The Intensity of Reflexion of X-Rays by Rock- Salt. 331 

 Fig. 5. 



Sin 8 



Values of F for Chlorine. 

 The small circles indicate the observed values. 



The values of F for Chlorine and Sodium are:— 



Glancing-angle 9. 



sin0. 



F C1- 



F NV 



(5 44) 



(0-100) 



(11-67) 



(6-90) 



7 30 



01305 



10-11 



6-88 



10 



01736 



8-78 



6-26 



12 30 



0-2164 



7-72 



4-98 



15 



0-2588 



6-88 



4-18 



17 30 



0-3007 



6-14 



3-47 



20 



0-3420 



5-56 



2-95 



22 30 



0-3827 



500 



2-41 



25 



0-4226 



. 4-50 



L-91 



27 30 



04617 



401 



L-49 



30 



0-5000 



3-43 



0-83 



The angle between the scattered and incident beams is twice bhe glanoing- 



ansle 9. 



