CHAPTERS ON THE CEMENT INDUSTRY 867 



Glens Falls plant being therefore the second in this country to 

 make use of this type of kiln. Though highly economical in fuel, 

 the kiln is rather expensive in both the quantity and quality of 

 manual labor required to operate it properly. A fire in August 

 1899, destroyed the plant, which was rebuilt to give a nominal 

 capacity of 500 barrels a day, and the manufacture of cement 

 was recommenced in August 1900. 



The materials used are limestone and clay. The former is of 

 Trenton age, and is obtained from the Glens Falls quarries. 

 Considerable care is required in the selection and mixing of the 

 stone from the various layers, in order to obtain a suitable and 

 uniform product. A very clean and uniform clay, found over- 

 lying the limestone in this area, is the other ingredient. Analy- 

 ses 1 of these materials follow: 



Limestone Clay 



Si0 2 . . 3.3 55 . 27 



Al 03 ) 



Al2U [ 1.3 28.15 



Fe 2 O s ) 



CaO 52.15 5.84 



MgO , ... 1.58 2.25 



S0 3 . .. .3 .12 



C0 2 40.98 



Organic and water 8 . 37 



The limestone and clay are separately dried, and crushed in 

 Blake crushers and rolls. After being weighed on automatic 

 scales, the materials are mixed dry and reduced to a fine powder 

 in Griffin mills. The powder is then fed into wet mixers, where 

 sufficient water is added to allow its being made up into bricks. 

 These are dried in tunnels, heated by waste heat (from the boiler) 

 driven through the tunnel system by blowers. 



After drying, the bricks are burned in Schofer kilns, using 

 coal as fuel. The clinker is passed first through Smidth ball mills, 

 and finally reduced in Davidsen tube mills. 



1 Lewis, F. H. Min. i»d. 6: 97. 



