some of the Principles of J'egetalles into Bitumen. 41 



From the animal kingdom we may select, as examples, 

 the fossil ivory, which retains its cartilage* ; the boiies in 

 the Gibraltar rock, consisting of little more than the earthy 

 part or phosphate of lime ; the shells forming the luma- 

 chella of Bleyberg, which still possess the lustre and irides- 

 cence of their original nacre ; and the shells found at Hord- 

 wcll in Hampshire, and in Picardy, which are chiefly por- 

 cellaneous, but more or less calcined ; also the fossil echini 

 and others so commonlv found in the limestone, chalk, 

 and calcareous grit of this island, which, although they 

 retain their origmal figure, are entirely, or at least exter- 

 nally, formed of calcareous spar, mcrusting a nucleus of 

 flint or chalcedony. And if, in addition to these, we may 

 be allowed to regard the more recent limestone and chalk 

 strata as having been principally or partly formed from the 

 detritus of anifnal exuviae, we shall possess a complete series 

 of gradations, commencing with animal substances ana- 

 gous in properties to those which are recent, and tern)i- 

 nating in bodies decidedly mineral, in which all vestiges of 

 organization have been completely destroyed; 



The vegetable kingdom has likewise produced many in- 

 stances not less remarkable; and it is worthy of notice, that 

 animal petrifactions are commonlv of a calcareous nature, 

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

 nerally siliceous f. 



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

 minute discussion concerning the formation of these ex- 

 traneous fossils ; I shall therefore proceed to consider other 

 equally or perhaps more important changes, which orga- 

 nized bodies, especially vegetables, appear to have suffered 

 (after the extinction of the principle of life), by being long 

 buried in earthy strata, and by being thus exposed to the 

 t fleets of mineral agents. 



§ ir. ■ 



The principal object I have in view is to adduce some 

 adiliiioiial proofs that the bituminous substances are derived 

 troni the organized kingdoms of nature, and cspcciallv 

 from vegetable bodies ; for although many circumstances 

 seem H) lead to the opinion that the animal kingdom has in 

 some measure contributed to the partial formation of bitu- 

 men, yet the proofs are by no means so numerous, nor so 



• I have also found tlic cartilage pcrfcft in the teeth oF the 

 ni.tininotii. 



I ryiitc";, oc'ifnccous iron ore, and fahlcrtz, are aUo occasionally 

 t.'UiiJ 111 ll,c Iviiii^ uf vrgetal>lc bodies. 



positive. 



