  Composite material was prepared from Bystr\"om-Evers metallic particles
Ag5Pb2O6 dispersed in a semiconducting matrix CuO-Cu2O. Partial substitution of
CuO by Cu2O increases electric conductivity at 673 K for 2-3 orders of
magnitude above Landauer conductivity e2/ha indicated by pure CuO matrix. Onset
of superconductivity at 86-375 K presented in this and previous works is
discussed in the framework of the exciton-polariton mechanism occurring on the
grain surfaces.
