Determination of Tin in Babbitts, White Metal Alloys, and Bronze

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<ul><li><p>April 15, 1943 A N A L Y T I C A L E D I T I O N 26 1 </p><p>independent analyses by the acetin method. Samples 10 and 11 are synthetic soap lyes, made from weighed amounts of the standard A. 0. C. S. crude glycerin, salt, and water, t o simulate the average soap lyes found in practice. </p><p>Summary This method offers many advantages. The over-all time </p><p>is about 4 hours, and the applied time is less than 1 hour. The technique is simple and the apparatus is readily avail- able. The deviation from accepted or independent analyses of crudes is less than 5 parts per thousand, a fact that recom- mends it as a cost-accounting tool. </p><p>Although the method has not been perfected t o the degree </p><p>t h a t the author would like, he feels t h a t i t is essentially use- ful as it stands and tha t refinements may be added when i t is generally tried out. </p><p>Literature Cited (1) Am. Oil Chem. Soc., Official and Tentative hlethods, p. D-5 </p><p>(2) Andrews, J. T. R., et al., Oil &amp; Soap, 18, 14 (1941). (3) Committee on Fats, Soaps, and Glycerine, Division of Industrial </p><p>Chemists and Chemical Engineers, AM. CHEM. SOC., J. IND. ENC. CHEX, 3, 682 (1911). </p><p>(1941). </p><p>(4) Govan, W. J., Jr., Oil &amp; Soap, 19, 27 (1942). (5) Lawrie, J. W., Glycerol and the Glycols, pp. 234-5, New York, </p><p>Chemical Catalog Co., 1928. </p><p>Determination of Tin in Babbitts, White Metal Alloys, and Bronze </p><p>EDWARD T. SAXER AND ROBERT E. MINTO, Otis Works, Jones and Laughlin Steel Corp., Cleveland, Ohio </p><p>seeking a more satisfactory method for the WHILE determination of small amounts (</p></li><li><p>262 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 15, No. 4 </p><p>TABLE 11. DETERXISATIOS OF T I K Iii TIX-BASE BEARING METAL </p><p>of tin present) (National Bureau of Standards sample 54a, 88.61 per cent tin. 0.4431 gram </p><p>Determination Determination NO. Tin Found No. Tin Found </p><p>Gram % Gram % 1 0.4437 8 8 . 7 4 6 0.4437 8 8 . 7 4 2 0.4437 8 8 . 7 4 7 0.4437 88 .74 3 0.4437 8 8 . 7 4 8 0.4432 88 .63 4 0.4432 88 .63 9 0.4432 88 .63 5 0.4426 88 .52 10 0.4432 88 .63 </p><p>Mean 0.4434 88 .67 </p><p>To the h s k add 15 ml. of sulfuric-perchloric acid mixture (666 ml. of concentrated sulfuric acid, specific gravity 1.84, and 333 ml. of 72 per cent perchloric acid) and 2.0 grams of potassium sulfate, heat the mixture on a hot plate a t 150 C. until all the carbon is oxidized, and then gradually increase the temperature to 400 C. to drive off the perchloric acid. Cool the solution, first in air and then for a moment with ta water, and dilute with 10 ml. of cold water, followed by 180 mf of 1 to 2 hydrochloric acid. Starting with the addition of Stanreduce and increasing the time of reduction to 15 minutes, complete the determination as in the case of lead-base bearing metal, but omit the addition of the 135 ml. of cold water. </p><p>- NOTES. When the samde is dissolved in 1 to 1 nitric acid and </p><p>evaporated to dryness, the product formed is a granular, sandlike precipitate of metastannic acid which filters out well. If concen- trated nitric acid is used, the metastannic acid tends to become colloidal, and upon filtering may pass through the paper. In dissolving the metastannic acid, completion of solution is indi- cated when the flask clears. At this point, fumes of sulfuric acid only come from the mouth of the flask. </p><p>Determination of Tin in Bronze The following procedure applies to bronze of the type of </p><p>National Bureau of Standards sample No. 124, containing: copper, 83.77 per cent; zinc, 5.46; tin, 4.69; lead, 4.78; iron, 0.38; nickel, 0.45; and antimony, 0.23 (see Table 111). </p><p>Place 1.0000 gram of the sample in a 300-ml. Erlenmeyer flask, and add 15 ml. of 1 to 1 nitric acid. Dissolve the sample on a hot plate a t 150 C., add one half of a 9-cm. soft filter paper, and con- tinue to heat and swirl until the paper is macerated. Dilute to 50 ml. with water and heat to boiling. Filter through a 9-cm. No. 42 Whatman paper containing a small amount of pulp, wash the </p><p>flask once with hot 2 per cent nitric acid, and pour the washings into the filter paper. </p><p>Wash the filter paper five times with hot 2 per cent nitric acid, discard the filtrate, return the filter paper with its contents to the flask, and add 15 ml. of sulfuric-perchloric acid mixture. Then add 2.0 grams of potassium sulfate, heat the mixture on a hot plate at 150 C. until all the carbon is oxidized, gradually increase the temperature to 400 C. and continue heating until the per- chloric acid is driven off. 6001 the solution, first in air and then for a moment with tap water, and dilute with 10 ml. of cold water followed by 180 ml. of 1 to 2 hydrochloric acid. Com lete as in fead-base bearing metal, starting with the addition of &amp;an- reduce, but omit the addition of the 135 ml. of cold water. The time of reduction can be reduced to 6 minutes. </p><p>Since metastannic acid is a colloidal precipitate, con- tamination is increased if the solution is evaporated to dryness, as some authors recommend (1). The process of eva orating to dryness consumes an excessive amount of time, and i r the evapo- ration is hastened by overheating, cupric nitrate may be de- \ nmposed, with consequent contamination of the metastannic ai4d If the analysis is carried out as directed with respect to acid concentration and filtration, the filtrate will be perfectly clear. Sufficient copper may remain in the metastannic acid to give a yellow tinge when hydrochloric acid is added, but the authors have found this insufficient to do any harm. </p><p>NOTES. </p><p>TABLE 111. DETERMINATION OF TIN IN BRONZE (National Bureau of Standards sample 124, 4.69 per cent tin. 0.0469 gram </p><p>of tin present) Determination Determination </p><p>NO. Tin Found No. Tin Found Gram % Gram % </p><p>1 0.0467 4 . 6 7 6 0.0462 4 . 6 2 2 0.0467 4 . 6 7 7 0 .0462 4 . 6 2 3 0.0462 4 . 6 2 8 0 .0462 4 . 6 2 4 0.0462 4 . 6 2 9 0.0462 4 . 6 2 5 0.0462 4 . 6 2 10 0.0462 4 . 6 2 </p><p>Mean 0.0463 4 . 6 8 </p><p>Literature Cited (1) Kolthoff, I. M., and Sandell, E. B., Textbook of Quantitative </p><p>Inorganic Analysis, 1st ed., p. 659, New York, Maomillan Co., 1936. </p><p>(2) Low, A. H., Weinig, A. J., and Schoder, W. P., Technical Methods of Ore Analysis, 11th ed., p. 242, New York, John Wiley 8 Sons, 1939. </p><p>(3) Saxer, E. T., and Minto, R. E., Steel, 109,66 (1941). </p><p>Sugar Analysis by Alkaline Ferricyanide Method Determination of Ferrocyanide by Iodometric and Other Procedures </p><p>D. T. ENGLIS AND H. C. BECKERI, University of Illinois, Urbana, Ill. </p><p>NE of the problems of special interest when reducing 0 sugars are t o be estimated by oxidation with alkaline ferricyanide solutions is the selection of the method for deter- mination of the amount of reagent which has been consumed. The reduction product, ferrocyanide, is frequently estimated volumetrically by titration with one of the stronger oxidizing agents. </p><p>Burriel and Sierra (2) titrated ferrocyanide satisfactorily with r tass ium dichromate in 0.3 N hydrochloric acid solution, using </p><p>enzidine acetate as indicator. Muller and Diefenthaler (6) em- loyed permanganate in a solution acidified with sulfuric acid. </p><p>h r m a n and Evans (3) used ceric sulfate in hydrochloric acid solution with c-phenanthroline as indicator. However, as they have shown, cerous compounds may be oxidized to ceric by ferri- cyanide in 30 per cent potassium carbonate solution. Where only ferrocyanide is to be considered, the use of some one of these stronger oxidizing agents generally is to be preferred. The res- ence of the oxidation products of the sugars along with the grro- </p><p>1 Present address, The Teraco Company, Beacon, N. Y </p><p>cyanide raises the question as to whether these substances may not also have reducing action upon the reagent used to titrate the ferrocyanide. </p><p>Strepkov (8) reports that oxidizing of dextrose and levulose with O8tS solution, removing the cuprous oxide, then adding a definite amount of ferrocyanide to the residual solution contain- ing the oxidation products of the sugars, and titrating the mix- ture with potassium dichromate gave results whirh were in good agreement with the blanks containing only the ferrocyanide. On the other hand, parallel experiments in which the augars were oxidized by a Fehlings alkaline-tartrate mixture showed a greater consumption of dichromate than was given by the blanks. Use of a weaker oxidizing reagent to estimate ferrocyanide would ap- pear to be advantageous in many instances where other reducing products than ferrocyanide are present. </p><p>Of the weaker oxidizing reagents, iodine has been employed for the titration of ferrocyanides. Considerable controversy ie apparent as to the conditions under which the reaction should be carried out. In neutral or weakly acid solution the reaction goes to the right, while in solution8 more strongly acidified it is reversed: </p><p>2KBe(CN)t + 11 +2KIFe(CNh + 2KI H+ </p></li></ul>


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