Oil-shale coke is that cellular, enhanced, solid material obtained as a result from the low-temperature carbonization of certain oil shales. It varies from a weak friable material is which the shale particles are cemented loosely together by a carbonaceous material, to a completely fused, coherent mass in which all shale particles have lost their physical identity. This coking property does not seem to bear any direct relationship to oil yield, but is generally associated with rich oil shales, since lean shales rarely form troublesome cokes. The shales which form coke are of such common occurrence, however, that any industrial organization which endeavors to process oil shale commercially will have of consider this problem, and it is serious, for the removal of coked mass from a retort may be a difficult and costly operation.