Origm ^ Mount Etna, S7ft 



breathing, and liad a strong odour of sulphurous acid. Sul- 

 phuretted hydrogen was also perceptible, but I did not recogi* 

 nise the odour of muriatic acid. Every circumstance, then, an- 

 nounced that the flame was supported by sulphuretted hydro- 

 gen, and afterwards, when the sun lighted up the mountain, a 

 long bluish cloud was seen taking its rise from tiiat particular 

 point. 



In the interior of the great crater I found several portions of 

 snow, but from many other points of its angular bottom there 

 issued hot vapours, having a whitish colour, more or less dense, 

 composed chiefly of watery vapour, but having nevertheless a 

 strong odour of sulphurous and muriatic acids ; one or the other 

 of these acids predominated alternately. The surfaces across 

 which the vapours were disengaged were in part covered by sa- 

 line efflorescences, which were sometimes white, and sometimes 

 coloured of an orange-yellow tint by the chloruret of iron, or of a 

 canary-yellow by particles of lava altered by the acid vapours. 

 - In some fissures I found white fibrous gypsum, mixed with al- 

 tered pulverulent yellow lava in which some small nodules of 

 sulphur were disseminated. In my memoir I have described the 

 products of the eruptions of Etna, but the hmits of this analysis 

 do not permit me at present to enter into details on this subject. 

 The products of the eruptions of Etna resemble externally 

 those of a great many other volcanoes, but they present a pecu- 

 liar composition which hitherto has not been met with except in 

 those of Stromboli. Professor Gustave Rose, in a memoir on 

 the composition of rocks called griinstein (greenstone), has pub- 

 lished for the first time the fact that the lavas of Etna do not 

 contain common felspar or orthose, but Labrador felspar. They 

 are composed o^ Labrador Jelspar, augitc, and peridote (olivine). 

 The observation of Professor Rose was not known at the time of 

 our expedition, but the true composition of the lavas of Etna 

 could not long escape the experienced eye of M. de Buch, who 

 pointed it out to me almost the first moment we reached the 

 volcanic mass. My subsequent excursions afforded a constant 

 confirmation of this first observation. 



The fear of encroaching on the time of the Academy induces 

 me to suppress also various remarks relative to the last eruptions 



