Failures

• Equation (3) suggests that the higher the valency the higher the conductivity should be. But the best metals have one or two valence electrons.

• The Hall effect allows to determine the sign of the charge carriers. But in contrast to the assumptions of the Drude theory some metals (e. g. Be, Mg, In, Al) show a Hall current indicating positive charge.

• The absolute size of the charge determined by the measurements of the Hall current disagrees in some metals (e. g. Cu, Ag, Au) evidently with the assumption of an integral number of valence electrons being responsible for the charge transport.

• The specific heat (4) is achieved only asymptotically at high temperatures. At low temperatures it generically shows an -proportional part which is present in semi-conductors and insulators, too. The only part remaining for a possible electronic contribution is T-proportional, at room temperature about 100 times smaller than (4). Therefore some other factor in (6) should be wrong by a factor of about 100, too.