142 



ELEMENTARY CHEMICAL MICROSCOPY 



The simplest of these consists of either metal or glass hemi- 

 ,spheres of such a size as to fit into the opening of the stage or into 

 the opening of a plate laid upon the stage ; the upper part of the 

 hemisphere is usually a truncated cone. Having a lower hemi- 

 spherical surface the apparatus may be tipped in any direction 

 and at any angle up to approximately 45 degrees. 



The Glass Hemisphere, as employed simply for the purpose 

 of facilitating the examination of irregular objects, is shown in 

 Fig. 72; a band around the hemisphere gg is rough ground so as 



FIG. 72. Large Glass Hemisphere. An Accessory which greatly Facilitates the 

 Study of Irregular Objects. 



to prevent slipping when the device is tipped. The object o laid 

 upon the upper or flat surface can be so tipped as to permit the 

 different surfaces to be studied without difficulty. 



In certain classes of microscopes as, for example, Dennstedt's 

 " 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. 



The application of the hemisphere is also found in several 



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



