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2. Data on the amount of foam or foaming volumes and on foam stabilities are given for a series of hydrocarbons and for a range of concentrations of aqueous ethylene glycol solutions. 3. It is shown that the amount of foam formed depends on the machinery of its production as well as on properties of the liquid; whereas the stability of the foam produced, within specific mechanical limitations, is primarily a function of the liquid. The information contained in this paper was obtained in connection with an investigation sponsored and financed by the National Advisory Committee for Aeronautics and carried out under the supervision of Professor James ITr. McBain. REFERENCES (1) BIKERMAN, J. J.: Trans. Ib-mxlay SOC.34, 634 (1938). A . P., A K D Ross, S.: J. Am. Chem. SOC.66, 1348 (1944). (2) BRADY, F. H., AND ERKUT, K. C . : Rev. facult6 sci. univ. Istanbul 9A, No. 1, 69 (3) CONSTABLE, (1944). (4) GRAY,P. P., A N D STONE, J.: Wallerstein Labs. Commun. 3, No. 10, 159 (1940). (5) HAZLEHURST, T. H., AND XEVILLE, H. A , : Ind. Eng. Chem. 33, 1084 (1941). (6) HOFFhIANN, IC., A N D PETER, H.: Kolloid-Z. 97, 161 (1941). (7) OSTWALD,W. A., AND MISCHKE, W.: Iiolloid-Z. 90, 17, 77, 205 (1940). S.: Ind. Eng. Chem., Anal. Ed. 16, 329 (1943). (8) ROSS, (9) Ross, S.: J. Phys. Chem. 47, 266 (1943). (10) ROSS,S.,AND RICBAIN,J. W.: Ind. Eng. Chem. 36, 570 (1N4).
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THE PRESSURES AGAINST WHICH OILS WILL SPREAD ON SOLIDS E. ROGER WASHBURX
AND
ELMER A. ANDERSON'
iivery Laboratoru of Chemistry, University of Nebraska, Lincoln, Nobraska Received A p r i l 8 , 2946
The use of monomolecular films in the direct measurement of the pressure against which an organic liquid will spread on water has recently been investigated (2, 5, 6, 7). The results of careful measurements of these spreading pressures and of the surface tensions and interfacial tensions involved indicate that, for the systems studied, the spreading pressures are identical with the spreading coefficients of Harkins (1, 5 ) . Briefly, the direct measurement of spreading pressures involves the measurement with a hydrophile balance of the maximum film pressure against which an added drop of organic liquid will spread on the surface of the n-ater. The confining film is compressed when this spreading occurs. A modification of this method has now been used t o measure the pressure against which an oil will spread on the polished surface of a metal. Because of 1
Present address: The Shell Development Company, Bneryville, California.
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E. ROGEI? IVASHDURK AND ELMER d. ANDERSOK
the difficulty of measuring directly the surface tensions and interfacial tensions involving a solid surface, it has not been possible to employ the equation of Harkins for the calculation of the spreading corfficients for such solid-oil interfaces. I n this modification a monomolecular film floated on a thin layer of water above a surface of polished steel is iiserl to restixin the spreading of i w i ous oils on the steel. il. series of oils of grndating spreading teiitlencies \ \ a s prepal-etl Lq, heating L: quantity of lubricating oil, in contact ivith liir, for :I period of several hours. Samples were removed from the bulk after different intervals of time. The extents t o n hirh thc different samples had been osidizetl were measured by determining the relative amounts of hydrophile group^ bv the method which Shanklin and MacI
