428 



WRIGHT— POLARIZED LIGHT IN THE 



are the abscissae, the ordinates the angles (t — A^), and the curves 

 the absorption indices. The curves show clearly that for substances 

 with high refractive indices and high or low absorption indices the 



TABLE 7. 



In this table are listed the phase differences between the vertically inci- 

 dent beam and one of the components reflected from a plate of refractive 

 index n and absorption index k. Thus for a plate of refractive index 1.5 

 and absorption index 0.2, the phase difference is 24° 07'. 



phase difference is only a few degrees and therefore, so far as useful 

 in measurements, is practically negligible. In other words the reflected 

 light, although elliptically polarized, approaches plane polarized light 

 in character and the essential phenomena to be observed are inten- 

 sity differences and rotation of the plane of vibration. This state- 

 ment is valid for all substances of refractive index above 3.0 and 

 for substances of still lower refractive index (1.5) provided the 

 absorption index is either high or very low (less than 0.3). The 



