COMPOSITION AND PROPERTIES OF NATURAL CEMENTS. 269 



sts, at various ages up to 3 years, on the "improved" natural cements 

 )f the Lehigh district of Pennsylvania. 



The results of a number of tests of natural cements from the 

 Cumberland-Hancock district of Maryland have been averaged and are 

 shown diagramatically in Fig. 56. 



400 



300 



200 



100 



/ 



/ 



k 6 I I 

 a! a J I 



A A A A A A 



J3 53 -M --M C3 



a a o a o a 



o o o o o o 



a a a a a a 



I 3 



fee 'i 

 a 3 

 a a 

 ooo 



a a a 



2 5 S 



FIG. 56. Tensile strength of Cumberland natural cements. 

 (Philadelphia tests, 1894, 1895, 1896.) 



Tests of natural cements from Akron, N. Y., and Cumberland, Md., 

 during 1897 and 1898, are shown diagrammatically in Fig. 57. These 

 tests cover ages, of 1 day to 6 months. 



