Small angle X-ray scattering data have been used to characterize the microscopic and submicroscopic structure of oak charcoals produced at different temperatures. The specific surface has been calculated for each sample. The observed scattering is ascribed to voids in a carbon matrix. The scattering data suggest that these voids have average dimensions that fall into two groups: (1) a relatively large-scale structure that is similar to the structure of the original wood and that has dimensions of the order of microns, and (2) a much finer structure, with dimensions about 15Å. In samples prepared at low temperature, only the large-scale structure is detectable. When charcoals are prepared at temperatures above approximately 1000 F, additional voids are generated. As a result, the average dimensions of the large-scale voids are apparently reduced and a small-scale structure develops
