VOLCANOES. 157 



activity smoke, flame, ashes, and lava; and henco it has been 

 argued tliat if lire issues from the crater, there must be lire inside. 

 ThK li"\vfviT, need not of necessity follow. The whole phen- 

 omena connected with both volcanoes and earthquakes, are 

 cuused by chemical action. The intense flame witnessed at the 

 mouth of a volcano, is caused by the ignition of tho vast 

 Volumes of gases which are issuing from it. The flame does not 

 extend inside the mountain, for it is subject to tho same condi- 

 tions as our coal gas is. When we light the gas in our rooms we 

 have flame, but it does not extend inside the pipe or burner 5 

 in fact there is a space outside, between the burner and the flame, 

 that will not ignite. This is owing to the fact, that until a 

 sufficient quantity of oxygen is combined with the hydrogen, 

 there can be no combustion or flame. If we could introduce 

 coal gas into a vessel containing other mineral gases, we could 

 not light it. In a similar manner, there can be no flame 

 in the interior of the mountain, for there is not sufficient oxygen 

 inside to induce a combustion. 



Under the surface of the mountain, in the interior of 

 the earth, there are immense stores of mineral materials, 

 such as sulphur, nitre, salt, iron, etc., saturated with water, 

 which chemically act npon each other. By this action, 

 they are continually dissolving, reforming and generating 

 gases, till they accumulate in such quantities that they 

 cannot be confined ; they then burst with terrific force, 

 combine with the oxygen of the atmosphere, and igniting, 

 burn until the explosive and combustible gases are exhausted. 

 The dissolving and reforming action with water may then con- 

 tinue, and fresh outbursts may occur until the whole material 

 is changed, then the volcano becomes extinct. Thus we 



