  We study the aggregation of insulating electrically charged spheres suspended
in a nonpolar liquid. Regarding the van der Waals interaction as an
irreversible sticking force, we are especially interested in the charge
distribution after aggregation. Solving the special case of two oppositely
charged particles exactly, it is shown that the surface charges either
recombine or form a residual dipole, depending on the initial condition. The
theoretical findings are compared with numerical results from Monte Carlo
simulations.
