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volatilized bituminous matters, a stratum of lime-stone, near Raith, 
in Fifeshire, which, though but slightly tinged with a black colour, 
contains bituminous matter like pitch, in many cavities which are 
lined with calcareous spar crystallized. 
Dr. Hutton’s opinions respecting the changes produced on sub- 
terranean bitumens, by the agency of fire, may be comprised in 
these two positions; first, That the purer and fluid bitumens are 
produced by distillation from coal; secondly. That the Kilkenny 
coal, and other similar natural coke, is the residuum of this distil- 
lation. In refutation of the first of these positions, which has been 
also endeavoured to be supported by most of the French chemists, 
little requires to be said, except to remark, that the quantity 
of the fluid, and purer bitumens, naphtha, petroleum, asphaltum. 
See. which has been found, far exceeds the proportion of such coal 
as, with all that diligence of research which so useful an article has 
excited, has been discovered to have suffered this spoliation. But 
that this substance, Kilkenny coal, &c. is common coal, deprived of 
its bituminous matter by heat, I acknowledge, seems at least to be 
probable. When we contemplate the situations in which coal mines 
are placed, enclosed on almost every side by strong barriers of stone, 
by which the access of atmospheric air is almost entirely prohibited, 
we cannot but conclude, that, should a seam of coal become ignited, 
the coal must be completely charred, as far as its combustion extends. 
That it furnishes any evidence in favour of all coal having been 
exposed to the fusing power of heat, I acknowledge I do not per- 
ceive ; but merely that such particular masses of coal have been 
subjected to fire. It also shows, that such is the wise provision 
made in this case, that, although a substance, formed to supply 
mankind with fuel, should casually be subjected to the premature 
influence of fire, it shall still continue fitted for the purpose for which 
it was originally intended : the very material changes which it has 
undergone, having even rendered it more highly useful, for certain 
