We report spectral measurements of the depolarized light scattered from a binary mixture (nitrobenzene and n-hexane) near its critical mixing point. The depolarized scattered light is mainly related to orientation fluctuations and multiple scattering. A spectral analysis performed with a 60 GHz free spectral range Fabry-Pérot spectrometer allows a rigorous separation of these two contributions to be made. The temperature dependance of the width of the reorientational spectrum is seen to behave in the same manner as the viscosity. Both the spatial and the temperature dependence of the multiple scattered light are well explained by a double scattering calculation when T is not too close to Tc, and are in good agreement with a recent theory given by Oxtoby and Gelbart if however one takes the turbidity into account