
144 The Principles of Thermodynamics
The last of these is traditionally called one of the Maxwell Relations, and following
Pippard, we denote it by M.1. Some authors (Huang) refer to the first two also as
Maxwell relations. We shall adhere to the traditional terminology. We have applied
our considerations to the internal energy U, even though the word potential may not
usually be applied to it. In a certain sense, to be made more precise shortly, one could
call U a thermodynamic prepotential. In a completely analogous fashion, one gets the
next set of relations by considering the enthalpy, H:
∂
H
∂
S
P
= T
∂
H
∂
P
S
= V
∂
T
∂
P
S
=
∂
V
∂
S
P
(7.20)
The Maxwell relati ...