X-ray computer tomography has been used to image the internal structures of coal samples. The samples covered a range of rank from anthracite to lignite. The images clearly showed the bedding plane alignment in the coal and areas of the coal with high mineral concentration. Calculations of CT number agree very well with experimental values and provide a basis for identifying components in the coal. Xenon gas has been used as a probe atom for the volumes of the coal accessible to the outside environment. Infusion of gas into the coal has been found to be very heterogeneous with no simple diffusion parameter to characterize it. 19 references, 68 figures, 13 tables.