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bourhood of all petroleum springs, the earth is impregnatedto a very considerable thickness. In the vale of Nolo, inSicily , where there is a spring of petroleum dischargingitself into the lake Paulius, the earth above it is so highlybituminized, even to its surface, that some years ago, havingtaken fire by accident, it burnt for several months. Thesefacts are mentioned for the purpose of affording a rationalreason why the bituminous schist which covers beds of coal,possess similar properties, which are evidently effected bvthe same means. This observation, we also submit, comesin confirmation of the theory of Mr. Parkinson , previouslygiven. From the same gentleman’s system, the followingobservations are subjoined. He remarks, that “ Bits menalone would not, however, accomplish that grand purposefor which nature formed coal; that of supplying future ageswith fuel, which, by a moderate exercise of the ingenuityof man, might be made to burn with almost every degree ofintensity; from that which is employed to convey to thehuman body a grateful sensation, to that which is necessaryto fuse some of the most untractable metals.
“ The rapidity with which pure bitumen burns, wouldnot only occasion a considerable waste of it, if it were at-tempted to be employed for purposes to which coal is apjlied,but would also render it so unmanageable, as utterly to pre-vent its useful application to even the most ordinary pur-poses which coal is intended to fulfil.
“ To moderate this high degree of combustibility, andto regulate the consumption of a substance so necessary toman, as to render it uniform and economical, was tlere-fore required. To accomplish this, the intermixture ofsome incombustible substance with the petroleum becamenecessary; but to produce these characteristic prope-tiesby which coal is distinguished from all other substance, ofthe same class, a particular kind of arrangement of the lar-ticles of this heterogeneous mass was requisite. It wasnecessary that the bituminous particles should be so invo.vedand insulated on every side as to be nearly defended f ; omthe action of fire. It was also necessary that the regu-larity of its combustion should not be disturbed by thesuperadded incombustible matter existing in the mixture, insuch gross particles, or in so irregular a state of diffusion, aswould have been the case if the earth had remained in it inthe state in which it had subsided along with the sumenvegetable mass.
" The arrangement of the respective particles of the masswhich would make the nearest approach to the attainment ofthe required object, would be that in which each indivicual