MAGN'ETO-OPTIC PHENOMENA OF IRON, NICKEL, AND COBALT. 
95 
In the particular case of rj-^, both zero, the equation to determine m would be 
(HOJ^ + A'TTi'p'f' = 0, 
so that if M be the value of m given by this equation, and fl the corresponding value 
of OJ 
and therefore 
and 
4" Iirip = 0, 
_ 4:inp 
- n ^ . 
M® 
( 20 ) 
the values coinciding in pairs. 
The sign of M is ambiguous; we determine it by requiring that M shall have its 
imaginary part negative, in which case we shall find that its real part is positive. 
As we neglect second and higher powers of and 173 , the equations (19) of the 
general case may now be written, introducing this quantity M, 
so that 
t. Hfl [Irji + M773) 
(o./ — = — I. HQ [Irj^ + hli^g) J 
ojp = 11 + I . {irjy + M773) j J 
w/ = n2 1 1 — t . (/771 + Mr^g) j J 
oj] = fi I I + t j I 
Wo = H I 1 — t . (/771 + M773) j 
m^- = ' + ‘ • (k\ + MiJs)} ) 
= 4P 11 - t. ^ (k, + M,,)} j 
m, = M I 1 + ‘ (^’)i + Mi)3)| ) 
Ml, = M 11 — i. gK {ly/i + Mijs) J I 
( 21 ). 
( 22 ). 
(23), 
■ • (20. 
. . (25), 
results which will be of use later on. 
