THE ALPHA-, BETA- AND GAMMA- RAYS. Ill 



ral enough that these waves set up by corpuscular vibrations 

 should be very different in properties from those arising 

 from the vibration of grosser atoms. It is probable that 

 the X-rays are due to ethereal vibration, not material par- 

 ticles, and that the gamma-rays from radium are X-rays. 



We have thus found in the alpha-, beta- and gamma-rays 

 from radium the positive ions, corpuscles and X-rays of 

 Part III, their natural progenitors in the history of discov- 

 ery. "What an anti-climax," says the reader. "We 

 started out to study a new property of matter, and here 

 we end up with an old one." Not a bit of it. We called 

 the new property of matter radio-activity not Becquerel 

 rays. " What is the difference ? " All the difference be- 

 tween a natural intrinsic property and a property of con- 

 dition. The light of an arc-lamp is a property of condition ; 

 suppose you found, deep in the earth, some natural substance 

 blazing forever with a light as great, that would be a natu- 

 ral intrinsic property and a very curious one radio- 

 activity. So with the positive ions, the corpuscles and 

 the X-rays of Part III. They arise from candle flames, 

 red-hot metals, or electrified vacuum "tubes, all of them 

 substances or mechanisms under very special conditions. 

 The Becquerel rays from radium, on the contrary, arise 

 from a substance dug out of the ground which will emit 

 them, apparently, for centuries in the future as it has 

 emitted them apparently through the countless centuries 

 of the past, without any extrinsic influence. It is their 

 natural intrinsic property a new property of matter 

 radio-activity. 



Part III taught us the existence, under special condi- 

 tions, of bodies a thousand times smaller than the smallest 

 atom. Part IV, so far, has taught us the natural emission 

 of such particles from a substance in its normal state. 



