234 THEORT of the EARTH. 



irony matter, or calcareous fubftance. Sometimes, again, which 

 is the cafe with that of Lochneagh, there does not feem to have 

 been any penetration of thofe two fubftances. The injected 

 flint appears to have penetrated the body of this wood, im- 

 merfed at the bottom of the fea, under an irnmenfe compref- 

 fion of water. This appears from the wood being penetrated 

 partially, fome parts not being penetrated at all. 



Now, in the limits between thofe two parts, we have the 

 moft convincing proofs, that it had been flint in a fimple fluid 

 ftate which had penetrated the wood, and not in a ftate of fo- 

 lution. 



Firft, BECAUSE, however little of the wood is left unpene- 

 trated, the divifion is always diftincl: between the injected part 

 and that which is not penetrated by the fluid flint. In this 

 cafe, the flinty matter has proceeded a certain length, which is 

 marked, and no farther ; and, beyond this boundary, there is 

 no partial impregnation, nor a gradation of the flintifying ope- 

 ration, as muft have been the cafe if filiceous matter had 

 been depofited from a folution. 2dly, The termination of the 

 flinty impregnation has afTumed fuch a form, precifely, as 

 would naturally happen from a fluid flint penetrating that 

 body. 



IN other fpecimens of this mineralizing operation, foflil 

 wood, penetrated, more or lefs, with ferruginous and calcare- 

 ous fubftances, has been afterwards penetrated with a flinty 

 fubftance. In this cafe, with whatever different fubftances the 

 woody body fhall be fuppofed to have been penetrated in a ftate 

 of folution by water, the regular ftruc~hire of the plant would 

 ftill .have remained, with its vacuities varioufly filled with the 

 petrifying fubftances, feparated from the aqueous menftruum, 

 and depofited in the vafcular ftruclure of the wood. 



THERE cannot be a doubt with regard to the truth of this 

 propofition ; for as it is, we frequently find parts of the confo- 

 Ldatea wood, with the vafcular ftruclure remaining, perfectly 



in 



