Band and Line Spectra of the same Metallic Elements. 
The spectrum of the uncon- 
densed spark passing between 
electrodes of metallic calcium in 
air, im vacuo, and in hydrogen, at 
normal and reduced pressures. 
The spectrum of the uncon- 
densed spark passing from solu- 
tions of calcium salts. 
The spectrum from a con- 
densed spark passing between 
metallic electrodes. 
The same, taken from solutions 
of calcium salts. 
129 
The spark is intermittent and variable, and, 
in hydrogen, at normal and reduced pressures, 
very irregular, intermittent, and uncertain.* 
The spectrum, under all these conditions, 
consists both of bands and lines. 
The spectrum consists of bands only, the 
less refrangible edges of which become re- 
duced to short lines with diminishing quantities 
of substance. A 4226-9 also appears. 
Very feeble bands, with very strong and 
numerous lines. The characteristic spark 
spectrum. 
Very feeble bands, with strong lines as 
above. 
In the above series of spectra we see the gradual development of a line 
spectrum from a band spectrum. The line which first makes its appearance may 
be supposed to be the fundamental vibration of the element, and its wave-length 
is 4226°9. It is the last to disappear, and may be termed, following M. A. 
de Gramont, the ultimate line. Next in importance are the red and green bands, 
which have a persistency almost equal to that of the ultimate line. But the most 
interesting fact is the production of band and line spectra simultaneously from the 
compounds of calcium in the oxyhydrogen flame, the lines of which belong to the 
same series as those produced by the condensed spark and the arc, but with less 
intensity. Here are rendered visible the conditions which obtain in the dissociation 
of compounds at different temperatures ; but that we are dealing with an element 
is evident; first, because the lines belong to a series for which a formula has been 
established in which the atomic weight is a function; secondly, the intense band- 
spectrum and the series of lines are obtainable direct from the element itself when 
vapourized in the flame; thirdly, seven strong bands, and five of the strongest 
lines observed in the arc and spark spectra, are simultaneously obtained from 
calcium compounds when heated in the oxyhydrogen flame. 
The compounds of strontium and barium yield similar results, but the number 
and variety of the different spectra examined have not been so great. Nevertheless 
it has been provedt that in these instances the spectra obtained are the spectra of 
* “ Note on the Spectra of Calcium and Magnesium as observed under different conditions.”—Scient. 
Proc. Roy. Dublin Soc., vol. xi. (N.S.), p. 243, 1907. 
} ‘‘On the Thermo-Chemistry of Flame-Spectra at High Temperatures.’”’—Proc. Roy. Soc., A, vol. 79, 
pp. 242-261. 1907. 
