According to Philostratus in his Life of Apollonius, athanor is an occult hill, surrounded by mist except on its southern side which is clear. On it is a well, which is four paces in breath, from which an azure vapor ascends, which is drawn up by the warm sun. The bottom of the well is covered with red arsenic. Nearby is a basin filled with fire from which rises a livid flame, odorless and smokeless and never higher or lower than the edge of the basin. Also, there are two black stone reservoirs, in one of which is the wind kept and in the other the rain. In extreme the water cistern is opened and clouds escape to water the whole country.
Clearly this description should be interpreted as alchemical symbolism, since athanor was the furnace which supplied the heat for the alchemical process. The term athanor is also employed to denote moral and philosophical alchemy. A.G.H.