J. W. Judd — On Volcanos. 



69 



to believe, so much have the hard masses of lava suffered in places 

 both from marine and subaerial denudation, that any record of this 

 great eruption can have survived. 



Fig. 9. — Sections of quartz-trachyte (Liparite) lava-streams at Porto delle Genti, illustrating' the 

 folding and crumpling of their interior portions, produced hy the slow movement of the viscous 

 mass. A. Exhibits a series of broad folds. B. A series of most complicated puckerings, exactly 

 like that seen in many gneissose rocks. 



To their permeation by gases and vapours, probably during the 

 latest period of eruption, the altered trachytes and tuffs, with their 

 veins of selenite and other minerals, are probably due. Only two 

 vents, constituting the dying efforts of volcanic activity, once so 

 powerful in this island, still remain, being situated on its western 

 side ; one of these is at Bagno, or la Fonte di San Calogero, and 

 gives rise to a hot mineral spring; the other is at Bagno Secco, a 

 little to the northward, and only dry stream, charged with hydro- 

 chloric and sulphurous acid gases, is evolved from it. 



The hot spring of San Calogero has long been celebrated for its 

 curative properties, having been mentioned by Diodorus Siculus ; in 

 1870 a bath-house and hotel were erected here by the municipality 

 of Lipari. In a medical tract by Dr. Guiseppe Eincotta, the use 

 of these waters in various rheumatic and cutaneous affections is 

 stated to be attended with the most beneficial results. 



The water, which has a temperature of 198° F., that of the sur- 

 rounding atmosphere being 77°, has been analyzed by Dr. Ferdinando 

 Bodriguez, and also by Prof. Guiseppe Arrosto, of the University of 

 Messina. It contains free carbonic acid and sidphuretted hydrogen, 

 with the carbonates of lime and magnesia, and chlorides of calcium 

 and sodium, and a little organic matter. 



The following is the result of Prof. Arrosto's analysis : 



