24 



considered, the difficulty of the necessary separation and 

 analysis must be obvious ; and the following results must 

 only be admitted to show the propriety of still further 

 extending the inquiry. By the exposure of opaline wood 

 in a retort to the heat of a furnace, the presence of carbon 

 was determined ; a strong empyreumatic smell, and an oily 

 sublimated matter possessing the same odour, was pro- 

 duced : the same results have proceeded from a similar 

 treatment of pitchstone^ bearing a ligneous appearance. 

 Mr. Klaproth, on igniting the brown red semiopal of 

 Telkabanya in an open crucible, found that the iron con- 

 tained in the fossil was reduced to a reguline state, although 

 there had been no admixture of any charcoal, or of any 

 other substance with a nearer affinity with oxygen, showing 

 that the carbonaceous principle existed in the fossil itself. 

 The same celebrated chemist analyzing the hydrophanous 

 opal of Saxony, obtained, as Mr. Pepys had done from 

 opaline wood, a water having an empyreumatic smell, and 

 covered with a thin greasy pellicle : he also determined 

 afterwards the actual presence of bitumen in the semiopal 

 of Mahren. 



Specimens exist which show the union of silex with 

 bituminous wood in all its different stages of bituminization. 

 In one specimen of black siliceous wood, pieces of coal 

 exist in its internal part: in one silicified specimen with 

 evident characters of previous bituminization, patches are 

 seen on its surface of a jet black, and possessing the re- 

 sinous lustre : in another are spread drusy crystals of 

 quartz, of a dark black, from the union of black bitumen 

 with silex ; whilst the black bitumen may also be seen 

 thus intimately combined with silex in the quartz crystals, 

 and imbedded, unaltered, in the interstices of the same spe- 

 cimen. But whether it be admitted or not, that the re- 

 sinous lustre proves the previous bituminization of the fossil 

 wood, the different degrees, and the presence or absence of 



