ABSTRACT: Fifteen 1-ton bulk samples of Indiana coal were studied in detail by the Indiana Geological Survey in an attempt to reduce the sulfur content. Laboratory techniques of crushing, screening, and making separations based on specific gravity simulated the cleaning process used in modern industry-operated coal preparation plants. Sulfide, sulfate, organic sulfur, and total sulfur were determined for each fractional sample of coal obtained by screening and float-sink methods. Only the sulfate (about 0.1 percent of coal) and the sulfide or pyritic sulfur (0.7 to 5.4 percent of coal) cannot be reduced by this method. Although about half of the pyritic sulfur can be removed at the 80-percent recovery level, Seelyville coal (III) and Springfield coal (V) still contain, in most places, more than 3 percent sulfur; Buffaloville coal, Hymera coal (VI), and Danville coal (VIII), 2 to 3 percent; and Survant coal (IV) and Upper Block coal, 2 percent or less.