iv SUMMARIES OF PAPERS I N THIS I S S U E [October, 1966Summaries of Papers in this IssueThe Application of the Oxygen-flask Combustion Technique tothe Determination of Trace Amounts of Chlorine and Sulphurin Organic CompoundsThe Schoniger oxygen-flask technique has been adapted to trace analysis.An electrically fired apparatus has been designed that is capable of com-busting up to 100 mg of material. As little as 0.1 pg of chloride can betitrated potentiometrically with silver nitrate solution.Sulphate is titrated with barium perchlorate with thorin as indicator.Visual and spectrophotometric detection of the end-point has been investi-gated and the latter is preferred for amounts down to 0.5 pg of sulphate.Cations which interfere can be readily removed by ion exchange.R.McGILLIVRAY and S. C. WOODGERICI Fibres Limited, Hookstone Road, Harrogate, Yorkshire.Analyst, 1966, 91, 611-620.An Assessment of Some Methods of Analysis for DimethoateResidues in Fruit and VegetablesThree methods for determining residues of dimethoate, 00-dimethylS-(N-methylcarbamoylmethyl) phosphorodithioate, in fruits and vegetableshave been investigated for the purpose of recommending a standard methodthat can be applied to a variety of temperate fruits grown in the UnitedKingdom. Laws and Webley’s general method for determining organo-phosphorus insecticide residues was satisfactory for residues of dimethoatein sprouts, lettuces and apples, but not in peas. Chilwell and Beecham’sprocedure was also satisfactory at the 1 or 2 p.p.m.level of added dimethoatein cabbages, lettuces, apples and peas. Giang and Schechter’s method,however, gave variable results.N. A. SMARTPlant Pathology Laboratory, Ministry of Agriculture, Fisheries and Food, Har-penden, Hertfordshire.Analyst, 1966, 91, 621-624.An Improved Method for Determining Residues of DiquatThe ion-exchange method for determining diquat residues in potatotubers1 has been modified to give a simpler operating procedure and increasedaccuracy. Experiments on untreated samples with 0.08 to 0.2 p.p.m. of diquatadded showed an average recovery of 76 per cent. with a standard deviationof 11 per cent. The method, with minor modifications, has been foundto be generally applicable to other food crops and to water. For a 250-gsample, the limit of determination is 0-01 p.p.m.A.CALDERBANK and S. H. YUENImperial Chemical Industries Ltd., Agricultural Division, Jealott’s Hill ResearchStation, Bracknell, Berkshire.Analyst, 1966, 91, 625-629.Improvement in Performance of a Simple Atomic Absorptiometerby Using Pre-heated Air and Town GasA simple atomic absorptiometer for the routine determination of mag-nesium, copper and zinc is described. A pre-heated air supply to the atomiserincreased the response efficiency of the absorptiometer 16-fold. An adjustableslot in the burner enabled a wide range of fuel gases to be used. A horizontalmonochromator slit gave improved light transmission and absorption.R. A. G. RAWSONRothamsted Experimental Station, Harpenden, Hertfordshire.Analyst, 1966, 91, 630-637vi SUMMARIES OF PAPERS IN THIS ISSUEActivation Analysis for Titanium and Niobium with Fast NeutronsFast-neutron activation methods have been developed for determiningtitanium and niobium. Scandium-47 formed by the (n,p) reaction on titan-ium-47 and yttrium-90 formed by the (n,cc) reaction on niobium-93 have beenused for determining these elements.Irradiations were carried out in theswimming-pool reactor “Apsara” a t the Atomic Energy EstablishmentTrombay, at a fission-flux of 3 x loll n per cm2 per second. l<adiochemicalprocedures were developed for the isolation of scandium and yttrium from theirradiated samples. The methods have been applied to the determination oftitanium in stabilised steels and the standard rocks G-1 and W-1 and ofniobium in stabilised steels.The advantages and limitations of the methodsare discussed.V. T. ATHAVALE, H. B. DESAI, S. GANGADHARAN, M. S. PENDHARKARand M. SANKAR DASAnalytical Division, Atomic Encrgy Establishment Trornbay, Bombay, India.[October, 1966Analyst, 1‘366, 91, 638-646.An Automatic, Modified Formaldoxime Method for Determining LowConcentrations of Manganese in Water Containing IronAn automatic method for determining manganese in fresh watcr withthe AutoAnalyzer is described, together with details of the analytical system.The method is based on a modification of the formaltloxime procedure pub-lished by Goto, Komatsu and Furukawa,l which consists in reacting man-ganese with formaldoxime in alkaline solution, and decomposing any ironformaldoxime formed with EDTA and hydroxylammoiiium chloride.Aluminium, zinc, copper, iron, calcium, magnesium, chloride and plios-phate do not interfere at concentrations above those normally found innatural water in Norway.The capacity of the method is 25 samples per hour, and the stanclsrddeviation is 5,ug of manganese per litre.A statistical comparison of the manual persulphatc oxidation mctlmdwith the automatic formaldoximc mcthod indicated that both mcthodsgive identical results.A. HENRIKSENNorwcgian Institiitc for Water Rcscarcli, (_>\lo 3 , Norway.Ancclyst, l!Mi, 91, 047-651.An Automatic Method for Determining Orthophosphate in Sewageand Highly Polluted WatersShort PuperA.HENRIKSENNorwegian Institutc for Water Research, ()slo 3, Norway.Analyst, IOCici, 91, 652-653.The Determination of 4-Aminobiphenyl in Aromatic AminesShort Paper0. NORMANStaveley Chemicals Ltcl., Stavcley Works, Chc.sterficlc1.and G. A. VAUGHANThc Coal Tar Rcscarch Association, Goincrsal, T,ccds.Analyst, 1066, 91, 653-654...Vlll SUMMARIES OF PAPEIZS I S THIS ISSUESpecific Spot Tests for Silver CyanideShoYt PapevF. FEIGLLabxatorio da Produ@o Mineral, 3linist6rio das Llinas e Encrgia, Rio de Janeiro.and A. CALDASEscola Nacional de Quimica, Univcrsidadc do B r a d .[Octuber, 1966Analyst, 19G6, 91, 634-636.The Determination of Benzylpenicillin Traces in PropyliodoneInjection B.P.Short PaperMrs. DOROTHY J .SIMMONS and J. P. JEFFERIESGlaxo Laboratories Lttl., Greenfortl, 3Iitltllcscx.Analyst, 1966, 91, 656-659.The Spectrophotometric Determination of TraceAmounts of TantalumShovt PapevJOHN H. HILLLawrence Radiation Laboratory, University of California, Livermor?, California.Analyst, 1966, 91, 659-662.The Organic-phase Spectrophotometric Determination of Ironwith ThiocyanateShort PapevE. CERRAI and G. GHERSINILaboratori C.E.S.E., Casella Postale 3086, Milano, Italy.Analyst, 1969, 91, 662-664.A Direct Photometric Procedure for the Determination ofBoron in NickelShovt PapevT. R. ANDREW and P. N. R. NICHOLSCentral Materials Laboratory, The Xullard Radio Valve Company, ?;ew Road,Rlitcham Junction, Surrcy.Analyst, 1966, 91, 664-667.A Modified Potentiostat for Controlled Potential AnalysisShort PaperJ. GRIMSHAW and R. K. QUIGGDepartment of Chemistry, Queen’s Univerqity, Belfast, Sorthcrn Ireland.Analyst, 1966, 91, 667-669.Determination of Specific Gravity of Glass Particles by aDensity Gradient MethodShort PaperS. S. KIND and L. SUMMERSCALESHome Office Forensic Science Laboratory, Haddon Lodge, 32 Rutland Drive,Harrogate, Yorkshire.Analyst, 1966, 91, 669-670