A form of the @G02627@ equation which includes an expression of the phenomenon of @E01941@: \[s\ \mathrm{d}T- \tau \ \mathrm{d}p+\mathrm{d}\gamma +\sigma ^{\alpha }\ \mathrm{d}E+\sum \mathit{\Gamma }_{j}\ \mathrm{d}\mu _{j}=0\] where \(s\) is the @S06171@ of @E02149@ of unit area of @I03118@, \(T\) is the temperature, \(\tau \) is the thickness or excess volume of unit area of the @I03118@, \(p\) is the external pressure, \(\gamma \) is the @I03088@, \(\sigma ^{\alpha }\) is the free @S06159@ on phase \(\alpha \) (areal amount of charge on the surface of phase \(\alpha \)), \(E\) is the generalized potential, \(\mathit{\Gamma}_{j}\) is the @S06171@, \(\mu _{j}\) is the @C01032@ and \(j\) is an electrically neutral component of one or other of the phases; the sum is over all the components but one in each phase.