ATHANOR

ATHANOR, in Alchemy, a large immovable Furnace, built of Brick or Stone, and covered with a tower-top; proper to maintain a temperate and equable degree of heat for a considerable time. See FURNACE, HEAT, etc.
The Heat of the Athanor is intended or remitted by opening or shutting a Register. See REGISTER.
It is made to communicate its Heat by Tubes or Apertures at the side of the Hearth or Fire-Place, to several adjacent Vessels; by which means different operations are carried on at the same time. We meet with divers Forms and Constructions of this Furnace, in the Writers of Alchemy.
The Athanor is also called Piger Henricus, Slow Harry; because chiefly used in the slower Operation; and because once filled with coals, it keeps burning a long time; whence the Greeks call it ἄληπτος, g.d. giving no trouble, as it does not need to be continually attended. It is also called the Philosophical Furnace, or Furnace of Arcana; and popularly, the Tower Furnace.
The Word Athanor is borrowed from the Arabs, who call an Oven, Tanur; from the Hebrew תנור, Tanur, an Oven; or Furnace; whence, with the additional Particle al, אל-תנור, Al-Tanur.

ATHANOR