in the Disl'illalion of Wood, &c, 215 



resembling bitumen, which is produced 1)y the action of fire in 

 the ordinary way on vegetables, differs from it essentially, and it 

 has been seen that solubility in naphtha is the readiest criterion 

 by which these substances can be distinguished. To assure my- 

 self of the accuracy of this test, I mixed the petroleum of coal 

 with the black oil of wood in several proportions, and by the ap- 

 plication of naphtha separated the one from the other. IJy this 

 simple method, therefore, I expected to detect not only the pro- 

 gress of bitumiuizatiou from simple turf to jet, but to assure 

 njvself whether, in the examinations hitherto made by others of 

 these different suiistances, a!iy mistake liad arisen from con- 

 founding the vegetable bitumen with true bitumen when distil- 

 hi,tion was used to investigate their nature. 



Vegetable turf in all its varieties, as well as brown coal, gave 

 a considerable colour to lixivium of potash, but the same men- 

 struum produced no effect on jet, or surturl)rand. Nor had 

 H.iphtha or alcohol any action except on the resinous lignite of 

 Bovey, from which they extracted tlie resinous matter which that 

 variety contains. 



I therefore suiijected these different substances to distillation, 

 trusting that by the produce I .should ascertain not only the 

 fact but the progress of bituminization. 



Submerged wood, from peat mosses in Cumberland, gave a 

 brown oil, smelling of the wood tar, and refusing to dissolve in 

 naphtha. In this case, therefore, uo appearance of a change 

 towards bitumen uas exhibited. A compact pitchy-looking peat 

 gave an oil which had a fetid smell, neither resembling that of 

 wood tar, nor bitumen, and which was very slightly soiuble in 

 naphtha. 



The Bovev brown (hoard) co.il produced an oil of a peculiar 

 fniell, l)ut most resembling that of wood tar, and muc!\ more 

 t-oluble in naphtha than the preceding. Having- a larger Cjunn- 

 tity of this, 1 separated the soluble part by u;ip'nt!ia, and in the 

 remainder, or iiisolulile oil, the sniell of wood tar v/as powerfi.!, 

 ^i.-jtwithstauding the .strong odour of the naphtha. Here then 

 the progrf ss of bituminization had advanced another step. Tlie 

 resin of this wood, on which a particular name has lately been 

 bestowed, 1 consider as an adventitious and accidental sub- 

 fetunce, and the natural produce of the tree, now jjrobably un- 

 known, which occupies these alluvial strata, as other lost pro- 

 ductions of Nature :\rc detected in other alluvial soils. 



A specimen of black lignite from Sussex gave an oil which re- 

 fcmblcd the former in smell, and perhaps did not differ much 

 from it in its soluijitity in uaplitha; but 1 had not enoughof the 

 bubstance to Jnslitiite an accurate comparison, )j«it)ier in fact 



4 «.onl(J 



