1898.] PECKHAM — THE GENESIS OF BITUMENS. 135 



the bosom of the earth. "^ The anthracites of the Alps offer con- 

 vincing proof that large amounts of organic matter have been 

 involved in the metamorphic action that has prevailed in that 

 region. In like manner the relation of the bituminous deposits of 

 Galicia and Roumania to the crystalline rocks of those countries 

 show the part that metamorphism has played in their occurrence. 



21. No theory that refers the origin of the bitumen to any phys- 

 ical or chemical action that has prevailed on a cosmic scale can sat- 

 isfactorily explain the differences that exist in crude bitumens. Mr. 

 Phillips has added the testimony of chemistry itself to show the 

 improbability of a chemical origin for bitumens on a cosmic scale. 

 Dr. Day has shown the reasonableness of an hypothesis which 

 regards the bitumens of Pennsylvania as distillates, but his idea that 

 the variation in the petroleums of that region is due to the effect of 

 filtration is, in my judgment, hardly tenable. In Pennsylvania the 

 darkest and heaviest oils are nearest the surface. The sulphur con- 

 tent of bitumen is too wide a subject to discuss here in detail ; yet 

 it may be said in general that sulphur enters bitumens by a second- 

 ary reaction between the bitumen and the sulphates dissolved in 

 natural waters. The freedom of Pennsylvania petroleum from sul- 

 phur has already been shown to be due to the absence of sulphates 

 in the natural waters of the region in which they occur. As has 

 already been stated, Prof. Mabery has shown that the sulphur com- 

 pounds found in Lima oil are sulpho-parafiines. This would natu- 

 rally follow the reduction of sulphates by parafilines, the reaction 

 being a double decomposition in which sulphur is substituted for 

 hydrogen in the parafifine. Filtration would not be likely to 

 remove such compounds from solution in the other constituents of 

 the petroleum. 



In his discussion of the " Occurrence of Petroleum in the Cavi- 

 ties of Fossils," Mr. Phillips has offered some ingenious but wholly 

 unnecessary suggestions to account for the presence of a nearly solid 

 bitumen in the cells of a coral reef uncovered in a quarry. Petro- 

 leum occurs in the rocks of the oil regions filling cavities of every 

 description. Geodes, fossils, sandstones, pebble conglomerates, 

 porous limestones, the Chicago dolomite, gravel, anything and 

 everything that has a cavity or a pore, has been found saturated 

 with it. Why? Simply because the enormous pressure under 

 which the bitumen has accumulated in the crust of the earth has 



^Afin. des Mines (5), iv, 334. 



