  We compare the results of measurements of the magnetic susceptibility Chi(T),
the linear coefficient of specific heat Gamma(T)=C(T)/T and 4f occupation
number nf(T) for the intermediate valence compounds YbXCu4 (X = Ag, Cd, In, Mg,
Tl, Zn) to the predictions of the Anderson impurity model, calculated in the
non-crossing approximation (NCA). The crossover from the low temperature Fermi
liquid state to the high temperature local moment state is substantially slower
in the compounds than predicted by the NCA; this corresponds to the
''protracted screening'' recently predicted for the Anderson Lattice. We
present results for the dynamic susceptibility, measured through neutron
scattering experiments, to show that the deviations between theory and
experiment are not due to crystal field effects, and we present
x-ray-absorption fine-structure (XAFS) results that show the local crystal
structure around the X atoms is well ordered, so that the deviations probably
do not arise from Kondo Disorder. The deviations may correlate with the
background conduction electron density, as predicted for protracted screening.
