PAPERS OX CHEMISTRY AND PHYSICS 231 



EFFECT OF X-RAYS OX THE RESISTAXCE OF TIX 



FOIL 



W. H. Saxders and C. J. L.ipp, University of Illinois 



Some unexpected results have been obtained recently 

 in an experiment on the action of X-rays on a beam of 

 electrons. In connection with this the question arose 

 whether X-rays would affect the resistance of a metallic 

 conductor. 



The first work in this field was reported by J. TT. Gril- 

 t^y^ in 1S96. Because of the similarity between X-rays 

 and light he anticipated that the resistance of selenium 

 would be altered by exposure to X-rays. Experiments 

 confirmed the prediction. Later work has been carried 

 to such point that this property may be applied to meas- 

 urement of the intensity and of the constancy of X-rays. 

 Gilt<iy mentioned an incidental test on a tin bolometer 

 which gave no indication of a change in resistance caused 

 by the X-rays. 



Selenium exhibits a change in resistance also when ex- 

 posed to the action of radium and radium compounds. 

 At first it might be supposed that the change manifested 

 is caused by the gamma rays. However, experiments 

 carried out by F. C. Brown and Joel Stebbins* indicate 

 that the change observed is the result of bombardment of 

 alpha and, particularly, beta particles, the gamma rays 

 having little or no effect. The action of radium bromide 

 on a bismuth spiral was studied by R. Paillot.^ who re- 

 ported his work in 1904. He found a change in resist- 

 ance of about one part in three thousand. The descrip- 

 tion of his experimental arrangement indicates that alpha 

 particles could not have participated in the action, but no 

 effort was made to isolate the effects of the beta particles 

 or the gamma rays and the work was not followed up. 



In view of the lack of quantitative data on any mater- 

 ial except selenium and the theoretical importance which 

 a positive result would have, it was thought advisable to 



1. J. W. Giltay, Xature, V. 54. p. 109. (1896). 



2. Brown and Stebbins, Phys. Rev., V. 25, p. 505 (1907); V. 26, p. 273 

 (1908). 



3. R. PalUot, Comptes Rendus, Vol. 138. p. 139 (1904). 



