TUNGSTEN X-RAY SPECTRUM 



193 



Other measurements indicate that these values, assuming the 

 exactness of the above value of d, are correct to within 0.1 per 

 cent. It is the belief of the writer that the resolving power of 

 a crystal may be much further increased and the X-ray spectrum 

 of the elements made almost, if not quite, as extended as the 

 light spectrum and by means of this greater resolving power the 

 finer details of atomic structure become known. 



Physical Laboratory, 



State University of Iowa. 



13 



