354 SLITS, IROVE SIMPMNIIN TES 
previous experiments. If the tests are made during the winter 
months when the temperature is below the freezing point, the 
samples can be saturated with water, cooled to nearly the freez- 
ing point, and then placed out of doors. If freezing tempera- 
tures do not prevail in the climate where the experiments are 
being performed, access may be had to a cold storage build- 
ing where the necessary temperature may be obtained. Freez- 
ing mixtures may also be used to produce the desired tempera- 
ture. 
The samples to be tested should first be thoroughly cleaned 
and dried in a hot air bath at a temperature of 110° C. and 
weighed. After the samples are thoroughly saturated with dis- 
tilled water, after the manner outlined in the specific gravity 
test, they should be cooled almost to the freezing point, taken 
from the water and removed tothe place of freezing and allowed 
to remain for twenty-four hours. The samples should be thawed, 
saturated, and frozen alternately each day for a period of thirty 
or forty days, after which they should be placed ina hot air 
bath and dried at a temperature of 110° C. They should then 
be removed to the weighing room and weighed. This final 
weight subtracted from the first gives the loss in weight. The 
samples should be examined to discover any cracks that may 
have formed as a result of the freezing. 
Finally the frozen cubes should be crushed in a testing 
machine to determine their compressive strength. The results 
thus obtained should be compared with the strength tests made 
on unfrozen cubes of the same stone. 
The loss in weight during a period of thirty-five days has 
been found to be due mainly to the removal from the surface of 
small particles which were previously loosened, in the process of 
cutting the sample. Many of the grains at the surface of sand- 
stone samples which have been sawed or hammer-dressed are 
partly loosened. Such grains fall away from the mass of the 
stone very easily. The pressure which is supplied by the freez- 
ing water, which fills the cracks and pores near the surface, is 
abundantly able to accomplish this. 
