The implications of the peculiarities of equilibria involving a cross-linked polymer network and a solvent were examined in the derivation of a thermodynamic consistency test. While strict application to a binary system achieves no tangible result, it is shown that a simple expression can be obtained from the Gibbs-Duhem equation if several sets of data, including both binary and ternary, are combined. The expression derived was applied to previously repel-red multicomponent data. The results and further developments of the newly proposed test are discussed.