1911 Encyclopædia Britannica/Ampsanctus
AMPSANCTUS, or Amsanctus (mod. Sorgente Mefita), a small lake in the territory of the Hirpini, 10 m. S.E. of Aeclanum, close to the Via Appia. There are now two small pools which exhale carbonic acid gas and sulphuretted hydrogen. Close by was a temple of the goddess Mephitis, with a cave from which suffocating vapours rose, and for this reason the place was brought into connexion with the legends of the infernal regions. Virgil's description (Aeneid, vii. 563) is not, however, very accurate.