706 



NEW YOEK STATE MUSEUM 



European cements 



Brand 



SiOg 



20.48 

 20 6t 

 22 08 

 21.14 

 23. ."^S 

 22 3 

 22.18 

 23.87 

 22.3 

 22.3 



AI3O3 



Fe^Og 



CaO 



MgO 



1.'6 

 2 3:^ 

 1.32 

 1.44 



1.42 



1.35 

 1 34 

 1.04 

 .45 

 1.C4 



SO3 



2.46 

 1 39 

 1 82 

 1.47 

 1.07 

 1 87 

 1 56 



.8i 



.7 



.75 



AUTHORITY 



White label Alsen •••.. 



7.2s 



7.15 



6.84 



5 95 



7.47 



7.35 



8.48 



6.91 



8.5 



7 



8.88 



3.69 



3.36 



4.01 



2.4 



4.77 



5.08 



2.27 



3.1 



2.5 



64.3 



63.06 



63.72 



63.24 



61 99 



61.46 



tl 44 



64.49 



62.8 



64.62 



B. G. B. 



Dyckerhofif 



fJftrTnania .........T.. ...... 





Hemmoor 





Lagerdorf er 





Brook, Shoobridge co 



Francis 



Condor 



Pandlot Fr 



Candlot 



Boulo&rne Fr 



k i 







Manufacture of Portland cement 



The steps usually followed are preparation of the raw mate- 

 rials, mixing, burning, grinding and bolting. 



In Portland cement manufactnre there are two general meth- 

 ods of preparation, the aim of each being to mix thoroughly the 

 raw materials. These methods are known as wet and dry meth- 

 ods. In the wet method proper the materials are mixed by 

 forming them into a thin paste with water, after which they are 

 dried before burning. In the dry method only enough water is 

 used to permit forming the materials into bricks, so that they 

 can be charged into the kiln. A modification of the dry method 

 consists in grinding the material dry and charging it in this man- 

 ner into the rotary furnace, or mixing only enough water to 

 make it ball. 



Wet process. The raw materials best adapted to this method 

 are soft chalk and plastic clay, which on account of their condi- 

 tion can be easily mixed with water. The material has sometimes 

 to be reduced to a powder by means of crushers, but this is not 

 always necessary, and the mixing is done in water. It is the 

 custom at some works to give the material a preliminary mixing 

 by spreading it in alternating layers of chalk and clay on the 

 floor, and, when it is removed to the washing mill, digging into 

 it vertically. e 



The wash mills in which the mixing is done consist of several 

 different forms, but they are essentially cylindric tanks, some- 



