NEW SOURCES OF RADIATIONS 21 



action on a small spark. I asked myself if 

 the spark should in this case be considered as 

 an electric phenomenon, or only as producing 

 incandescence like a small gaseous mass. If 

 this latter supposition were correct, the spark 

 could be replaced by a flame. I then produced 

 a quite small flame of gas at the extremity of 

 a metal tube having a very small orifice. This 

 flame was entirely blue. I ascertained that the 

 flame could be used to reveal the presence of 

 " N " rays just like the spark ; for when it 

 receives these rays, it becomes whiter and 

 brighter in just the same way. Its variations 

 in glow allowed of four foci being found in a 

 pencil which had passed through a quartz 

 lens ; these foci are the same as those 

 detected with the small spark. The small 

 flame behaves therefore, in regard to " N " 

 rays, just like the spark, save that it does 

 not allow of the observation of polarization 

 phenomena. 



In order to study more easily the variations 

 in glow, whether of flame or spark, I examine 

 them through a plate of ground glass, about 25 

 or 30 mms. distant. In this way one obtains, 



