OF FOSSILS* 257 



after fcveral years, fo little changed to the eye,- 

 that the -individual could be remembered by ( 

 his countenance : In other rcfpecls however thejr 

 were rigid like a ftatue, formed of falinc mat- 

 ter. When expofed to the free air they began 

 to crack. By a fimilar procefs, no doubt, even. 

 lofter fubftances may be fo hardened, as to pre- 

 ferve their ilruclure a long time, exempt from 

 putrcfadioii. 



$ c. Bodies impregnated with Bitumen. 



IN like manner organic bodies, impregnated 

 with bituminous matter arc enabled to prefcrvci 

 thcmfelvcs from decay, and retain their figure 

 and flruclurc* 



$ ci. Petrifaction of organic Bodies. 



NEITHER the bodies of animals nor of vegeta^ 

 tales can be wholly penetrated by fiony particles* 

 The harder parts only, as the bones, fliclls, ex- . 

 tcrnal covering, roots, woods, fruit, and fimilar 

 fubflances, are liable to this change; which, if I 

 miftakc not, proceeds in' the following manner: j 

 At firft, the parts of foftcfl texture putrefy, and , 

 leaving feverul empty fpaces, through which 

 water loaded \\ith earthy particles paiTes, and , 

 in its courfe depofuing them, the vacuities are 

 nt length filled by their gradual accumulation. 

 Then follows the deft rucl ion of the more iirm 

 confidence, to be penetrated in the fame order. 

 R -If 



