To determine the retorting characteristics of a column of mine-run, ungraded oil shale ranging in size from fines to pieces weighing as much as 5 tons, a 150-ton batch retort was designed and constructed. The retort vessel is 45 feet high by 11-1/2 feet in inside diameter and is supported in a 92-foot-high steel super-structure. Mine-run shale assaying about 25 gallons of oil per ton, is currently being used as the test shale. To date, three runs have been completed. Results of the second and third runs are reported in the paper. The two runs considered in the report are the first of a series of nine to determine operating conditions that will yield maximum oil recovery from a column of mine-run shale. Variables studied are the oxygen content of the retorting gas and the space velocity of the retorting gas expressed as cu ft gas/sq ft bed/min. Oil recoveries for the two runs reported are 62.2 volume percent of Fischer assay for the run using higher oxygen and a lower space velocity were used.