We present computer simulation data for the dielectric constant of a system of uniform polarizable spheres randomly distributed in a homogeneous background. The deviations from the Clausius-Mossotti formula are found for seven values of the volume fraction. In addition, the spectral density which appears in the Bergman representation of the dielectric constant is determined. The spectrum obtained with a sufficient number of higher-order multipoles differs significantly from that found with just dipolar or dipole-quadrupolar interactions.