146 F. A. Perret — Lava Fountains of Kilauea. 



this case, by the wind which frequently prevents the photo- 

 graphing of this phase of the gaseous outburst. 



The emission of gas is also constantly, if quietly, going on 

 over the entire surface of the lake. With a powerful binocu- 

 lar the writer was able to observe that every one of the 

 innumerable small openings in the crust had its own little 

 blowpipe jet of burning gas. The pressure was high and the 

 jets of flame, inclined in all directions by the obliquity of the 

 holes, were straight, pointed and perfectly motionless. Fis- 

 sures in the crust produce broad sheets of flame as steady as 

 the pointed jets. 



On the subject of the chemical composition of this gas the 

 writer prefers not to enter at present. The research work 

 now being carried on at Kilauea will soon result in the com- 

 plete analysis of the gases collected over the boiling lava 

 before burning in air, and until this is forthcoming it is 

 advisable to be patient. The present paper is intended to 

 form a contribution to the physical, and not the chemical, 

 study of the lava fountains. It should be stated, however, 

 that, in all my experience with Italian volcanoes, wherever 

 fresh, active lava has first issued into contact with the atmos- 

 phere the gases have burned with a flame identical in appear- 

 ance with those at Kilauea. At Etna in 1910 a continuous jet 

 had a height of from 10 to 20 meters and was blown in all 

 directions by the wind. 



But these gases which issue from the liquid lava of a volcano 

 are not, in the writer's opinion, 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 forma- 

 tion of those oxidized and hydrated compounds of sulphur, 

 carbon, chlorine, etc., which constitute the gaseous emanation 

 of ordinary volcanic activity. But the pure magmatic emana- 

 tion, i. e. the paroxysmal gases of a great eruption which, 

 after the expulsion of the liquid lava in the throat of the vol- 

 cano, issue directly from the depths in a cloud of magmatic 

 ash, are sweet and clean as the air itself and appear to have the 

 same composition. On two occasions at Vesuvius in 1906 and 

 once at Stromboli in 1912 the writer was enveloped in the 

 cloud of gas and ash at distances of from 1500 meters to only 

 250 meters from the crater during paroxysmal activity. The 

 darkness was absolute from the density of the cloud and the 

 condition continued, in one case, fully twenty minutes ; yet, not 

 only was there no difficulty in breathing but no trace of HC1, 

 S0 2 , H 2 S, etc., could be perceived by one accustomed to detect- 

 ing these in small amounts. 



