STATE GEOLOGIST. 300 
It is the object of these tests to accelerate the slaking of the quick- 
lime, if any be present in the cement, or the breaking down of the alu- 
minates or imperfect hydraulic silicates,and thus bring about the destruc- 
tion of the cement or produce evidence of disintegration. They are carried 
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Fig. 71. Bauschinger apparatus for determining constancy of volume. 
out by making a pat about 3 inches in diameter and 0.5 inch thick at 
the center, sloping to a thin edge on a clean glass plate. 
of cement is then allowed to harden in an atmosphere of moist air for 
24 hours. For the boiling test the specimen is put in cold water, which 
23—S. G. Bull. 3. 
This pat 
