UNDERGROUND MIGRATION OF OIL AND GAS 
167 
oil was later displaced from the earth by water. Fractions of 
the earth removed from the tube and dropped into water, rapidly 
gave up their content of oil, and the pores formerly occupied by 
oil became filled with water. Several experiments which ap- 
proximate more closely the conditions existing within the earth 
have been described by McCoy, Mills, and Cook.i-^ 
of McCoy’s experiments, an open glass cylinder was placed in 
a pan of wet sand, so that the sand filled the lower one-third 
of the cylinder. The water had free access from the sand in the 
pan to the sand in the cylinder. A layer of oil-saturated mud, 
made by adding Oklahoma crude oil (38°Beaume) to a mixture 
of dried clays, the particles of which measured from 0.005 to 
0.001 mm., was placed in the cylinder upon the wet sand; this 
mud occupied about one-third of the cylinder and was above the 
level of the water in the pan. The cylinder was then filled with 
dry sand, and the top sealed with a tube attachment to a closed 
barometer. Within twenty-four hours, the water migrated up- 
ward about 1 cm. into the mud, and the oil moved about the 
same amount into the dry sand; some of the oil also migrated 
down into the wet sand and collected in the larger openings; 
the mercury rose in the closed barometer to a height of about 
2.5 cm. above that corresponding to the atmospheric pressure. 
As thus described the experiment is essentially a modification 
of the Daubree experiment of 1861, in which water passed 
through sandstone against pressure, or of the ^Atmometer”^^ 
which gives similar results. The most significant, obvious 
A. W. McCoy, Some effects of capillarity on oil accumulation, Jour. GeoL, 
vol. 24, pp. 798-805, 1916; reprinted. Bull. Southwestern Assoc. Petrol. Geolog., 
vol. 1, pp. 140-47, 1917. 
R. V. A. Mills, Experimental Studies of subsurface relationships in oil and 
gas fields, Econ. GeoL, vol. 15, pp. 398-421, 1920. 
1^ C. W. Cook, Study of capillary relationships of oil and water, Econ. GeoL, 
vol. 18, pp. 167-72, 1923. 
1® Daubree, Etudes Synthetiques de Geologic Experimentale, Paris, 1879, 
pp. 238. 
17 J. Johnston and L. H. Adams, Observations on the Daubree experiment and 
capillarity in relation to certain geological speculation. Jour. GeoL, vol. 22,. 
pp. 1-15, 1914. 
