NOTE ON THE HEATING EFFECTS PRODUCED 



IN METALS BY BOMBARDMENT WITH 



KATHODE RAYS 



By Oliver C. Lester 



During the year 1905 Professor H. A. Bumstead of Yale University 

 investigated the heating effects produced in lead and zinc when they 

 were exposed to Roentgen rays and found that, when the two metals 

 received the same amount of energy in the form of radiation from an 

 X-ray tube, approximately twice as much heat was developed in the 

 lead as in the zinc. 1 He explained this result as probably due to the 

 fact that the X-rays exerted a trigger-like action on the more unstable 

 molecules of lead, causing some of them to disintegrate, thereby liberat- 

 ing atomic energy. This apparent difference in the effect on lead and 

 zinc was afterward found by Professor Bumstead to be due to an 

 error caused by the imperfect heat insulation of the two metals. 2 Both 

 his own later work and that of other investigators show that while there 

 may be liberation of atomic energy due to the action of the Roentgen 

 rays, it is not a large enough fraction of the total energy produced to 

 be detected by the means employed. 



In the year 1906 the writer, then at Yale University, undertook, at 

 Professor Bumstead's suggestion, a similar investigation, using kathode 

 rays as the energizing agent. It is well known that the negatively 

 charged kathode particles, under proper conditions, possess a great 

 amount of energy, as is shown by their penetrating, heating and other 

 familiar effects. There was thus the possibility that two metals, differ- 

 ing considerably in atomic weight, might develop different amounts of 

 heat when bombarded with kathode rays though each should receive 

 the same amount of energy. For, if enough energy could be communi- 

 cated to the atoms to render them unstable and cause them to disin- 

 tegrate, the metal composed of the most unstable atoms should ultimately 



• "Heating Effects Produced by Roentgen Rays in Different Metals and Their Relation to the Question 

 of Change in the Atom," Phil. Mag., Vol. II, p. 292, 1906. 

 « American Journal oj Science, p. 299, April, 1908. 



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