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ELEMENTARY CHEMICAL MICROSCOPY 



" Universal" microscope 1 the stage itself consists of a huge 

 hemisphere, thus permitting the orientation of irregular objects 

 in all directions. This microscope was designed to meet the 

 requirements of forensic investigations where large objects of 

 irregular outline are the rule. 



FIG. 58. Large Glass Hemisphere. An Accessory which greatly facilitates the 

 Study of Irregular Objects. 



The application of the hemisphere is also found in several mi- 

 croscopes intended for the study of metals. Here, however, we 

 are dealing with opaque objects, and needing reflected light only, 

 the orienting device can be constructed entirely of metal. A 

 good example of this style of construction is found in Robin's 

 metallograph. 2 



In this instrument the stage is attached, Fig. 59, to the micro- 

 scope stand by a ball-and-socket joint as shown, making it pos- 

 sible to focus upon any given area of very irregular specimens. 



To facilitate the examination of crystals with reference to their 

 different behavior toward polarized light according to the direc- 

 tion through them that the light is sent, Schroeder van der Kolk 

 suggested fastening the specimens to a small glass hemisphere. 



1 Dennstedt, Die Chemie in der Rechtspflege, p. 285, Leipzig, 1910. 

 * Robin, Traite" de Metallographie, p. 50, Paris, 1912. 



