Doulton Porous Ceramic Materials possess a l l the properties essentiali n present-day industrial filtering media. There are many advantagesin using this range ; among them the following :Regulated porosity and permeability with high resistance to aggressivechemicals. 0 Good resistance t o thermal shock and t o high tempera-tures. 0 Good mechanical strength. @ Adaptability and long life. DOULTONDOULTON & CO. LIMITED * LAMBETH LONDON - S.E.1lf you have aproblem-consultthe Pioneers-Matthews & Yates Ltd., have over 50years’ progressive experience in thedesign, manufacture and applicationof FANS FOR EVERY CONCEIVABLEPURPOSE.AII ” Cyclone ” Fans are economical infirst cost and operation.Our experts are at your service fostudy your own particular require-ments, to submit plans and estimates.When writing please state our Ref.C/P.c 1I ”WATSON-LAIDLAW” CENTRIFUGALS I1 Centrifugal force accelerates drying, separation and recoveryof chemicals, and gives results which would be impossible toattain by gravity settlement.” Watson-Laidlaw ’ I centrifugals embody the latest improve-ments and are designed and constructed to give efficient andreliable service.Thousands in use daily-write for particulars.WATSON, LAIDLAW & to., Ltd.,S o u t h Telephone 2545. : 9 8, L A I D L A W S T R E E T, .sF$$”’z&$.,.GLASGOW, ... C.511Tekgruphic Address :'' Casthermo, Smith,London."Telephone :Terminus 2030.,,d*The mark of precision and efficiency.BRITISH MADETHROUGHOUTIf you use heat-it pays to measure it accuratelyB.BLACK & SON, LTD.1, Green Terrace, Rosebeiy Avenue,LONDON, E.C.lThermometer Manufacturers(MERCURY IN GLASS T Y P E )Original Makers of the Improved, Gas-filled, Permanent Thermometers forLaboratory and Industrial Processes.Standard Thermometers of the highestaccuracy covering over a range fromminus zoo to plus 5zoo C.The black filling-in etchings will resistall solvents with the exception of thosethat attack the glass itself.The National Physical LaboratoryCertificates supplied, with any type.0 f all the principal Scientific Instrument and LaboratoryApparatus Manufacturers.iHomogeneous Lead Lined h s e l sThey Oxley process of homogeneous lead coatingprotects any form of chemical vessel with a coating,inside or out, of chemically pure lead.Operators are specially trained for this work, anda strict system of supervision and inspection giveperfect confidence that the finished work will standboth pressure and vacuum tests of the utmost severity.W e undertake the manufacture of all kinds of steelvessels, welded o r rivetted, and their lining by thehomogeneous or ordinary lead lining process.Alsoall chemical lead work, including coils, etc.H U N S L E T , LEEDS, 10London Omce : Winchester House Old Broad Street E.C.1’Phones: 27468 (3 lines) ‘Grams: ‘‘ OXBROS,” Leeds, 10THE DERBYSHIRE SILICA FIREBRICK CO., LTD.FRIDEN - HARTINCTON - Nr. BUXTONManufacfurers of theHIGHEST GRADE REFRACTORIESFOR THECHEMICAL, CARBONIZING AND STEELI NDUSTRI ESand WATER TUBE BOILERSGas-fired wire patenting Furnace built with D.S.F.Bricks and Insulated with” Dome “ Insulating BricksU S E” DOME ” BRAND INSULATING BRICKSFOR FUEL CONSERVATIONManufactured by the D.S.F. Co., Ltd.Telegrams :” Silica,” Friden, HartingtonTelephone:Hartington 30vSCIENTIFIC BOOKS0 .EWE & Co. Ltd.Comer of Cower Street and CowerPlace adjoining Uniuersify College.A very large selectionof new and standard worksin every branch of Sciencealways available.The Department for ScientificBooks, English and Foreign, is onthe first floor. 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EUSton 4282 (5 lines).iCHEMICAL PLAITREBUILT & GUARANTEEDBYBARBERS’ENSURESC 0 M PLETESATISFACTIONOur comprehensive stock at Hayesincludes-STILLS fabricated in various metalsMIXERS & KNEADERS,STEAM JACKETED MIXERS & PANS,CALORIFIERS, CONDENSERS,FRACTIONATING COLUMNS,HYDRO EXTRACTORS,VACUUM OVENS & PUMPSDEPHLEGMATORS & HEATEXCHANGERS,GLASS LINED EQUIPMENT,AUTOCLAVES all types,KESTNER FILM DRYERS,VACUUM DISTILLATION PLANT,TRIPLE ROLL MILLS,DISINTEGRATORS & BALL MILLS,SCREENING PLANT,CRYSTALLSIERS, EVAPORATORS,CONFECTIONERY PLANT,GAS PRODUCERS, ACID PUMPS,DUST EXTRACTORS,MILLING & GRINDING PLANT,ALUMINIUM & COPPER VESSELS,FILTER PRESSES all types & sizes,SULPHONATORS, CENTRIFUGES,VULCANISERS.PAINT PLANT, DYEING PLANT,ETC., ETC.WE HOLD COMPREHENSIVE STOCKSOF REBUILT & GUARANTEEDCHEMICAL PLANT BY LEADINGMAKERS.IMMEDIATE DELIVERY OF PLANTREQUIRED BY THE CHEMICAL &ALLIED TRADESC.BARBER LTD.CHEM l CAL ENGINEERSandMACHINERY MERCHANTSSILVERDALE GARDENSHAYES, MIDDX.Tclcphone : Telegrams :Hayes, Middx. “ Barchem,”73516 Hayes, Middx.QUEEN MARY(University of London)Principal :Maj.-General Sir Frederick Maurice,K.C.M.G.,C.B., LL.D., D.Lit.Degree Courses in Arts, Scienceand Engineering. 1st M.B.and Pre-Medical Courses forLondon Hospital MedicalCollege.Provision is made for ResearchWork for Students preparingfor M.Sc., Ph.D. and D.Sc.Degrees in Chemistry. Theresearch laboratories are wellequipped with apparatus foradvanced work in Chemistry.Fees from S30 12s. a year.Entrance Scholarships andExhibitions.~Halls of Residence for MenStudents and for WomenStudents.Prospectus Free on af@licationto the REGISTRAR-QUEEN MARY COLLEGE, E.lReady in AprilCALCIUM SUPERPHOSPHATECOMPOUND FERTl LISERSANDTHEIR CHEMISTRY AND MANUFACTUREby P.PARRISH, F.I.C., M.I.Chem.E., M.I.GasE.A. OGI LVI E, M.1.Mech.E.andCONT€NTSChap. I. General Survey of the Fertiliser Posifion, particularly as regardsCalcium Superphosphate - Chap. I/. World’s Phosphate SupplyChap. 111. The History and Chemistry of the Manufacture of SolublePhosphates . Chap. IV. Crushing and Grinding Plant - Chap. V .Manufacture of Calcium Superphosphate Mixing Plant a Chap. V I .Mechanical Dens and Excavators-Batch Type - Chap. VlI. MechanicalDens and Excavators-Continuous Types - Chap.VIlI. The OberphosProcess . Chap. I X . Artificial Drying of Superphosphate . Chap. X.Methods for Dealing with Toxic Gases . Chap. XI. Treatment andStorage of Superphosphate - Chap. X I / . Compound Manures andMixing Systems - Chap. XIII. The Manufacture of Phosphoric Acidand Double Superphosphate Chap. XIV. Treatment of Bones, andManufacture of Bone Superphosphate . Chap. XV. Manufacture ofBasic Slag . Chap. XVI. Mechanical Handling of Raw Materials andProducts Conveying Plant - Chap. XVII. Crystallisation and Granulationof Fertilisers - Chap. XVIII. Structure of the British SuperphosphateIndustry, and the Design and Conduct of a Calcium Superphosphate Works.Crown4fo750 illustrations 35’- nefProvisionalHUTCHINSON‘S SCIENTIFIC & TECHNICAL PUBLICATIONS34, PATERNOSTER ROW, LONDON, E.C.4xTHE INSTITUTE OF CHEMISTRYOF GREAT BRITAIN AND IRELANDThe Institute of Chemistry was established in 1877 to providethe Government and the public with the means of recognis-ing those who have been properly trained and proved to becompetent to practise chemistry as a profession.In 1885 theInstitute was granted a Royal Charter with authority to grantcertificates of competency, and to register persons qualifiedto practise, The aims of the Institute include the elevationof the profession of chemistry and the maintenance of theefficiency, integrity and usefulness of persons practising thesame, by compelling the observance of strict rules ofmembership, and by setting up a high standard of scientificand practical efficiency.Particulars of the Regulations and Examinations of theInstitute can be obtained (free) on application.All communications fo be addressed to the Registrar,THE INSTITUTE OF CHEMISTRY30 Russell Square, W.C.1London BuiltVACUUMEVAPORATORSIn double and quadruple effect, plusThermo Re-compression, the world’smost economic system.Jahn’s Britishand U.S. Patents. Numerous large in-stallations concentrating various tradeliquors operating in home and overseatropical factories. Steam jet producesVacuum, its exhaust heets. Air PumpPower at no cost !BEEF EXTRACT,BONE, GELATINE, HIGHVACUUM GLYCERINEAND FATTY ACIDDISTILLING PLANTFILTER, FOR OUTPUT,washable pulp medium.** FARMA” MILKCONDENSING PLANTMACHINERYIN STOCKxi!Telegrams: BELLAMY, PHONE, LONDONTelephone: EAST 1892JOHNBELLAMYLTD.43 BYNG ST., MILLWALL, E.14TANKS for OIL, PETROL,&c.MIXING& BLENDING Plant,PRESSURE and VACUUMVessels,AIR RECEIVERS, AUTOCLAVES, etc.,STORAGE BUNKERS andHOPPERS,STEEL CHIMNEYS, FLUESand DUCTS“LYTE-WATE” ROADWAGON TANKMODERN RUBBERCHEMISTRYby HARRY BARRONPh.D., BSc., A.I.C., A.I.R.I." A chemist will probably be most interested in Ihe chapter onthe analysis of rubber, which provides a complete scheme forIhe analytical examination of the product."-Engineering." The book constitutes a valuable addition to rubber literature,and its claim to be up-to-date has been entirely substantiated .. .f t contains so much which is excellent."-The Industrial Chemist.Demy 8vo. /flus t ra te d 78'- nefPOISON:The History, Constitution, Uses and Abuses ofPoisonous Substancesby HUGO GLASERTranslated by MARGUERITE WOLFF" This book i s not a scientific treatise on poisons, but it containsa lot of valuable information, and i s most pleasurable reading."M edica l Press.". . . should interest most medical students, and indeed beinstructive to them. All the common and many uncommonpoisons are dealt with, the range covering such diversesubstances as illuminating gas, alcohol, bacterial poisons, andgases used in warfare. . . ."-Kings College Hospital Gazette.Crown 8vo. 6'6 nefHUTCHINSON'S SCIENTIFIC & TECHNICAL PUBLICATIONS34, PATERNOSTER ROW, LONDON, E.C.4xiiCERAMIC COLOURS GLAZES & MATERIALSENAMELS FOR IRONBRITISH SEGER CONES-The Ideal temperature recorderHARRISON & SON (HANLEY) LTD.Phoenix Chemical Works,H A N L E Y , S T O K E - O N - T R E N T , E N G L A N DTelephone: HANLEY 5313 (7 lines) Telegrams: PHOENIX, HANLEYC H E M I C A L S O C I E T YMEMORIAL LECTURES(Suitable for presentation as school prizes)VOLUME I, 1893-1900.(Reproduced by a photo-lithographic process.)Price 105. 6d. Postage 6d.VOLUME 11, 1901-1913. (Reproduced by a photo-lithographic process.)Price 85. Postage 6d.VOLUME 111, 1914-1932.Price 6s. 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CODD, M.A.Crown 8vo 6s. net *- 10 Orange Street London W C 2xPRICES OF THE PUBLICATIONS OFTHE CHEMICAL SOCIETYFOR 1939f J. d .Journal of the Chemical Society(issued monthly) . . . , 3 5 0 perannum,postfreeBritish Chemical and PhysiologicalAbstracts " A " (issued monthly)A I General, Physical and In-organicchemistry .. . 2 5 0A I1 Organic Chemistry . . 2 5 0A I11 Physiology and Bio-chemistry . . . , . 3 5 0A1 andAII together . . . 4 0 0A I and A111 together . . . 5 0 0A I1 and A 111 together . . . 5 0 0A I, A I1 and A I11 together . . 6 0 0These prices include one copy of the General Index in eachcase.Abstracts as above printed on one side of the page, butwithout the General Index, are obtainable at the same prices.General Index, including " A "(Pure Chemistry and Physi-ology) and "B" (AppliedChemistry) separately . . 15 0 per copy, post freeAnnual Reports on the Progressof Chemistry, Vol. XXXV, 1938 . 13 0 ,, ??PUBLISHERS : THE CHEMICAL SOCIETYBURLINGTON HOUSE, PICCADILLY, LONDON, W.1xvTHE POLYTECHNIC, REGENT ST., W.1DEPARTMENT OF CHEMISTRY AND BIOLOGYHead of Department: H. LAMBOURNE, M.A., M.Sc., F.I.C.Day Courses:B.Sc. Degree Special and General (External), London University.Associateship of the Institute of Chemistry (A.I.C.) Diploma.I st Medical, Pre -Medical and Preliminary Scientific Courses inChemistry, Biology, Physics.Evening Courses :(a) B.Sc. Degree Special and General (External), A.I.C., Inter-mediate Science, Pre-Medical Course in Chemistry and Physics,National Certificates in Chemistry.( b ) Applied Courses in Gas Engineering and Manufacture; Pig-ments, Varnishes, Paints, Enamels and Cellulose Finishes ; Oils,Fats and Waxes ; Cosmetics.Full prospectus on application to the Director of Education.APPOl NTM ENTS BOARDof theIMPERIAL COLLE6E OF SCIENCE & TECHWOLO6VSouth Kensington, S.W.7Including :ROYAL COLLEGE OF SCIENCE, ROYAL SCHOOL OF MINES,CITY AND GUILDS COLLEGE.EMPLOYERS requiring graduates trained in scientific or technical studiesare asked to make use of the services of the Board.In the Chemical Department students are trained in Inorganic, Organicand Physical Chemistry, with special attention to analytical methods,and graduates who have done postgraduate research work in one of thesebranches, and in Agricultural Chemistry, are available.In the Department of Chemical Technology, the post-graduate coursesinclude instruction and research in the Chemistry of Fuel and Combustion,Reactions under High Pressure Catalysis, Chemical Engineering, etc.The services of the Board are free, and the Registrar will be pleased todeal with any enquiry. Employers can be put into direct communicationwith the Professor respecting any student considered for an appointment,so that first-hand information as regards suitability for the work proposedcan be obtained.Enquiries should in the first instance be addressed to the Registrar,Imperial College Appointments Board, Prince Consort Road, S. W. 7.* XviPURIFICATIONOFWATERFOR ALL PURPOSESBOILER FEEDPROCESS WORKTEXTILE PURPOSESTOWN SUPPLY, Etc.IS THE SPECIALITY OFJOHN THOMPSON(KENNICOTT WATER SOFTENERS) LTDM A D OFFICE AND WORKSWO LVE RH A M PTO NEstablished 40 YearsPLACE YOUR WATER PROBLEMSBEFORE US AND AVAIL YOUR-SELF OF OURUnrivalled ExperienceAlso Manufacturers of Domestic Water SoftenersTo face titk page. XVii