280 REPORT— 1885. 
The Copper Spectrum. 
Wave-lengths 
Scale numbers 
1 per cent. 0-1 per cent. | 0°01 per cent. | 0°001 per cent. 
Hundredths of an inch 
113°10 3306°8 3306°8 
115710 3289°9 
117-25* 3273°2 32732 3273°2 
120°7 3246°9 3246°9 3246°9 3246'9 
164-53 2959°5 
19013 2823°2 
201°36 2769°1 2769'1 
211°8 2721°2 
212°55 2718°4 2718°4 
213-7 2713-0 2713°0 
21671 2702°7 
216°58 2700°5 
219°37 2688°8 2688°8 
224°7 2666°7 
236°45t 2617°8 
241-1 2599-7 
241°58 2598°3 
255°94 2544°6 2544°6 
260°25 2528°8 2528°8 
261-00 25262 
266°77 2506°2 2506:2 
27091 2491°4 
271°65 2489°1 
272°72 2485°6 
276745 2473°2 
298°31 24033 
299°4 2400°1 
309-17 23716 23716 
309°57 2370°1 2370°1 
336°8 2295°0 
343-67 2277-0 
355°27f 2248-2 2248'2 
355°5 2247°7 2247-7 
357-1 Cae 2244:0 
357-32 2243°5 2243°5 
* This pair of lines differs from all others in the spectrum by not being shortened 
on dilution, but becoming attenuated till at last they disappear. They remain long 
lines till the last. 
¢ This is a very fine and very long line. 
{ This group is distinctly seen to be composed of four lines in the photographs 
of the 1 per cent. solution, and some lines, to the number of four or five, more 
refrangible than these are visible. 
