The osmotic pressure of compressible solutions of any degree of concentration

Abstract

This paper is an attempt to make more complete the theory of solutions, at the same time maintaining as great simplicity of treatment as is possible without sacrificing precision. Renewed attention has been called to the subject, owing to the success of the experiments of the Earl of Berkeley and Mr. E. J. Hartley on the osmotic pressure of concentrated solutions of sugars. Diversity of opinion has existed in regard to the interpretation of these experiments, insufficient attention having been previously paid to the influence of the hydrostatic pressure of the pure solvent upon the value of the osmotic pressure. The principal advances made in this paper consist in simply demonstrating the influence of pressure upon osmotic pressure for compressible solutions and in including the effect of the variability of vapour pressure with hydrostatic pressure. The influences of accidental properties (such as the effects of gravitation) are excluded. Summary of Notation . The following is the notation employed. All the values are isothermal values. Solution .— Hydrostatic pressure ................................................................ p Vapour pressure corresponding to hydrostatic pressure p .. π p Vapour pressure when solution is in contact with its own vapour alone.............................................. π π Volume at hydrostatic pressure p .......................................... V p Reduction of volume when 1 gramme of solvent escapes....... s p Osmotic pressure for hydrostatic pressure p ........................... P p Osmotic pressure for hydrostatic pressure π π ....................... P π