The invention relates to a method of, and apparatus for, distilling shale, coal, or other oil or tar-yielding minerals, to obtain gases, liquids, or other products. The distillation is effected in vertical retorts by the combustion of the partially spent material in the lower part of the retorts, to which steam and air are admitted. The retorts are built of firebrick, and provided with iron casings. They are fed through hoppers and discharged through the openings. The discharging is facilitated by a cone, or its equivalent, in the base of each retort. Steam and air are admitted through the pipes. The interior may be viewed through holes. The products are taken off from the space around the hopper.