  We study the role of the electrical double layer (EDL) in the formation of
the quasistatic electrical conductivity of suspensions of nanosized particles.
A suspension is viewed as a system of hard-core--penetrable-shell particles.
The shells are electrically inhomogeneous, with a radially symmetrical
conductivity profile. It is assumed that the real microstructure of the
suspension can be reflected in terms of this profile and also the rule of
dominance for overlapping regions that the local conductivity in the system is
determined by the nearest particle. Using our earlier rigorous results for
systems with this morphology, we derive general integral relations for the
desired conductivity which incorporate the effect of the EDL and make it
possible to look into the contributions from its different parts and
parameters. Specific features, internal consistency, and flexibility of the
model are demonstrated by further elaborating it to describe experimental data
for latex suspensions in aqueous electrolyte solutions with high ionic
strength.
