78 "N n RAYS 



(5) As I state in the text, these' rough data on the trans- 

 parency of different substances will have to be completed by 

 new experiments methodically conducted. I have since found 

 that copper continues to transmit " N " rays emitted by a Nernst 

 lamp, even when used in thicknesses of 65 cms. ; that, similarly, 

 glass is very transparent, etc. M. Bichat has studied the trans- 

 parency of various bodies ; in particular, he has ascertained 

 that the opacity of a sheet of lead is due to the fact that it is 

 superficially covered with oxide and carbonate. Metallic lead 

 lets pass certain of the " N " radiations. (See C. R. t. cxxxviii. 

 p. 548, February 29, 1904.) 



(6) See the communications of May 25 and June 15, 1903. 



(7) I have since found " that, on the contrary, " N " rays 

 have much shorter wave-lengths than those of light. (See my 

 communication of January 18, 1904 (p. 53 of the present 

 volume). ) 



(8) See note above (7). 



(9) The phosphorescence may be intense, provided it be not 

 at its maximum. 



(10) The piece of gold must of course be also receiving the 

 " N " rays. 



(11) These researches have since been communicated to the 

 Academy of Sciences. (See C. R. t. cxxxvii. p. 1049, December 

 24, 1903.) 



(12) According to some experiments which I have made 

 with an aluminium lens on rays issuing from a knife-blade, 

 these should have very large indices. M. Charpentier has 

 found that wet cardboard transmits these rays. These questions 

 remain to be studied. 



