Theory of the Earth, by James Hutton, [1788 and 1795]
The Mineralogical Operations of the Earth illustrated from the Theory of Fossil Coal. There is not perhaps a greater difference among the various qualities of bodies than that which may be observed to subsist between the burning of those two substances, that is, the inflammable bodies on the one hand, and those that are combustible on the other. I have treated of that distinction in Dissertations upon subjects of Natural Philosophy, part 3d.