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LXXXVI. Polarization Phenomena in X-ray Bulbs. 



To the Editors of the Philosophical Magazine, 

 Gentlemen, — 



MR, S. RATNER in the January issue of the Philo- 

 sophical Magazine contributed a paper, entitled 

 "Polarization Phenomena in X-ray Bulbs," in which he 

 describes certain experiments made with vacuum tubes, and 

 puts forward certain explanations. 



Mr. Ratner, however, appears to have overlooked some 

 previous contributions which have an important bearing on 

 the subject of his investigation, and which in fact would seem 

 to anticipate some of his results and contradict some of his 

 conclusions. 



I refer particularly to the publications of Winkleman in 

 1901, of Campbell Swinton later, and my own notes in the 

 Proceedings of the Cambridge Philosophical Society, vols. xvi. 

 and xvii. of 1912. 



The results of these investigators challenge Mr. Ratner's 

 opening statement that " Hitherto the sparking potential in 

 well exhausted vacuum tubes has been considered to be the 

 property of the gas in the tube, being determined entirely 

 by the nature and the pressure of the gas." 



It is well known that the disposition of the electrodes 

 within the evacuated envelope exercises a profound effect; 

 one only has to mention the Lodge rectifying valve in. this 

 connexion to illustrate the point. 



In the notes above cited it was pointed out that a probable 

 explanation of the influence of the position of the electrodes 

 on the hardness of the vacuum tube was to be sought in the 

 charge gathering on the walls of the tube surrounding the 

 cathode, and some supporting experimental evidence was 

 adduced. 



Such an effect would clearly be influenced by the amount 

 of metal sputtered on the walls during the working of the 

 tube. In fact, many if not all peculiarities in working such 

 tubes which I have so far met, receive at any rate qualitative 

 explanation on the lines just mentioned. 

 The University, Leeds, Yours faithfully, 



January 28, 1922. R. Wm D DINGTON. 



