88 SCIENCE PROGRESS 



The evidence seems to point to the blast having been made 

 up of an intensely hot heavy gas. Sulphurous vapours were 

 given out before the blast but did not accompany it. M. Molinar, 

 who observed the whole occurrence from Mont Parnasse, 

 relates that the volcano vomited fire during a quarter of an 

 hour and then became completely quiet ; at eleven o'clock, lava 

 and smoke began to pour out. Had the blast been water- 

 vapour, there should have been some clouds due to the con- 

 densing vapour, but though the wind was blowing away from 

 where M. Molinar stood and the view was perfectly clear, no 

 clouds were seen to form. The statements at any rate establish 

 the fact that a volcano can discharge a mass of gas downwards 

 and that this gas is like that of a mine explosion. It desiccates, 

 as witness the trees in the outer zone which were rendered 

 sapless, but the leaves still hung from the brittle twigs ; and 

 it is certainly not water-vapour. What this gas is can only be 

 guessed from Brun's researches. 



Dr. Brun commenced his work in 1901 and finished his field 

 observations in 1910(6). During this time he had visited the 

 Italian volcanoes, those of the Canary Islands, Java and the 

 Hawaiian Islands. His laboratory work consisted in deter- 

 mining the melting-points of rocks and rock-forming minerals, 

 especially those of volcanic origin, and the analysis of gases 

 collected from actual volcanoes either in the explosive stage or 

 driven out of lavas in which they had become dissolved or 

 occluded during cooling. Brun's method in the field may be 

 gathered from his account of the ascent of Mount Semeroe 

 in Java. Having watched the crater in eruption from a distance 

 for some time, Brun desired to look down into the working 

 chimney. Profiting, then, by an interval between two explosions 

 he rapidly approached and stood on the actual rim of the crater. 

 He was able to snap three photographs one after the other. 

 Hardly had he finished when an explosion burst out— still he 

 could photograph, though incandescent blocks fell all around. 

 He observes that investigations made overlooking the volcanic 

 orifices during the paroxysmal stage are very rare and to profit 

 by them one must have complete control over oneself and know 

 beforehand on what one must concentrate one's attention. 

 When he arrived at the rim of the crater the western chimney 

 of the three that were filled with liquid lava was belching forth 

 gas and bluish smoke ; little masses of lava were being gently 



