110 THE NEW KNOWLEDGE. 



erty consists apparently in their power of penetrating 

 matter generally considered opaqua. They will pass 

 through a foot of solid iron or through several inches of 

 metallic lead. They seem to be neutral electrically, and 

 they are seemingly the agent chiefly concerned in the phys- 

 iological action of radium. They also affect a photographic 

 plate. They appear to be X-rays, or at least some type 

 of X-rays. In our study of the properties of corpuscles 

 (Part III) we learned that whenever corpuscles of a Crookes' 

 tube struck against a metal plate or the walls of the glass 

 containing vessel, X-rays were developed; and that, in 

 fact, an ordinary X-ray bulb was nothing but a tube in 

 which corpuscles were generated. If the beta-rays from 

 radium are in solid truth the corpuscles of Part III, it is 

 natural to expect that they should generate X-rays in 

 their back-stroke as they left the radium, and consequently 

 it should be no matter of surprise to find in the gamma- 

 rays nothing but X-rays as a natural accompaniment to the 

 corpuscles. While the gamma-rays are, therefore, in their 

 nature probably nothing but X-rays it is at this time not 

 positively certain. Of course, the identity of the gamma- 

 rays with X-rays does not tell us what the gamma-rays are 

 in themselves unless we know the nature of the X-rays, and 

 in the X-rays we have still, more or less, a mystery. X is 

 an xmknown quantity. It is probable that they are not a 

 form of matter, that is, that they are not particles at all, 

 but more in the nature of pulses or waves in the sur- 

 rounding ether set up by the impact of the corpuscles or 

 beta-rays. It is natural and, indeed, inevitable that the 

 vibrations of corpuscles should disturb the surrounding 

 ether into waves just as shaking a stick in water must set 

 up water waves, or as the grosser atoms of matter set up 

 the etherial waves of heat and light And it is also natu- 



