EXPLANATION OF PLATE. 



Figure A. Iron Spectrum through CS 2 , and Direct. 



The upper spectrum, taken through 96 cm. of the liquid, shows the rapidly 

 increasing absorption of carbon bisulphide iu the extreme violet. The lower 

 spectrum was taken direct. 



Figure B. Electrodes. — Silvered glass bars wedged face to face ready to be 

 used as condenser electrodes. 



Figure C. Typical Photographic Observation showing Dispersion in 

 the Electric Double Refraction of Carbon Bisulphide. 



The dark line throughout each band is the central dark fringe crossing the slit 

 of the spectroscope at right angles and produced by the Babinet compensator. 



The amount by which this line is displaced from horizontal in the " Voltage 

 Band " shows the excess of dispersion in the double refraction of carbon bisul- 

 phide over that of the quartz compensator. 



Each band was taken with a different setting of the compensator screw, and 

 with an exposure of about forty minutes. 



The strong bright lines in the extreme violet are carbon lines from the arc. 



The reference spectrum was produced by a cadmium spark and sodium flame 

 with exposures of from one to three minutes. 



