Isotope, isotone and isobar yield ratios are utilized to obtain an estimate of the isotopic composition of the gas phase, i.e., the relative abundance of free neutrons and protons at breakup. Within the context of equilibrium calculations, these analyses indicate that the gas phase is enriched in neutrons relative to the liquid phase represented by bound nuclei.

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Light charged fragments from the reactions Ar+ 'V at 35 MeV/nucleon and ' C+ ' C at 50MeV/nucleon have been measured with a 4m array. Transverse collective motion is observed for all fragment types and increases in strength for the heavier fragments. The transverse momentum is qualitatively similar for the di6'erent impact parameters selected by the midrapidity charge. The global transverse momentum analysis includes corrections for correlations due to momentum conservation. The results are compared to those at higher energies to investigate whether the same or a new reaction phenomenon produces the collective motion. We outline some implications for the extraction of thermodynamic information from the kinetic energy of emitted fragments.