

Nature of Dielectric Capacity. 7 



compounds B/(M 2 /)2 = 10~* 5 , and for the element gases it has 

 double this value. Since B, is 'constant, r is constant in both 

 cases, though for the element gases it seems to have only 

 half the value for these substances in their compounds. Let 

 us take the case of hydrogen as element with R = 0*795 x 10 -8 

 and 6 = 4-65 xlO" 10 , then r = O0054 x 10" 8 . In that paper 

 it was shown that in H 2 , He, N 2 , and 2 an ion in contact 

 with a molecule has with it potential energy due to the 

 electron of the ion at its centre and a pair of electrons in 

 the molecule which are at the same distance apart in these 

 four cases. For hydrogen this distance was estimated as 

 being 0*0352 x 10~ 8 . But with the molecular data used in 

 this paper and with the concept of a vibrator for each atom 

 that estimate requires some alteration. With N = 4xl0 19 

 the potential energy of 'hydrogen ion and hydrogen molecule 

 in contact was given as 916 x 10~ 16 , which ought to have 

 been 967 x 10~ 16 , if allowance had been made in the numerical 

 reductions for the difference between 15° 0. and 0° C. If 

 N = 2*77xl0 19 to go with the value of e given above, this 

 potential energy becomes 1396 x 10 -16 . If this is e 2 /,v(2a) 2 

 where a is the radius of the hydrogen atom, taken here to 

 be 0-861 X lO" 8 , then ^ = 0*0192 x 10~ 8 , which is 3'54 times r. 

 According to this computation x and r are not so nearly 

 equal as I stated them to be in " The Ions of Gases." Pro- 

 bably they will be found to be equal or both to be simply 

 derived from the same length, when we know more about 

 the details of contact between ion and molecule. 



2. A Theory of Dielectric Capacity. 



In an atom within the sphere of absolutely constant radius 

 H there are two electrons of special importance. The one is 

 uniformly distributed through this sphere, or on account of 

 its rapid random motion within the sphere behaves in certain 

 respects as if so distributed. The other may be treated as a 

 point electron at distance r from the centre of the sphere. 

 Suppose the atom placed in an electric field of intensity F 

 with whose direction the electric axis r makes an angle 6. 

 Then for all values of 6 the average projection of r on an 

 axis at right angles to F is r/2. So we place an electron at 

 the centre of the sphere of radius R and an opposite electron 

 at distance r/2 from the centre along any radius which is at 

 right angles to F, and treat this? electron pair as representing 

 an average case. The electrons experience two opposite 

 forces of amount ^F iu the direction of F. These may be 

 regarded as tractive forces over the average sectional area 



