Abstract: The apparatus disclosed herein is useful for testing unconsolidated sand samples from oil-bearing or gas-bearing earth formations. Basically, the device comprises a cylinder equipped with opposing pistons. The sand sample is placed in the cylinder between the pistons and then compacted by moving the pistons toward each other. The force for moving the pistons is supplied by a fluid, such as air or hydraulic oil, which is injected under pressure into a chamber defined in the cylinder behind each piston. The compacted sample is then subjected to various test procedures involving permeability measurements, consolidation tests, and flow studies.