164: Jaggar — Yolcanologic Investigations at Kilauea, 



Mechanism of Heating. 

 Is Lava Lake Hotter Beloio Surface f 



Daly points out that a volcano may be a true furnace in that 

 heat-producing chemical reactions necessarily take place where 

 free hydrogen is present. I^evertheless he considers that the 

 heat, generated partly from reaction between the gases under- 

 ground, is continuously distributed by " two-phase" convection 

 with a cooler liquid phase of the melt sinking while a hotter 

 and lighter gas-bubble phase is rising. The rising gas by 

 expanding would have a strong cooling effect, so that if there 

 were no compensatory heat reaction, Daly calculates that a 

 bubble rising at the surface at a temperature of 1200° C. would 

 at depth of 37 meters (120 feet) have a temperature over three 

 times as great or 3700° C. He iinds that the loss of heat at 

 the surface of the lava lake is vastly greater than the heat lost 

 by conduction into the wall rock enclosing the volcanic pipe. 

 Accordingly the heavy surface lava, losing its dilating gas and 

 growing denser for that reason and by cooling, sinks at the 

 grottoes and fountains, and pours in subsurface currents down- 

 ward. This hypothesis necessarily makes the lava lake hotter 

 and less dense below the surface for several hundred feet of 

 depth, if the lake is over the conduits. 



Ferret also clearly expresses belief that the lava lake is hotter 

 below for he conceives the islands as floating and extending 

 " to a considerable distance below the surface where the tem- 

 perature and the chemical activity of the lava are much 

 greater." "With reference to chemical activity Ferret writes : 

 " These gases which issue from the liquid lava of a volcano are 

 not to be considered as juvenile gas in its primal state, but that 

 which, expanded into and worked over with the lava in the 

 volcanic edifice, is subjected to the action of air, water and 

 oxidizing and transforming processes of the most complicated 

 kind resulting in the formation of those oxidized and hydrated 

 compounds of sulphur, carbon, chlorine, etc., which constitute 

 the gaseous emanation of ordinary volcanic activity.^ 



Day and Shepherd, on the other hand, reached the conclu- 

 sion that such oxidized gases as water vapor and sulphurous 

 acid are primal, and that chemical action is still going on 

 among the gases, that at these temperatures free sulphur could 

 not remain inactive in presence of carbon dioxide nor free 

 hydrogen in presence of both of those and sulphur dioxide in 

 addition ; '^ the heat generated .... 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."f The absence of 



* Loc. cit,, this Journal, xxxv, p. 146, 1913. 



f Loc. cit., p. 600. The present writer has measured the thermal gradient 

 of the lava recently (Jour. Wash. Acad., July, 1917). There is hot surface 

 reaction, a sub-surface cool zone, and rise of temperature next below that, 

 until the bottom lava is reached. 



