Determination of Alumin Aluminum Using the Mercury ALBERT C . HOLLER AND United States \letal Produq
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!%AUK-; of t,he increased use of manganese and aluminum bronzes, it was necessary to find a newer and more rapid and accurate method for the determination of aluminum in these alloys. This paper describes a procedure that fills the above requirements. After a thorough search of the literature, it was decided that the mercury cathode cell (S, 6, 8, 9 ) would be best suited for the rapid and complete separatinn irnn . m .~-..~--, n ~ s n ~._--, ls e d ..... , ....~ ~ m ".".."f"._____, ..9_ . .d .~C~ ~O. ~,~P Pfrom aluminum. The composition of typical manganese and aluminum bronzes is given in Table I. ^
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TABLEI. COMPOSITIOX OP B R O N E E ~
C" Zn 111,
Fe I1
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Manganese Bronze. Bureau of Standsrds. YO. 62% To 61.50 33.05 1.50 1.04
Aluminum Heat 3794, Bronze. 70
0.92
Ni
0.84 0.61
Ph
0.50
u,,,,,, b l m U,""Zt. "a> " I X , " L Y F U all" b u r " I l Y r l "I " L u ' " 6 r u .2>c driven off. Add 100 ml. of hot Nater. brinc to a boil. and allow to digest on a hot plate for 1hour or longer, kFeping the temperatue just below the boiling point. Filter off the metastannic acid (double thickness of No. 42 Whatman paper) and wash thoroiiehlv with boiline hot water. Discard the nrecinitate. To the add 10 ml.-af sulfuric acid (sp. gr. f.84)+and evaporate until copious fumes of sulfuric acid are evolved. Complete removal of the nitric acid is essential. Allow to cool, add 50 ml. of wn,t,er. hmt, t,o hoilinz to dissolve all soluble salts. and filter off the lead sulfate formYd through a Gooch crucibli. Wash thoroughly and transfer the filtrate to a GOO-ml. beaker. Neutralize the acid present with sodium hydroxide solution (10 per cent) and add 5 ml. in excess. Bring the solution back to acidity with acetic acid (1 to 3), heat to boiling to complete the reaction, and add 5 ml. of glacial acetic acid in excess. Cool, dilute to 350 ml., and add 2 to 3 drops of defoaming agent. Transfer to the Melaven mercury cathode cell and electrolyse at a current of 1 to 2 amperes for 3 hours. To test for the complete deposition of copper and iron, use potassium ferrocyanide and potassium ferricyanide, respectively, using fine-bore capillaly tubes to take the spot tests (7). When the elcctralysis is complete, lower the leveling bulb until the mercury reaches the upper cnd of the stopcock bore, turn the stopcock through 180 degrees, and allow the electrolyte to drain off into a GOO-ml. beaker.
91.87
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... 0.89 0.41 0.40
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Experimental The prooedures of Shubin (11) and Gerke and Lyubomirskaya (6) were tried but each had its limitations: mainly, that two steps were necessary for complete separation of iron from aluminum (5), the rather large error ( l f ) and , the use of sulfuric acid zs the indifferent electrolyte. For alloys of high manganese content (1 per cent or higher), the mixed hydrous oxides (iron, man-
ganese, and aluminum) which were formed on neutrahzatlan w t h ammonium hydroxide failed to redissolve on acidification u~ithsulfuric acid. Consequently, a new conducting medium was sought. Acetic acid gave very good results. The hydrous oxides readily dissolved. With an acetic acid medium the electrolytic separation of aluminum from iron, manganese, lead, zinc, nickel, and copper was found to be complete and quantitative. Acetic acid foams bxdly, but this can be overcome by adding a defoaming agent such as oetyl alcohol (IO)or Antifoam L F X (du Pant). To test tho aocuracy of the rocedure, samples of National Bureau of Standards Standard gample G2a, manganese bronze (0.92 per cent aluminum), were run. The average accuracy was 0.005 per cent.
FIGURE 1. APPARATUS Wash out the electrolytic cell with water. Filter off the precipitated manganese dioxide (No, 40 Whatman paper) and wash thoroughly with warm water. To the filtrate add 10 grams of ammonium chloride, 2 to 3 drops of methyl red, and ammonlum hydroxide (1to 2) until the solution is distinctly yellow. Heat the solution to boiling and boil gently far 1 to 2 minutes, filter off the aluminum hydroxide (No. 40 Whatman pzzper), and wash the precipitate 2 to 3 times with hot ammonium chloride solution (2 per cent). Discard the fltrate and dissolve the precipitate in 40 ml. of hat hydrochloric acid (1 to 1). Wash the filter thoroughly and dilute to 100 ml. Add methyl red and neutralize with ammonium hydroxide (1 to 2) as before. Heat to boding, filter off the aluminum hydroxide, and wash with hot ammonium chloride solution. Place the paper and the precipitate in a platinum crucible, char the paper, and burn off the carbon. Then ignite the oxide in a furnace or over a blast lamp at R temperature of 1200' C. Cool and weigh as ALO,. 11. Weigh out a 1-gram sample and determine the tin, lead, and copper stepwise by standard methods ( I ) . To the filtrate from the electrolytic copper determination add sodium hydroxide and acetic acid 8.8 in procedure I. After nentraliaation and acidi-
Apparatus and Reagents APPARATUS. Figure 1 shows the complete setup, whioh oonsists of a Melaven mercury cathode cell (9) and a Fisher electroanalyzer to supply the current and stirring action. The anode, which is of the platinum stirring typ?, is attached to the motor of the clectroanalyzer. REAGENTS.Ammonium chloride solution (2 per cent) wa6 prepared by mixing 15 ml. of hydrochloric acid (sp. gr. 1.19) with 250 ml. of water, adding 2 t o 3 drops of methyl red, neutralizing with ammonium hydroxide (sp. gr. 0.90), and diluting to 500 ml. with water. The mercury used was purified by shaking with a few milliliters of water and mercurous nitrate crystals (4). Octyl alcohol (IO)or Antifoam L F X worked exceedingly well as defoaming agents.
Procedures I. Weigh out a I-gram sample of bronze and transfer to a 250-ml. beaker, add 20 ml. of nitric acid (sp. gr. 1.4% and heat 719
720
INDUSTRIAL AND ENGINEERING CHEMISTRY
ficationwith acetic acid, place the solution in the mercury cathode cell and proceed with the determination of aluminum as given in procedure I. If preferred, &hydroxyquinoline may be used instead of ammonium hydroxide as a reagent far the precipitation of aluminum.
Discussion Aluminum in a Bureau of Standards Standard Sample No. 62a (manganese bronze) was determined by the above procedure. A few comparative results are given: Procedure of This Paper
% 0.928 0.925 0.922
47.
0.925
The use of an acetic acid medium eliminates the two-tep procedure of Gerke and Lyubomirskaya (5)for the sepdration of iron and also increases the accuracy of the determination. The maximum accuracy that Shubiu (If), using a sulfuric acid medium, could obtain was 0.07 per cent, whereas with the acetic acid medium the minimum accuracy is 0.008per cent. The procedure is far superior to the old sodium hydroxide separation, whose main disadvantage was that the sodium hydroxide dissolved to a slight extent the iron and manganese hydroxides (B).
Vol. 14, No. 9
Acknowledgments The authors wish to express their appreciation to A. Devor, Erie Center, University of Pittsburgh, for the sample of octyl alcohol and to E. I. du Pont de Nemours & Co., Inc., for the sample of Antifoam L F X.
Literature Cited (1) Am. SOC.Testing Materials, "A. S. T..M.. Methods .. . -. .of .Chemical . . . Analysis of Me tala'', 'Tentative Method3 Of Chemical Analysis of Mmganese :Bronue, B 27:36T, pp. 113, 129 (1939). (2) Churchill. H. V., and Bridges, R. W.. "Chemioal Analysis of Aluminum", p. 10. New Kensineton. Penna.. Aluminum Research Laborat Craighesd, C. M., IND.NNG.C~AEM..ANAL. ti^., z,IUY (IYBU). Easly, H. F., Ibid., 9,82 (1937). Gerke, F. K., and Lyubomirskaya. N. V., Zavodskaya Lab., 6, 746 (1937). Hillebrand and Lundell, "Applied Inorganic Analysis", p. 390 New York. John Wiley & Sons. 1929. Holler, A. C., Chemist-Analyst (publication pending). Lundell, G. E. F.. Hoffman, J. I., and Bright. H. A.. "Chemical Analvsis of Iron and Steel", I). 48. New York, John Wiley & Sons; 1931. (9) Melaven. A. D.. IND.ENQ.Cam., Cam%.,ANAL.ED.,2,180 (1930). (10) Mellan. I., "Organic Reagents in Inorganic Analysis", p. 176, Philadelphia, P. Blakiston's Son & Co.. Philadelnhia. Co., 1941. ZavodskayaLab., (1936). (11) Shubin. M. I., Zavodskaya Lab., 5, 407 (1936) ~
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Testing Writing Inks With Rubber Fountain Pen Sacs ROBERT S. CASEY AND ROGER MACDONALD, W. A. Sheaffer Pen Co., Fort Madison, Iowa
Many commercial writing inks hasten deterioration of soft-rubber fountain pen parts. Soft rubber affects stability of some writing inks, particularly permanent inks. Methods of testing are proposed.
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H E present . necessity . '. for conserving rubber and extendmg the hie of existing rubber articles prompts the authors to report their observations of the action of writing inks on soft-rubber fountain pen parts, and to propose a comparative test.
F I G ~I E , SACS FROM SCRAP Box
There is a dearth of published data on this subject, though Waters (6) stated, "The general use of the self-filling pen, which has almost supplanted the older kind with the medicine dropper, seems to be good evidence that the rubber bags are not damaged by ink. The failure of a bag in an old pen is no proof that the ink is to blame. Rubber does not last indefinitely." These latter two statements are true., It is well known that oxygen acts upon soft rubber, causing loss of tensile strength and eventual hardening. However, many substances have a profound effect on the rate of such aging (3). Casual observations over limited periods of time may reveal no serious action of inks on rnhber sacs, but examination of the sacs customarily dismantled from pens returned for repair always shows some hardened and broken from causes other than mere time in service. Figure 1 shows a representative handful of sacs taken from a scrap box, with some of the worst specimens moved into the foreground. The condition of these sacs is duplicated by sacs subjected to the authors' aging test. Incidentally, the effectof stress on aging is also illustrated by the sacs that became twisted in the pen barrel and hardened p r e maturely The authors subjected sacs, after immersion in inks, to oxygen or air a t elevated temperatures, the recognized methods of accelerated testing (4), and found that many writing inks greatly hastened and some retarded the aging of the sacs.
