184 R. W. CLARK AND HOLBROOK G. BOTSET 
off the dome for at least 14 mile, and the radon content was still 
practically as high as was found in the producing area. This seemed 
to indicate that the presence of oil had little to do with the radio- 
activity of the soil. 
Knowing the association of radioactivity with heavy minerals,’ it 
was decided to make another profile parallel to and near the first and 
to take samples of the soil from the bottom of each hole. These 
samples were taken to the laboratory for quantitative determination 
of their heavy mineral content. 
hen TH 



ELECTROSCOPE READINGS 
---- PERCENT HEAVY MINERALS 
8 8 
! ' 
PERCENT HEAVY MINERALS 
ELECTROSCOPE READINGS 
(°) 360 600 720 840 960 1200 1320 
FEET 
Fic. 3.—Radon profile across South Liberty salt dome. 
HEAVY MINERAL SEPARATION 
About 30 grams of each of these samples were ground to pass a 
130-mesh sieve. The heavy minerals were first separated by using 
bromoform in a separatory funnel. This bromoform had a density, as 
determined by the pyknometer, of 2.5. It was found, however, that 
the heavy mineral fraction obtained by this separation contained 
quartz and calcite. Consequently, this heavy mineral fraction was 
again separated, Thoulet’s solution (density 3.15) being used. This 
gave a very complete separation and was adopted as standard pro- 
cedure. 
1 E. H. Biichner, Jahrb. f. Radioahkt., Vol. 19 (1913), p. 516. 
W. Waters, Phil. Mag., Vol. 19 (1910), p. 903. 
R. H. Strutt, Proc. Roy. Soc., Vol. 84 (1910), p. 377. 
A. Gockel, Die Radioaktivitat von Boden und Quellen (Braunschweig, 1914). 
St. Meyer and Schweidler, Radioaktivitat (Leipsic, 1927). 
514 
