Nanocrystallites of CdS of constant mean radius are embedded in various concentrations (up to 29%) in pure silica glass obtained by a sol-gel technique. Doped glass samples as well as thin glass layers deposited on microscope slides are prepared and structurally characterized by electron microscopy. The linear optical properties (absorption coefficient and index of refraction) of these CdS-doped glasses are measured as functions of the CdS volume fraction in the samples. Their third order nonlinear optical susceptibility is also determined by degenerate four-wave mixing experiments near resonance. The values obtained for samples with different CdS volume fraction are compared to those of bulk CdS platelets.