52 " N RAYS 



The spontaneity and the indefinite duration 

 of the emission by steel suggests the idea of 

 assimilating it to the radiant properties of 

 uranium, discovered by M. H. Becquerel, pro- 

 perties which the bodies since discovered by 

 M. and Mme. Curie, viz. radium, polonium, 

 etc., exhibit with so much intensity. Never- 

 theless, " N " rays are certainly spectrum radi- 

 ations ; they are emitted by the same sources 

 as spectrum radiations ; they are reflected 

 and polarized, and possess well-defined wave- 

 lengths, which I have measured. The energy 

 which their emission represents is most likely 

 borrowed from the potential energy correspond- 

 ing to the strained state of tempered steel ; 

 this expenditure is doubtless very slight, since 

 the effects of the " N " rays are likewise slight, 

 which explains the apparently unlimited dura- 

 tion of the emission. 



An iron plate, bent so as to impress on it a 

 permanent deformation, emits " N " rays ; but 

 the emission ceases after a few minutes. A 

 block of aluminium, fresh-hammered, behaves 

 in an analogous manner ; but the time of emis- 

 sion is even shorter. In these two cases the 



