From Abstract: "This bulletin traces the development of high-pressure, coal and tar hydrogenation technology, based on intensive review of the pertinent literature. The bulletin was written as a part of the Bureau of Mines research program on synthetic liquid fuels. It covers the history and economics of the process; the chemical aspect of hydrogenation of coal, tar, and middle oil; the engineer aspect of converting coal and tar to liquid fuels, principally gasoline; and the equipment of the process."