VOLCANIC ACTION. 



355 



pen of Humboldt, the memoir on the mountain- 

 chains and volcanoes in the interior of Asia is the 

 only one which can add any interest to our pages ; 

 the rest being of a character too strictly scientific. 

 Of this paper a brief account is here given. 



In our present state of knowledge volcanic phe- 

 nomena are not to be considered as relating peculiarly 

 to the science of geology, but rather as a depart- 

 ment of general physics. When in action they 

 appear to result from a permanent communication 

 between the interior of the globe, which is in a state 

 of fusion, and the atmosphere which envelopes the 

 hardened and oxydated crust of our planet. Masses 

 of lava issue like intermittent springs ; and the su- 

 perposition of their layers which takes place under 

 our eyes bears a resemblance to that of the ancient 

 crystalline rocks. On the crest of the cordilleras of 

 the New World, as well as in the south of Europe 

 and the western parts of Asia, an intimate connexion 

 is manifested between the chymical action of volca- 

 noes, properly so called, or those which produce 

 rocks, — their form and position permitting the escape 

 of earthy substances in a state of fusion, — and the 

 mud-volcanoes of South America, Italy, and the Cas- 

 pian Sea, which at one period eject fragments of 

 rocks, flames, and acid vapours, and at another vomit 

 muddy clay, naphtha, and irrespirable gases. There 

 is even an obvious relation between the proper vol- 

 cano and the formation of beds of gypsum and an- 

 hydrous rock-salt, containing petroleum, condensed 

 hydrogen, sulphuret of iron, and, occasionally, large 

 masses of galena ; the origin of hot-springs ; the ar- 

 rangement of metallic deposites ; earthquakes, which 

 are ever and anon accompanied by chymical phe- 

 nomena; and the sometimes sudden, and the some- 

 times very slow elevations of certain parts of the 

 earth's surface. 



This intimate connexion between these diversified 

 appearances has of late years served to elucidate 



