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XXXII. A Note on the X-ray Spectrum of Nickel. 

 By W. F. Rawlinsok, B.Sc, University of Manchester*. 



THE interference phenomena exhibited when X rays are 

 scattered by a crystal made possible the determination 

 of the frequencies of the various types of X radiation emitted 

 by an anti-cathode. Professor Bragg f first determined the 

 wave-lengths of the strongest lines in the X-ray spectra of 

 nickel, rhodium, and tungsten, and these have again been 

 determined by Moseley % during his systematic examination 

 of the elements. 



It seemed, however, desirable to investigate with greater 

 detail the case of a particular element, and for this purpose 

 nickel was chosen and an attempt made to determine with 

 still greater accuracy the angles of reflexion from rock-salt, 

 heavy-spar, and potassium ferrocyanide. 



The apparatus used is shown roughly in the diagram (fig. 1). 

 It consisted of an ordinary focus X-ray tube provided with a 

 side tube. This tube was designed by Mr. H. G. J. Moseley 

 for Professor Rutherford, and was used by the latter for 

 testing different crystals. The X rays from the anti-cathode 

 A passed through a fine platinum slit S and finally emerged 



Pig. 1. 



to pump. 



by way of an aluminium window 1*3 cm. in diameter and 

 0*00236 cm. thick. The bulb was exhausted by means of a 

 Gaede mercury pump, and finally controlled by charcoal 

 cooled with liquid air. The crystal was mounted on the 

 table of a spectrometer and the photographic plate on the 



* Communicated by Sir Ernest Rutherford, F.R.S. 



t Proc. Koy. Soc. lxxxix. p. 246 (1913). 



+ Phil. Mag. Dec. 1913, p. 1024. Phil. Mag. April 1914/ p. 703. 



