Soffioni (sometimes spelt suffioni), a name applied in Italy to certain volcanic vents which emit jets of steam, generally associated with hydrogen sulfide and carbon dioxide, sometimes also with a little ammonia and marsh gas.
The soffioni are usually arranged in groups, and are best represented in the Maremma of Tuscany, where they contain a small proportion of boric acid, for which they are utilized industrially. For such natural steam-holes, the French geologists often use the term soufflards in place of the Italian soffioni.
This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press.