142 A. L. DAY MINERAL RELATIONS FROM LABORATORY VIEWPOINT 



of the component minerals. They therefore offer for investigation a 

 number of problems of broad scope, requiring for their solution not onl}^ 

 the application of the principles of geology, but also of physics, chemistry, 

 and allied sciences. The problems are also complex in detail and do not 

 admit of satisfactory analysis without correlating a great variety of evi- 

 dence, both from the field and from the laboratory. The field evidence 

 was, of course, the first to be sought; forces had to be recognized before 

 they could be measured; but, having been identified, the next step is to 

 seek to establish their relation to each other in the laboratory and to 

 make use of the evidence from experiment for further and more accurate 

 field studies. 



, Until recently, petrologists have confined their attention largely to the 

 collection and examination of the field and microscopic evidence bearing 

 on the rocks and their mode of occurrence, while the more precise quanti- 

 tative methods of attack have been slower in development and are only 

 now beginning to be considered seriously. This is especially true of ex- 

 perimental evidence, and one of the chief purposes of this paper is to 

 invite the consideration of geologists, or, more particularly, of petrolo- 

 gists to certain phases of the problem of rock formation as they begin to 

 appear from the viewpoint of the laboratory investigator, in order that 

 men who are at work with a common scientific purpose, but with widely 

 divergent training, may cooperate more effectively, both in gathering and 

 interpreting the data on which to build the quantitative science of 

 petrology.^ 



It will be well to recall that the tendency of scientific effort for a half 

 century or more has been very definitely in the direction of more intense 

 specialization. With perhaps an occasional exception, the men engaged 

 in different branches of science have not been working along convergent 

 lines, but along divergent lines, which are now so far apart that individual 

 workers in one field do not find it easy to use the tools of another, nor at 

 once to estimate the scope or point the application of the facts and rela- 

 tions established with these unfamiliar tools. It therefore happens quite 

 naturally, in entering a new field of investigation such as that lying mid- 

 way between geology on the one hand and physics and chemistry on the 

 other, that the individual chemist, physicist, or geologist should feel that 



2 George F. Becker has repeatedly directed attention both to the need and to the oppor- 

 tunity for such cooperation. With Barus and King, he planned the first physical meas- 

 urements made in the U. S. Geological Survey in the early 80's, and when these were 

 interrupted in 1892 through failure of appropriations, it was his vigorous and continued 

 interest which finally secured the reestablishment of the physical laboratory in 1901 and 

 brought to it additional support from the Carnegie Institution of Washington in 1904. 

 The introduction of the quantitative methods of physics and chemistry in the service of 

 geology is therefore very largely due to Doctor Becker. 



