THE STRUCTURE OF THE SERIES OF LINE- AND BAND-SPECTRA. 569 
between series belonging to different chemical atoms is still closer. If we write our 
original equation (2) in the form 
il 2 b 
= 2 eh IL 
a,[(m + p) wel GS (9) 
we find that in certain cases the expression within the brackets is the same for two 
series. Under this special condition we have obviously 
Pas 
Vv 
= const. 
Nao > n 
I have found the following four instances of this kind : 
(1) Zine, 1st S.S., and Indium, Ist 8.8. Calling the difference (v» —v) in the case of 
Zn: |v]z, and in the case of In: [v],, we find from the preceding tables 
[van [vin 0-94374[7],, 
13029 13807 13030 
iy 7647 7217 
4585 4860 4587 
3173 3357 3168 
2326 2471 2332 
1779 1882 1776 
Hence we have, with suthcient accuracy : [v]z, = 0°94874[7],,. 
(2) Zine, 1st 8.S., and Mercury, Ist 8.8. 
[Vv] zn [vu | 1:01137[v]y, 
13029 | 12884 | 13031 
WT | 7134 7215 
4585 | 4537 | 4588 
3173 3134. 3170 
It obviously follows that [v],, = 0°94874[v],, =1°01137[)]z, . 
(3) Zinc, 2nd 8.8., and Mercury, 2nd §.S. 
ie wives | O0286lvly, 
| : 
22138 21856 | 22138 
10374 10243 10374 
6061 5986 | 6063 
3985 3934 | 3985 
2824 2788 | 2894 
