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Observations on the Change of some of the proximate Principles of 

 Vegetables into Bitumen ; with analytical Experiments on a pecu- 

 liar Substance which is found with the Bovey Coal. By Charles 

 Hatchett, Esq. F.R.S. Read June 14, 1804. [Phil. Trans. 1804, 

 p. 385.] 



Among the several spontaneous permutations in the productions 

 of nature, none perhaps are more striking, and in many cases more 

 unaccountable, than those which transfer bodies from one kingdom 

 of nature into another : and those changes which transform organized 

 into fossil substances are certainly not the least extraordinary and 

 instructive. 



The most numerous instances of this transformation are, no doubt, 

 what we distinguish by the name of Extraneous Fossils ; some of 

 which still retain part of their original substance, whilst others can 

 only be regarded as casts or impressions. An attentive observer will 

 soon perceive a kind of gradation in these fossils, whether from ani- 

 mals or vegetables, commencing with those whose matter retains a 

 marked analogy with that of the recent substances, and terminating 

 in bodies decidedly mineral. And a curious remark occurs here, 

 that as animal petrifactions are most commonly of a calcareous na- 

 ture, so, on the contrary, vegetable petrifactions are generally sili- 

 ceous. 



Without entering any further into a general disquisition on this 

 important subject, our author proposes to discuss, in this paper, one 

 particular case of the changes which organized, and especially vege- 

 table, substances undergo, by being long buried in earthy strata, and 

 thus exposed to the effects of mineral agents : and the instance he 

 selects is the bituminous substances, concerning which he has long 

 suspected that they are derived from the organized kingdoms, and 

 especially from the resin and juices of vegetable substances, by the 

 action of some of the mineral principles. 



He cites three instances in this kingdom in which nature points 

 out these changes, and which exhibit the gradations above intimated. 

 These are, 1. The submarine forest at Button, on the coast of Lin- 

 colnshire, the timber of which has not suffered any very apparent 

 change in its vegetable characters ; 2. The strata of bituminous wood 

 (called Bovey Coal) found at Bovey, in Devonshire, which exhibit a 

 series of gradations, from the most perfect ligneous texture to a sub- 

 stance nearly approaching to the characters of pit-coal ; and 3. All 

 the varieties of pit-coal, so abundant in many parts of this country, 

 in which almost every appearance of vegetable origin has been ob- 

 literated. 



As the Bovey coal appears to be the mean in that gradation, and 

 therefore most likely to afford instructive results, our author resolved 

 to limit his inquiry into this process of nature, which may not im- 

 properly be called Carbonization, to that fossil, and to a peculiar 

 bituminous substance with which it is often accompanied. But here 

 he finds it expedient to premise some observations on a remarkable 



