The titer of permanganate solut ions standardized with sodium oxalate by the procedure usually employed (McBride's) has been found to be too high when compared wit h the values obtained with other primary standards, the error in some cases being as much as 0.4 percent. However, by modifying this procedure the titer obtained with oxalate agrees satisfactorily with the values found with potassium dichromate, pure iron, and arsenious oxide. In the recommended procedure, 90 to 95 percent of the permanganate is added rapidly to a diluted sulphuric acid (5+95) solut ion of sodium oxalate at 25 to 30° C, the solution warmed to 55 to 60° C and titration completed as usual. Data are presented which show the effect on the new procedure of variations in acidity , t emperature, and other conditions. CONTENTS Page
A procedure is given for the determination of nickel, manganese, cobalt , and iron in a high-temperature alloy. Niobium , tantalum, tungsten, and silicon are r en d ered insoluble b~' hydrochloric acid d ehydration after solution of the alloy in aqua regia. Molybde num and copper a r e precipitated with h ydrogen sulfide, and the sol ution is filtered. The filtrate is evaporated several t imes wiLh hyd r ochlori c acid and hydrogen perox ide to obtain a chloride so lu t io n of these e lements in the proper valence. The resulting solution is transferred to an anion-exchange column contain in g Dowex-l. The nickel and manganese, with chromium and some other elements. a re collected in t he first frac t ion by elut ion with 9 N hydroch lori c acid . Cobalt is collected in a seco nd fraction by elution wit h 4 N hydroc h loric ac id , and iron in a third by el ut ion w ith 1 N hydrochloric acid . The cobalt is determined by electrolysis from a weakly ammoniacal chloride solution co ntainin g hydroxylamine h yd r ochloride, and the oth er elements arc deLermined by con ven tional methods.
The r es ul.ts of a ~y ste n;ati c stud y of t~e elution be~lavior of titanium , tungsten, mol y bd enum , and 11l0blUm In vanous hydrochlonc-hydroflounc acid m edia are given. These data de~on st rate the behavi or . of th e anion c.ompl ex~s of thes~ el~m ents on an anion-exchange r eSIn ~olumn. The posslbJI Jty of severallllterestJJl g quantItat Ive separation s is eviden t, and expenmen ts are descnbed t hat demons trate that t hese elem ents can be sepa rated from ea ch oth er.
A colorimetric meth od is described for the determination of phosphorus in steels and irons. The phosphomolybdenum blue reaction is utilized, and the transmittancy of the colored solution is measured with a photoelectric colorimeter and a Corning Lantern Shade Yellow filter, No. 349. Provision is made for the effects of arsenic and silicon, and a method of compensating for the color of alloying constituents is given. An accuracy of ± 0.003 percent was indicated for steels whose phosphorus content ranged from 0.01 to 0.11 percent. With cast irons containing 0.25 to 0.80 p ercent of phosphorus, values accurate to ± 0.02 percent were obtained. A single determination of phosphorus in steel can be made in about 20 minutes, and a set of eight determinations can be completed in approximately 45 minutes.
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