NATURAL SCIENCES OP PHILADELPHIA. 3G5 



of the "Hogback," in over 60 feet distance the "dike?" or bed 

 of metamorphic iron ore, etc., was reached, cutting off the coal 

 completely. Upon following upwards the face of the intruded 

 bed of ore, the " big coal bed" was again reached in fifteen feet 

 vertical elevation. The mine was worked for a long distance 

 northwards, until a sudden flow of choke-damp killed all the 

 miners, when the last named drift was abandoned, and the new 

 drift driven crosswise to locate and open up the workable coal 

 bed. 



Having selected different varieties of the ore that the intruded 

 "dike" contains, and having them analyzed, I find that the in- 

 truded "dike" carries from 2 to T 2 <y per cent, of uranium, and 8 oz. 

 bullion ; that iron is present in a large proportion, but no zinc 

 or manganese. The coal is of the same general quality as the Mur- 

 phy, Coal Creek, and Golden coal. It is metamorphosed lignite, 

 and contains 47 to 51 per cent, carbon, 13^ to 19^ per cent, of 

 water, 4^ to 5 per cent, ash, 35 to 32| per cent, volatile matter. 

 The fossil vegetation of the shale and coal bed sandstones contain 

 fossil leaves of cinnamomum platanus, pharagmites, magnolia 

 platanus, and juglens, etc. etc. One and one-half miles southwest 

 of this mine, and in the cretaceous outcrop one-half mile west of 

 Murphy's mine, we find the summit of the Hogback formed by a 

 "dike" of erupted basalt or dolerite whose course is nearly on 

 the meridian. 



Notes on Mr. Berthoud 1 s Paper. Dr. George A. KffiNiG re- 

 marked that the facts detailed in the above paper are of great 

 interest, but the Academy cannot endorse the author's views 

 upon the origin of this mineral deposit. There was a time when 

 anything unusual in the earth's architecture was attributed to the 

 mischievous agents of the great fiery abyss. 



But* chemical investigation has proved that all the fissure veins, 

 as well as stratified ore beds, are the result of a long process of re- 

 duction, crystallization, and deposition of mineral substance from 

 aqueous solution. 



While in many cases the satisfactory explanation of disturb- 

 ances in stratified rocks and especialfv mineral veins and coal beds 

 is very difficult with our present knowledge, nay impossible, yet 

 in this instance, there is no difficulty, nor even anything strange. 



