DECEMBER, 1958 THE ANALYST Vol. 83, No. 993 PROCEEDINGS OF THE SOCIETY FOR ANALYTICAL CHEMISTRY JOINT MEETING A JOINT Meeting of the Society and the Association of Public Analysts was held at 3 p.m. on Wednesday, December 3rd, 1958, in the Wellcome Building, Euston Road, London, N.W.I. The meeting took the form of a Symposium on “Food Analysis.” During the afternoon session, the Chair was taken by the President of the Society, Dr. J. H. Hamence, MSc., F.R.I.C., and the following papers were presented and discussed: “The Determination of Chemical Antioxidants in Fats after Separation by Partition Chromato- graphy,” by K. G. Berger, M.A., N. D. Sylvester, M.Sc., F.R.I.C., and Miss D. Ril. Haines, B.Sc. ; The Estimation of Egg in Certain Foods by Enzymic Hydrolysis of the Phospholipids,” by C.B. Casson, BSc., F.R.I.C., and F. J. Griffin, BSc., A.R.I.C. Mr. H. E. Monk, B.Sc., F.R.I.C., P.A.I.W.E., President of the Association of Public Analysts, took the Chair at the evening session, which was opened by J. R. Nicholls, C.B.E., D.Sc., F.R.I.C. Under the general heading “The Identification of Coal Tar Colouring Matters in Foodstuffs,” two papers were presented by P. S. Hall, BSc., F.R.I.C., and R. C. Spalding, M.A., F.R.I.C., and were discussed. DEATHS WE record with regret the deaths of Alexander Hutcheon Bennett William Lincolne Sutton. SCOTTISH SECTION AN Ordinary Meeting of the Section was held at 7.15 p.m. on Wednesday, October 15th, 1958, at the Kenilworth Hotel, 5 Queen Street, Glasgow, C.1. The Chair was taken by the Vice-chairman of the Section, Mr.A. N. Harrow, A.H.-W.C., F.R.I.C. The following papers were presented and discussed: “The Determination of Acidity in Dark Lubricating Oils,” by W. Gibb, BSc., Ph.D., A.R.I.C., A.R.C.S.T., A.M.Inst.F., and H. Gibson, BSc. (see summary below); “Volumetric Analysis of Stannous and Total Tin in Acid-soluble Tin Compounds,” by J. D. Donaldson, B.Sc., and W. Moser, BSc., A.R.I.C. THE DETERMINATION OF ACIDITY IN DARK LUBRICATIXG OILS DR. W. GIBB said that the deterioration of mineral lubricating oils under conditions found in internal combustion engines was primarily the result of the reaction of oxygen with the oil at elevated temperatures. Acidic bodies, inter alia, were formed, and the oil became dark coloured. The determination of acid number was complicated by this dark colour, the weak acidity and the small amounts present.The direct determination of the oxygen content of the deteriorated oil by the Unterzaucher method (Analyst, 1952, 77, 584) now made possible an oxygen balance and the separate determination of the various groups of acidic constituents of major importance. Two-phase colour indicator methods of acid-number determination were unreliable (H. P. Ferguson, Anal. Chem., 1950,22, 289) owing to the absorption of carbon dioxide, saponification and emulsion formation. With heavily oxidised oils of high acid number, 653654 PROCEEDINGS [Vol. 83 even I.P. 1/55 method A (“Standard Methods for Testing Petroleum and Its Products,” The Institute of Petroleum, London, 1957, p. 13) could give a two-phase system. The newer method I.P.139/57T was only suited to lightly oxidised material, as the solvent (isopropanol - benzene - water) had difficulty in dissolving heavily oxidised sludges, and the p-naphtholbenzein end-point was difficult to see in black solutions. Determination of the end-point was improved by observing the colour change in froth (Ibid., p. 4), in narrow-bore glass tubing (Ibid., p. lo), in special titration flasks with narrow necks or narrow side-limbs (Ibid., p. 13; I. Kukin, Anal. Chem., 1957, 29, 461) or by means of fluorescent lamps (“Standard Methods for Testing Petroleum and Its Products,” p. 4), or a photoelectric colorirneter (R. H. Osborne, J. H. Elliott and A. F. Martin, Ind. Eng. Chem., Anal. Ed., 1943, 15, 642). The A.S.T.M.potentiometric method D664 (“A.S.T.M. Standards,” American Society for Testing Materials, Philadelphia, Pa., U.S.A., 1955, part 5 , p. 285) made use of the same solvent as I.P. 139/57T. The technique was time-consuming, and the electrodes had to be scrupulously clean and carefully shielded from electrical inter- ference. Since most oxidised samples gave no points of inflexion on the titration curve, end-points had to be taken at meter readings corresponding to suitable standard buffer solutions. Potentiometric titration of oxidised oils in a strongly basic solvent had attractive possibilities, since in such a medium weak acids showed a much greater acid strength than in water or alcohols (M. L. Moss, J. H. Elliott and R. T. Hall, Anal. Chem., 1948,20, 784; V.2. Deal and G. E. A. Wyldl, Ibid., 1955,27,47). Accordingly, potentio- metric curves that did not show points of inflexion in alcohol solvents should show them in a suitably basic solvent, so permil ting differentiation between carboxylic acids and phenols. With basic solvents, such as ethylenediamine, a totally enclosed anhydrous titration system was necessary. Anomalous titration curves had been reported for in- sufficiently basic solvents (H. B. van der Heijde, Anal. Chim. Acta, 1957, 16, 378). For the rapid determination of the acid number of very dark oils, Fenske’s fluorescein - methyl red indicator (Ind. Eng. Chem., 1941, 13, 51) had been used successfully. The red form of methyl red masks the fluorescence, which can be made to show up clearly on the alkaline side.Observation of the end-point is aided by illuminating the titration vessel strongly from the side and using a dark background to reduce transmitted light. No difficulty had been experienced in dissolving the sludges of heavily oxidised oils in the n-butanol - toluene solvent. Improved accuracy could be obtained with insufficiently dark samples by the addition of a neutral black dye to the oil solution. A complete oxygen balance also required the determination of carbonyl compounds. The oil was treated with hydroxylamine hydrochloride and the liberated acid was determined potentiometrically (J. Knotnerus, J . Inst. Petrol, 1956, 42, 355). A.S.T.M. method D664 was applicable. For rapid determination of liberated acid, the Fenske method in its original form was useless, as sodium butylate and methyl orange react with hydroxylamine hydrochloride.I.P. 139/57T solvent and titrant in conjunction with fluorescein - methyl orange indicator had been used successfully. The titrant was sodium butylate. AN Ordinary Meeting of the Section was held at 7.15 p.m. on Friday, October 31st, 1958, in the Lecture Room cf the Royal Society of Edinburgh, 22 George Street, Edinburgh 2. The Chair was taken by the Chairman of the Section, Dr. Magnus Pyke, F.R.I.C., F.R.S.E. The following paper was presented and dscussed: “The Analytical Chemistry of Phos- phorus,” by N. T. Wilkinson, F.R.I.C. AN Ordinary Meeting of the Section was held at 7.15 p.m. on Wednesday, November 19th, 1958, in the Upper Hall of the Royal Philosophical Society of Glasgow, 207 Bath Street, Glasgow, C.2. The Chair was taken by the Chairman of the Section, Dr. Magnus Pyke, F.R.I.C., F.R.S.E. The subject of “Developments in Gas Chromatography” was introduced by A. F. Williams, BSc., F.R.I.C., and the following papers were presented and discussed: “Quanti- tative Analysis Using Thermal Conductivity Detection,” by G. R. Jamieson, B.Sc., F.R.I.C. ; “The Application of Gas Chromatography tcl Reaction Kinetics,” by J. H. Knox, B.Sc., Ph.D. ; “Chromatographic Examination of a Low-temperature Tar,” by L. Irvine, BSc., Ph.D., A.R.C.S.T., A.R.I.C.Dec., 19581 PROCEEDINGS 655 MIDLANDS SECTION A JOINT Meeting of the Midlands Section and the Birmingham and Midlands Section of the Royal Institute of Chemistry was held at 7 p.m. on Thursday, November 13th, 1958, in the Main Chemistry Theatre, The University, Edgbaston, Birmingham, 1.5. The Chair was taken by the Chairman of the Midlands Section, Dr. R. Belcher, F.R.I.C., F.1nst.F. The following paper was presented and discussed : “The Infra-red Analysis of Solid Sub- stances,” by Professor G. Duyckaerts (Li&ge University).