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prove to be that mineral, the fact would be one of interest, as 
it has not been hitherto found in this country. 
Dr. J. S. NEWBERRY, made some remarks regarding the 
Genesis of Sandstones, in criticism of the theory put forward 
by Prof. Wurtz, at a late meeting of this society, that the 
Sandstones of New Jersey contiguous to the Palisade Range 
are not siliceous, but have been formed from the disintegra- 
tion of the Trap of which that Range is mainly composed. 
He called attention to the comparative compositions as 
evinced by chemical analysis, of a typical Sandstone and 
Trap rock, as follows: 
Sandstone. Trap. 
Silica, 92°40 50°10 
Tron, 2°85 12°20 
Alumina, 3°00 18°30 
Lime, 36 8:00 
Soda, 50 2°03 
Potash, 35 1:02 
Magnesia, 18 5°00 
From such an analysis, he remarked, it was difficult to 
understand how such a sandstone could have originated from 
Trap, but, as Prof. Wurtz had promised analyses of both 
rocks under consideration we must wait for the revelations 
which such examinations would make. Mcantime he was 
having analyses made of some of the New Jersey Sandstones. 
Pror. A. M. Epwarps called attention to the, revelations 
made by Messrs. Sorby and Forbes in the genesis of crystalline 
rocks at least, by examining them, in thin section, by means 
of the microscope and this was the plan he would recommend 
to be employed in the present case. No chemical examina- 
tion of a crushed and finely-powdered fraction of a rock 
which was made up of several associated but chemically . 
different minerals in varying quantities would give the 
slightest hint as to its true composition or mode of formation, 
but if a specimen could be so examined by means of a mag- 
nifying glass that we had, to all intents and purposes, large 
masses of the different minerals under examination, then 
Crystallography, Polarized light or any other assistants could 
