Meaning of the Tait Coefficients and the Structure of Liquids

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Abstract
The coefficient L is in the main concerned with the volume of the large clusters. While this volume is positive for clusters of low molecular weight, it becomes small and finally negative as the clusters increase in size. The clusters can increase in size due to a temperature rise or an increase in molecular weight. Hence the value of L goes through a maximum. It is shown that at the critical temperature Pc=—L. Calculations from this relationship give the critical pressure of liquid helium I to be 2.258 atm (experimentally 2.26 atm). This relationship also gives insight into the nature of the critical state. The coefficient J is a function of the change in the fraction of holes with a change in volume at constant temperature. While J appears to be constant with pressure along an isotherm, it is not, however, constant with temperature; it is only a slowly varying function. Various deductions are drawn from the fact that J has almost the same value for groups of related substances. A resume of the structure of liquids in the light of this theory is given.