114 



J. W. Judd — On Volcanos. 



cially in the manner in which, on reaching a somewhat less steep 

 slope, its materials have been piled up into a high ridge, this current 

 affords a most striking illustration of the extremely imperfect state 

 of fluidity in which the vitreous lavas of Lipari were poured forth. 

 (See Fig. 11.) 



Fig. ii. — Profile-sketch of the obsidian lava-stream (of 1775) on the north-west side of the cone 

 of Vulcano, with the stratified tuffs seen in the side of the Fossa Anticcha below. 



The present fresh appearance of this lava-stream, uncovered as it 

 remains by fragmentary ejections, is strongly confirmatory of the 

 very recent date, that of 1775, which Dolomieu assigns to it. On 

 the south side of the cone of Vulcano is another lava-stream, evi- 

 dently of far older date, and almost completely buried under ejected 

 materials. All the solid ejections of the existing cone of Vulcano 

 appear to have consisted of the most highly acid rocks — Liparite, 

 obsidian, and pumice — like the materials of the later eruptions in 

 Lipari. 



Between Vulcano and Vulcanello rises the mass of volcanic tuffs, 

 evidently the denuded fragment of a cinder cone, which is known as 

 the Faraglione. In a grotto in this mass, the sides of which continually 

 drop with water abounding in acids and various salts, the most 

 beautiful stalactites of sulphate of alumina, and various compounds 

 of lime, iron, and occasionally of copper are formed. In this grotto 

 I collected the brillant crystals belonging to the cubic system, of 

 the hydrated compound of ferric and ferrous sulphates, called 

 " Voltaite," a mineral first discovered by Scacchi in the Solfatara of 

 Naples. Around the Faraglione, fumaroles discharging vapour with 

 sulphuretted hydrogen and carbonic acid gases at an elevated 

 temperature occur, while others are found giving off the latter gas 

 only at the ordinary temperature of the atmosphere ; these latter 

 have been justly compared by Deville to the Grotto del Cane, at the 

 Lago Agnano, near Naples. 



The isthmus joining Vulcano and Vulcanello, and composed of 

 fragmentary matters ejected by the volcanos, appears to have been 

 formed in the sixteenth century. It is doubtful if Vulcanello be 



