58 
ELEMENTARY CHEMICAL MICROSCOPY 
supported by the substage the plate lie upon the work 
table, its angle of inclination being obtained by means of a pro¬ 
tractor and the plate held in place by means of plasticine for a 
temporary mounting. A very simple arrangement of the 
Cheshire plate may then be as indicated in the diagram, Fig. 24, 
Fig. 24. Obtaining Polarized Light by Reflection. 
the support being an ordinary object slide, while the polarizing 
plate consists of a half-slide, ground upon its lower surface by 
rubbing upon a piece of glass carrying very fine emery and tur¬ 
pentine. After cleaning off the abrasive, the ground surface 
is blackened. A small mass of plasticine is placed upon the 
slide and the polarizing plate is pressed down until the proper 
inclination is obtained as indicated in the diagram. Thus pre¬ 
pared, this polarizer is pushed into the opening in the horse¬ 
shoe base of the microscope until the center of the plate falls in 
the optic axis of the microscope, the mirror of the instrument 
having been removed or swung aside. Light thrown upon the 
plate will be polarized and reflected in the line of the optic axis 
of instrument. 
