8 Jarl A. Wasastjerna. 



Theoretical Considerations. 



Theoretically, by introduciiig complex values for the 

 dielectric constants, oiie easily finds that the coefficient of 

 absorption x, like the speed of transmission, constitutes an 

 unambiguous function of the oscillatory direction, and that 

 for a uniaxial crystal, x, as a function of g, is indicated by 

 the equation 



— = A^ cos^g + B^ sin^g 



A and B being two constants. For a strongly pleochroitic 

 material n^ in relation to x may be regarded as constant, 

 from which it follows that in such a case the equation 



— ^ = A^ cos^^ + B^ sin^g 

 fl 



where fj, and g are to be considered as polar coordinates, repre- 

 sents an ellipse. 



The above stated theoretical conclusions, which entirely 

 coincide with previously reported experimental results, are 

 perfectly independent of the physical nature of absorption, 

 on which depends only the size of the ellipse axes, considered 

 as functions of the wave-length. 



