The Intensity of Reflexion of X-Rays by Rock-Salt. 11 



intensity of reflexion by the corresponding faces, this means 

 that fjb diminishes in passing to less intense reflexions (cp. 

 equation (5)). 



The effective coefficient ju can be calculated more readily 

 by plotting the results as in fig. 5. 



Since ^ 



~= Q.* o sec0*- w ° 8ec «, 



log e .( Tm _ D ) + cons = ~/jLt sec 6. 



It sec 



Fiar. 5. 



t„ m centimetre. 



In fig. 5, logJ-Y^-j is plotted against t . The slope of 



the curve then gives yu directly, allowing for the factor sec 6. 

 The results are tabulated below. 





Effective 



Extinction 



Reflexion. 



coefficient, 



coefficient, 



100 



(i. 



1630 



5-60 



110 



1360 



2-90 



200 



12-66 



1-96 



300 



10-72 



002 



Intensity of reflexion 

 in arbitrary units. 



100 

 50-5 

 L9-90 



4-87 



Normal coefficient of absorption. 10*70. 



