124 Examination of a few American Minerals. 



per cent. lime. Manganese was precipitated by sulphide of 

 ammonium, re-dissolved in hydrochloric acid, and precipitated 

 as carbonate, found 1'383 per cent, protoxide. 



Magnesia was precipitated as phosphate, found 28*803 per 

 cent. 



The following is the result of the analysis. 



99-625 99-67 



7. Dolomite, "Westchester Co. 



This mineral is found, according to Dr. Stevens, traversing 

 portions of the Island of New York. It was observed on 49th 

 St., near Columbia College. 



Mr. J. W. Alsop, Jr., analysed a specimen of the stone used 

 in the construction of the Roman Catholic Cathedral on 5th 

 avenue, between 50th and 51st streets. It was found to be 

 nearly pure dolomite, answering to the formula CaO, C0 2 + 

 MgO, C0 2 . 



Mr. Alsop found : — 



* Smith and Brush. Am. J. Sci [2], XVI., 49. 



