ON THE MEASUREMENTS OF WAVE-LENGTHS. 
133 
The Spectrum of Bismuth (continued). 
Scale- 
numbers. 
Description of lines. 
Wave¬ 
lengths. 
Remarks. 
334-40 
Weak, continuous, fine. 
23013 
335-83 
Weak, continuous, fine. 
2297-6 
337T3 
Weak, continuous, fine. 
2294 1 
338-09 
Very faint, short, nebulous .... 
2291-6 
342-20 
Short, faint. 
2281-0 
343-73 
Strong, continuous, sharp. 
2276-9 
353-59 
Faint, short, nebulous. 
2252-5 
354-41 
Weak, short. 
2250-5 
355-78 
Weak, short. 
2247-0 
362-20 
["Very strong, continuous, somewhat 
1 
J nebulous. 
2231-4 
S. Prominent lines. 
36310 
| Very strong, continuous, somewhat 
nebulous. 
2229 1 
- 
369-05 
Strong, continuous. 
2214-8 
373-83 
Strong, continuous, nebulous . . . 
2203-3 
379-29 
Faint, nebulous, continuous .... 
21904 
380-78 
Strong, continuous, nebulous . . . 
2187-0 
385-35 
Very faint, nebulous, short .... 
2176-6 
395-00 
Very weak, continuous, broad, nebulous 
2168-5 
400-16 
Weak, discontinuous, nebulous . 
2144-3 
405-17 
Weak, continuous, broad, nebulous 
2133-8 
416-40 
Faint, continuous, nebulous .... 
21098 
435-60 
Faint, short. 
2070-2 
441-69 
Faint, continuous, nebulous .... 
2058-2 
Coincidences of lines reed or apparent. 
Those lines the wave-lengths of which are approximately the same have been 
tabulated, and a close examination of photographs taken from electrodes of such metals 
as appear to have coincident lines has been made. The instances where lines appear 
to coincide are extremely rare. One particular case may be referred to, it is that of 
the two lines 2307 cadmium, and 2306’9 indium. The latter line is the stronger, 
which points to the occurrence of indium in cadmium, assuming the difference in 
the numbers to be accidental. An electrode of the one metal was opposed to the other, 
and a spectrum photographed with the diffraction spectroscope shows that the indium 
line is distinctly more refrangible than that of cadmium. Many air lines are coincident 
with metallic lines : this arises not only from their great numbers, but from their breadth 
and band-like character. In many parts of the spectrum some of our photographs 
show a continuous background to the metallic lines, which is formed of what to all 
appearance are finely and very closely ruled lines, these belong to the spectrum of air. 
