256 Sosman — Work of the Geophysical Laboratory. 



tries. The best example of this is the facility with which 

 the experience and the personnel of the laboratory has 

 been adapted to the very important problem of manufac- 

 turing an adequate supply of optical glass for the needs 

 of the United States in the present war. 



It has further been possible to show within the last two 

 years that rock formation in which volatile ingredients 

 play a necessary and determining part can be completely 

 studied in the laboratory with as much precision as 

 though all the components were solids or liquids. 



Along with the laboratory work on the formation of 

 minerals and rocks has gone an increasing amount of field 

 work on the activities of accessible volcanoes, such as 

 Kilauea and Vesuvius, where the fusion and recrystal- 

 lization of rocks on a large scale can be observed and 

 studied. 



There was once a time when the confidence of the lab- 

 oratory in the capacity of physics and chemistry to solve 

 geological problems was not shared by all geologists. 

 There were some who were inclined to view with consid- 

 erable apprehension the vast ramifications and com- 

 plications of natural rock formation as a problem 

 impossible of adequate solution in the laboratory. It is, 

 therefore, a matter of satisfaction to all those who have 

 participated in these efforts to see the evidences of this 

 apprehension disappearing gradually as the work has 

 progressed. A careful appraisement of the situation 

 to-day, after ten years of activity, reveals the fact that 

 the tangible grounds for anxiety about the accessibility 

 of the problems which were confronted at first are now 

 for the most part dissipated. 



It will not be possible to review in detail the lines of 

 work sketched above. An outline of the synthetic work 

 on systems of the mineral oxides and a paragraph on the 

 volcano researches will perhaps suffice to indicate the 

 general plan and purpose of the laboratory's work. It 

 should be added that the results of many of the researches 

 of the laboratory, detailed below, have been published in 

 the pages of this Journal (see 21, 89, 1906, and later 

 volumes). 



Mineral Researches. — The mineral studies include : 



I. One-component systems: silica, with its numerous 

 polymorphic forms and their relations to temperature 



