Photographs of the Spark Spectra of Elementary Substances. 235 
Description of the Cadmium Spectrum.—Vhe lines to the extreme left”hand of the 
photograph of cadmium which appear faint, are air lines with wave-lengths 464°4 
and 463°0. 
Cadmium line No. 7, =441-4, (Mascart).—A fine distinct line in the violet, 
discontinuous, coincident with an air line, 
a and %. Two continuous lines near together, very fine. 
Cadmium No. 8. =398°56, (Mascart).—This is an air line. 
Cadmium No. 9. =360°7, (Mascart).—This consists of a pair of exceedingly 
closely adjacent lines, strong, continuous, and extended. 
c. A sharp, faint, fine line, discontinuous. 
d. Very faint, nebulous, discontinuous. 
Cadmium No. 10. =346'4, (Mascart).—Shows indications of being double when 
the photograph is examined with a microscope and an object glass magnifying 
about 45 diameters. The line is strong, continuous, and extended. 
Cadmium No. 11. =340°3, (Mascart).—This is a single line, strong, continuous, 
and extended. 
eand f Between lines No. 11 and No. 12 of cadmium, there are two small 
discontinuous lines which are nebulous. 
There are at least forty of such lines in the spectrum, some of these are sharper 
and more distinct than others. There is a considerable number lying between the 
Ines Nos. 12 and 17. Omitting air lines, which are easily recognisable, we 
come to— 
g. A sharp, distinct, continuous line. This is coincident with oneof the strongest 
lines in the spectrum of indium, and it probably belongs to that element. 
It is very near No. 12. 
h. This is comparatively a faint line, but very distinct and closely adjacent 
to the line No. 12 of cadmium, 
_ Cadmium No. 12. =328-7 (Mascart).—Sharp, discontinuous if the spark be 
feeble or the exposure short, thin in the centre if the spark be strong and the 
exposure sufficient. 
There are many discontinuous lines or dots between Nos. 12 and 14. Fifteen 
are easily counted. 
Cadmium No. 14, (Mascart).—Not measured. Strong, continuous line with 
much of the appearance of an air line. 
Cadmium No. 15, (Mascart).—Not measured. A strong fine line somewhat like 
an air line. 
Cadmium No. 16, (Mascart)—Not measured. A very fine continuous line. 
2. Next to the former a very fine discontinuous line which proceeds froin 
_ one electrode only. 
Jj. A very fine discontinuous line of the same character as 7. 
k. A fine, faint, continuous line near cadmium, No. 17. 
