The petrographic investigations of coal of the last two decades have stimulated applied research in the field of preparation and utilization. Definition of the different types and varieties of coal was followed by the accumulation of a body of information on the specific physical characteristics. Differences in specific gravity, conductivity, and friability have been utilized in commercial and laboratory preparation to separate coals into their component parts. The availability of quantities of the different types in concentrated form has made largescale combustion research possible. Laboratory tests for ignition temperature, agglutinating value, and swelling index are being perfected and, when correlated with coking, briquetting, and combustion practice, will facilitate the solution of problems arising in these fields.