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Indiana University Studies 



10. Acme Bedford Stoiie Company, Clear Creek, Monroe coimty. Twentieth 

 Ann. Rept. U. S. Geol. Sm-vey, pt. 6 (continued), 1899, p. 381. 



11. Hunter Brothers quarry. Hunter Valley. W. A. Noyes, analyst. Twenty- 

 first Rept. Indiana Dept. Geology, 1897, p. 320. 



12. Indiana Stone Company, Bedford, Lawrence coimty. W. A. Noyes, 

 analyst, Idem. 



13. Twin Creelt Stone Company, Salem, Washington county. W. A. Noyes, 

 analyst. Idem. 



14. Romona Oolitic Stone Company, Romona, Owen county. W. A. Noyes, 

 analyst. Idem. 



15-16. Hoosier Stone Company, Bedford, Lawrence county. F. W. Clarl<e, 

 analyst. Bull. U. S. Geol. Survey No. 42, 1887, p. 140. 



17-18. Indiana Steam Stone Works, Big Creek. L. H. Streaker, analyst. 

 Twenty-first Rept. Indiana Dept. Geology, 1897, p. 320. 



"Cement consists of certain anhydrous double silicates of 

 calcium and aluminum, which are capable of combining chemi- 

 cally with water to form a hard mass." The above definition 

 is given in most texts on industrial chemistry but from an in- 

 dustrial standpoint it is an intimate mixture of limestone and 

 shale or marl and clay that has been calcined and ground until 

 it will harden under water. Cements differ from lime mortars in 

 that they do not require carbon dioxide from the air in hardening 

 and are insoluble in water. The hardening of the cement takes 

 place thruout the whole mass simultaneously and thus makes it 

 very useful as a building material. 



Cements are of three classes, as follows: 



1. Those cements formed from volcanic tufas or materials 

 resembling them such as Pozzuolana, blast-furnace slags, etc. 

 These cements require the addition of lime before showing their 

 hydraulic properties. 



2. Those cements which contain large quantities of free 

 lime such as Roman cement and ''hydraulic" limes. These 

 cements have been formed by burning a natural argillaceous 

 limestone at a temperature that has driven off all the carbon 

 dioxide present in the limestone, without being sufficiently high 

 to fuse the product. 



3. True Portland cements or those which have been prepared 

 by burning at a high temperature an intimate mixture of clay 

 or shale with a calcium carbonate rock. 



The chemical composition of Portland cement has not been 

 definitely determined, but the most exhaustive work on the sub- 

 ject has been done by a French chemist, Le Chatelier. After 

 careful synthetic determinations he gave the following formula 

 for its compostion: 



x(3CaO, SiOa) y(CaO, AI2 O3) 



