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 . 
O 
Per cent. 
Per cent . 
Percent. 
By calcimeter (total CO 2 calculated to CaCOs) 
94. 50 
0.00 
0.00 
By titration (total acid neutralized calculated to CaCOs) 
95.40 
2.60 
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 N hydrochloric acid, gives the 
results shown in Table IV, calculated to the basis of the original 
sample. 
Table TV.— -Constituents of the two s-ilicates. 
Silicate. 
1 . 
2 
Iron and aluminium oxides 
Percent. 
2.57 
2.26 
Per cent. 
6.65 
3.08 
1 Calcium oxide (calculated to CaCOg) 
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. 
