52 



OF Calicite.— By \V. J. Jackson, M. A. 



1 4- T 



na.6 



Curves A and B, Fig. 6, indicate the variation of current 

 with time for crystal No. 2, while C and B are the correspond- 

 ing curves for a direction at right angles to the first case.t 



Effects of X-Rays on Polarization. 



A potential of 200 volts was applied to the crystal for three 

 or four hours before exposure to X-Rays. The results are graph- 

 ically shown in Fig. 6, curves A and A', B and B'. 



t In some later work done at Princeto'n University using crystals sput- 

 tered with silver, the writer was unable to find any difference in conduc- 

 tivity in opposite directions through the crystal. It is quite possible that the 

 earlier results on directional conductivity may have been an effect due en- 

 tirely to contact. 



