[ 544 ] 
“ wood, and it does not confume To faA. Many of 
££ thefe pieces are fprinkled with marcafite, and there 
cc exfudes from it a white bituminous fubAance, like 
“ rofin. It is full of crevices, in all directions, and the 
£c pieces appear in a variety of forms,” which the au- 
thor has exhibited, together with a reprefentation of the 
veins of the foffil, in feveral copper-plates accompany- 
ing his work. He is clearly of opinion, ££ that this 
cc fubftance is not generated from the feed or roots of 
££ any plant, but from a cretaceous earth transform- 
£c ing itfelf into wood, by the affiAance of fulphu- 
££ reous water minerals, and fubterraneous heat, 
££ which appears there in a thick fmoak, and fome- 
£C times in flames, particularly in rainy weather.” 
He forms his fuppolition on the different appear- 
ances of this foflil, £C fome pieces of it being like 
£C chalk, others like wood, and again others like 
££ coal ; fome are either totally or partially petrified, 
££ being ftone without and wood within, or vice 
££ verfa” But thefe various appearances may be 
eaffly accounted for, from the different kinds and 
proportions of earthy matter, with which the bitu- 
men is mixed. 
Of the fame kind are the foffil flrata in Iceland, 
mentioned in the Mufaeum Wormianum, and by 
Horrebow, in his natural hiftory of that ifland. The 
former of thefe authors * defcribes it as ££ a laminated 
£C fubftance, generally of a black, but fometimes only 
<£ of a dark colour, heavy, and, when dry, brittle ; 
£C though the merchant, who gave the fpecimen, 
££ affured him, that when it was firA dug out of the 
* Lib. ii. cap. 16. p. 169. 
£t earth 
