144 THE X-RAYS. 



have tbe property of discharging electrified bodies, and I intimated 

 that it was the X-rays and not the cathode rays passing unchanged 

 through the ahiminum window of his apparatus which produced the 

 effect described by Lenard on electrified bodies at a distance. I have, 

 however, delayed publication of my experiments until I could present 

 conclusive results. 



These can be obtained only when the observations are carried on in a 

 room which is not only completely insulated from the electrostatic 

 forces emanating from the vacuum tube, the conducting wires, the 

 induction apparatus, etc., but is also closed to the air which comes in 

 the neighborhood of the discharge apparatus. 



For this purpose I had a box constructed by soldering together 

 zinc sheets, and this box was large enough to contain me and the 

 necessary apparatus, and was air-tight with the exception of an open- 

 ing which could be closed by a zinc door. The side opposite to the door 

 was mostly lined with lead, and immediately adjacent to the discharge 

 tube an opening 4 centimeters wide was cut in tbe lead and zinc wall, 

 and its place filled up air-tight with aluminum foil. Through this 

 window passed the X-rays to be investigated. I have with this appa- 

 ratus verified the following results: 



[a) Positively or negatively electrified bodies placed in air are dis- 

 charged when immersed in X rays, and the action is the more rapid 

 the more intense the radiations. The intensity of the rays is deter- 

 mined by their action upon a fluorescent screen or a photographic 

 plate. ' 



It is in general immaterial whether the electrified substance is a con- 

 ductor or nonconductor. Thus far I have discovered no difference in 

 the behavior of different bodies relative to the rapidity of their dis- 

 charge, or between positive or negative charges. These points are, 

 however, open to further investigation. 



{b) When an electrified conductor is surrounded by a solid insulator, 

 as for example, j)araffine, the radiation produces the same effect as 

 would the flashing of the insulating shell by a flame placed in contact 

 with the ground. 



(c) If this insulator be in its turn closely surrounded by a grounded 

 conductor and both itself and this outer conductor be transmissible to 

 X-rays, the action of the X-radiations upon the inner conductor is 

 unnoticeable with the apparatus at my command. 



{(l) The observations recorded under (a), (h), and (c) indicate that 

 the air through which X-rays pass possesses the property of discharg- 

 ing any electrified bodies with which it comes in contact. 



{e) If this be indeed the case, and if the air retains for some con- 

 siderable time this property imparted to it by the X-rays, it must be 

 possible to discharge electrified bodies not themselves under the influ- 

 ence of X-rays by bringing to them air which has been subject to these 

 radiations. 



