274 W. M. HAMLET. 



S0 3 1-78 



C0 2 -90 



OH 2 -43 



Loss and undetermined ... *25 



100 

 It will be seen that the cement contained 58*96% of lime. 



The hydraulic modulus was 1*79 by which it would pass as a 

 good cement, but on apportioning the lime to the different acid- 

 forming radicles it was found that these required 62*18% of lime, 

 so there was not enough lime in the cement to enable the con- 

 stituents to combine with each other. 



Lime wanted ... ... 62*18 



Lime in the cement ... 58*96 



Deficiency 3*22 



and hence the failure in the cement ; and yet by adding carbon 

 di-oxide to the raw cement, it was found to take up as much as 

 would represent 3% of lime. 



These results point to the conclusion that the value of a Port- 

 land cement cannot be appraised by mere inspection of the figures 

 given by chemical analysis, but by calculating the necessary 

 quantities of lime distributed among the various acid radicles 

 in the proportions required by theory, one is enabled to dis- 

 criminate between good and bad cements, which cannot be done 

 in all cases by the calculation of the hydraulic modulus. 



In conclusion I desire to thank my assistant Mr. Doherty and 

 Mr. Petrie for their valuable help in the analysis and preparation 

 of microscopic sections of the cements examined. 



