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which had been formerly organized, acquired a considerable polish, and 
projected beyond the general surface, which was more rubbed down, 
ftnd which, although somewhat smoothed, had not obtained any polish. 
The difference of the two substances was more accurately determined, by 
immersing this same surface for a few minutes in marine acid, since 
although a considerable degree of effervescence, and a removal of some of 
the substance, evinced its action on the interposed lime-stone, no trace 
of its influence on the polished projecting parts was discernible ; even the 
polish was not in the least impaired. 
To what a remote period of past time, and to what astonishing changes 
in the structure of the surface, at least, of this globe, does this cir- 
cumstance direct our contemplation ! A body, differing from any 
animal substance now known, has been formed, by the energies of 
animal life, in the depths of the ocean of a former world ; and is now 
found imbedded in a rock, many miles inland, and at a considerable 
height above the sea : and these, wonderful as they are, are not the 
only circumstances of this case, which, in the present state of our know- 
ledge, may be considered as inexplicable. The substance, of which this 
body is composed, has undergone a most extraordinary change : origi- 
nally formed chiefly of carbonic acid and lime, with a small portion of 
animal matter, it has now become a mass, in which, except perhaps a 
portion of animal matter, these substances are no longer to be found : 
the space of which was formerly allotted to them being now filled almost 
entirely with the earth of flint ; and to add to the wonder, the silicified 
mass is found imbedded in lime. 
In what situation this body was*placed at the period it suffered this 
change of its substance? By what process its original constituent 
principles were removed, and those of which it is now composed were 
added, and how so great a change could be effected, with apparently no 
alteration whatever of its form?^ — These are questions which perhaps 
cannot be answered, until a considerable farther advance is made 
