A POINT of view is presented with respect to rate processes in liquids. In the now widely applied statisticalmechanical approach to thermodynamic properties, one starts with a known or assumed molecular model, and from that is able to predict the properties of matter in bulk.Similarly in the study of dynamic processes in liquids we may start from a model of how single molecules behave, and from that we are able to predict the relations of such processes to one another and to the thermodynamic properties of the liquids, and to predict the functional dependence of such processes on different variables.

By coordinating our information on viscosity, diffusion, melting, and other rate and thermodynamic properties, we arrive at a detailed picture of liquid structure. Thus we find that a liquid is best thought of as a solid to which a large number of empty equilibrium positions are added. In fact the expansion on melting, as well as the expansion with a rise in temperature, arises almost entirely from this introduction of new equilibrium positions, and only to a minor extent from lattice expansion. We shall obtain information as to the number, size and energy of formation of these empty lattice points.

The equation of state for gases is intimately connected with the law of force between the individual molecules. We are interested in making this relationship explicit. From a set of accurate measurements of PVT or Joule-Thomson coefficients, we should obtain the energy of interaction, E(r), of a pair of molecules separated by a distance r. Or, conversely, if E(r) is calculated from the quantum-mechanical perturbation equations, we should derive the corresponding equation of state. Fowler (6), , and others have expressed the second virial coefficient in terms of E{r), so that the experimental data at low pressures determine the interaction energy. However, the experimental difficulties in obtaining the imperfections of gases accurately at low pressures restrict the use of this method of analysis to a comparatively few simple substances which have been studied with extraordinary care. For this reason, it is desirable to perfect an equation of state which is fairly accurate for high pressures and which still can be interpreted in terms of the intermolecular forces.In this paper we consider first what information can be obtained from experimental data at low pressures and then that from data at high pressures.The equation of state for gases at reasonably low pressures can always be written in the form (6, 27):where B'(T), C'(T), D'(T) are functions of temperature but not of pressure.These are usually referred to as the second, third, fourth .... virial coefficients, respectively. There is some ambiguity in the literature as to the definition of the virial coefficients, but in the course of this paper we shall always define them with reference to equation 1.

The following reaction was studied chemically and found to be a truly and easily reversible reaction 2Fe + + + + 2Hg ;=i 2Fe + + + Hg2 + + 2. The equilibrium constant of the reaction was calculated either from total concentration by suitable graphical and mathematical treatments or from ionic strength of dilute solutions, and was found to be 0.0180 * 0.0005.3. The principle of ionic strength may not be considered to hold even in solutions as low as 0.01 when there is too much acid present as compared with the other salts.4. The oxidation-reduction potential of the ferric-ferrous electrode, calculated from the equation -E-OFe -0.05915 °Hg log K was found to be -0.7473 v. This value agrees very closely with -0.7477 v. obtained from our former e. m. f. measurements.

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