regarded as Compounds of tlie First Order. 449 



paper (loc. cit. cxv. p. 279 (1919)). As required by the 

 theories of Rutherford (Phil. Mag. xxi. p. 669 (1911), xxvii. 

 p. 488 (1914)) and Langmuir (loc. cit.), the positive nucleus 

 is at the centre of the sphere, and its volume is exceedingly 

 small compared with the volume of the sphere as a whole. 

 We may therefore suppose the attractive force of the nucleus 

 which binds the valency electrons to he equally distributed 

 over the surface of the sphere of the atomic kernel, into 

 which sphere the valency electrons are unable to penetrate. 



Adopting the convention used in the former paper (loc. 

 cit.; see also Lodge, 'Nature/ lxx. p. 176 (1904)), according 

 to which the unit positive charge when completely saturated 

 by an electron is joined to the electron by u lines of force, 

 it follows that a kernel X^ with one positive charge- can 

 bind u lines of force from electrons, but that this attractive 

 force is distributed equally over the sphere of the kernel. 

 If the kernel is now united to an electron to give the atom 

 X*E, since only a part of the spherical surface of the kernel 

 comes directly under the influence of the electron, the 

 kernel and electron will be bound by a number of lines of 

 force less than u. Let this number be v. Then the electron 

 and kernel are partially unsaturated, and can attach them- 

 selves to other kernels and electrons respectively by u — v 

 lines of force. 



We may therefore write the atom X /v E in the form 



>X A '«- — E >, the full arrow representing the v lines of 



force, and the dotted arrows representing the unsaturated 

 affinity of the kernel and electron, corresponding to u — v 

 lines of force. 



This formula may be compared with the formula for a 



strong electrolyte like potassium chloride >K*<<- — CI' > *, 



(Briggs, loc. cit. cxv. p. 278 (1919)). If now the kernel has 



* In these formulae the arrow-head always points towards the nucleus 

 which is the source of attraction. 



When potassium and chlorine combine, the potassium atom gives up 



its valency electron to the chlorine, as seen in the formula K >C1 (1). 



Here the thick arrow denotes the passage of an electron from potassium 

 to chlorine. 



The potassium kernel (potassium ion) has one positive charge and the 

 chloride ion has a kernel with seven positive charges united to eighl 

 electrons. The electrons in the chloride ion are therefore unsaturated. 

 and will be linked up to the potassium ion in the molecule KC1 by v 

 lines of force, where v<u owing to geometrical considerations. For 

 potassium chloride written as a compound of two ion3 we therefore 



have the formula >K*< — 01' ■> (2). Combining (1) with (2) we 



obtain - >lQI^Cl >, since (1) is equivalent to K'CT. 



The general formula >A^"^B >, includes all compounds from 



Phil. Mag. S. 6. Vol. 42. No. 249. Sept. 1923. 2 11 



