7 
144 a curious petrifaction: Nov. 28 
_ In mocho stones, leaves of mofs, and other small vege. 
table substances, and in the stones called Venus’ and Thetis’ 
hair, found in Rufsia, fibres of fhorl have been evidently in- 
veloped by ‘some transparent fluid in. the act of crystu- 
lization, exactly as small flies have been buried in amber 
while in its fluid state, and there preserved when it har- 
dened. But the petrifactions of which we speak are en- 
tirely different from these, for here there is no inveloping 
matter. The wood before it was petrified was a solid sub- 
stance, whose pores could contain only a small quantity of 
fluid, andthe whole of the mafs now occupies precisely the 
same bulk as it did when in the state of wood. 
But fhould we be able to formsome kind of idea of the 
manner in which vegetable substances might be gradually 
corroded while in the earth, and liable to be acted upon by a 
menstruum there, which might contain a solution of certain. 
kinds of stone that might be gradually deposited in its stead, 
‘still this hypothesis will afford us no aid when we try to 
account for the production of the mafs under consideration. 
It must have been formed in the heart of the tree, while 
it was yet growing, and sound; and not by the corrosion 
of water dropping through holes from above ; for no mark. 
of such defect in the timber. was perceived, or it could not. 
have been selected for the use intended. We have no way, 
of accounting for the stony impregnation but by supposing 
it to have been introduced along with the sap of the tree ; . 
and how it fhould happen, on this supposition, that a small 
part of the heart of the tree fhould have been so entirely 
converted into stone, while no other part of the wood wa, 
affected by it in any degree, will puzzle the best philoso- 
pher to account for. 
_ We must regret that no part of the wood which inve- 
loped this stone has been sent; but when we consider 
the great expence of transporting such a mafs, and the yet 
