  We compare the recent experimentally measured forces between charged
colloidal particles, as well as their effective surface potentials (surface
charge) in the presence of multivalent counterions in a bathing monovalent salt
solution, with the predictions of the dressed ion theory of strongly charged
colloidal systems. The benchmark for comparison is provided by the DLVO theory
and the deviations from its predictions at small separations are taken as an
indication of the additional non-DLVO attractions that can be fitted by an
additional phenomenological exponential term. The parameters characterizing
this non-DLVO exponential term as well as the dependencies of the effective
potential on the counterion concentration and valency predicted by the dressed
ion theory are well within the experimental values. This suggests that the
deviations from the DLVO theory are probably caused by ion correlations as
formalized within the dressed ion theory.
