COMPOSITION AND PROPERTIES OF NATURAL CEMENTS. 257 

 TABLE 115. Continued. 



"F. O. Norton." Private communication. 



Quoted by Cummings. "American Cements", p. 35. 



Quoted by Lewis. Mineral Industry, vol. 6, p. 96. 

 "Beach's." J. O. Hargrove, analyst. Private communication. 

 "Brooklyn Bridge." Quoted by Cummings. "American Cements", p. 35. 

 C. Richardson, analyst. Brickbuilder, v9l. 6, p. 229. 



Newark Lime and Cement Co. Quoted by Cummings. "American Cements", p. 35. 

 Newark and Rosendale. C. Richardson, analyst. Brickbuilder, vol. 6, p. 229. 

 "Old Newark." Booth, Garrett, and Blair, analysts. Mineral Industry, vol. 6, p. 96. 

 "Lawrence", Rosendale Cement Co. Mineral Resources U. S. for 1883-1884. 

 Lawrenceville cement. A. W. Dow, analyst. Mineral Industry, vol. 6, p. 96. 

 "Hoffmann'', Lawrence Cement Co. C. Richardson, analyst. Brickbuilder, vol. 6, p. 229. 



" " Quoted by Cummings. "American Cements", p. 35. 

 " " " Haas and McGraw, analysts. Engineering News, April 



30, 1896. 



Hoffmann", Lawrence Cement Co. Mineral Resources U. S. for 1883-1884. Very ex- 

 ceptional analysis. 



17. "Rock Lock." C. Richardson, analyst. Brickbuilder, vol. 6, p. 229. 



18. Quoted by Cummings. "American Cements", p. 35. 



19. "Hudson River." C. Richardson, analyst. Brickbuilder, vol. 6, p. 229. 



20. Rondout, N. Y. L. C. Beck, analyst. "Mineralogy of New York", p. 78. 



21. "Hoffmann." 



22. "Newark and Rosendale." } Tests of Metals, etc., at Watertown Arsenal, 1901. 



23. "Norton." 



The following analysis is of the natural cement made at Howe's 

 Cave by the Helderberg Portland Cement Company: 



2. 



3. 



4. 



5. 



6. 



7. 



8. 



9. 

 10. 

 11. 

 12. 

 13. 

 14. 

 15. 



16. 



ANALYSIS OF NATURAL CEMENT, SCHOHARIE COUNTY, N. Y. 



Silica (SiO 2 ) .' '. 26.54 



Alumina (A1 2 O 3 ) 1 5 89 



Iron oxide (Fe 2 O 3 ) / 



Lime (CaO) 45.30 



Magnesia (MgO) , 17.06 



Cementation Index 1 . 17 



The cements of central New York are of low index, though usually 

 not so low as those of the Akron-Buffalo district. 



The natural cements of the Akron-Buffalo district carry usually 

 20 to 25 per cent magnesia and are of very low index. 



