The molar refraction of chelate compounds Co~(II),Co~(III),Ni~(II),Cu~(II)-EDTA was de-termined by the measurement of the refractive index of these salts.The ionicrefraction of chelate ions Co~(II)Y~(2-).Co~(III)Y~(-).Cu~(II)Y~(2-).Ni~(II)Y~(2-) was calculated inaccordance with the additivity of the ionic refraction by the molar refraction.Theresults show that:1.The ionic refraction of a definite chelate ion in different crystalline compoundsremains constant,which indicates that the mutual polarization betw...