116 



Philippine Journal of Science 



1919 



under the prevailing conditions at the plant. It is not practical 

 to dry each sample before analysis, because the results cannot 

 be obtained as rapidly as they are needed. The limestone as 

 it comes from the quarry is frequently contaminated to a greater 

 or less extent with clay different in composition and in analyt- 

 ical behavior from the two siliceous materials regularly used 

 in making the mix. The results obtained by testing the three 

 raw materials by the calcimeter and the alkali-acid titration 

 method are shown in Table III. 



Table III. — Partial analyses of the three raw materials by different 



methods. 



Calcium carbonate. 



Lime- 

 stone. 



Silicate. 



1. 



2 



\ 



Per cent. 

 94.50 

 95.40 



Per cent. 

 0.00 

 2.60 



Per cent. 

 0.00 

 3.30 











It will be noted that although the two silicates contain con- 

 siderable calcium there is no evolution of gas when they are 

 treated with. acid. However, although they contain no car- 

 bonates, they have acid-consuming values equivalent to 2.60 per 

 cent and 3.30 per cent calcium carbonate, respectively. The 

 portion of each, soluble in 0.4 iV hydrochloric acid, gives the 

 results shown in Table IV, calculated to the basis of the original 

 sample. 



Table IV. — Constituents of the two silicates. 



Iron and aluminium oxides 



Calcium oxide (calculated to CaCOs) . 



Silicate. 



Percent. 

 2.57 

 2.26 



Per cent. 

 6.65 

 3.08 



The sources of error with the analytical methods employed 

 and their effect on the results are illustrated in fig. 1. This is 

 based on the typical analysis shown in Table V. 



