INFLUENCE OF CHEMICAL PROCESSES 733 



points which seem to indicate a mutual relationship between coal and 

 petroleum in the second or georliemical stage of development, and that 

 both react to the same geophysical influences, as follows: (1) That in 

 regions where the coals and other carbonaceous debris in the strata are of 

 the rank of brown lignites, the oils in the same or closely associated geo- 

 logical formations are also of low rank, averaging 20° to 26° Baume; (3) 

 that where the organic debris (coals, etcetera) has advanced to the sub- 

 bituminous rank, the oils of the same or of nearly contemporaneous un- 

 derlying formations are of higher rank, averaging 28° to 35°; (3) that 

 when the deposits of organic debris have been regionally transformed (by 

 elimination of volatile matter) until they have reached the bituminou& 

 rank, the oils have in general attained a rank of 35° or more, the highest 

 grade of petroleum being found in the areas where the regional alteration 

 of the organic debris has progressed farthest; except (4) that in those 

 regions where the organic debris, whether it be represented by beds of 

 coals, by bogheads, or by carbonaceous matter in shales, has passed the 

 point corresponding to a content of 65 per cent of fixed carbon, pure coal 

 basis, the oils which may formerly have been present in the same or in the 

 underlying formations have mostly disappeared; and (5) that wherever 

 the devolatilization of the coals, etcetera — that is, the solid residues in 

 the strata — has progressed so far that they have a fixed carbon content of 

 70 per cent or more, oils, if present, will be "freak" oils, and in pockets 

 , or amounts too small to be of commercial importance, though gas pools 

 may persist. I know of no commercial oil pools in the world that are 

 found in or beneath formations in which the regional carbonization of the 

 organic debris has passed 75 per cent fixed carbon, pure coal basis ; in fact, 

 I have not yet been able to learn of an oil pool in or beneath a formation 

 in which the fixed carbon percentage of the organic debris exceeds 70, and 

 it is most improbable that oil pools exist under such conditions. 



It will at once be seen that these conditions seem to define a law re- 

 stricting the distribution of productive oil pools, and to afford a basis on 

 which to eliminate many areas of great extent in which fruitless and 

 costly exploration by the drill is now going forAvard. 



Effects of Progressive Regional Alteration 



But what is the genetic significance of all this? It is certain that the 

 progressive regional alteration of the rocks, including coals, etcetera, is 

 attended in general by a corresponding progressive advancement of the 

 oils to the point where they have a maximum content of light hydrocar- 

 bons, and that beyond this point they seem to have been in some way 

 eliminated or distilled off. Ts not this general advancement of the petro- 



