The Influence of Insoluble Materials on the Physical Properties of Liquids

Abstract

BAKER in his recent presidential address before the Chemical Society (Jour. Chem. Soc., 131, 949; 1927) directed attention to some interesting observations on the changes in the vapour pressure and the surface tension of a number of liquids brought about by the presence of insoluble foreign materials. Charcoal, thoria, platinum black, and finely divided nickel, materials already well known for their power of catalysing chemical reactions, were used, and he found that they brought about a change in vapour pressure, increasing with time to a constant value and, furthermore, that whilst heating increased and cooling diminished this difference it gradually returned to the original maximum. Baker attributed these changes to alterations in the complexity of the molecular association of the liquid with the establishment, eventually, of a new equilibrium. It appeared to the present writers that any change in the degree of association must necessarily be accompanied by a more or less corresponding alteration in the density of the liquid, and it seemed to be desirable to apply the delicate method of density determination now available (Robinson and Smith, ibid., 129, 1262; 1926) to the elucidation of this question.