The solubilities of the ternary system,Y(ClO4)3.3H2O-B15C5-CH3OH,at 25℃ havebeen investigated by the semimicro method of phase equilibrium study.The refractive indexes ofsaturated solutions have been determined. There are three coordination compounds formed inthe system at 25℃. The compositions of the three coordination compounds arc:4Y(ClO4)3.3B15C5.12H2O. 12CH3OH(Ⅰ),Y(ClO4)3. B15C5.3H2O.1.5CH3OH(Ⅱ)and Y(ClO4)3.ZB15C5.3H2O. CH3OH(Ⅲ).The coordination compounds (Ⅰ) and (Ⅱ) are solubleincongrucntly.The coordi...