220 
PROFESSORS G. D. LIVEIRG AND J. DEWAR OR 
but they lie in a part of the spectrum so near the limit of transparency of calcite that 
it is quite possible that there may be more beyond, which will show themselves when 
quartz prisms are used ; a strong triplet near N appearing in the spark, wave-length 
about 3605, 3598, 3585, does not show in the arc so far as we have observed. 
Aluminium lines. 
Approximate 
wave-length. 
Remarks. 
Approximate 
wave-length. 
Remarks. 
2659-8 
2652-0 
' 
■ Strong, frequently reversed. 
2268-7 
2263-1 
1 Strong, diffuse. 
2574-5 
1 
1 
2257-3 
2567-5 
J 
>> 55 ?? 
2216-0 
2378-4 
2373-2 
2366-9 
I 
A fourth faint line close to the 
2210-0 
Strong, diffuse. 
middle line of this group. 
Middle line very strong, 
generally reversed. 
2205-0 
Diffuse. 
Lead. 
The lines of lead are numerous and strong, and many of them readily reversed. We 
have not yet traced any probably harmonic series amongst them. 
Lead also gives some indefinite bands of continuous light about the region wave¬ 
length 2500. 
Lead lines. 
Approximate 
wave-length. 
" 
Remarks. 
Approximate 
wave-length. 
Remarks. 
4019-0 
280M 
Often reversed. 
3801-0 
2721-0 
3739-3 
2706-1 
3683-3 
Strong, often reversed. 
2697-0 
Middle of a vgry diffuse band. 
3670-7 
2662-7 
3639-3 
2650-5 
Diffuse. 
3572-0 
2627-8 
3260-0 
Rearly coincident with a line 
2613-7 
Strong, often reversed. 
3238-6 
of tin. 
2575-7 
Very diffuse. 
3219-6 
2476-5 
Strong, reversed. 
3118-5 
2446-1 
55 55 
2981 0 
] 
2443-7 
5 5 5 5 
2973'5 
>Weak lines. 
2428-5 
2967-0 
J 
2411-5 
5 5 5 5 
2872-0 
2401-8 
5 5 5 5 
2850-5 
A little above the magnesium 
2399-4 
line, sometimes hidden by the 
2393-7 
Very strong, reversed. 
expansion of the latter. 
2388-8 
2832-9 
Very strong and diffuse. 
2332-0 
2822-5 
Generally reversed. 
I: 
