THE RELATIVE VALUE OF CEMENTS. 



669 



3 



6 



<1 



D 



-<1 



O 



a 



H 



O 



'A 

 



H 



co 



H 



CO 



V! 



H 



H 



H 



t 



H 



>-) 



W 



M 



a 



a 



o 



a 



2Q 



a 





