146 Mr. Hatchett'j Obfervations on Bituminous Subftances. 



but no doubt can be entertained in refpect to vegetables, for it 

 appears that bitumen is formed from them by long maceration, 

 and by other procefles at prefent unknown to us : 



That when certain portions of vegetable matter remain undecom- 

 pofed, and are mixed with the petroleum thus produced, the varieties 

 of turf and peat are formed : 



That wood in general contributes to the production of bitu- 

 men ; but does not feem to retain it, after the formation of it, in fo 

 confiderable a proportion as the foregoing fubftances : 



That the bituminous matter thus formed, and occafionally fepa- 

 rated, is in different ftates according to the degree of infpiflation : 



And laftly, with various proportions of carbonic and earthy 

 matter, it forms jet, coal, and bituminous fchiftus ; and with me- 

 tallic fubftances it produces thofe compounds called bituminous 

 ores. 



§7- 



ABOUT the year 1786 a new fpecies of bitumen was difcovered 

 near Caftleton, in Derbylhire, which much refembles, in elafticity 

 and colour, the fubftance known by the name of cahout-chou, or 

 Indian rubber. 



Mr. de Born was, I believe, the firft who mentioned it*; but as he 

 appears to have known only one variety of this fingular fubftance, 

 1 am induced to hope that a description of many other varieties, 

 which have fince been found, will not be unacceptable to this Society. 



The elaftic bitumen, which refembles the cahout-chou, was firft 

 difcovered in the cavities of a vein in the lead-mine called Odin, 

 which is near the bafe of Mamtor, to the north of Caftleton. The 



* CataUgv* dt U Cdltttien de M 11 *- dt Raah> torn. H. p. 77. 



ore 



