272 W. M. HAMLET. 



Now in order to state the results of an ordinary complete 

 chemical analysis in terms of the type-analysis here set forth, it 

 is necessary to apportion the lime to the acid forming bodies, thus 

 the Si0 2 x 1*858 = the amount of lime to form the orthosilicate. 

 A1 2 3 x 1*641 = the lime for the aluminate, and Fe 2 3 x 0-3503 = 

 the lime required to form ferrite, the respective logs, for these 

 co-efficients are for the silica 0*26834; for the alumina 0*21582 ; 

 for the iron oxide 1*54444. Applying these numbers to the 

 sample analysed we find the lime apportioned thus : — 



• the silica ... 



.. 40*41 



„ alumina 



.. 12*51 



,, iron oxide 



.. *84 



„ carbon di-oxide 



.. 1*62 



„ sulphur trioxide 



.. 1*01 



„ sulphur as sulphide . 



•21 





56-60 



Now the total lime shown by analysis is 62*70 (the mean of 

 two different estimations by different methods) 



62*70—56*60 = 6-10 

 the lime is thus accounted for by actual combination to within 6% 

 and this is the free and unappropriated lime which will change 

 into hydrate on setting and will become in due time a varying 

 mixture of carbonate and hydrate ; and further, as this unappro- 

 priated lime is capable of becoming wholly hydrated at the time 

 of setting it may be safely reckoned that the cement will stand 

 all the physical tests, there being no inimical compounds to modify 

 this action ; it will therefore follow that if this lime be in the con- 

 dition I have assumed it to be, and if we cause it to combine with 

 carbon di-oxide, the quantity of carbon di-oxide so combined when 

 subtracted from the balance in our calculation, ought to satisfac- 

 torily account for the whole of the lime in the cement analysed. 

 Accordingly, a given quantity of the cement was treated with pure 

 ammonium carbonate and ignited, making of course the necessary 

 corrections for loss on ignition of the raw cement. The amount 



