  It was shown recently that the structural alpha-relaxation time tau of
supercooled o-terphenyl depends on a single control parameter Gamma, which is
the product of a function of density E(ro), by the inverse temperature T -1. We
extend this finding to other fragile glassforming liquids using
light-scattering data. Available experimental results do not allow to
discriminate between several analytical forms of the function E(ro), the
scaling arising from the separation of density and temperature in Gamma. We
also propose a simple form for tau(Gamma), which depends only on three
material-dependent parameters, reproducing relaxation times over 12 orders of
magnitude.
