PROCEEDINGS 
OF THE 
Camlmbx^ |JIjil0S0p{tttHl StfmtjR 
The influence of a strong magnetic field on the spark spectra 
of lead, tin, antimony, bismuth and qold. By J. E. Purvis, M.A., 
St John’s College. 
[Read 6 May 1907.] 
The author has continued the investigations of the Zeeman 
effect on the spark spectra of various metals, the results and con- 
clusions of some of which have been already communicated to the 
Society*. In a preliminary paper describing the apparatus used 
in the experiments {Proc. Gamb. Phil. Soc. Vol. xil. Pt II. p. 82), 
he gave an account of the general effect on the spark spectra of 
the stronger lines of lead, tin, antimony, bismuth and gold. The 
experiments have been repeated with these metals, and some of 
the lines, which then appeared to be widened doublets, have been 
further separated. The lines of the first four metals were very 
diffuse and nebulous and there were frequent reversals. Also, the 
rapid oxidation of the electrodes, when the spark passed between 
them, produced an irregular discharge, so that the image had never 
the same clear definition as in metals less easily oxidised. The 
result was an absence of sharpness in the appearance of the con- 
stituents of the divided lines, and the constituents often overlapped 
when the line divided into more than three, and, occasionally, even 
when there were only three, so that some of the affected lines 
appeared to be widened doublets. By using a very narrow slit 
attached to the spectroscope, by shorter exposures and by intro- 
ducing a calcite prism between the spark and the focussing lens, 
in order to separate the constituents vibrating in different planes, 
some of these doublets have been further subdivided. 
But there may be still some doubt in distinguishing between 
* Trans. Camb. Phil. Soc. Vol. xx. No. vm. p. 193 ; Proc. Gamb. Phil. Soc. Vol. 
xiii. Pt vi. p. 325 and Vol. xiv. Pt i. p. 41. 
VOL. XIV. PT. III. 
15 
