427
ANALYTICAL EDITION
NOVEMBER 15, 1935
Conclusions The average Conductivity value of Canadian sirups is higher than t&t of American sirups. Sirups originating in Maryland, Pennsylvania, and southwesternN~~ York show higher average conductivities than those from eastern New York, Vermont, and New Hampshire, with the exception of those from southeastern Vermont. The average value for light-colored sirups is lower than that for the darker sirups.
"Buddy" sirups, regardless of color, usually show higher conductivity values than normal sirups.
Literature Cited (1)
Official Agr. Chem., Official and Tentative Methods Of Analysis, 2nd ed., p. 204 (1925).
ASSOC.
393 (1930). (2) Ibid,, 3rd (3) h e l l , J. F.,J. IND. ENG.CHEM.,5,740 (1913). (4) Ibid., 8,331 (1916). RECEIVED August 30, 1935.
Bismuthate Method for Manganese. I1 BARTHOLOW PARK, Michigan College of Mining and Technology, Houghton, Mich.
I
N THE reaction between arsenite and permanganate in acid
solution used in the bismuthate method for manganese, the manganese is not reduced to the bivalent state (4, 6, 7,9, 10,
14,171. Lang (13) has shown that a dilute solution of potassium iodate catalyzes this reaction and causes it to proceed according to the equation 2Mn+++++++ 5As++++. 2Mn++ 5As+++++if the permanganate is added t o the arsenite in either sulfuric or hydrochloric acid solution. Cantoni (1)proposed the addition of one drop of 0.1 per cent potassium iodide solution as catalyst. Lang (18) studied this procedure. Swift and Gregory (16) make use of iodine monochloride in hydrochloric acid solution. Gleu (6) proposed the use of 0.01 M osmium tetroxide in sulfuric acid solution. Because the bismuthate method is usually carried out in nitric acid solution, it was thought advisable t o test these catalysts in its presence. For this work an electrotitration outfit similar to that described by Kassner, Hunze, and Chatfield (11) was set up with the followin modification: The 201-A tube was replaced by a Cunningham 8 3 3 tube, the two platinum electrodes were replaced by one platinum and one tungsten, and a milliammeter with a large scale was employed. This set-up was found to be extremely sensitive and it was very easy to determine the end point within one drop of the very dilute solutions used.
+
+
Preparation of Solutions STANDARD ARSENITE. Bureau of Standards arsenious oxide No. 83 (1.8019 grams) was dissolved in water by the addition of a little sodium carbonate and diluted to 2 liters. The per cent purity of this sample, obtained by titration, is given on the certificate as 99.97. This figure is based on calculations made with the 1925 atomic weights. Recalculating on the basis of the 1935 weights gives a value of 99.93 per cent which was used. A well-aged strong solution was STANDARD PERMANGANATE. diluted with distilled water in the ratio of 1 to 10 and then restandardized frequently with Bureau of Standards sodium oxalate No. M a . The results obtained corroborate the work of Halverson and Bergeim (8). After standing only 15 minutes the dilute solution was 0.5 per cent weaker than the value calculated from the strong solution. Four days later it was 1 per cent weaker than the calculated value. NITRICACID. Ordinary c. P. nitric acid was freed from oxides of nitrogen by blowing air through it as proposed by Cunningham and Coltman (3).
Experimental Results All titrations were carried out electrometrically, the drop which caused the largest deflection being taken as the end point. Twenty-five cubic centimeters of arsenite solution were pipetted out and the volume was made u p to about 200 cc. The other conditions were as noted in Table I. On the basis of this work a modification of the procedure for the bismuthate method in iron and steel is proposed. After filtering out the excess bismuthate on a Jena glass iilter No. 4, add the filtrate to a measured excess of standard arsenite solution containing 3 drops of 0.01 M osmium tetroxide and titrate with standard permanganate to the electrometric end point. (Cheishvili (8) has shown that washed and ignited asbestos reduces a small amount of permanganate when used as a filtering medium.) Bureau of Standards steel No. 65a was run by this method with the following results: found, 0.746 and 0.743 per
cent of manganese. The certificate gives 0.746 per cent of manganese. Bureau of Standards Norrie iron ore No. 28 was run by the bismuthate method as modified b y Park (16), using arsenite with the addition of osmium tetroxide instead of ferrous ammonium sulfate. The results obtained were 0.442 and 0.438 per cent of manganese. The average value for manganese as given by the certificate for all methods is 0.465 per cent. Blum found 0.44 per cent by the bismuthate method.
TABLE I. EXPERIMENTAL RESULTS Ratio Difference Acid Calculated Determined P. p. lOOd 1.004b Uncertainc 10 cc. HzS04 1.004 fine 10 CC. HzS04 1.004 1.006 +2 10 cc. &SO4 1.004 10 co. HzSO4 1.004 Uncertainc ii Izr 10 cc, %So4 1,004 1,022 OsOih 10 cc. &So4 1.004 1.0048 +0.8 0804 NaCli 10 CC. HzSOn 1.004 1.0048 +o.s KIOaa 15 cc. "03 1.00R Uncertainc 15 cc. "03 1.008 UncertainC I2 0 -pi. OsO4h 15 cc. "03 1.008 1.010 One drop of 0.0025M solution. b From weights of AszOa and NazCzOa standardization of KMnO4. 0 No determinable end point., d One drop of 0 . 0 0 2 5 M solution plus 1 gram of NaC1. a 1 gram of NaC1. f 1 gram of NaCl plus small crystal of 12. u Small crystal of 11. h Three drops of 0.01M solution. i Three drops of 0.01M solution plus 1 gram of NaC1.
Catalyst KIOP KIOa NaCld NaCl 6 Id NaCl
+
+ +
4
...
Q
Acknowledgment The writer wishes to thank T. R. Maki of this college for setting u p the electrotitration apparatus and assisting with the titrations.
Literature Cited (1) Cantoni, O., Ann. chim. applicata, 16, 153 (1926). (2) Cheishvili, P., J . Russ. Phys. Chem. Soc., 42, 856 (1911). (3) Cunningham, T. R., and Coltman, R . W., IND. EXG.CHEM.,16, 58 (1924). (4) Geloso, Max, Bull. SOC. chim., 37, 641 (1925). (5) Geloso, Max, Compt. rend., 171, 1145 (1920). (6) Gleu, K., Z . anal. Chem., 95, 305 (1933). (7) Hall, W. T., and Carlson, C. E., J. Am. Chem. Soc., 45, 1615 (1923). (8) Halverson, J. O., and Bergeim, O., J. IND.ENG.C H ~ M .10, , 119 (1918). (9) Holluta, J., Z. anorg. allgem. Chem., 168, 361 (1928). (10) Ibbotson, F., Chem. News, 117, 157 (1918). (11) Kassner, J. L., Hunze, R. B., and Chatfield, J. N., J . A m . Chem. Soc., 54, 2278 (1932). (12) Lang, Rudolf, Z. anal. Chem., 85, 176 (1931). (13) Lang, Qudolf, Z. anorg. allgem. Chem., 152, 197 (1926). (14) Oryng, T., Ibid., 152, 197 (1926); RocznikiChem., 7,334 (1927). (15) Park, B., IXD.ENG.CHBM.,18, 597 (1926). (16) Swift, E . H., and Gregory, C. H., J . A m . Chem. Soc., 52, 901 (1930). (17) Travers, H., Bull. SOC. chim., 37, 456 (1925). RECEIVED July 13, 1935
