70 Notice of Active and Extinct Volcanos. 



Art. XV. — Conclusion of the Notice and Analysis of Pro- 

 fessor Daubeny's work on Active and Extinct Volcanos, 

 from Vol. IS, page 310. 



Remarks on Volcanic Phenomena. 



From page 355 to 436, Professor Daubeny has given a very 

 candid, able, and perspicuous statement of his course of rea- 

 soning upon volcanic phenomena. It is compatible with our 

 limits to state and quote only the outlines, and we will blend 

 with the article, a few additional hints, such as the present 

 state of science appears to us to warrant. 



Theories suggested anterior to the discovery of Galvanism 

 and the Metals of the fixed Alkalies, and Earths. 



It is necessary, we apprehend, to occupy very little time, 

 either in reciting or discussing these obsolete theories. We 

 wish, however, not to treat them, or their authors, with con- 

 tempt ; for they were, perhaps, the best that the then exist- 

 ing state of science presented. 



" According to the first and most antient of these, volcanos 

 were attributed to the combustion of certain inflammables, similar 

 to those which exist near the surface of the earth, such, for in- 

 stance, as sulphur, beds of coal, and the like ; and, in order to ac- 

 count for the spontaneous inflammation of these substances, an 

 appeal was often made to an experiment of Lemery's, which 

 went to prove, that mixtures of sulphur and iron, sunk in the 

 ground, and exposed to the influence of humidity, would give out 

 sufficient heat to pass gradually into a state of combustion, and 

 to set fire to any bodies that were near." 



Brieslak supposed, that volcanos are produced by petro- 

 leum, collected in subterranean caverns, and kindled in some 

 unknown way. Brieslak has shewn, that petroleum is very 

 abundant in the globe ; a conclusion which has been still fur- 

 ther extended by the researches of Hon. George Knox. 

 (See Vol. 12, page 147 of this Journal.) It appears also, 

 that petroleum is found, abundantly, in the vicinity of volca- 

 nos, and that it is exhaled during their eruptions. The uni- 

 form presence of sulphur also, in volcanos, and its copious 

 exhalation, during their state of activity, seem to counte- 

 nance the general idea, that they may arise from the burning 

 of combustibles. 



