The process initially started with pieces of brick, which were heated red hot in live coals, and extinguished in an earth half-saturated with olive oil.
Being then separated and pounded grossly, the brick absorbs the oil.
It was then put in a retort, and placed in a reverberatory furnace, where the oil was drawn out by fire.
[1] Oil of brick was used in pre-modern medicine as a treatment for tumors, in the spleen, in palsies, and epilepsies.
[1] It was used by lapidaries as a vehicle for the emery by which stones and gems were sawn or cut.