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tion, of those fine earthy particles, which have been merely sus- 

 pended in the water. On the contrary, in, by far, the greater 

 number of instances of vegetable petrifactions, the combination of 

 both operations is discoverable. 



In thus endeavouring to account for the formation of most of 

 the endless variety of vegetable petrifactions; which, from the 

 wonderful appearances they display, and the circumstances under 

 which they are found, are considered as, almost, anomalies in nature, 

 I am aware, that the theory proposed, respecting the formation of 

 bitumens, will be exposed to a severe test : tried by such a touch- 

 stone, the degree of estimation to which it is entitled, can hardly 

 fail of being determined. 



Although convinced of almost the universal agency of bitumini- 

 zation, on such vegetable substances as have been rendered sub- 

 jects of the mineral kingdom, yet it does not appear to be the 

 sole process, by which vegetable matters may be preserved from 

 total decay, a sufficient length of time, to admit of their slow 

 impregnation with lapideous or metallic substances. The ligneous 

 substance we have already seen, is of so indestructible a nature, as 

 to secure its long continuance, in various situations without under- 

 going any material change of appearance ; even after the other con- 

 stituent parts of the wood have been removed. This appears to be 

 the state in which light rotten wood, or touch- wood, exists : all the 

 constituent parts, excepting the ligneous substance, having been 

 removed, either by the long continued action of the air, or by some 

 morbid action of the vessels of the wood. If this species of wood, 

 therefore, be placed in situations, in which water holding earth in 

 solution can permeate it, there exists but little doubt that it may 

 become petrified. Another mode 03' which the mineralization of 

 vegetables may be secured, appears to be, that of decaying, but 

 comparatively, recent vegetables, becoming impregnated by some 

 saline, metallic solution, of iron, for instance, whilst a precipitated 



