Notice of Active and Extinct Volcanos. 77 



depth, at which the chemical action, giving origin to the heat, 

 is sustained. 



Professor Daubeny is not disposed to attribute the occa- 

 sional eruptions of mud and petroleum, to the immediate ac- 

 tion of volcanos — but to the accumulation of sulphur, petro- 

 leum, and other inflammable materials, produced perhaps 

 by primeval volcanos, existing even (it may have been) un- 

 der the ancient oceans, before the now existing volcanos be- 

 gan their operations. He alludes, particularly, to the mud 

 volcanos of Maculaba, in Sicily, which are detached from 

 Etna, and appear to depend on the combustion of sulphur. 



There can be no doubt that Water is a great agent in pro- 

 ducing Volcanos. 



Mons. Arago enumerates one hundred and sixty three ac- 

 tive volcanos, nearly all of which are situated near to the 

 sea, "in islands and maritime tracts." 



The apparent exceptions are few, and generally when ex- 

 amined, they will not prove to be real exceptions. 



If there are, as is stated, but not fully confirmed, one or 

 two volcanos in the centre of Tartary, they may communi- 

 cate with the lakes of that country, some of which are saline. 



Joridlo, in Mexico, is one hundred and twenty miles from 

 the ocean — but Colima, on the Pacific, and Tuxtla, on the 

 Atlantic, may be regarded as the wings of a vast subterrane- 

 an gallery, by which the waters of either ocean, may, ulti- 

 mately, communicate with Jorullo, and we may presume, 

 that a similar state of things exists with respect to the vari- 

 ous mountain groups of Guatimala, Columbia and Chili. 



It does not appear to us important to insist, that the com- 

 munication supposed, should, in every case, be with salt wa- 

 ter. It is true, that muriate of soda is frequently sublimed 

 in volcanos, and we may generally attribute this to the prox- 

 imity of, or at least communication with salt water. But 

 those great agencies, for which water is necessary in volca- 

 nos, depend, not upon the foreign ingredients it may chance 

 to contain, but upon its action in its own proper character, 

 either fluid or aeriform, and upon the agency of its elements. 

 It would, therefore, in our view, not militate, seriously, against 

 the reasoning founded upon the supposed presence of wa- 

 ter, if volcanos should break out, or be discovered in the 

 midst of our greatest continents. We are always at liberty 



