282 MR - hatchett's observations 



properties to thofe which are recent, and terminating in bodies 

 decidedly mineral, in which all veftiges of organization have 

 been completely destroyed. 

 •and m the vege- The vegetable kingdom has likewife produced many in-, 

 fiances not lefs remarkable ; and it is worthy of notice, that 

 animal petrifactions are commonly of a calcareous nature, 

 while, on the contrary, the vegetable petrifactions are general- 

 ly filiceous *". 



It is not, however, my intention here to enter into a minute 

 difcuflion concerning the formation of thefe extraneous foflils ; 

 I (hall therefore proceed to confider other equally or perhaps 

 more important changes, which organized bodies, efpecially 

 vegetables, appear to have fuffered, (after the extinction of the 

 principle of life,) by being long buried in earthy ftrata, and by 

 being thus expofed to the effe£ts of mineral agents. 



§ It 



Bituminous mat- The principal objecf I have in view, is to adduce fome ad-? 

 ters are derived ^itional p r0 ofs, that the bituminous fubftances are derived 



from organized r 



matters; chiefly from the organized kingdoms of nature, and efpecially from 

 vegetables. vegetable bodies; for, although many circumflances feem to 



lead to the opinion, that the animal kingdom has in fome 

 meafure contributed to the partial formation of bitumen, yet 

 the proofs are by no means fo numerous, nor fo pofitive, as 

 thofe which indicate the vegetable kingdom to have been the' 

 grand fource from which the bitumens have been derived. 

 But this opinion, (founded upon very ftrong prefumptive 

 evidence,) although generally adopted, is however queftioned 

 by fome perfons ; and I (hall therefore bring forward a few 

 additional fa<5ts, which will, I flatter myfelf, contribute to 

 demonfirate, that bitumen has been, and is actually and im- 

 mediately formed, from the relin, and perhaps from fome of 

 the other juices of vegetables. 

 Pure bitumens The chemical characters of the pure or unmixed bitumens, 

 differ much from f^ as jjaptha, petroleum, mineral tar, and afphaltum, are, in 

 certain refpecfs, fo different from thofe of the refins and other 

 infpiffated juices of recent vegetables, that, had the former 

 never occurred but in a feparate and unmixed ftate, no 

 pofitive inference could have been drawn from their pro- 



* Pyrites, ochraceous iron ore, and fahlertz, are alfo occasional- 

 ly fpund in the forms of vegetable bodies. 



perties 



