94 ELEMENTARY CHEMICAL MICROSCOPY 



removing the illuminator, inserting an objective directly over 

 the prism V, and attaching an Abbe condenser A and mirror m 

 to the rod r, the microscope may be employed for the examina- 

 tion of transparent objects by transmitted light. This arrange- 

 ment of the instrument is shown in Fig. 44. 



The adjustment of the illumination in the Leitz metallurgical 

 microscope is in every way similar to that followed in the Leitz 

 vertical illuminator already described. For high powers the 

 makers suggest employing only the disk reflector, for moderate 

 powers the reflecting prism is used, while for very low magnifica- 

 tions a plate reflector is supplied so arranged as to fit between 

 the objective and the preparation. This last device is restricted 

 to such low magnifications, however, as to be rarely applicable 

 to ordinary metallographic studies. 



The Reichert Metallurgical Microscope. This instrument, 

 Fig. 45, is one of the most convenient and most substantially 

 built of its class. The microscope itself consists of a heavy base 

 A from which rise four pillars; the largest of these, fashioned into 

 a handle H, carries the stage S provided with rack and pinion 

 adjustment for roughly focusing the preparation. The pillar P 

 supports the microscope proper, consisting of a prism chamber 

 to which the objective O, the illuminator tube V and the body 

 tube are attached. The fine adjustment of the instrument is 

 accomplished by the milled screw F. The prism chamber fur- 

 ther carries a tube whose axis is at right angles to that of T, 

 fitting into a light tight sleeve joint in C. The tube C, sup- 

 ported by a pillar provided with rack and pinion vertical adjust- 

 ment, fits into the front of the photographic camera and serves 

 as a carrier for a projection eyepiece. To the fourth pillar is 

 attached the tube B, fitted with a lens for projecting parallel 

 rays into V, a rotary disk provided with diaphragm openings of 

 different sizes, a glass cooling cell W for water or for colored 

 solutions to be employed as color screens and a slot for the 

 insertion of green, yellow or black glass slips G to modify the 

 brilliancy of the strongly illuminated surfaces. For greater con- 

 venience in making photographs a shutter s for exposures may 

 conveniently be attached to the end of the tube B. 



