GEOPHYSICAL LABORATORY 287 



tigated. In connection with the sulphide investigations, 

 the hydrated oxides of iron have been studied chemically 

 and microscopically and the results will soon be ready for 

 publication. 



Throughout the work the mere accumulation of bodies 

 of facts has been held to be secondary in importance to 

 the development of new methods of attack and the eval- 

 uation of new general principles, and the specific prob- 

 lems studied have been selected from this point of view. 



Volcano Researches. A branch of the laboratory's 

 work that is of general as well as petrological interest 

 is the study of active volcanoes. Observations and col- 

 lections have been made at Kilauea, Vesuvius, Etna, 

 Stromboli, Vulcano, and (through the courtesy of the 

 directors of the National Geographic Society) Katmai in 

 Alaska. The great importance of gases in volcanicity is 

 emphasized by all the studies. The active gases include 

 hydrogen and water vapor, carbon monoxide and carbon 

 dioxide, and sulphur and its oxides, as well as a variety 

 of other compounds of lesser importance. The crater of 

 Kilauea proves to be an active natural gas-furnace, in 

 which reactions are continuously occurring among the 

 gases, often resulting in making the lava basin hotter at 

 the surface than it is at some depth. These reactions 

 are being studied in the laboratory on mixtures of the 

 pure constituent gases in known proportions, in order to 

 lay the foundation for accurate interpretation and pre- 

 diction concerning the gases as actually collected from 

 the volcanoes themselves. 



