On the different sorts of oils and bitumens, see Dr. Watson's (the present bishop of Llandaff's) Chemical Essays, vol. iii. essay i., a classic book, the best adapted to infuse the taste and knowledge of chemistry. The less perfect ideas of the ancients may be found in Strabo (Geograph. l. xvi. p. 1078) and Pliny, (Hist. Natur. ii. 108, 109).
Huic (Naphthae) magna cognatio est ignium, transiliuntque protinus in eam undecunque visam.
Of our travellers I am best pleased with Otter (tom. i. p. 153, 158).