600 DAY AND SHEPHERD WATER AND VOLCANIC ACTIVITY 



the surface is approached. These reactions are accompanied by evolution 

 of heat, which obviously operates to raise the temperature of the sur- 

 rounding lava so long as the reacting gases remain in contact with it. 

 The heat generated by these gas reactions, in the region near the surface 

 where the amount of gas is large, may well be much more than sufficient 

 to counteract the cooling effect of the expansion within the rising lava 

 column, which may thus become hotter and not cooler as it approaches 

 the surface. 



Precise figures can hardly be given for the difference in magnitude 

 between the two forces which have been assumed to oppose each other 

 here, the adiabatic cooling on the one hand and the heat of reaction be- 

 tween the gases on the other, for we do not yet know what all the reac- 

 tions are in such a complicated chemical system, nor do we possess any 

 knowledge of the height of the lava column through which the gases are 

 free to react. In fact, if the tube which feeds the volcano from below be 

 supposed to contain both ascending and descending columns of liquid 

 lava of widely variable temperature (Daly) in which the circulation is 

 primarily controlled by the (relatively very large) differences of specific 

 gravity, then it is indeed questionable whether the common equations for 

 adiabatic expansion find application here at all. In any event, if we may 

 assume such reactions to be going on between the gases as : 



H 2 + C0 2 = CO + H 2 + 10,000 calories (Haber) 

 or 



CO + i/ 2 2 = C0 2 + 68,000 calories (Haber) 



or the reaction between gas and lava : 



3FeO +' H 2 = Fe 2 4 + H 2 + 15,400 calories (Chamberlin) 



then the effect of adiabatic cooling is certainly of negligible magnitude 

 in comparison with these. This is reasoning far beyond the data now in 

 hand, but it serves to show that there is no cooling effect of comparable 

 magnitude with the heating effect of the reactions going on within the 

 active lava. 



If the reactions quoted above afford a proper measure of the order of 

 magnitude of the heat quantity thus released by chemical reaction within 

 the tube and surface basin of the volcano, we have here happened on an 

 enormous store of volcanic energy which reaches its maximum tempera- 

 ture at the surface itself. It is by no means certain at the moment that 

 this discovery throws any new light on conditions far below the surface, 

 except perhaps to relieve us of the necessity of postulating extreme tern- 



