According to J. D. Bernal a liquid may be regarded as a random, close-packed assemblage of molecules possessing certain distinctive geometric properties. At any instant in time the centers of mass of the "heap of molecules" define the junctions of a polyhedral honeycomb, the individual cells of which consist of slightly distorted versions of but five deltahedral the tetrahedron, octahedron. tetragonal dodecahedron, trigonal prism capped with three half octahedra, and an archimedian antiprism capped with two half octahedra.

We conjectured that the complex polyhedral honeycomb, which changes in detail every 10–12 – 10–11 seconds as a result of thermal motion, can be represented by an average polyhedral hole Which, in most cases. is identifiable as an undistorted specimen of one of the five Bernal deltahedra. The average polyhedralhole exists only in a time or spatial-average sense, but this makes it no less real than the crystallographer's more static unit cell.

Procedures for identifying the average polyhedral hole of a liquid will be presented. From the geometric properties of this unit cell, surface tension can be calculated as the two-dimensionalcohesive energy density (internal pressure) and the spreading pressure as the two-dimensional kinetic pressure.

When two immiscible liquids are placed incontact, structural changes occur on both sides of the physical interface. Both liquids tend to minimize surface to volume ratio. Once the vicinal geometries are known, the interfacial tension can becalculated. The effect of confinement within porous media on liquid architecture and, hence, interfacial tension, will be explored far some hydrocarbon-water pairs


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