Interferometric Studies on Coals

Abstract

THE familiar known correlation between the rank and the reflectivity of coals prompted me some years ago to apply interference methods to the examination of polished coals, and it is the purpose of this brief note to indicate the possibilities of this new approach which I am now making. It can be expected that at least three different features will be revealed by an interferogram of a polished sample of coal. Thus the general topography will largely be determined by the homogeneity or heterogeneity of the material, especially if there exist regions of different resistance-hardness to polishing. Then again, inclusions and cleavages might be expected to reveal themselves. Finally, the local fringe-width will afford a critical indication of local reflectivity and of local mattness.