  Structural relaxation times and viscosities for non-associated liquids and
polymers are a unique function of the product of temperature, T, times specific
volume, V, with the latter raised to a constant, g_tau. Similarly, for both
neat o-terphenyl (OTP) and a mixture the entropy for different T and pressures,
P, collapse to a single curve when expressed versus TV^g_s, with the scaling
exponent for the entropy, g_s, essentially equal to the thermodynamic Gruneisen
parameter. Since the entropy includes contributions from motions, such as
vibrations and secondary relaxations, which do not affect structural
relaxation, g_s < g_tau. We show herein that removal of these contributions
gives a satisfactory accounting for the magnitude of g_tau. Moreover, the
relaxation times of OTP are found to be uniquely defined by the entropy, after
subtraction from the latter of a V-independent component.
