Described by Philostratus (ca. 170-245 C.E.) in his Life of Apollonius as issuing from a basin in a well on the hill Athanor. A blue vapor was said to rise from the well and change into all the colors of the rainbow. The bottom was strewn with red arsenic; on it was the basin full of fire, and from it rose flame without smell or smoke. Two stone reservoirs were beside it, one containing rain, the other wind. This description is probably a symbolic one.
"Secret Fire." Encyclopedia of Occultism and Parapsychology. . Encyclopedia.com. (January 20, 2019). https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/secret-fire
"Secret Fire." Encyclopedia of Occultism and Parapsychology. . Retrieved January 20, 2019 from Encyclopedia.com: https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/secret-fire