The Second Spark Spectrum of Sulphur, S III

Analysis of the sulphur III spectrum.—With experimental data previously obtained the spectrum of sulphur III is analyzed. Most of the triplet terms predicted by the Hund theory are found and the strongest lines in both the visible and extreme ultra-violet regions are classified. The ground term $3s^{2}3p^2{}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}$ gives the ionization potential as 34.9±0.4 volts. Complete term tables and a list of classified lines are given. The term $3s^{2}3p·4s{}_{}{}^3{}_{}{}^{}P$ is anomalous, having a total separation of 450 while the $p$ doublet of the ion is 950. The interval ratio of this term is 10 to 1, instead of the 2 to 1 give by Landé's rule. Combinations of this term with the ground term in the extreme ultra-violet are unusually weak.