X 
CONTENTS. 
LETTER XI. Page 
Bituminous Wood...Surturbrand of Iceland.. .Bovey Coal of England, 101 
LETTER XII. 
In Answer, from Bovey. ..Present State of the Coal Pit at Bovey... Strata, &c 123 
LETTER XIII. 
Bitumens... Particular Kinds described.. .Known to Writers of the highest Antiquity... History of 
Naphtha, Petroleum, and Asphaltum, from the more ancient Naturalists, . . . . . . 127 
LETTER XIV. 
Account of Bitumens continued, from more modern Authors... Ray, Dolomieu, &c...Tar Lake in 
the Island of Trinidad...Petroleum Wells in the Burmha Dominions, Russia, &c 
LETTER XV. 
Amber... Known to the earliest Writers in Natural History...Jet...S«cciraMm nigrum of the Ancients 
...Cannel Coal... Difference between it and Jet, 
LETTER XVI. 
Coal described... Different Kinds of Coal... Doubtful if known to the Greeks, or early Romans 
...Brought into common Use, in this Island, but in Modern Times. ..Pound in various parts 
of the World, 
150 
159 
173 
179 
LETTER XVII. 
Particularities observable in different Coal-pits... Cannel Coal. ..Pyrites, &c. 
LETTER XVIII. 
Bituminous Fermentation... Compared with the other Species of Fermentation.. .Bitumens, the Result 
of this Process. ..Peat, a Vegetable Fossil, the First Product of this Fermentation, . . 
LETTER XIX. 
Fossil Trees, imbedded in Peat, have undergone the Bituminous Fermentation... The Changes which 
mow-burnt Hay undergoes, somewhat similar to that produced by the Bituminous Fermentation, 189 
LETTER XX. 
Examination of Opinions respecting the Origin of Peat.. .Aboriginal Formation.. .A Marine Deposit 
...Mineral Origin... Floating Islands.. .A recent Vegetable Substance, 
LETTER XXI. 
The purer Bitumens, the Result of the same Fermentation by which Peat has been formed. ..Bitu- 
minous Fermentation imitates, in its Result, the Operation of Secretion. ..Mineral Tallow, per- 
haps of Animal Origin... Other Arguments in favour of Bituminous Fermentation, 
LETTER XXH. 
Of the Origin of the purer Bitumens. ..Naphtha.. .Petroleum.. .Mineral Tar.. .Mineral Pitch... Asphal- 
tum.. .Amber.. .Mellite... Jet and Cannel Coal, 
LETTER XXIII. 
Opinions respecting the Formation of Coal... Earth impregnated with Petroleum, the Opinion of 
Buffon and Gensanne... Opinion of Sign. Arduino...Of Dr. Hutton and Professor Playfair.. .Of 
Mr. Williams... Of Mons. Tingry...Of Dr. Darwin.. .Of Mr. Kirwan...Of Mr, Hatchett. ..Of 
Mons Patrin...Of Mons. Fourcroy. 233 
195 
206 
218 
