WIEN PROPE RIES OF BULEDING STONE SLE. 349 
completely saturated with water, in water; and finally dividing 
the weight in air by the difference. These ideal conditions of 
absolute freedom from interstitial water in the one case, and 
complete saturation in the other, are difficult to obtain. Never- 
theless, if accurate methods are employed and care is exercised 
in manipulation it is thought that a high degree of accuracy. can 
be attained. 
As previously stated, it is advisable to perform all tests on 
two-inch cubes. In obtaining the specific gravity, the samples 
should be cleaned by carefully washing, and dried for twenty- 
four hours in a hot air bath at a temperature of 110° C. The 
samples should then be weighed and the weights recorded in 
grams to the second decimal place. The samples should then 
be transferred to a large bottle or other glass receptacle, corked 
tightly, and sealed. This bottle should then be transferred to a 
water bath having a temperature of 100°C. Three glass tubes, 
one leading to an air pump, another to a manometer, and a third 
to a basin of boiling water are passed into the bottle through 
holes in the cork. By means of the air pump, the air in the 
bottle should be exhausted until the pressure, as indicated by the 
manometer attachment, is lowered to at least one twelfth of an 
atmosphere. The pressure should be maintained at this point 
while distilled water at a temperature of 100° C is drawn into 
the bottle through the third tube. This tube which conveys the 
water should be partly rubber and should extend to the bottom 
of the bottle. A stop cock is used to regulate it. By starting 
the air pump and operating the stop cock at the same time it 1s 
possible to keep the pressure nearly constant and at the same 
time draw any desired amount of water into the bottle. By this . 
process, the air in the pores is gradually replaced by the water 
which fills the vessel from below. After the cubes are com- 
pletely covered with water, they should be allowed to remain in 
the bottle twenty-four hours maintaining a pressure of one 
twelfth of an atmosphere. 
The saturated samples should then be quickly transferred to 
a basin of distilled water and removed to the weighing room. 
