A method for the quantitative spectrographic analysis of the materials used in oxide coated thermionic cathodes for Fe, Cu, Pb, Mg, Mn, and Al, is described. The materials consist of barium-strontium carbonate or barium-strontium-calcium carbonate. The basic raw materials consist of barium nitrate, strontium nitrate, and calcium nitrate. The method employs briquetted samples and a high voltage alternating current arc. Fifteen samples can each be analyzed for six elements in two hours with an elapsed time of eighty seconds per determination.
T. J. ORGAN and S. L. PARSONS, "A Method of Spectrographic Analysis of Impurities in Materials for Oxide Coating of Thermionic Cathodes," J. Opt. Soc. Am. 38, 191-194 (1948)