21 Professor Bischof s Reasons against 



it can merely be supposed to exist in such places where there 

 is no red heat. An enormous quantity of chlorine must be pre- 

 sent to unite with the hydrogen evolved. For instance, 

 5.6 parts of hydrogen, calculated above, require 187 parts of 

 chlorine to be present for producing 100 parts of lava, when 

 the hydrogen separated from water is to unite with it. 



Whatever be the importance of these reflections, every one 

 must come to the conclusion, that the production of lava, by 

 oxidation of its metallic principles, requires immense quantities 

 of atmospheric air or water, and that the hydrogen separated 

 by the decomposition of water, supposes the presence of sul- 

 phur or chlorine for uniting with them in such quantities as 

 to exceed those of the lava itself. 



It is true, the quantities of gaseous matters rising from the 

 crater of a volcano during its eruption cannot be estimated in 

 proportion to the lava issuing from it at the same time. How- 

 ever, as soon as these matters should exceed the lava in quan- 

 tity, the atmospheric air round about the volcano, to a consi- 

 derable distance, would be quite fatal to animal life. Accounts 

 of the eruptions of Vesuvius and other volcanos do not men- 

 tion such phenomena. Gaseous exhalations, it is true, take 

 place in abundance in the environs of Vesuvius, but only after 

 the cessation of the eruption and the issuing of lava. These 

 exhalations, consisting of carbonic acid gas, cannot be con- 

 nected with oxidations of the metallic bases supposed to exist 

 in the interior. Professor Daubeny himself assumes that these 

 disengagements cannot be derived directly from chemical pro- 

 cesses which produce the phenomena supposed by him, but 

 that they are only caused by the heat which these processes 

 tend to diffuse through the adjacent rocks. 



Among the simple bodies for which hydrogen possesses a 

 strong affinity, oxygen occupies a high rank. Professor Dau- 

 beny speaks of this gas uniting with the hydrogen separated by 

 the decomposition of water. However, it seems to me rather 

 difficult to suppose its presence in a place where, according to 

 him, mighty oxidations take place. But even granting atmo- 

 spheric air, after having acted upon the metallic principles, to 

 reserve a sufficient quantity of oxygen for the ignition of the 

 hydrogen evolved, tins supposition leaves the explanation gene- 



