Use of the inclined-surface retort as a means of producing aromatics is the last in a series of four methods investigated for high-temperature retorting of oil shale. The first three methods have been describe in Intra-Bureau Reports OSRD-48, 49 , and 50, issued by the Laramie Station, The purpose of these investigations, as well as a cost estimate of a commercial-size plant based on the inclined-surface retort, has been presented in Intra-Bureau Report OSRD-, "Production of Benzene, Ethyl Alcohol, and other Products from Oil Shale," by Walter I. R. Murphy and W. I. Barnet, dated August 12,1951. The inclined surface retort appears to have several advantages. Based on a similar retort for carbonization of coal, the materials of construction would be largely ceramic. Thus the large amounts of steel necessary in some of the other types of retorts would not be necessary. Mass shale rates are high for this type of retort, and use of a gravity feed simplifies handling of the shale. Estimates of heat requirements have indicated that sufficient heat ;for the process can be obtained form the carbon residue on the spent shale and the gas remaining after removal of ethylene. The retorting system does not require introduction of fluids; therefore, the problem of product dilution by steam or other substances is not encountered. Attempts were made in this series of experiments to retort in the same temperature range used in the vertical tube retort experiments (1200-1700 F.), and to obtain conditions favorable to maximum benzene production. Several variations in operating procedure were used. For some runs inert swamp gasses were used to reduce vapor residence time in the retort, while in others an extension of the retort in the form of a reactor, heated electrically, was used to increase residence time of the vapors at the retorting temperature. This reactor was also used to study the possibility of retorting at a low temperature and then subjecting the vapors to higher temperatures before condensation had taken place.