Fig. 4. First derivative curves at different frequencies of powdered cystine after 

 x-irradiation in a vacuum. The markers at the base are 68 gauss apart. The top 

 curve for 2.7 kMc requires a magnetic field of 960 gauss; the middle curve at 9 

 kMc, one of 3200 gauss; the bottom curve at 23 kMc, one of 8200 gauss. 



to face p. 250 



