Solfata'ra

Solfata'ra (Fr. Soufrière, Ger. Schwefelgrube or Schwefelsee), the Italian names for such volcanoes as, having ceased to be violently active, emit from crevices gases, steam, and chemical vapours, chiefly of sulphurous origin. The most notable are found in Italy, in the Antilles, in Mexico, in the interior of Asia, and in Java. Probably the best known are those between Rome and Tivoli, and that at Pozzuoli (q.v.), near Naples. This last is an irregular plain almost surrounded by the walls of an ancient crater. From the crevices rise steam and gases, chiefly sulphuretted hydrogen, mixed with minute quantities of muriatic acid and muriate of ammonia. The cracks and fissures of the rocks abound with sulphur, alum, and sulphate of iron. The vapours exhaled are used as medicinal baths, which are taken in wooden huts on the spot. The Soufrière of the island of St Vincent, West Indies, about 3 miles in circuit and over 500 feet in depth, was in active eruption in 1880.