14 Professor Bischof's Beasons against 



Thus he expressed his two most cherished affections, and in 

 his last words associated the two most powerful sentiments of 

 his soul, — his tenderness for his son, — his admiration for his 

 brother. 



Farther Beasons against the Chemical Theory of Volcanos. 

 By Professor Gustav Bischof of Bonn. Communicated 

 by the Author. 



Professor Daubeny* has replied to my objections to the 

 chemical theory of volcanos, with that fairness which might 

 be expected from a scientific man, who only looks to the topic 

 of the discussion, not to the opponent. Venturing to con- 

 tinue the discussion on this subject a little farther, I by no 

 means wish to forget the merits of a naturalist, who has dis- 

 tinguished himself so much by his description of active and 

 extinct volcanos, and by a variety of valuable memoirs on 

 similar subjects. I feel happy to meet with such a man in 

 the very same field of science, and I hope that the differences 

 in our opinions will become less considerable, the more they 

 are explained. 



The chief question is, whether the internal heat of our 

 globe is sufficient to account for volcanic phenomena? or, 

 whether the supposition of intense chemical actions explains 

 them in a more satisfactory manner 1 ? As for the internal 

 heat of the earth, I am of opinion that it may not be con- 

 sidered as an hypothesis, but as a fact well grounded on nu- 

 merous phenomena. Granting this, it must be imagined that 

 the rocks of the earth are, at a certain depth, in a liquid ig- 

 nited state. Indeed, it is well known that, by volcanic action, 

 melted masses (lava) arise from the interior, and that, on 

 slowly cooling, they produce rocks such as basalt, trachyte, &c, 

 forming a considerable part of the external crust of the sur- 

 face of the earth. The chief explanation of volcanic pheno- 

 mena depends, therefore, according to the theory alluded to, 

 upon demonstrating the means which nature makes use of to 

 bring such melted masses to the surface of the earth. In my 



* Jameson's Philosophical Journal, vol. xxvi. p. 291. 



