  Measurements of the reflectivity of a 2-D electron gas are used to deduce the
polarization of the Composite Fermion hole system formed for Landau level
occupancies in the regime 1<\nu<2. The measurements are consistent with the
formation of a mixed spin CF system and allow the density of states or
`polarization' effective mass of the CF holes to be determined. The mass values
at \nu=3/2 are found to be ~1.9m_{e} for electron densities of 4.4 x 10^{11}
cm^{-2}, which is significantly larger than those found from measurements of
the energy gaps at finite values of effective magnetic field.
