  We present a detailed study of chemical freeze-out in p-p, C-C, Si-Si and
Pb-Pb collisions at beam momenta of 158A GeV as well as Pb-Pb collisions at
beam momenta of 20A, 30A, 40A and 80A GeV. By analyzing hadronic multiplicities
within the statistical hadronization model, we have studied the parameters of
the source as a function of the number of the participating nucleons and the
beam energy. We observe a nice smooth behaviour of temperature, baryon chemical
potential and strangeness under-saturation parameter as a function of energy
and nucleus size. Interpolating formulas are provided which allow to predict
the chemical freeze-out parameters in central collisions at centre-of-mass
energies > 4.5 GeV and for any colliding ions. Specific discrepancies between
data and model emerge in particle ratios in Pb-Pb collisions at SPS between 20A
and 40A GeV of beam energy which cannot be accounted for in the considered
model schemes.
