A. W. Ewell — Rotatory Polarization. 



365 



Apparatus. 



The general apparatus in its final form is illustrated in out- 

 line in fig. 1. It is a biquartz polarimeter, without lenses and 



Fl a. I 



m® A 



with certain attachments for this particular work. The light 

 passes from the frosted incandescent lamp, a, through the first 

 Nicol, c, the biquartz, d, the jelly tube, 2, and the second Nicol, 



