WATER AND VOLCANIC ACTIVITY— DAY AND SHEPHERD. 



Table 2. — Tim yaaes from Halemaumuu {Kilauea), May, 1912. 

 [Percentages by volume.) 



289 



THE INI'LUENCE OF THE IRON COLLECTING TUBE. 



Ill the 15 niiinites during which pumping was continued the short 

 length of iron pipe which extended into the dome was partly de- 

 stroyed by the joint action of the sulphur and SO.. Owing to the 

 high temperature and the splashing of the molten lava, neither 

 glass nor porcelain would have withstood the ordeal, and a tube of 

 silica glass was, unfortunately, not available; so that iron appeared 

 to be the best material at hand through which to reach the interior 

 of the dome and to insure the capture of the gases at the temperature 

 of emergence from the lava (about 1,000°) before any opportunity 

 for cooling or contact with air had been given. 



The effect of this small section of iron pipe on the relations between 

 the gases collected in the tube is not as great as might at first appear. 

 The action of SO, on iron at this high temperature is quite vigorous, 

 the iron going over to ferrous oxide and setting free the sulphur. 

 But both these ingredients are present in the lava already, as may 

 be seen from the analyses (Table 1), so that no new component is 

 added, nor is any new reaction precipitated through the introduction 

 of the iron. It might be assumed further that the free hydrogen 

 present would be partly oxidized to water in reducing the ferrous 

 oxide formed from the SO. and iron (this is one of the reactions 

 when these components are brought together at this temperature in 

 the laboratoiy), but if this reaction has had a share in the disposi- 

 tion of our bit of exposed iron we must admit its presence in over- 

 whelming magnitude over the entire inner surface of the dome, which 

 is everywhere lined with liquid lava containing nearly 10 per cent 

 of ferrous oxide. The assumption of this reaction would therefore 

 liave the immediate effect of establishing the presence of water in 

 quantity among the volcano gases and at the same time relegate the 

 influence of the iron tube to a position of entire insignificance. 



There is still further evidence, if more is needed, that the local 

 reactions set up by the iron are of subordinate importance only in 

 their effect on the proportions of the gases collected, and of no effect 

 whatsoever on their identity and chemical relation. Supposing these 



44863°— SM 1913 19 



