'668 Mr. W. Sutherland on the Electric 



to the case of liquids and solids with only this difference, that 

 the electric axis of a molecule may not change its position in 

 the molecule so frequently through a large angle as in the 

 case of a gas where the free motion causes numerous and 

 rapid changes of neighbours. 



In the further development of this conception interest 

 centres round the laws of es, the electric moment of a mole- 

 cule. These have been investigated in several of my Phil. 

 Mag. papers on molecular attraction. In a broad way we 

 can divide chemical compounds into two classes, those which 

 are ionized in solution and those which are not. To the 

 former belong the great majority of organic compounds and 

 the compounds of the non-metals with one another. Typical 

 of the latter are the salts of the metals. In both classes of 

 compounds es for a molecule can be derived from values of es 

 belonging to each atom. In those compounds which are not 

 ionized in solution there is an approximation to the following- 

 simple rule, that in each atom es is proportional to the volume 

 of the atom, and therefore that es for the molecule is pro- 

 portional to the volume of the molecule. But as es divided 

 by the volume of the molecule gives the intensity of electri- 

 zation or the electric polarization per unit area, we have the 

 simple approximate result that in this class of compounds 

 the intensity of the electrization of molecules is an absolute 

 constant. This result shows that for a detailed investigation 

 of the structure of atoms, especially in connexion with the 

 electron theory of matter, it will be necessary to carry out 

 more extended studies of es or of (M 2 /) ]/2 , as a proportional 

 quantity is denoted in some of my papers. 



Summary. 



The electric polarity of molecule or atom may be repre- 

 sented as caused in two ways, either by the separation of 

 two electrons e of opposite sign through a distance s giving an 

 electron pair or bipole of moment es, or by considering the 

 molecule or atom to be uniformly or variably electrized so 

 as to have a total electric moment es. In the same way, the 

 Earth as regards external magnetic effects may be treated 

 either as a uniformly magnetized sphere or as a pair of 

 opposite magnetic poles near the centre and having a mag- 

 netic moment equal to that of the Earth. At present we 

 may regard the atom as electrized in both ways to account 

 for the electron of electrolysis and for the electron structure 

 of matter. Doubtless the two ways are but different aspects 

 of one phenomenon, and for many purposes we can regard 

 the resultant electric polarity of an atom as being due purely 



