  In part I of this paper a modified BCS mechanism of Cooper pair formation of
electrons was proposed. This mechanism is connected with the existence of a
narrow, roughly half-filled "superconducting energy band" of given symmetry.
The special symmetry of the superconducting band was interpreted within a
nonadiabatic extension of the Heisenberg model of magnetism. Within this
nonadiabatic Heisenberg model, the electrons of the superconducting band are
constrained to form Cooper pairs at zero temperature because in any normal
conducting state the conservation of crystal-spin angular momentum would be
violated. Except for this participation of the angular momentum, the pair
formation is mediated in the familiar way by phonons. Superconducting bands can
be identified even within a free-electron band structure. Therefore, in this
paper the band structures of the bcc and hcp solid solution alloys composed of
transition elements are approximated by appropriate free-electron band
structures with s-d symmetry. From the free-electron bands, the number n of
valence electrons per atom related to the maxima of the superconducting
transition temperature Tc in these solid solutions is calculated within the
nonadiabatic Heisenberg model. The observed two maxima of Tc are reproduced
without any adjustable parameter at valence numbers n approximately equal to
4.9 and 6.5 in bcc and 4.7 and 6.7 in hcp solid solutions. This result is in
good aggreement with the measured values of 4.7 and 6.4 of Hulm and Blaugher.
The upper maximum is predicted not to exist in bcc transition elements but to
occur in several ordered structures of bcc solid solution alloys.
