Effects of Inert Atmospheres on Emission Spectra in the Interrupted Arc

A comparison of the spectra of several elements produced in the interrupted arc in helium, helium-oxygen mixtures, argon, and air has been made. It has been found that the differences observed in the spectra are not uniform, but vary according to the ionization states of the spectral lines; those lines requiring large energies for excitation being more intense in a rare gas atmosphere than in air, and those lines requiring small energies for excitation being more intense in air than in a rare gas. It is shown that with the interrupted arc the use of rare gas atmospheres cannot lead, except in isolated cases, to an improvement in the sensitivity of emission spectrographic analysis.