LIME AND CEMENT INDUSTRIES 829 



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

 tlieir average composition is as follows. 



Silica , • • .) .98 



Ferric oxid • .3 



Alumina ... . .1 , .84 



Lime 31.4 



Magnesia 16.96 



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

 limestone running very low in silica and probably suitable for 

 tbe 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 ^tTewark 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. 



1 2 3 4 



Silica . 6.77 5.94 5.12 2.05 



Ferric oxid . ) .99 



., . [ 1.81 2.82 .75 -, ^-i 



Alumina J 1.11 



Lime 45.02 29.05 25.42 34.68 



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 



