to cover the samples completely. Air is then admitted to bring the pressure to 

 atmospheric. After saturation, the samples are taken from the jar; the excess 

 liquid is removed by touching the sample to a filter paper; and the volume of 

 saturant displaced by the saturated sample is determined in a pycnometer. Many 

 different liquids have been suggested and used for this purpose, but it has been 

 found that kerosene is satisfactory and is usually easy to obtain and less ex- 

 pensive than other liquids. 



(2) Bulk-Volume Determination By Displacement With Mercury 



Presaturation of the sample can be avoided by submerging the specimen 

 just below the surface of mercury and measuring the displaced mercury. A 

 pycnometer having a cap with a ground taper and a small hole drilled through 

 the cap is filled with mercury; the cap is inserted; and the excess mercury that 

 overflows is collected and set aside. The cap is removed, the sample placed on 

 the surface of the mercury and submerged by a short set of rods on the under- 

 side of the cap, and the reseating of the cap causes overflow of a quantity of mer- 

 cury equivalent to the bulk volume of the sample. This mercury is collected and 

 measured. Available commercial types of apparatus that determine the rise of 

 the mercury level by electrical contacts or hydrostatic connections are less time 

 consuming than the pycnometer; apparatus of this nature is calibrated by steel 

 balls or slugs, and the volume is read directly on a curve. 



Another method involves the determination of the dry weight of the sample 

 and the weight necessary to submerge it in mercury. The sample is submerged 

 with pointed steel rods, and the weight required to submerge the rods alone to 

 the same depth is determined. The bulk volume is calculated by dividing the 

 sum of the dry weight and the weight required to submerge the sample, less the 

 weight required to submerge the rods, by the density of the mercury. 



(3) Bulk-Volume Determination By Calipering 



The cylindrical sample with ends squared by a diamond saw, or the cube, 

 is admirably suited to linear measurement and arithmetical calculation of the 

 bulk volume. Calipers, micrometers, or similar instruments are used to measure 

 the average diameter and length of the sample, and the volume is read from 

 prepared tables. A dial comparator, though expensive, is remarkably rapid 

 and accurate for these measurements. 



The above are the preferred methods of bulk-volume determination. Obvious- 

 ly, the type of sample to be tested and the number of analyses will influence the 

 method to be used. Calipering is more universally adaptable than submergence 

 or displacement, but it cannot be used with irregular specimens or loosely con- 

 solidated sandstones that sluff easily. Submergence, though somewhat more 

 time consuming than the other methods, has the advantage that it can be applied 



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