CH. XVL] COHESION 159 



Fig. 21 shows a couple of atoms both electrically 

 polarised, as by a positively charged rod held above 

 both. To vary the illustration, the constituents of C 

 are shown polarised into hexagonal order an effect 

 such as might also be caused by lateral pressure 

 in some cases ; while the constituents of D are 

 depicted in diagonal square order which has the 

 effect of violent electric polarisation. In any case 

 polarised atoms such as C and D are clinging by 

 forces much stronger than the force of ordinary 

 cohesion at that distance. They represent adjacent 

 atoms of a momentarily polarised coherer. 



It is not to be supposed that the electrons in a 

 polarised atom need really ever be disturbed as 

 much as is shown in the diagram, nor any more 

 than an almost imperceptible amount, in order to 

 produce this chemical cohesion effect. For that is 

 what polarisation accomplishes : it converts ordinary 

 molecular force, or cohesion, into incipient but real 

 chemical affinity ; both kinds of forces being on the 

 above hypothesis electrically explicable. 



