SOIL CHEMICAL ANALYSISBy M. L. Jackson. Med- 8vo. 498 pages. Illustrated.57s. 6d.This book gives the most frequently used soil chemical analysis pro-cedures, useful in instruction and research in soil chemistry, soil fertilityand soil genesis. Because plant growth is essentially related to thesefields, procedures are given for plant inorganic constituents. The authoris Professor of Soils, University of Wisconsin.ELECTROCHEMICAL PROCESSES IN CHEMICALINDUSTRIESBy A. Regner. Translated by K. Kutif, J. Wirner, A. G.Evans. Ex. Cr. 8vo. Paper. 464 pages. 149Jigures.1957. 30s.The theoretical part of this book deals with the basic laws of electro-chemistry and of chemical equilibrium. It then goes on to discuss elec-trolytic conductance and various types of galvanic cells and concludeswith a section on electrolysis and polarization.The second part dealswith industrial applications, beginning with the construction of electro-lytic cells from the general point of view, and the electrolysis of water.Then follows an account of the manufacture of chlorine, hydrogen per-oxide, etc.CHEMICAL ENGINEERING OPERATIONS: An Tntro-By F. Rumford, Ph.D., B.Sc., F.R.I.C., M.1.Chem.E. (De-partment of Chemistry, The Royal Technical College,Glasgow). 2nd Edition. Demy 8110. 387pages. Illus-trated. 1957. 32s. 6d.duction to the Study of Chemical PlantCHEMICAL ENGINEERING MATERIALSBy F. Rumford, Ph.D., B.Sc., F.R.I.C., M.1.Chem.E.Demy 8170. Illustrated. 2nd Edition.AN INTRODUCTION TO THE THEORY AND PRAC-TICE OF SEMICONDUCTORSBy A.A. Shepherd. Ex. Cr. 8vo. 212 pages. Illustrated.1958. 18s. 6d.CONTENTS: Structure of Solids - Conduction in Semiconductors -Minority Carriers - Semiconductor Single Crystals - Rectification bySemiconductors - Transistors - Light Sensitive Semiconductor De-vices - Semiconducting Compounds.Complete catalogue available on requestCONSTABLE & CO. LTD10 ORANGE STREET, LONDON WC2iRecommended B.D.H. Indicatorsfor Calcium TitrationsAmong the many indicators suggested for thecomplexometric titration of calcium three show evident practicaladvantages. We recommend them for laboratory use :o= Cresolphthalein complexoneAnderegg, Flaschka, Sallmann and Schwarzenbach, Helv. Chim. Acta,1954, 37, 1 13.Complexes metal cations and forms deep red chelates with calcium,strontium and barium.The magnesium chelate is pink,Titrations, at pH 10-11, should be carried out in 2550% alcoholsolutions to suppress the faint pink colour of the indicator molecule.lg 6s. 3d. 5g 24s. 3d.Patton & Reeder’s Reagent(2-h ydrox y-l -( 2-h ydrox y-4-sulpho- 1-naph thy1azo)-3-naphthoic acid)Patton & Reeder, Anal. Chem., 1956, 28, 1026.For the complexometric titration of calciumin the presence of magnesium; a verysharp colour change from wine red to pureblue. The indicator may be diluted withsodium sulphate (1 :loo), l g of the mixturegiving a satisfactory end-point.lg 4s. 6d. 5g 15s. 9d.Solochrome dark blue (calcon)Hildebrande and Reilley,Anal.Chem., 1957, 29, 258.For the complexometric titration ofcalcium in the presence of magnesium,giving a sharp colour changefrom pink through purple to blue atpH 12.3 in a diethylamine buffer.25g 3s. Od. lOOg 7s. 6d.THE BRITISH DRUG HOUSES LTDB a D o H o LABORATORY CHEMICALS DIVISION POOLE DOWETSCIENTIFIC & TECHNICAL BOOKSLARGE STOCK OF BOOKS on the Biological, Physical,Chemical and Medical Sciences supplied from stock, or obtained to order.FOREIGN DEPARTMENT. Books not in stock obtained toorder with the least possible delay.LENDING LIBRARYSCIENTIFIC AND TECHNICALAnnual Subscription from f I 17s. 6d.THE LIBRARY CATALOGUE, revised to December, I 956, con-taining a classified Index of Authors and Subjects, to Subscribers,& I 5s.net; to Non-Subscribers, A2 2s. net; postage 2s.Prospectus post free on application.Bi-monthly list of New Books and New Editions added to the Librarysent post free to any address regularly.LONDON: H. K. LEWIS & Co. Ltd.136 GOWER STREET, W.C.1 TELEPHONE: EUSTON 4282F e DARTON & COe LTDeWATFORD HERTS ENGLANDESTABLISHED 1834 IITHERMOGRAPHSHYGROGRAPHSBAROGRAPHSMakers ofKEW PATTERN BAROMETERSFORTIN BAROMETERSHYGROMETERSMAN OM ETERS/ REGISTERED \ I +--- I TRADE MARKALTl METER CALIBRATORS IvBRITISH MADE CRYSTALLINE ENZYMESThe folloming high purity crystalline enzymesare available from British sources(a) partially purified, salt free, lyophilized having 25% activity of crystalline material:(b) highly purified, lyophilized, associated with MgSO,.In sterile vials each of one millionDEOXYRIBONUCLEASE: (in two forms:Dornase Viscosity Units).RIBONUCLEASE: Salt free, 4 x cryst.HYALURONIDASE: ex Bovine Testes.a-CHYMOTRYPSIN, 3 x cryrt. salt free.TRYPSIN (five activities), i.e.:50 Kunitz units per mgm.Salt free, 300 IU per mgm.Trypsin free, 6.0 haemoglobin units per gram.(I) 2 x cryst. + <50% MgSOIactivity 25 Anson units per gram of protein:(a) contains Chymotrypsinactivity 2.5 Anson units per gram of material;(b) activity 3.5 Anson units per gram of material;(c) relatively free of Chymotrypsinactivity 5.0 Anson units per gram of material.PEROXIDASE, ex horse radish, pure.(2) lyophilized, salt free, from f i r s t crystals activity 25 Anson units per gram of material;(3) partially purified + <SO% (NH4)PS0,;Your enquiries for these and other Enzymes and Biochemicalsare invitedL.LIGHT & CO. LTD Colnbrook Bucks EnglandAnnual Reports on theProgress of ChemistryBack Numbers (less certain volumes now out of print)are available-Volumes 1(1904) to LIV (1957)AlsoCollective Index of Volumes I to XLVIItrquiries are invited by:THEC H E M I C A LSOCIETYBurlington House . London, W.lOxford BooksExperimentuZ Techniqtces inLow-Temperature PhjsicsGUY KENDALL WHITE(Monographs on the Plysics and Cbemijtry of Materials)Illustrated 4js netDetermination of MoZectcZar StrmtweP. J. WHEATLEYIllmtrated 3 j~ netThe ChemicaZ Kineticsof Enzyme ActionKEITH J.LAIDLERIkrtrated 60s netA Modern Approuchto Organic ChemistryJ. PACKER A N D J m VAUGHANIlZustrated 8 4 netEZectronic Theoriesof Organic ChemistryA n Introdzrctory TreatmentIlhstrated 3 0s netJ O H N WILLIAM BAKERThe Physics of R&er EZusticityC. R. G. 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