164 
KIRTLEY F. MATHER 
Capillary action on crude oil in dry materials; experimental data 
Dissemination through fuller’s earth. Experiments conducted 
by David T. Day^ indicate that in spite of its relatively low sur- 
face tension crude oil disseminates rapidly in dry, finely divided 
material such as fuller’s earth. Not only does oil rise directly 
against gravity to a height of 5 or 6 feet in a tube packed with 
fuller’s earth, /^but if the tube be sealed at the upper end the oil 
will still rise in the tube, driving out the air in the pores of the 
earth and compressing it in the upper part of the tube with 
a pressure sufficient to blow out the clay if the top of the tube 
be suddenly broken off and the air thus released.” 
No experimental data are available as to the exact size of the 
capillary spaces through which the oil is thus forced to migrate, 
but somewhat similar movement is known to take place through 
finely divided quartz sand and amorphous silica.^ More than 
likely the upper limit of pore sizes conforms to that suggested 
above as the theoretical dimensions of capillary openings for 
crude oil. 
Effect of dissemination upon composition of crude oil. ^^When 
a glass tube is packed tightly with dry fuller’s earth, and one 
end is allowed to stand for one or two days in crude petroleum 
the oil diffusing up through the clay fractionates to a consider- 
able extent. Thus, when the upper fifth portion of the clay is 
dropped into water, a lighter gravity oil is driven out by the 
water. This first fraction is entirely colorless. The lower frac- 
tions are heavier and more and more highly colored. The bottom 
section may be almost solid, and is darker in color than the 
original oil. A fractionation by diffusion has been effected, 
which is similar to fractionation by distillation, but is not so 
complete.”^ Richardson^*^ made similar tests with crude oil 
from Texas and found that sulphur compounds could be sepa- 
rated from that oil by their failure to migrate into fuller’s earth. 
7 David T. Day, The conditions of accumulation of petroleum in the earth, 
Am. Inst. Min. Eng., Trans., vol. 41, pp. 219-224, 1911. 
® David T. Day, Experiments on the diffusion of crude petroleum through 
fuller’s earth. Science, N. S., vol. 17, pp. 1007-1008, 1903. 
9 Day, loc. cit., p. 222. 
Clifford Richardson, Journ. Soc. Chem. Ind., vol. 21, pp. 316-17, 1902. 
