54 
DR, A. SCHUSTER ON THE SPECTRA OF METALLOIDS. 
60101 
5960 J 
59001 
5840/ 
56301 
5553 J 
52921 
5205/ 
There is another band still more towards the red end than the least refrangible of 
these bands, but it was too weak to be measured. Unless care be taken, the two first 
bands might easily be regarded as one; but even with weak instruments a dark space 
is seen to separate them. The following are the more detailed measures of the centres 
of each line making up the two most refrangible bands. The second column gives 
half the width of each fine. The maximum of light in most of the lines is, however, 
not in the middle but towards the least refrangible edge of each line. Plate 1 gives 
a drawing of the bands when seen with large magnifying powers. The excessive 
weakness of the bands is an insurmountable obstacle to any very great accuracy. Thus 
it is possible that the five most refrangible lines of the most refrangible band (Plate 1, 
fig’- 1), which seem somewhat irregularly placed, are really at equal intervals, but I 
do not consider this likely. If the light is strong, the eye can readily detect an un- 
symmetrical arrangement without measurement; but, with the narrow slit necessary 
for measurement, the light was so weak that nothing but the line, which was specially 
fixed by the eye, could be seen, and no general view of the band could therefore be 
obtained. 
Least refrangible of the two green bands. 
Most refrangible of the two green bands. 
5552-8 
+ 0-5 
5205-0 
+ 0-6 
5558-4 
+ 0-5 
5213-3 
+ 0-6 
5564-5 
+ 0-5 
5216-9 
+ 0-6 
5570-1 
+ 0-5 
5225-3 
+ 0-6 
5575-8 
0-5 
5231-2 
+ 1-7 
5576-5 \ 
Limits of the maxi- 
5239-0 
+ 0-6 
5586-0 / 
mum of light. 
5247'7 
+ 1-9 
5591-4 
0-7 
5255-0 
+ 1-9 
Brightest part. 
5601-2 
0-5 
5262-7 
+ T7 
5611-2 
0-5 
5269-5 
+ 1-6 
5618-8 
0-5 
5276-9 
+ 1-0 
5629-6 
0-5 
5284-4 
+ 1-2 
5292-5 
+ 0-6 
The experiments were all made in the Cavendish Laboratory, Cambridge, and I am 
much obliged to Professor Clerk Maxwell for the kindness with which he has 
placed the resources of the laboratory at my disposal, 
