LIME AND CEMENT INDUSTRIES 829 



A number of samples were collected from Marks's quarry, and 

 their average composition is as follows. 



Silica ■ , .98 



Ferric oxid .3 



Alumina .84 



Lime 31.4 



Magnesia 16.96 



This, it will be noticed, presents a high grade of magnesian 

 limestone running very low in silica and probably suitable for 

 the lining of Bessemer converters. There are certain layers in 

 the quarry which have a tendency to become silicious in their 

 character, and these have to be avoided in mining. 



The rock from Marks's quarry has been shipped to Newark for 

 a number of years to be used as flux. In this case the sorting 

 was probably not as careful as it would have been for some pur- 

 poses; and consequently the following series of analyses, kindly 

 furnished by G. H. Stone, of the New Jersey zinc and iron co., 

 show greater silica contents. 



12 3 4 



Silica 6.77 5.94 5.12 2.05 



Ferric oxid ) .99 



A1 . [ 1.81 2.82 .75 1 -- 



Alumina J 1 . 11 



lime 45.02 29.05 25.42 34.63 



Magnesia 3.16 20.05 22.35 15.37 



Phosphoric acid . 027 



Carbon dioxid 44 . 11 



The good rock of the Sing Sing lime co. shows even less silica 

 than that from Mark's quarry, as will be seen from the following 

 analysis : 



Silica .87 



Ferric oxid .25 



Alumina - .57 



lime 31.4 



Magnesia 19 . 95 



