CAUSES OF VOLCANIC ACTIVITY — DAY 259 



tween the amount of gas discharged through the lava and the tem- 

 perature of the fluid lava itself. The gases somehow contribute to 

 the heat of the lava body. 



One of the purposes of this expedition of 1912 Avas to collect 

 gas from the lava basin at Kilauea if it should prove in any way 

 practicable to do so. We Avere accordingly equipped Avith collecting 

 tubes, pumps, and pipe lines, but it Avas some days before a favorable 

 opportunity offered. Just how fortunate we were in this collection 

 we did not then appreciate, nor indeed for some years afterward, 

 but it is probable that the gases then collected from a lava fountain 

 on the crater floor, immediately adjacent to the lake itself, contained 

 less evidence of contamination by atmospheric air than any volcano 

 gases collected before or since. The conditions under which these 

 gases were collected have been described before* and need receive 

 no detailed attention at this time. They Avere studied in part by 

 extemporized tests on the ground and in part through careful analy- 

 sis in the laboratory some time later. 



Two conspicuous features Avere revealed by these studies Avhich 

 bear intimately upon the subject of this paper and upon the study 

 of Aolcanism in general, namely, (1) that the gas content of the 

 different tubes filled at that time Avas widely different; (2) that 

 the gases, whose composition Ave determined, could not be in equi- 

 librium at the time and at the temperature of their escape from 

 the lava. The first observation leads directly to the conclusion that 

 the composition of each bubble Avhich breaks through the surface, 

 even from the same opening, is different ; the second to the conclusion 

 that the gases are necessarily in process of reaction at the time of 

 their release. From our knoAvledge of gas reactions it folloAvs, 

 further, that gases still in process of reaction at the time of release 

 after passage up through the basin of liquid lava, must have been 

 in process of reaction throughout their upward progress, that is to 

 say, there must have been bubbles of gas of different composition 

 uniting beneath the surface at frequent intervals during this 

 excursion. 



The analyses of the gases collected at that time revealed the 

 presence of the following gases in different proportions in the collec- 

 tions: N3, H2O, CO,, CO, SO,, free H, free S, CI, F, and NH3. 

 Argon was also found after the first announcement was made. 

 It is of course plain that free hydrogen can not exist side by side 

 with SO2 or COo at a temperature in the vicinity of 1,000°. Nor 

 is free sulphur appropriately found in this group at 1,100° C. In- 

 deed the fact that the proportions of these gases vary from tube to 

 tube when collected by continuous pumping from the same opening 



* Arthur L. Day and E. S. Shepherd, op. cit. 



