LIMESTONES. 



315 



carries less than 90 per cent of lime carbonate it should give a value 



SiO 2 



of between 2.25 and 3.0 for the ratio 



These are comfort- 



able limits, and will give the manufacturer considerable latitude in his 

 choice of a clay to mix with it. 



FIG. 66. Working heavy horizontal bed of limestone. 



Prospecting and examining limestone deposits. The prospector 

 looking for a deposit of good limestone, or the engineer engaged to 

 report on a deposit already located, should both realize that much 

 trouble can be avoided if they will first familiarize themselves with 



14-15. Bedford P. C. Co., Bedford, Ind. A. W. Smith, analyst. 20th Ann. Rep. U. S. Geol. 

 Survey, pt. 6, p. 381. 



16. Tola P. C. Co., Tola, Kansas. H. N. Stokes, analyst. Bull. 78, U. S. Geol. Survey, p. 124. 

 17 -18. lolaP. C. Co., lola. Kansas. 



19. Kansas P. C. Co., lola, Kansas. 

 20 -24. Alpena P. C. Co., Alpena, Mich. 

 25-26. Atlas P. C. Co., Ilasco, Mo. 



27. Atlas P. C. Co., Ilasco, Mo. E. Davidson, analyst. 



28. Catskffl P. C. Co., Smith's Landing, N. Y. 



29-30. Helderberg P. C. Co., Howe's Cave, N. Y. Black, analyst. 

 31-33. Cayuga P. C. Co., Portland Point, N. Y. J. H. McGuire, analyst. 



34. Glens Falls P. C. Co., Glens Falls, N. Y. Mineral Industry, vol. 6, p. 97. 



35. Ironton P. C. Co., Ironton, Ohio. C. D. Quick, analyst. 



36. Alma P. C. Co., Wellston, Ohio. 21st Ann. Rep. U. S. Geol. Survey, pt. 6, p. 402. 

 37-39. Diamond P. C. Co., Middle Branch, Ohio. E. Davidson. 



40. Wellston P. C. Co., Wellston, Ohio. W. S. Trueblood, analyst. 

 41-44. Crescent P. C. Co., Wampum, Pa. Robertson Bros., analysts. Report Q. Q., Penna. Geol, 



Surv., p. 107. 

 45. Virginia P. C. Co., Craigsville. Va. Cement Industry, p. 235- 



