LIME AND CEAIENT INDUSTRIES 



683 



that found in the Lehigh valley and the upper Potomac is not. 

 Likewise some of the deposits of the west; but it can be said in 

 general that over 90^ of the rock used is dolomitic. The Rosen- 

 dale and the Louisville cements contain 16 fo to 25^ of magnesia. 

 The amount of the two carbonates in the two limestones varies 

 from 64:fc to 75fc, while the silica and the silicates may vary from 

 20^ to 47^. The rock may even vary considerably in one local- 

 ity, it being sometimes found that certain layers in a quarry make 

 excellent cement, while others are useless or give a product of 

 low grade. A good example of this is furnished by the following 

 analyses quoted by Kichardson in the BricJchuilder, 1897, p. 152. 



Analyses 





1 



36.56 

 14.61 



3.83 



2.49 

 25.25 

 16.18 



.78 



2 



3 



4 



5 



6 



7 



8 



Light 

 9 



Dark 

 9 



10 



11 



Loss on ignition. . . 



Silica 



Alumina and iron 



Insoluble 



Soluble 



Lime . 



29.5 

 23.99 



5.6 



4.17 



20.16 



13.33 



1.29 



41.95 

 6.68 



2.03 



1.58 



31.59 



15.81 



trace 



34.82 

 15.97 



4.54 



3.05 



2S.7i 



15.64 



.71 



31.09 

 21.45 



4.01 



2.86 



23.87 



12.93 



.22 



39.65 

 9.89 



2.77 



2.73 



28.63 



15.15 



.34 



23.55 

 33.06 



3.26 



3.26 



20.33 



10.26 



.82 



33.23 



20.47 



5.09 



2.67 



26.2 



11.59 



.58 



37.34 

 15.01 



3.22 



5.22 



25.85 



39.64 

 9.06 



4.84 



2.51 



27.88 



30.94 

 19.7 



4.84 



5.09 



20.25 



15.23 



.34 



38 95 

 8.01 



2.63 



1.89 



39.77 



Magnesia 



Sulfur as S02. 



18.fc4 

 tiace 



15.67 

 ,38 



7.43 

 .44 



Lime carbonate... 



Magnesium c a r- 



bonate 



45.09 



33.98 

 79.07 



36.01 



27.99 

 64 



56.42 



33.2 



89.62 



42.36 



32.84 

 75.2 



42.63 



27.26 

 69.89 



51.13 



81.82 

 82.95 



36.31 



21.55 

 57.86 



46.79 



24.34 



71.13 



46.17 



39.56 

 85.73 



49.79 



33.91 

 8-i.7 



26.16 



31.98 

 68.14 



71.0 J 

 15.6 



Total carbonate. . . 



86.63 



Silica etc., coarser 

 than 100 mesh.... 



9.51 



•6.93 



1.29 



.04 





4.84 



.32 



1.31 



.32 





2.02 



.83 



Mr Richardson states as follows: 



It was recommended that stratum 1 be rejected, as it con- 

 tained 9.5^ of sand coarser than would pass through an ordinary 

 screen of 100 meshes to the inch. This rock is also too rich in 

 •carbonates and would have given, under the best handling, an 

 inferior cengfCnt; as magnesium cements deficient in clay are not 

 constant in volume after use. 



Stratum 2 had an excellent chemical composition but physically 

 was too coarse, and, lying among inferior strata, it would natur- 

 ally be rejected for economic reasons. 



