Abstract
The pT-spectra of negative particles from 200 GeV/nucleon O + Au and S + S collisions, measured at CERN by the NA35 collaboration, are fitted by a thermal distribution of massive pions which are strongly out of chemcial equilibrium. Both sets of data are consistent with the same values of temperature and chemical potential, T ≈ 165 MeV and μ ≈ 120 MeV. The low pT behaviour of the measured spectra seems to indicate that the transverse flow in these collisions is not strong.