Electron 'Theory of Matter. 187 
we get 
&-v)Q+Vf =0, 
(lM ( Q+ f) +f {r + ^^h}-{S-o, K24) 
From these equations it follows at once that 
C'=0, 
Peli sin 
CJ = 
T P , *_ 2 ffJl+F)_ „ S*_ 
L p p 3 ^ j p 2 
Since the corresponding moment is equal to —^ne/3C and 
is along the axis of a, we get the effective moment of the 
ring by multiplying by sin 6. Averaging the result for all 
values of 0, we get for the mean effective moment due to the 
radial magnetic force the expression 
.. l»*P f25 x 
p p z 2 
Q^E^ffl^H}^" 
§ 20. The total mean effective moment per ring is equal to 
fan = 8m! + Sni 2 ; since all these quantities are proportional 
to h, at any rate for small displacements, we introduce the 
specific moments, defined by equations such as p = -=-, 
If N be the number of rings per unit volume, the magnetic 
susceptibility is given by £ = Np, if the several rings do not 
act upon each other ; this is at any rate an approximation for 
small concentrations, such as we find in amalgams of iron and 
cobalt. 
In order to form some idea as to the performance of our 
expressions (20) and (25) we shall consider some special 
arrangements of rings, without enquiring into their stability 
and permanence. 
