iv SUMMARIES OF PAPERS IN THIS ISSUE [June, 1966Summaries of Papers in this IssueThe Determination of Phenol, o-Cresol and p-Cresol in AqueousSolution by a Kinetic MethodCertain phenols can be determined in aqueous solution by a kineticallycontrolled bromination in which the only measurement is the time taken forthe bleaching of an indicator. This time is proportional to the concentrationof the indicator. Since no specialised apparatus is needed, the method is notrestricted to the laboratory.A. E. BURGESS and J. L. LATHAMDepartment of Chemistry and Biology, Harris College, Corporation Street,Preston, Lancashire.Analyst, 1966, 91, 343-346.A Continuous Monitor for Hydrogen in GasesThe construction and use of an instrument for the continuous monitoringof hydrogen in gas streams is described.The principles upon which theinstrument is based are the catalytic oxidation of hydrogen to water, and thesubsequent determination of the water with an electrolytic hygrometer.Factors relevant to the efficient operation of the instrument for laboratory andplant conditions are discussed. Results indicate a coefficient of variation ofthe order of &Fi per cent. for the 80 to 1000 v.p.m. hydrogen range.J. A. J. WALKER and P. CAMPIONU.K.A.E.A., Reactor Materials Laboratory, Culcheth, Warrington, Lancashire.Analyst, 1966, 91, 347-349.The Determination of Helium-3 in Argon at Levels of 10-l2The helium in the argon is first concentrated by removing the argon onan activated charcoal trap at -190” C.The helium is then transferred to amodified A.E.I. Ltd., MS2 mass spectrometer equipped with a Vibronamplifier, in which the volume of the helium-3 (and helium-4) is measured.With 1-litre samples the limit of detection is approximately 2 x p.p.m.by volume.Current experience on establishing the level of helium-3 in the argonblanket gas of the Dounreay Fast Reactor is outlined.K. R. MELHUISH and H. CHAPMANDounreay Experimental Reactor Establishment, Thurso, Caithness.Analyst, 1966, 91, 350-354.A Precise CoulometerThis paper is a contribution to the application of coulometry to accurateanalysis, and describes an apparatus which can be used for the accurateassay of “pure” sodium carbonate. An instrument has been built whichmeasures coulombs with a probable error of &25 p.p.m.as the product ofa constant current and its time of flow. The current is maintained constantby an electric servo-system, and it is adjusted so that the voltage drop acrossa precise resistor is equal to the e.m.f. of a standard cell. Time is measuredby a quartz-crystal clock. The resistor and cell are checked against localstandards, which in turn have been calibrated against international standardsby the National Physical Laboratory. The clock is checked against a broad-cast frequency and the General Post Office Speaking Clock. Thus the quantityof electricity for a titration is referred ultimately to the fundamental standardsof mass, length and time; the titre is independent of knowledge of the purityof any chemical substance.J. C.QUAYLE and F. A. COOPERImperial Chemical Industries Ltd., Heavy Organic Chemicals Division, P.O. BoxNo. 2, Billingham, Co. Durham.A~~aEyst, 1966, 91, 355-362vi SUMMARIES OF PAPERS IN THIS ISSUEPrecise Coulometry : The Titration of Pure Sodium CarbonateA method is given for the precise and accurate titration of sodiumcarbonate with hydrogen ions generated by the coulometer described in thepreceding paper. This coulometer maintains automatically a constantcurrent for a measured length of time. The results are in good agreementwith those obtained by titration with standard acid referred to pure silveras the ultimate standard, and support proposals to establish the coulomb asa standard in volumetric analysis.Factors are discussed that affect theaccuracy and precision of analysis by controlled current coulometry.F. A. COOPER and J. C. QUAYLEImperial Chemical Industries T,td., Agricultural Division, P.O. Box No. 6, Billingham,Co. Durham.Analyst, 1966, 91,. 363- 373.[June, 1966Iodimetric Determination of Organo-aluminium CompoundsThe alkyl groups in various types of organo-aluminium compounds havebeen shown to react with iodine in hydrocarbon solution, and the stoicheio-metry has becn determined of the reactions occurring between iodine andtrialkylaluminium, dialkylaluminium chloride and dialkylaluminium alkoxidecompounds.Based on these reactions a reasonably rapid and accurate iodimetricmethod has been devised for the determination of low concentrations oforgano-aluminium compounds in various hydrocarbon solvents.Themethod is applicable to the analysis of the hydrocarbon solutions of organo-aluminium catalysts used for the polymerisation of ethylene and propene.Good agreement is obtained between the iodimetric procedure and aprocedure based on conductiometric titration with a standard solution ofisoquinoline for trialkylaluminium compounds and dialkylaluminium chlorides.The iodimetric procedure is also applicable to dialkylaluminium alkoxidecompounds, which cannot be determined by isoquinoline titration.T. R. CROMPTONCarrington Plastics Laboratory, Shell Chemical Company Limited, Carrington,Cheshire.Analyst, 1966, 91, 374-382.A Flame-photometric Method for Determining Traces of Calciumin Lithium ChlorideThe determination of calcium in solutions of lithium chloride (1-5 percent.w/v) containing up to 2 ,u,g per ml of calcium, and up to 1 pg per ml ofaluminium has been investigated. The use of different organic solvents hasbeen studied, and the sensitivity of the determination has been increased3-fold by the use of an aqueous methanol - butanol mixture. It has beenshown that the only serious interference effect, that arising from the presenceof the aluminium content, can be prevented by the addition of trans-1,2-diaminocyclohexane-NNN’N’-tetra-acetic acid (CDTA) . Recoveries fromsynthetic samples showed no appreciable bias, and replicate results indicateda satisfactory precision and a sensitivity of about 0-02 ,u,g per ml.P.EMMOTT and G. LAWM.G.O. Inspectorates, Chemical Inspectorate, Headquarters Building, RoyalArsenal, Woolwich, S.E.18.Analyst, 1966, 91, 383-387viii SUMMARIES OF PAPERS I N THIS ISSUEThe Colorimetric Determination of Hydroxamic AcidsN-Hydroxycarbamates, mono-hydroxyureas and di-hydroxyureas intissue extracts have been determined by diazotising sulphanilamide with thenitrite produced on oxidation and coupling with N - 1 -naphthylethylene-diamine. Mixtures of hydroxylamine and hydroxamic acids were determined( a ) , by selective oxidation a t pH 3.5 and pH 8.0, and ( b ) , after separation ofthe components by thin-layer chromatography.R. NERYChester Reatty Research Institute, Institute of Cancer Research, Royal CancerHospital, Fulham Road, London, S.W.3.[June, 1966Analyst, 1966, 91, 388-394.Plant Mineral Analysis by X-ray Fluorescence SpectrometryShort PaperR.JENKINS, P. W. HURLEYM.E.L. Equipment Co. Ltd., London.and V. M. SHORROCKSHill Farming Research Organisation, Edinburgh.Analyst, 1966, 91, 395-397.The Determination of Total Available Oxygen in Di- tertiaryShort PaperButyl PeroxideD. B. ADAMSLaporte Chemicals Ltd., Luton, Bedfordshire.Analyst, 1966, 91, 397-399.Modification of a Simple and Rapid Titrimetric Method forDetermining Carbon in Iron and SteelShort PaperR. F. JONES, P. GALE, P. HOPKINS and L. N. POWELLThe Steel Company of Wales Limited, Abbey Works, Port Talbot, Clamorgan.Analyst, 1966, 91, 399-400.A Simple Method of Preserving Thin-layer ChromatogramsShort PaperH. A. FONERCeramics Department, The Houldsworth School of Applied Science, The Uni-versity, Leeds 2 .Analyst, 1966, 91, 400-401.The Detection of Cashew-nut Shell Liquid by Thin- layerChromatographyShort PaperT. W. HAMMONDSTropical Products Institute, Gray’s Inn Road, London, W.C. 1.Analyst, 1966, 91, 401-402