(M153) The ancients were acquainted with such noxious vapours in their own country, and they regarded the vents from which they were discharged as entrances to the infernal regions.(614) The Greeks called them places of Pluto (_Plutonia_) or places of Charon (_Charonia_).(615) In Italy the vapours were personified as a goddess, who bore the name of Mefitis and was worshipped in various parts of the peninsula.(616) She had a temple in the famous valley of Amsanctus in the land of the Hirpini, where the exhalations, supposed to be the breath of Pluto himself, were of so deadly a character that all who set foot on the spot died.(617) The place is a glen, partly wooded with chestnut trees, among limestone hills, distant about four miles from the town of Frigento. Here, under a steep shelving bank of decomposed limestone, there is a pool of dark ash-coloured water, which continually bubbles up with an explosion like distant thunder. A rapid stream of the same blackish water rushes into the pool from under the barren rocky hill, but the fall is not more than a few feet. A little higher up are apertures in the ground, through which warm blasts of sulphuretted hydrogen are constantly issuing with more or less noise, according to the size of the holes. These blasts are no doubt what the ancients deemed the breath of Pluto. The pool is now called _Mefite_ and the holes _Mefitinelle_. On the other side of the pool is a smaller pond called the _Coccaio_, or Cauldron, because it appears to be perpetually boiling. Thick masses of mephitic vapour, visible a hundred yards off, float in rapid undulations on its surface. The exhalations given off by these waters are sometimes fatal, especially when they are borne on a high wind. But as the carbonic acid gas does not naturally rise more than two or three feet from the ground, it is possible in calm weather to walk round the pools, though to stoop is difficult and to fall would be dangerous. The ancient temple of Mefitis has been replaced by a shrine of the martyred Santa Felicita.(618)