A chamber of brick or other heat-resistant material in which coal is destructively distilled. Coke ovens are of two principal types: (1) beehive ovens, which were originally built round with a spherical top like an old-fashioned beehive. They had an opening in the top and various small openings for draft at the base. The ovens were developed into banks (rows) of joining cubicles; coke in long columnar pieces is characteristic and is still known as beehive coke. Tar, gas, and other byproducts are lost. (2) Byproduct ovens, which were built in rectangular form with the front and back removable, but so arranged that they may be luted to practical gastightness and all byproducts gaseous at the high temperatures may be pumped out.