THE EFFECT OF TENSION ON THE ELECTRICAL RESIST- 

 ANCE OF CERTAIN ABNORMAL METALS. 



By p. W. Bridgman. 



Received October 7, 1921. Presented October 19, 1921. 



TABLE OF CONTENTS. 



Page. 



Introduction 41 



Description of Apparatus and Method 42 



Detailed Data 44 



Lithium 44 



Calcium 46 



Strontium 47 



Antimony 48 



Bismuth 50 



Nickel 52 



Cobalt 53 



Manganin 53 



Therlo 56 



Discussion of Results, excepting Nickel 57 



Discussion of the Effect in Nickel 63 



Summary 66 



InTPvODUCTION. 



Under hydrostatic pressure the electrical resistance of most metals 

 decreases. On the other hand the resistance of these metals increases 

 under tension. There are, however, a few metals which are abnormal 

 in that their resistance increases under pressure. It has been known 

 for some years that bismuth is such a metal, and I have recently added 

 to the number lithium, calcium, strontium, and antimony. It seemed 

 to me of considerable interest to determine the effect of tension on the 

 resistance of these metals. These data are presented in this paper. 

 When I started this work, such measurements had not been published 

 for any of these metals. During the course of my work, however, 

 data were published in Italy for the effect of tension on the resistance 

 of bismuth.^ The resistance of this was found to decrease under 

 tension, so that this metal is abnormal with respect to both tension 

 and pressure. I have verified this result. I find that strontium is 

 the only one of the remaining four which is also abnormal with respect 



1 E. Zavattiero, Rend. Accad. Lincei, 29 (1) 48-54, 1920. 



