wood may have been formed by such an impregnation, and under 

 such circumstances, every character which it possesses, eithr phy- 

 sical or chemical, serves to demonstrate. 



Yours, &c. 



LETTER XXXIX. 



CALCAREOUS FOSSIL /WOOD.... WHERE FOUND. ...CALCAREOUS WOOD 

 OF OXFORDSHIRE. ...DORSETSHIRE.... SOMERSETSHIRE.... AN A LY- 

 SIS. ...MIXTURE OF SPAR AND BITUMEN. ...C ALC AREOUS WOOD 

 OF NEW SOUTH WALES. ...ALUMINOUS WOOD, &C. 



AT has been said, that calcareous wood is found, in various parts 

 of the continent, and particularly in the neighbourhood of Arund- 

 see in Brandenberg ; near Joachimsthal, in Bohemia ; at Schem- 



