Thermal-neutron flux perturbation factors have been measured for dysprosium - aluminum alloy foils in water and uranyl fluoride-water solutions. The foils are representative of a type widely used for thermal-neutron flux surveys. The measurements provide additional data for comparison with analytical calculations of foil perturbation factors in water. The uranyl fluoride-water solutions used comprise absorptive diffusion media different from water or graphite that have been studied exclusively in the past. The edges of the thicker dysprosium-aluminum foils used are a significant part of the total foil surface so that the data provide a test for several proposed edge corrections to perturbation factor calculations. The experimental perturbation factors are in good agreement with the predictions of published calculational methods except for the dimensionless generalization of Dalton and Osborn.