ne, WT. BORN ANDI. ES OWEN 
of measured volume was weighed, evacuated, saturated with water 
and reweighed. It was found that the sample absorbed 23 per cent of 
water by volume or 12 per cent by weight. 
In order to ascertain the structure of the rock, a section was made 
for microscopic study. Through the courtesy of Parker D. Trask, of 
the United States Geological Survey, several photomicrographs of 
the section were obtained and are here reproduced in Figures 1 and 
2. The following brief description of the section is the result of ex- 
aminations made by Miss Margaret C. Cobb and Bruce H. Harlton, of 
the Amerada Petroleum Corporation. 
The rock is a comparatively pure quartz sandstone. It shows no secondary 
growth of crystals. The bond is a very fine siliceous iron-bearing silt. Excel- 
lent porosity is developed. Feldspar is almost completely absent. Magnetite, 
hematite, and chloritic alteration products from mica, as well as holite itself, 
are fairly abundant, and there are the usual heavy residuals. 
It is of interest and importance to note that the major constit- 
uents of this sandstone are insoluble in water. In order to obtain a 
rough idea of the amount of water-soluble material present, a 200- 
gram sample was pulverized and digested with 500 cubic centimeters 
of distilled water at room temperature for a period of 4 hours. The 
water was decanted and filtered, the filtrate evaporated to dryness, 
and the residue weighed. In this way the water-soluble material was 
estimated to be less than 0.05 per cent by weight. 
METHOD AND RESULTS 
The method used is a refinement of a method previously? described. 
The apparatus used is shown schematically in Figure 3. The sample 
bar is held in a horizontal position by a support at its midpoint. Small 
MAGNET MAGNET 


SUPPORT 
AMPLIFIER 
METER RECTIFIER 
Fic. 3.—Arrangement of apparatus used to determine natural frequency of bar. 
3B. B. Weatherby, W. T. Born, and R. L. Harding, “Granite and Limestone 
Determinations in Arbuckle Mountains, Oklahoma,” Bull. Amer. Assoc. Petrol. Geol., 
Vol. 18, No. 1 (January, 1934). 
672 
