18F5.1 4U4 [Frazer. 



The following is the result of an analysis of the Mumper mine in the 

 Mesozoic sandstone, one mile north-east of Dillsburg (C, p. 71.) 



P. C. 



Ferrous oxide (FeO) 18.643 



Ferric oxide (Fe 2 3 ) 42.100 



Pyrites (FeS 2 ) 4.093 



Copper sulphide (CuS) 0.093 



Cobalt sulphide (CoS) 0.766 



Alumina (A1 2 3 ) 2.417 



Manganese sesqui-oxide (Mn 2 8 ) 0.186 



Lime(CaO) 6.132 



Magnesia (MgO) 6.738 



Potash and Soda 0.350 



Phosphoric oxide (P 2 5 ) 0.052 



Sulphuric oxide (S0 3 ) 0.119 



Carbonic acid (C0 2 ) 1.760 



Water(EI 2 0) 1.080 



Silica (Si0 2 ) 15.120 



Sum 99.654 



Metallic Iron. 45.880 



" Manganese 0.129 



Magnetic Oxide of Iron 59.040 



Ferric oxide 1.703 



Sulph ur 2. 680 



Phosphorus 0.023 



Note 4. In MM, p. 344, Prof. Lesley gives some analyses which derive 

 their interest from the fact that they are very numerous, and all froin a 

 comparatively small thickness in the Walton limestone quarry opposite 

 Harrisburg. His paper in the Am. Phil. Soc. was presented Dec. 20, 

 1877, but the article just referred to is dated June 23, 1879. From analysis 

 of 115 layers of the limestone exposed in the quarry, it appears 



P. C. 



That the Carbonate of Lime constituted 80.662 



" " " " Magnesia constituted 14.215 



The insoluble residue constituted 4.715 



Those proportions will give a better idea Of the average constitution of 

 the good merchantable York and Cumberland limestone than any number 

 of scattered analyses. Prof. Lesley's attempt to ascertain a connection 

 between a given horizon and a constant proportion of the carbonates of 

 lime and magnesia to each other may have been suggested b} r some analy- 

 ses which I had published previously with the same end in view (See CC, 

 p. 307), in 1875. 



