1486
ANALYTICAL CHEMISTRY
factors varying from 1.25 to 2.38. Corrections for unresolved background emission were necessary with the magnesite, the stainless steels, and the mixture of aluminum and manganese containing a small amount of manganese. The background emission in the magnesite sample was attributed to the magnesium oxide band which has its maximum emission a t 383 mp. T h e quantity of magnesium in this material mas over 200 time^ the manganese content. The interfering background emission in the stainless steels was probably caused by iron which lias a series of emission lines in the vicinity of 400 mp or by iron oxide which produces a band spectrum in this region, I n the case of aluminum-manganese mixtures, the background emission is detectable only when the sample contains over 85% aluminum and is presumably due to a iveak band spectrum from aluminum oxide. T h e results of several determinations for manganese on six Tvidely differing materials are given in Table I. The accuracy found in these determinations is consistent with tha,t reported b y other workers who have employed the flame photometric technique and is superior to that obtained by other emission spectrographic methods. Although this accuracy may he surpassed in absorptiometric or titrimetric methods for manganrsp.
the flame photometric method should he especially valuable where a simple, reasonably accurate, and rapid determination is required. After dissolution of the samples the time necessary to complete a duplicate analysis for manganese by the method suggested was never greater than 20 minutes. LITER4TURE CITED
Brewster, D., and Clanaen, C.. I r o n &e, 166, S o . 18, 88 (1950). Cholnak, (J., and Hubhard. D. AI., ISD. EXG.C H m r . , ASAL.ED., 16, 728 (1944). Gri-gs, AI. d.,Johnstin, II., and Elledge, B. E., I b i d . , 13, 99
(1941). ~I
Inman, W.R., Rogers, 1%. d.,and Fournier, J. A, har.. CHEY., 23, 482 (1951). Kuernmel, D. F., and Karl. H. L., Ibid., 26, 387 (1954). Meloche, 5'. IT., Ilamsay. .J. 13.. Mack, D. J., and Philip, T. V.. Ibid.,26, 1387 (1954). Mitchell. It. L.. J . Soc. C h e w I d . London. 55. 267 (1936) Xakai, T., hhida, It., and Hidaka, S., J . Chem. Soc. Japan: P u r e Chem. Sect., 73, 19 (1952). Kamage. H., .Vature. 123, 601 (1929). Strange, E. E., ah-.
