Abstract
A rotating electrode for the spectrographic analysis of metallic samples is described in detail. The method uses cast disc samples 2 1/2 inches in diameter from one-fourth to one-half inch thick. Samples are rotated in a plane perpendicular to the primary slit of the spectrograph at speeds up to five R.P.M. The method of supporting the sample necessitates machining only one surface of the sample to provide both the supporting and sparking surfaces and assures a constant analytical gap distance during rotation. Analytical results are given for the determination of tin and aluminum in zinc and are statistically analyzed for precision by the rotating and conventional methods of analysis. Excitation conditions, line pairs and rotational speeds are given for the analysis of aluminum (.07–.2%), lead (.3–1.5%), iron (.005–1.5%) and tin (.2–2.0%) in zinc.
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