152 Ohservaiions on the Change of 



stance which accompanies it, nature seems to have per- 

 tbrmcd only the halt" of her work, and, from some unknown 

 cause, \o have stopped in the middle of her operations. 

 But, by this circumstance, much light is thrown on the 

 history of bituminous substances ; and the opinion, that 

 they owe their origin to the organized kingdoms of na- 

 ture, especially to that of vegetables, which hitherto has 

 been supported only by presumptive proofs, seems now, in 

 a great measure, to be confirmed, although the causes which 

 operate these changes on vegetable bodies are as yet undis- 

 covered. 



Many flxcts indicate, tlat time alone does not reduce ani- 

 mal or vegetable bodies to the state of fossils. In thi,^ coun- 

 tr}', there are numerous examples of large quantities of tim- 

 ber (even whole forests) which have been submerged prior 

 to any tradition, a;id which nevertheless completely retain 

 their ligneous characters *. Other local causes and agents 

 must therefore have been required to form the varieties of 

 coal and other bituminous substances. In some instances 

 (as in the formation of Bovey coal) these causes seem to 

 have acted partially and imperfectly, whilst, in the forma- 

 tion of the greater part of the pit coals, their operation has 

 been extensive and complete. 



In the pit coals, the mineral characters predominate, and 

 the principal vestige of their real origin seems to be bitu- 

 men ; for the presence of carbon in the state of oxide cgn-f 

 not alone be considered as decisive. 



Bitumen, therefore, with the ex'uvi:s and impressions s(> 

 commonly found in the accompanyi^ig strata, must be more 

 immediately regarded as the proofs in favour of the origin 

 of pit coal from organiiied bodies ; and, considering the 

 general facts which have been long observed, together with 

 those lately adduced respecting the Bovey coal, and the sulj- 

 stance which is foulxl with it, we seem now to have al- 

 most unquestionable evidence that bitun^en has essentially 

 heen produced by the modification of some of the proximate 

 principles of vegetables, and especially resin. 



Modern chemistry had comparatively made but a small 

 progress when the illustrious Bergmann published his Disser- 

 tation entitled Proc/7/(7/a Igvls suhterrauii chem'tce consideruta; 

 for at that time the extent and power of chemical action in 

 the humid way were very imperfectly undeistoocl- In that 



*■ Phil. Ti-niis. for J^n'i iry 1671. PI)!!. Tmhs. vol. xix. p. 516. 

 ihul. vol, xxii. p. 980. Ihi'.l. vol. x.-iii. p. 1073. Ibid. vol. xxvii. 

 p. 298, ibid, fcr i7';9- p. 145- ' • 



