LIME AND CEMENT INDUSTRIES 817 



In the quarries of the Helderberg cement co. (pi. 63) at Howe 

 Cave, 120 feet of the two limestones just mentioned is exposed. 

 They are used for the manufacture of Portland cement, being 

 mixed with clay. Underlying the limestone is a bed of natural 

 rock cement, which is also utilized. The following analyses were 

 furnished by C. R. Ramsey, superintendent of the works. 



Gray stone Blue limestone Clay 



Lime 52.18 52.58 2.9 



Magnesia 1.27 .79 



Silica 2.7 3.12 71.67 



Alumina ard ferric oxid 1 . 64 .93 15.08 



Sulfur 17 .24 



Ignition 15.13 18.8 5 



The first two analyses are not very consistent; for it is hard to 

 conceive how a stone containing 52.18$ of lime could yield only 

 15.13$ on ignition. 



The cement rock is said to yield on analysis: 



Lime carbonate 55 . 17 



Magnesium carbonate 19.71 



Silica 12 . 89 



Ferric oxid and alumina 11 . 15 



"Water .Q6 



Another analysis of Howe Cave limestone, made by C. A. 

 Schaffer, 1 gave: 



Lime carbonate 97 . 24 



Magnesium carbonate 1.39 



Ferric oxid and alumina .73 



Silica 1.27 



Sulfur tr. 



Phosphoric acid none 



100.63 



l 20th rep't U. S. geol. sur. pt 6, p. 428. 



