1897.] ORIGIN OF PENNSYLVANIA PETROLEUM. 115 



Pennsylvania measures were deposited that even suggest^a sufficient 

 source for the great bodies of petroleum which have already been 

 brought to the surface in that region." 



In a communication received from Mr. MacGonigle to-day he 

 calls attention to the fact that a line drawn from Brady's Bend to 

 Waynesborough, Pa., will show the eastern limit of profitable oil 

 pools in that region. East of that line, however, some of the most 

 prolific gas pools of Pennsylvania have been developed, notably, 

 Murrysville, Grapeville, Latrobe, etc. This would at least suggest 

 a side light in favor of the theory above mentioned, showing that 

 as the area approached the line of greatest upheaval and conse- 

 quently greatest temperature, the volatile oil (gasj was, without 

 condensation, retained in its condition as it came up from Silurian 

 horizons. 



I believe that this theory of Mr. MacGonigle is more probable 

 than any that has been advanced as to the present condition of oil 

 in Pennsylvania. It does not seem, however, necessary to intro- 

 duce the idea of any redistillation whatever from the fact that if 

 sufficient cracks existed in the cover over the Silurian limestones, 

 the oils would leak through the shales to their present position with- 

 out the application of any heat, and by experimental work it may 

 easily be demonstrated that if we saturate a limestone such as the 

 Trenton limestone with the oils characteristic of that rock and 

 exert slight pressure upon it, so that it may flow upward through 

 finely divided clay, it is easy to change it in its color to oils similar 

 in appearance to the Pennsylvania oils, the oil which first filters 

 through being lightest in color and the following oils growing 

 darker. Further, if we examine oils in the new fields of Tennessee 

 and Kentucky, we find as we go lower that oils which were light in 

 color at the surface are dark in color when we go through the 

 shales and find them in the lower limestones. In fact it is possible 

 to watch the process of filtration from dark oils similar to the Ohio 

 sulphur-bearing oils to the lighter oils of Pennsylvania found nearer 

 the surface. The means by which the sulphur has been taken from 

 the Ohio oil is far more difficult to explain, although the ease by 

 which sulphur compounds and unsaturated compounds can be re- 

 moved from petroleum by the use of aluminum chloride points to 

 the chloride of some metal as a means by Avhich this may have been 

 accomplished. 



