(64) 
Our next question is, for what value of 2 this will be a maximum. 
At all events this value will lie in the neighbourhood of i, and 
if the absorption bands are narrow, it will be permitted to replace 
* by 9, in the numerator of (19). Consequently, the denominator, 
for which we may write 
must become a minimum. [I shall neglect the variation of the two 
last terms, and replace in them # by A. Then, the minimum will 
be reached if 
Pree greet Apa en iy 
and the maximum of absorption will be determined by 
gtk 3,3 
yi2 Io es" q' 9 : 
2 %max. = 
In order that this may be very small, I shall suppose that g? is 
' 
. . ve . . . 
greatly inferior to a In this case, the last term in the denomi- 
t 
0 
nator may be negleeted, so that 
Fo 
9 
2 Amax. = q 
At the same time we see that the last term in (20) may be neglected 
in comparison with the preceding one; consequently our result will 
be true, provided that we may neglect the variation of the second 
term in (20), while the first term passes through its minimum. This 
condition will always be fulfilled, if the absorption bands are suffi- 
ciently narrow. 
The equation (21) may be replaced by 
2 . y De 2 9.2 
GERD =d =D 
We shall suppose # much smaller than 9,. Then, from what 
has been said, g? will be much smaller than 1, and in the absence 
of a magnetic field, i.e. for R=0, the maximum of absorption 
will lie in the immediate neighbourhood of 5. If, moreover, & Rip 
be very large in comparison with 3 4°,?, we shall have approxi- 
mately 
a 
