A dynamic method of measuring adhesion tension is described for liquids moving through powders. In the method a gradient of hydrostatic pressure is present across the sample and this leads to a particularly convenient relation between the distance travelled by an interface and the time of displacement. For a single liquid displacing air, measurements at a number of different pressures allow the radius of the equivalent capillaries and the tortuosity constant to be determined independently. Adhesion tensions were measured for crude oil displacing simulated sea water from sand. The effect of adding emulsifying agents to the oil was to reduce the adhesion tension, i.e. to increase the wetting of the sand by the oil. For a series of emulsifying agents with increasing h.l.b. number a minimum in the adhesion tension was observed.