In this note, measurements are presented on optical density, silver concentration, and index of refraction within uniformly exposed and processed holographic film. These data are important because they determine the diffraction efficiency of holograms. The silver analysis was performed by X-ray diffraction. The index of refraction was measured by a Brewster-angle method. The data show that the refractive index variation is of the order of 0.06 at an optical density of 2. The influence of these results on the design of holographic experiments is discussed.