ijo Origin and Analyfis [Book VI. 



firm and compact texture of coal. In feme places, 

 the remains of forefts have been obferved converted 

 into an imperfect pit coal, in which the trunks, 

 branches, bark, and roots of trees, are difcernible. 

 In molt of the varieties of coal, imprefiions of ve- 

 getable matters, and particularly of fern, are ufu ally 

 obfervable. Now it is remarkable, that both peat 

 mofs and fern are produced on wild and unculti- 

 vated lands, and this renders it ftill more- probable, 

 that coal in general owes its origin to peat mofs. Coal 

 is found in thin and broad ftrata, fuch as might be 

 expected on the fuppofition of its being derived from 

 the decay of peat mofs, or collections of other vegeta- 

 bles on the furface of the earth. Coal is often covered 

 with matter which cannot be fuppofed to have been 

 created in its prefent ftate, as fandftone, the particles 

 of which are evidently owing to the motion and friction 

 cccafioned by water. It has been already mentioned, 

 that the products afforded by the diiliilation of peat 

 mofs and pit coal are precifely the fame. We know 

 of no fubftance purely and unqueftionably mineral, 

 which affords products at all fimilar, and it therefore 

 on the whole feems probable, that the ftrata of coal 

 found in different countries, however extenfive, owe 

 their origin to vegetable matter. The bituminous 

 matters feem alfo to be exudations from vegetable 

 iubftances buried in the earth. 



In confirmation ojf the fame opinion, I add the fol- 

 Jowing extract from the late ingenious Mr. White- 

 hurft's Inquiry into the original State of the Earth. 

 All the ftrata incumbent on coal, whether argilla- 

 ceous ftone or clay, contain figured ftones, reprefent- 

 i:rg a vaft variety of vegetables, or the impreflions of 

 them, as reeds of various kinds, ftriated and jointed 

 at different diftances, the euphorbia of the Eaft Indies, 



the 



