154 ELECTRIC VIEW OF MATTER [CH. xvi. 



complex molecule can be brought about, and are 

 practically utilised for the generation of new com- 



CH 3 . CH 3 = C 2 H 5 . H. 



It is probable that the same sort of thing is possible 

 with simple bodies, but that the so-called "elements" 

 constitute a peculiarly stable group, the ingredients of 

 which so far have only partially been re-associated 

 into isomeric or allotropic forms, and have not yet 

 been detached from each other. 



When chemical combination occurs between two 

 oppositely charged atoms, there is no electric dis- 

 charge between them : the two atoms retain each its 

 own charge, and cling together for that reason. 

 When they are separated, each is an ion and possesses 

 its appropriate charge. 



It is possible to charge an assemblage of neutral 

 molecules with an excess or with a defect of one or 

 more electrons, by processes of ordinary electrification, 

 such as friction ; but the attachment of these super- 

 numerary electrons is loose and they can be shaken 

 away by the agitation of ultra-violet light and in 

 many other ways. Even splashing of water into 

 spray shakes some loose, and can thus perturb an 

 electroscope, although the liquid was not charged 

 beforehand ; * a fact which adds to the probability 

 that the water unit is a molecular aggregate. And 

 in the case of massive atoms, of high atomic weight, 

 they occasionally appear automatically to reach a 

 condition of instability, and rearrange themselves 

 in such a way as to throw off one or more electrons 

 spontaneously, which then fly off tangentially with 

 whatever orbital velocity they may have had, giving 



*Lenard on electrification near waterfalls. See also Chap. VII., . 

 above, on ionisation. 



