PHILIPPINE RAW CEMENT MATERIALS. 215 



is replaced by iron and showing that iron-ore cement has lieen used 

 with efficiency for such works of construction.^^ 



If the international atomic weights for 1909 are used in the above 

 limiting molecular formula of Bleininger, then for every part Ijy weight 

 of silica 2.60 of calcium oxide are required, for every part of alumina 

 1.10 of calcium oxide, for every part of ferric oxide 0.70 of calcium 

 oxide, and for every jjart of ferrous oxide 0.78 of calcium oxide. As 

 the clay itself contains a certain proportion bj^ weight of calcium oxide, 

 this amount must be deducted from the total required (the amount of 

 magnesiam present is equivalent to 1.4 its weight of calcium oxide). 

 On the other hand, the limestone contains silica, alumina and oxides of 

 iron which take uj) some of the calcium and accordingly reduce the 

 amount available. , 



The calculation of a cement mi.xture from shale number 1 and the limestone 

 would be as follows : 



SHALE. 



42.72X2.60=111.07 parts calcium oxide required by silica in 100 parts 



shale. 

 17.23X1.10= 18.95 parts calcium oxide required by alumina in 100 parts 

 shale. 

 2.13X0.70= 1.59 parts calcium oxide required by ferric oxide in 100 



parts shale. 

 4.11X0.78= 3.21 parts calcium oxide required by ferrous oxide in 100 

 parts shale. 



134.82 parts calcium oxide required by 100 parts shale. 

 11. 12-f (3.65X1.4) = 16.23 parts calcium oxide equivalent to calcium and mag- 

 nesium in 100 parts shale. 



(1) 118.59 parts calcium oxide to be added to 100 parts shale. 



LIMESTONE. 



53.86-|- (0.21X1.4) =54.13 parts calcium oxide equivalent to calcium and mag- 

 nesium in 100 parts limestone. 



0.97X2.60= 2.52 



0.56X1.10= 0.62 3.40 parts calcium oxide in 100 parts limestone which 



0.25X0.70= 0.17 f is not available. 



0.11X0.78= 0.09 



(2) 50.73 parts calcium oxide available in 100 parts limestone. 



- — i-= '- — =2.34 parts limestone required by 1 part shale. 



(2) 50.73 ^ H J 1 



The limestone and shale numlier 1 combined according to this cal- 

 culation give the following results: 



"Newberry, S. B.: Cement Age, 4, 38; Monthly Consular a,nd Trade Report 

 (1908), June, 165; Cement atid Eng. ^'ews (1908). 20, 112, 168. 



