88 



ELEMENTARY CHEMICAL MICROSCOPY 



able substage by removing the condenser or polarizer and sup- 

 porting the specimen upon the substage ring. In the case of the 

 chemical microscope, the stage is removed by loosening the 

 centering screws and lifting out the stage. An " auxiliary " 



Fig. 38. Chemical Microscope with Stage removed and Auxiliary Stage inserted 



in the Substage Ring. 



stage is then inserted in the substage ring, the specimen placed 

 upon it and the focusing is done by means of the substage quick- 

 acting screw. Delicate focusing may then be made by the fine 

 adjustment of the microscope. This method possesses the 

 advantage of producing no disturbance of the alignment of radi- 

 ant and reflector in changing objectives or in studying sue- 



