THE INTERPRETATION OF CEMENT ANALYSES. 



269 



Si0 2 (insol.) 



... 0-25 



A1 2 3 



... 7-61 



Fe 2 3 



2-41 



MgO 



... 0-43 



K 2 ) 



Na 2 Oj 



... 1-00 



S 



. l .. 0-12 



S0 3 



1-44 



co 3 



1-25 



C (from fuel) 



•10 



OH 2 



•94 



Chlorides 



. . . traces 





100-00 



The value for M was found to be 2*004, and the sum of the 

 sulphur tri-oxide and magnesia was 1 '87, which comes well within 

 the figures required by an undoubtedly good cement. 



The object of the present paper is to give a more extended 

 meaning and value to an analysis of a cement and to express as 

 clearly as possible all the information that an analysis affords. 

 In doing so it seems rather remarkable that this has not been 

 done long ago, as it would have given greater confidence in judg- 

 ing of the value of a cement, and removed that perplexity that 

 existed in the minds of both analyst and engineer in times past. 



By analogy a cement resembles gunpowder, at least in one 

 conspicuous feature, namely, that it may be regarded as* " a 

 system in such a condition of chemical equilibrium that a variation 

 of the condition involves a transformation of energy," so that 

 when the gunpowder is fired, the nitrate, carbon and sulphur 

 become resolved into simpler and more stable bodies. 



* In like manner the cement just awaits the gauging or addition 

 of the water whereupon a transformation occurs, hydration taking 

 place, resulting in the formation of certain definite and stable 



* Threlfall in Watt's Dictionary of Chemistry, Vol. 11., p. 530. 



