104 ELEMENTARY CHEMICAL MICROSCOPY 



The development of microscopic methods for the study and 

 identification of opaque minerals 1 within the last few years has 

 created a demand for inexpensive, easily transportable instru- 

 ments of simple construction which may be carried and used 

 in the field. A microscope of this sort was described by Davy 

 at the August, 1920, meeting of the American Institute of 

 Mining and Metallurgical Engineers. 



1 Murdoch, J., Microscopical Determination of the Opaque Minerals, 1916. 

 Wiley & Sons, N. Y. Davy, W. M., and Farnham, C. M., Microscopic Examina- 

 tion of the Ore Minerals, 1920. McGraw-Hill Book Co., N. Y. 



