Molecular Association

Abstract

THE progress of chemical theory has been connected in an intimate way with the study of the complexity of molecules. By the introduction of Avogadro's hypothesis the determination of molecular complexity in gases was reduced to a comparatively simple problem. The development of the osmotic theory of solutions provided a theoretical basis for the interpretation of the results obtained in the investigation of the vapour pressures and freezing points of solutions. In so far as dilute solutions are concerned, the problem of molecular complexity is partially solved by the application of osmotic methods, although the question of the association of solute and solvent in the same molecule does not lend itself to attack in this way. When we pass from dilute to concentrated solutions or liquid mixtures, the problem acquires an entirely different character. For such mixtures there is no general guiding and reconciling principle such as is afforded by the hypothesis of Avogadro. The same difficulty confronts us when we deal with pure liquids. The methods available for the investigation of the molecular condition of pure liquid substances are entirely empirical, and the value to be attached to the various methods which have been proposed is at present largely a matter of personal opinion.

Molecular Association.

By Dr. W. E. S. Turner. Pp. viii + 170. (London: Longmans, Green and Co., 1915.) Price 5s. net.