microbalance has been used to measure the rate of uptake of wetting fluid, 1,3-propandiol, into a cube of compacted calcium carbonate. The cube had sides 12 mm long, with a wax band applied to the outer perpendicular edges of one basal plane to prevent external surface uptake, and the liquid was applied in a highly controlled manner at this single face only. The percolation characteristics of an identical sample were measured by mercury porosimetry, A three-dimensional void structure was generated with the same percolation characteristics using a software package called "Pore-Cor." The wetting of 1,3-propandiol into this model structure was then calculated using an extended Lucas-Washburn equation, developed by Bosanquet, which includes viscous, inertial, and capillary force effects. Neither the experimental nor the simulated wetting can be explained in terms of an "hydraulic stream tube" or "effective hydraulic radius" model. A mathematical function is presented which compensates for the differences in the boundary conditions between the simulation and the experiment. The wetting is found to be initially slowed by inertial flow, then speeded up to a t(0.8) dependence by the connectivity of the three-dimensional void network, The effect of the inertial Row is most pronounced for larger pores.