Structure of Graphite

A RECENT communication by Gibson1 sought to show that X-ray powder photographs of graphite contained ‘extra’ reflexions that could not be explained on the basis of the co-existence of the hexagonal and rhombohedral structures described by Lipson and Stokes2. It is of some importance that the crystal structure of graphite should be correctly specified3, and, because of our experience in examining by X-ray methods graphites from many different sources, we have thought it useful to investigate the validity of the observations made by Gibson. Besides the particular problem of the structure of graphite, there are also involved some questions of X-ray technique on which comment appears called for.