120 The Limestones, and Lime. [March, 



appears from the following analysis of limestone, from the same 

 formation : 



Carbonate of lime, - 81.95 98.30 



Carbonate of magnesia, - none trace 



Alumina and oxide of iron, 3.10 none 



Insoluble matter, - - 14.60 1.30 



Water, .... 0.50 0.40 



100.15 



The first rock is six miles above the Delaware Water-Gap. Its 

 color is gray, and both sparry and crystalline. The second is at 

 Loyalsock, near Williamsport. It is used as a flux at the As- 

 tonville furnace, Lycoming county. Color blueish black; com- 

 pact, fracture conchoidal; fossil iferous. 



The best limestone in New-York, which has a wide distribu- 

 tion, and is generally known, is the Onondaga limestone. It is 

 the upper member of the Helderbergh division, and extends from 

 the Hudson river to Lake Erie. It is usually divided into two 

 parts; the lower, which is gray and crystalline, is the Onondaga 

 limestone proper; the upper is dark colored, more compact, and 

 contains a large amount of chert or hornstone. It is not entirely 

 free from magnesia. It is burnt for lime, and supplies the Albany 

 market. 



Analysis of the lower part. 



fine 

 grained; subcrystalline. 



The only limestone which remains to be noticed, is the Tully 

 lime-stone; a rock which succeeds the Hamilton group, in the 



