The solubilities and the refractive indexes of saturated solns. of the title systems at 30?were studied and the corresponding equilibrium diagrams were constructed. All the solubility curves and refractive index curves of these systems are consisting of four branches, corresponding to 4-ClCH2COAp, Ln(4-ClCH2COAp)3(ClO4)3譶H2O(Ln = La, n = 7; Sm, 8; Er, 4), Ln(4-ClCH2COAp)2(ClO4)3譶H2O(Ln = La, n = 7; Sm, 6; Er, 4), and Ln(ClO4)3譶H2O(Ln = La, n = 8; Sm, 9; Er, 6) resp. Both kinds of complexes are incongruently soluble in water.

Key words: PHASE EQUILIBRIUM, WATER, LANTHANUM COMPOUNDS, COMPLEX COMPOUNDS, SOLUBILITY, TERNARY SYSTEM, PERCHLORATE, ERBIUM COMPOUNDS, ANTIPYRINU, REFRACTIVE INDEX