Structure of Silver Crystals. 



85 



For the reflexion planes (100) and (111), for which the 

 crystal had corresponding crystal-faces, the maxima of 1st, 

 2nd, and 3rd order were found. The calculation gave 

 fora the values -\-V and — 1' for the two faces respectively. 

 Thus the fault in the direct determination of the zero position 

 is practically negligible. 



The crystal, however, had no marked (110) face, and to 

 get the reflexion from these planes the cube-faced crystal 

 was put up with the (110) plane vertical and the edge (100) 

 horizontal. But in this way the image of the reflected beam 

 will not be a vertical slit, but will be (>) shaped, and the 

 determination of the glancing angle less accurate. Further, 

 the reflexion from the (110) plane was so weak that only 

 the first maximum could be measured. But as the zero 

 position is known, the first maximum will be sufficient for 

 the determination of the glancing angle. 



In fig. 1 is given the maxima corresponding to the strongest 



Fig. 1. 



Rh line observed with the narrow slit, and in the table is 

 given the glancing angle 6 for the first order spectrum, the 

 grating constant d, and the relative intensities of spectra of 

 different orders. 



