High Series Terms in the Arc Spectrum of Mercury

The spectrum of luminous mercury vapor drawn into a low pressure chamber was found to have the series lines developed to high members. Wave-length measurements of these higher members in the singlet and triplet diffuse and sharp series were made. The ${}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}$ terms developed to $m=20\mathrm{}$ show that this series follows a Ritz formula accurately. The ${}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ series and especially the ${}_{}{}^{1\mathrm{and}3}{}_{}{}^{}D$ series also follow a Ritz formula with definite indications of slight perturbations near the end of the series.