In 1944, under the Synthetic Liquid Fuels Act, the Bureau of Mines was directed to supply the scientific, engineering, and economic information required for the establishment of an American shale oil industry. To develop the necessary retorting technology, numerous paper studies of existing processes were made. Also, several field trips were made to obtain information and, where possible, to observe the operation of existing retorting plants (3,4,5). Later several processes were tried at Rifle on a pilot-plant scale (6 through 12). The gas-combustion process is the result of the development work to date.