A third graphical method of indexing powder photographs of long-spacing compounds

A third graphical method of indexing X-ray powder photographs is described; it is suitable for compounds with identifiable long-spacing reflections. If the long axis is the c axis, all the reflections having the same h and k indices lie on the graph on a straight line. By this means all the possible solutions are displayed on the same graph, which can be prepared on a large scale, eliminating overcrowding and resulting in increased accuracy.