78 Notice of Active and Extinct Volcanos. 



to suppose a communication with water, when we have so 

 much evidence of its existence in the bowels of the earth, in 

 caverns, and internal lakes and springs, and rivers, besides 

 the vast stores which we see on the surface. 



As to the extinct volcanos of France and other countries, 

 as neither history nor tradition reaches to the period of their 

 activity, although the evidence of their existence is unques- 

 tionable, we may, with good reason, refer them to the period, 

 when the countries in which they are situated, were sub-marine, 

 or, when water existed abundantly, on the surface, in natural 

 hollows, forming Jakes and inland seas, more or less extensive. 

 But, it must be allowed, that water at the bottom of the 

 ocean, existing under an enormous pressure of we know not 

 how many miles of fluid, would be much more prone to reach 

 the seat of igneous agency through those natural chinks and 

 fissures by which the earth is, more or less, intersected, and 

 therefore, this is an additional reason to prove, that the 

 oceanic waters are principally active in producing volcanos. 



It does not follow, that the volcano, which is fed by the 

 waters of the ocean, must, of course, be submarine ; it 

 may break out through the communication, by which the 

 water was admitted, or elsewhere, under the sea or the land, 

 according to circumstances, depending upon the strength, 

 nature, and connexions of the superincumbent strata. 



"The most constant and essential phenomenon of an active 

 volcano, is the evolution of certain seriform fluids, which, 

 forcing themselves a passage through the incumbent strata, 

 carry up with them, whatever comes within the sphere of 

 their violence, thus giving rise to ejections of stones, of ash- 

 es, and of water." p. 371. 



What are the gases and aeriform bodies emitted by volca- 

 nos ? Our author ascertained, that, at Solfaterra, there is 

 sulphuretted hydrogen, and at Volcano, sulphurous acid ; 

 but both are not found at the same place, as they mutually 

 decompose each other, precipitating the sulphur of both, and 

 forming water from the union of the hydrogen of the one and 

 the oxygen of the other. Etna, as our author found, was full 

 of sulphurous acid, but the vapor collected and examined, 

 proved to be principally water, with a trace of muriatic acid. 



It is probable, however, that during an eruption, muriatic 

 acid is evolved in great quantity, forming white clouds in the 

 air, and the muriates of soda and ammonia are found abun- 

 dantly in volcanic matters ; the former, Monticelli obtained 



