1847.] The Limestones, and Lime. 79 



Limestones of Sheffield. From this quarry the stone for the 

 Girard College was taken. 



100. 

 Specific gravity, 2.60. Per cent of lime, 51.97. 



Williamstown limestone, at the foot of Saddle mountain. 

 Analysis. 

 Carbonate of lime, - - _ 55.79 

 Carbonate of magnesia, - - - 42.96 

 Peroxide of iron, - _ _ ,47 



Silica and alumina, - - - .78 



100. 

 Specific gravity, 2.79. Per cent of lime, 31.14. 



Limestone of North Adams; color white and coarsely crystal- 

 line. 



