J. W. Judd — On Volcanos. 11 



From these analyses it appears that the central volcano of the 

 Liparis, so far as its rocks are open to our observation, consists of 

 various trachytic materials approximating to, but never reaching, the 

 basalts on the one hand, and the quartz -trachytes on the other. 



The only signs of volcanic activity still exhibited by this vast 

 central volcano, the antiquity of which is sufficiently indicated by 

 its greatly denuded and altogether ruinous condition, consists in an 

 insignificant sub-aerial stufe, in the island of Panaria, and a sub- 

 marine fumarole, situated in the channel between Lisca nera and 

 Lisca bianca. The occurrence of this still active vent of volcanic 

 energy in the midst of the submerged and altogether ruined crater 

 of the Liparis may be paralleled with that which exists in the midst 

 of the similar crater of Santorin, which is, however, in a far more 

 violent stage of action, and has given rise to eruptions that have 

 attracted so much attention during the last few years. The sub- 

 marine fumarole of the Liparis, which is opened in the white 

 pumiceous rocks of the sea-bottom at a depth of 25 feet from the 

 surface, pours forth considerable quantities of carbonic acid and 

 sulphuretted hydrogen gases, the bubbles of which produce a 

 beautiful effect in rising through the clear blue Mediterranean waters 

 and cause the sea to appear in a state of ebullition. As an amus- 

 ing instance of the power of imagination, we may mention that in 

 a recently published and popular book of travels, the authoress 

 describes in very graphic language the sensations of scalding which 

 she experienced on thrusting her hand into this " boiling water " ! 



2. — Second Period of Volcanic Activity in the Lipari Islands. 



Turning our attention to the second period of igneous activity, 

 which has been characterized in the Lipari Islands, we find that we 

 shall have to refer to it by far the larger portion of the rocks of the 

 group. Constituting the entire masses of the islands of Salina, 

 Filicudi, and Alicudi, they form also the basis of those of Lipari, 

 Vulcano, and Stromboli, in which, however, they are to some extent 

 buried and concealed under the products of the third and latest 

 period of eruption. 



The materials ejected during the second period consist of lavas and 

 the agglomerates, tuffs, and ashes derived from them — the accumu- 

 lations of fragmentary matters generally greatly preponderating in 

 quantity over the solid rocks ; which latter, nevertheless, in conse- 

 quence of their greater power of resisting denuding forces, often 

 constitute all the most prominent and conspicuous parts of the 

 islands. 



Nearly the whole of the lavas of the second period belong to the 

 trachytic class, but there appears to be a constant tendency in the 

 later formed of them to approximate towards the rocks of the 

 basaltic type. This gradual change in the character of the lavas is 

 well exemplified in the series of successive cones and craters so well 

 displayed in the southern part of the island of Vulcano. As an ex- 

 ample of the composition of the lavas of this period, we may instance 

 the rock constituting the central mass, and forming by far the larger 



