[The subjects illustrated in the engravings are indicated by _italics_, the names of authors are in Capitals.] ABICH, cited, 122 -- researches of, 4 Absorption of gases by liquids and solids, 354, 355 Acid lavas, 48 Æolian Islands. _See_ Lipari Islands Æolus, origin of myth, 35 Africa, volcanoes of, 227 -- South, diamonds of, 147 Agates, formation of, 150 Allport, Mr., cited, 259 Alps, formation of, 292 Altered lavas, names given to, 261 America, volcanoes of, 227 Amygdaloids, formation of, 140, 141 Andesites, 50, 59 Andesite-volcanoes, 126 Andrews, Professor, cited, 321 Anne Boleyn and Etna, 3 Armstrong, Sir W., hydro-electric machine, 29 Arthur's Seat, 275 Artificial stone, 55 Asia, volcanoes of, 227 Asiderites, 316 Asmanite, 314 Astroni, crater-ring of, 170 Atlantic, volcanoes in, 223 Auvergne, _breached cones of_, 123, fig. 40 -- _denuded cones in_, 124, fig. 42 -- incrusting springs of, 184 -- puys of, 152, 212 -- volcanic cones in, 79 BALL-AND-SOCKET structure in basaltic columns, 107 Barrancos, formation of, 209 Basalt, controversy concerning origin of, 249 Basalts, 49, 50, 59 Basaltic columns of Bohemia, 107 -- -- of Central Germany, 107 -- -- of Monte Albano, 107 -- -- _from the Giant's Causeway_, 107, fig. 29 Basic lavas, 48 Bath, hot spring of, 219 Ben Nevis, 274 Bohemia, volcanoes of, 126 -- lavas of, 103 Boiling. _See_ Ebullition Bonney, Professor, cited, 69, 109, 259 Boracic acid at volcanic vents, 216 _Bourbon, volcano of_, 176, figs. 74, 75 _Bracciano, crater-lake of_, 178, fig. 77 _Breached cones_, 123, fig. 40 Babbles of steam, escape from lava, 21 _Bubbles, spontaneous movement of, in liquid cavities_, 62, fig. 8 -- -- cause of, 65 Buch, Von, researches of, 4 Buda-Pesth, deep well of, 335, 341 Büdos Hegy, Transylvania, 215 Bunsen, cited, 201 Burning, does not take place at volcanoes, 2