  We apply the muffin-tin effective medium approximation to calculate the
temperature dependence of the resistivity and of the thermopower of amorphous
and liquid metals. The results show unambiguously that a large resistivity is
accompanied by a negative temperature coefficient, in agreement with the
experimental situation. This behavior is shown to result from a pseudo-gap
which opens in the 1-particle spectrum due to strong scattering at the quasi
zone boundary. In turn the thermopower is found to have non-trivial density and
temperature dependences.
