Jaggar — Yolcanologic Investigations at Kilauea. 163 



carbon dioxide and nitrogen, with a residne of about seven per 

 cent rather equally divided among the infianiioable i>:ases sul- 

 phur, carbon monoxide and hydrogen, the latter predominant 

 among these. There was in addition less than O'l per cent in 

 all of fluorine, chlorine and ammonia. 



All of these workers agree that rising gas achieves the work 

 known at the surface of the earth as volcanic activitv. I think 

 that they all agree that the gases rise from deep sources, and 

 so far as the water problem is concerned, they all agree, in 

 opposition to the older geological text books, that gases other 

 than water in large measure heat and operate the volcanic 

 engine. In this they verify a conclusion reached many years 

 ago by Dr. A¥m. T. Brigham,* Director of the Bishop Museum, 

 and Mr. Wm. Lowthian Green. f Their differences of opinion 

 concern the extent to which the combinations with oxygen 

 above listed are original gases or products of union with air, 

 and more especially the extent to which surface heating, by 

 chemical combination among these unstable mixtures, is respon- 

 sible for the liquid lava pools and flows. 



Brun believes that original carbon in the form of hydro-car- 

 bons exists in lava, and nitrogen combined w^ith hydrogen in 

 the form of ammonia. He insists that there is no original 

 water from deep-seated sources emitted by lavas. Ferret 

 believes that the oxides and hydrates which come forth as 

 gases are the result of union with superficial air and water but 

 that the unadulterated gas from the deep region is more ele- 

 mental and is frequently quite breathable in great volcanic 

 explosions, whereas the oxidation products are disagreeable or 

 poisonous. In some cases, such as Vesuvius and Stromboli, he 

 has breathed the rush of gas from great explosions and per- 

 ceived no chlorine, sulphur or poisonous carbon compounds. 

 This agrees with some recent observations of the writer in 

 Hawaii, when a few feet from and immediately to leeward, of 

 the Halemaumau lava lake on its shore (fig. 12), of a pahoehoe 

 overflow on its border and of an aa flow on Mauna Loa, he 

 found no difificulty whatever in breathing the intensely hot 

 products of small bubblings all over these glowing surfaces and 

 perceived almost no sulphur odors; whereas at a greater dis- 

 tance to leeward of a positively flaming grotto or cone, the 

 bluish fume which condenses is full of intolerable compounds of 

 sulphur with oxygen. The Selby commission determined that 

 one ten-thousandth part SO^ in air is intolerable to human 

 beings. It hardly seems probable, therefore, that as much as 

 50 per cent of the magmatic gas rising directly from fresh lava 

 can be SOjij: (see below). 



* Kilauea and Manna Loa, Mem. Bish. Mus., 1909. 

 f Vestiges of the Molten Globe, Honolulu, 1887. 

 iBull. Haw'n. Vol. Obs'y., Sept. 1914, p. 121. 



