A drop of liquid

The structure and thermodynamic properties of the interface between a drop of liquid and its vapour have long been matters of controversy. The system can be described in terms of its macroscopic thermodynamic properties, in terms of local thermodynamic properties or in the language of statistical mechanics. It is shown that the second of these routes leads to difficulties but that there is good evidence that the first and third are concordant, at least as far as the term in R -1 in an expansion in powers of the reciprocal of the drop radius, R. There are, however, serious problems if the expansion is taken to higher powers of R -1 .