The systems La(BrO3)(3)-Y(BrO3)(3)-H2O and La(BrO3)(3)-Yb(BrO3)(3)-H2O were
studied by the isothermal saturation method at 298 K. The solid phase comp
ositions were determined by Schreinemakers' method of residues. Two series
of solid solutions were found to exist in the systems. The systems belong t
o Type IV in Roozeboom's classification.