IN a recent communication1, Ahrens reported some data on the frequency distribution of some of the elements in igneous rocks, and enunciated a geo-chemical law to the effect that the concentration of an element in a specific igneous rock is lognormally distributed. Observations have been made at the Fuel Research Station of the Department of Scientific and Industrial Research on the trace elements in coals and coal ashes. Our data, although applying to this special type of sedimentary material, have suggested certain considerations which appear to be relevant to the subject of Ahrens's communication.