- die Durchlässigkeit der drei untersuchten Kohlen arten schwankt bei maximalen Drücken innerhalb eines sehr grossen Bereichs (0,1 bis 100 m darcy) ###>- The permeability of the three coals studied varies very widely at the minimum pressures (from 0.1 to 100/mïlidarcy). - If the pressure applied to the sample is increased, permeability is greatly reduced.