ISSN:0003-2654    

DOI:10.1039/AN94873FX013

出版商:RSC    

年代:1948

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94873BX015

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

iv THE ANALYSTA C A D E M I C R E S E A R C HPRODUCTION CONTROLI N D U S T R I A L R E S E A R C HCALL FORSpectrographicallySTANDARDISED SUBSTANCESIYith the increasing applicationo f the spectrograph in academicresearch, industrial research andin production control, the needfor a standard range of elementsin the forms of pure metals,oxides or other compounds hasbecome essential.We are now able to supplysixty-eight elements in the higheststate of purity, all of which havebeen subjected to rigorouschemical and spectrographicanalysis. For details of theforms in which these elements aresupplied write for publicationNo. 1760.JOHNSON, MATTHEY 44 CO., LIMITETHE ANALYST vHE Civil Service Commissioners invite applications forTestablished and temporary posts of Assistant TechnicalExamining Officer (Male) in the Victualling Department ofthe Admiralty.Candidates must be British subjects born on or after 2ndAugust 1910 and on or before 1st March, 1923. They mustpossess’eithe; a First or Second Class Honours degree of aBritish University with chemistry as the principal subject orAssociateship or Fellowship of the Royal Institute ofChemistry and have had at least two years post-graduateexperience in one of the three main groups of stores detailedbelow.The duties consist of technical examination of victuallingstores (and developmental work connected therewith), viz.:-(i) Provisions (canned foodstuffs, cereals, etc.).(ii) Clothing (textile piece goods, knitwear, footwear,unifonn clothing, etc.).(iii) Mess Gear (table wear, cooking utensils, etc.),and include responsibilities for the laboratory examination ofsamples drafting of specifications and supervision of Sub-ordinatd Examining Staff.Successful candidates must be prepared to take up dutya t any Victualling Depot at home or abroad.The inclusive London salary scale for Established Officersisa-4475 x 835-l750.(The minimum is linked on entryto age 25, with addition of ,@5 for each year above that age,subject to an upper limit of f;600.) For Officers serving out-side London deductions range froni L13 to A15 a t IntermediateCentres and L26 to 630 a t Provincial Centres. Londonscales, together with Colonial Allowance, are payable duringservice abroad.The salary ranges for Temporary Officerszre co-terrninous with the scales for Established Officers.Further particulars and forms of application are obtainablefmni the Secretary, Civil Service Commission, ScientificBranch 27 Grosvenor Square, London, W.l, quoting No.2166 to’whdm completed appliration foniis should be returnednot later than 10th June, 1948.HEMIST qualified wanted. Modern Laboratory. C Analyticdl control r b material and finished productsB.P. Medicines and Foods. State age, qualifications,proposed commencing salary, Managing Director, Burdall’sLtd., Hillsborough, Shefield, 6.RO JECTION Microscope wanted preferably “ Vickers.”PFuU details to Box No. 3679, TH; ANALYST, 47 GreshamStreet, London, E.C.2.JOHNSONS OF HENDON HAVEINTRODUCED A NEW RANGE OFTEST PAPERS FOR THE EXACTDETERMINATION OF pH VALUESU N I V E R S A LOne paper which covers the completerange from pH I (strongly acid) to pH 10(strongly alkaline), enabling the exactpH value to be ascertained to within0.5 pH.C O M P A R A T O RFor work requiring still reater accuracy(to within 0.3 pH) the (!omparator TestPapers should be employed. These aremade in four separate indicator groupscovering pH 3.6 to 5.1, 5.2 to 6.7, 6.8 to8.3 and 8-4 to 10.Descriptive leaflet willbe sent free on requestJOHNSON & SONS MFG.CHEMISTS LTD.HENDON, LONDON, N.W.4. ESTAB. 1743P E P T ON E SCULTUREMEDIAThis roup of Difco Peptones meets thevarief requirements of the most exactingtypes of bacteria.BACTO-PEPTONE is most widelyused in routine culture media.It formsclear solutions with a reaction of pH 7.0.BACTO-TRYPTONE is an excellentpeptone for detection of indol andhydrogen sulfide production. It isrecommended in “ Standard Methods forthe Examination of Dairy Products.”BACTO-TRYPTOSE was ori inallydeveloped for cultivation of theBrucella. It is also an excellent nutri-ment for the Streptococci and otherdiscriminative bacteria.PROTEOSE-PEPTONE is univer-sally used for elaboration of diphtheriatoxin. It is also employed in media forproduction of scarlet fever and botulinustoxins.PROTEOSE-PEPTONE No. 3 isparticularly useful for propagation ofmany fastidious pathogenic bacteria.NEOPEPTONE is especially recom-mended for isolation and cultivation ofPneumococci and Streptococci.Specify DIFCO ”THE TRADE NAME OF THE PIONEERSIn the Research and Development ofBacto-Peptone and Dehydrated CultureMediaBAIRD & TATLOCK(LONDON) LTD.,Sole Agents for Great Britain and IndiaLONDON, E.C.I14-17 ST. CROSS STREETvi THE ANALYSTb ‘AM B R I DGE POLAROGRAP t(HEYROVSKY DROPPING MERCURY ELECTRODE METHOD)For the rapid electro-chemical analysisof solutions, enabling traces of metalsand many acid radicals and organicsubstances to be determined. It hasvaluable applications inPHYSICAL CHEMISTRY METALLURGYMEDICINE MINERALOGYOIL DISTILLING SUGARDYEING & BLEACHINQ EXPLOSIVESG E RAM IGS GASESWATER PURIFICATION AGRICULTUREetc. etc.I CAMBRIDGE13 GROSVENOR PLACE, LONOON,S.W.IWORKS: LONDON & CAMBRIDGE%.THIS PUBLICATION 109-U gives full details, with valuable notes on technique.SAVORY & MOORE L‘l-D.MAY FAIR A BRANDALUMINIUM OXIDEof British ManufactureS tandardised forCHROMATOGRAPHICADSORPTIONANALYSISSEPARATIONandFurther in formation from :SAVORY k MOORE LTD.LAWRENCE RD., TOTTENHAM, N.15ON THE CHEMICAL BOOKS & ALLIED SCIENCESLarge Stock of Recent Editions.Foreign Books.Select Stock. Booksnot in stock obtained from U.S.A. andthe Continent at the most favourablerates under Board of Trade Licence.SECONDHAND DEPT.140, Gower Street, W.C.l.Large Stock of Scientific and TechnicalLiterature availableLENDING LIBRARYScientific and TechnicalAnnual Subscription from ONE GUINEAProspectus post free on request.Bi-monthly List of New Books and NewEditions sent post free to subscribersregularlyH.K. LEWIS & Co. Ltd..LONDON :136, GOWER STREET, W.C.l.Telephone : EUSton 4282Established 184viii THE ANALYSTThe most popular items and sizes of Chance Brothers’ cc Hysil”Laboratory Glassware are now available in Standard Cases.Furnishers and Users will find that this new arrangement greatlysimplifies the ordering, handling and stocking of cc Hysil.”EXkiMPLE CASESTall Beakers, 600 ml. . . . . . . . . . . . . . . . 60Squat Beakers, 250 ml. . . . . . . . . . . . . . . . 84Flat-bottom Flasks, SO0 ml. ............ 72Distillation Flasks, 1,000 mi. ......... 12Round-bottom Flasks, 5,000 ml. ...... 6A new price list of ‘ Hysil ’ Laboratory Glasswaie is nowavailable and will be sent on request. All popufar itemsand sizes are specially indicated and by confining theirorders to these sizes Furnishers and Users will obtainquicker delivery than if their orders include items whichare not in such general demand,CHANCE BROTHERS LIMITEDGLASS WORKS, SMETHWICK, 40, Nr. BIRMINGHAMTel: West Bromwich 1051. London OAfce: 28 St. James’sSquare, S. W.1. TeL : Whitehall 1603. Branch Works atGlasgow, St. Helens and Malvern.DISCOUNTSI to 9 10 %I0 a d 2*%10 and 5%10 and 74%10 and 10%NUMBEROF CASES10 to 1920 to 2930 to 3940 and ove

ISSN:0003-2654    

DOI:10.1039/AN94873FP019

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction

ISSN:0003-2654    

DOI:10.1039/AN9487300185

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE.By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time.The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years.The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion.The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on.Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp.15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C.Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner.He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction

ISSN:0003-2654    

DOI:10.1039/AN9487300186

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE.By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time.The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years.The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion.The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on.Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp.15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C.Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner.He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction

ISSN:0003-2654    

DOI:10.1039/AN9487300191

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

April 19481 LESTER SMITH PENICILLIK ASSAY 197 Methods of Penicillin Assay : their Purpose Scope and Validity .4 Symposium held at a Joht Meeting of the Physical Methods Group and the Biological Methods Group on Thursday January 29th 1948. The following papers were read at the afternoon session.* CHEMICAL AND PHYSICAL METHODS FOR PENICILLIN ASSAY Introductory Survey BY E. LESTER SMITH THIS historical survey of the many chemical and physical methods that have been described for the estimation of penicillin covers mainly those that for one reason or another have fallen into disuse because most of the more interesting and valuable methods are the subjects of other papers in this symposium. I shall also mention however a few techniques that have been published too recently to permit critical appraisal.CH %-CH-COON~ CHs\C4H-COOXa CH3’I I C H 4 NH I S N \ / I CH COONa ‘ck (or Penicillinase) ‘ C 4 412 NH-CO-R I NH-CO-K Penicillin_ Penicilloic acid ^.I COOH COOH I NH-CO-R Penicillamine Penicillaminic acid I t is first necessary to review briefly some aspects of the chemistry of penici1lin.l The molecule contains a thiazolidine ring carrying a carboxyl and two methyl groups fused to a p-lactam ring carrying a long side-chain. The various penicillins differ only in the nature of the group R in the formula as shown in Table I. Evidence has been presented for the occurrence of at least eleven different penicillins of which five commonly occur in appreciable proportions in commercial samples. The nomenclature is confused owing to the use of numbers in this country and letters in America.There is now a move to replace both, where possible by an abbreviated chemical name composed of the name of the group R followed by “penicillin,” e g . benzyl penicillin instead of penicillin G or 11. The nomenclature of the salts is clumsy because penicillin was not originally named as an acid; thus we must say sodium benzyl penicillin or benzyl penicillin sodium salt. A recent American paper introduced the new style “ sodium benzylpenicillinate.” This is slightly confusing because “ penicillinic acid” has been employed already for a degradation product although it fell into disuse with the discovery that the substance so named was a mixture. I t should be observed that the alternatives “ penillate ” or “ penicillate ” are not admissible because “ penillic acid” has been used for an acid degradation product of penicillin and “penicillic acid” for another mould metabolite unrelated to penicillin.* The papers on Biological Methods of Penicillin Assay read at the evening session will be published in the May issue LESTER SMITH CHEMICAL AND PHYSICAL METHODS [Vol. 73 198 Alkali or penicillinase opens the lactam ring the resulting dibasic penicilloic acid is split by hot acid into penicillamine and a penaldic acid which breaks down further to yield eventually the side-chain acid R.COOH. Iodine oxidises penicilloic acid vigorously to yield presumably the products shown. Most of the reactions that are utilised analytically are shown in the formulae.TABLE I THE PENICILLINS (In order of separation on partition chromatograms) Nomenclature I.U./mg. B. subtilis - r-A- S. ,aureus U.S.A. Great Britain R Groups S . aureus B. subtzlzs ratio s ? ? S ? ? s* VI ? ? G I1 -CH,.C,H *1670 *1670 * 1.00 X I11 -CH,.C,H,OH($) 900 1450 1.61 F I -CH,.CH CH.CH2.CH3 1640 1100 0.67 Flavicidin -CHz.CHz.CH CH.CH 1400 1000 0.72 Dihydro-F (?)IV -CH~.CH,.CH,.CH,.CH 1610 1010 0.63 K -(CHJ,.CH 2400 750 0.3 1 “K-type” (?)VII ? ? “ K-tyw ” ? ? * By definition. One must distinguish sharply between methods for the assay of total penicillin and those for the assay of individual penicillins. The unit of penicillin is defined in biological terms; the Oxford unit was an arbitrary one and has now been replaced by the international unit, which has the same magnitude but is defined as the anti-bacterial activity against a certain organism of 0.6 pg.of the international standard preparation of benzyl penicillin sodium salt. A chemical or physical method can give a precise result for total penicillin expressed on a weight or on a unitage basis when the sample contains this variety of penicillin only. Many commercial samples however contain in addition other varieties of penicillin. Besides differing slightly in molecular weight these penicillins have different anti-bacterial activities expressed in units per mg. Chemical and physical methods therefore are not capable of giving precise results for mixtures of penicillins in unknown proportions; it is only possible to quote the results in terms of the chemically equivalent weight or unitage of penicillin G.To put it differently chemical and physical methods determine the molarity of a penicillin solution. It happens that the factors for conversion to international units do not differ very greatly from one penicillin to another; this combined with the very fortunate circumstance that most penicillin samples now available commercially contain a high proportion of benzyl penicillin means that the non-biological methods can give results, despite the above limitation that often agree with the biological results within the usually accepted limits of experimental error. ESTIMATION OF TOTAL PENICILLINS POLAROGRAPHIC M E T H O W The polarographic method2 is properly taken first because it was the first non-biological method for penicillin estimation to be described.It was developed by my colleague Dr. J. E. Page and was described in confidential reports in 1944; the method has not yet appeared in other publications. The penicillin is first hydrolysed with dilute alkali to penicilloic acid and then with dilute acid to break this down further to penicillamine. This compound is dimethyl cysteine and has a free SH group which is utilised for the polarographic estimation. The sensitivity compared with that of the more usual polarographic estimations can be much increased by carrying out the measurements in presence of ammonia and a cobalt salt. Under these conditions the polarographic SH step is enormously magnified by the catalytic effect of the cobalt making it possible to estimate penicillin solutions as dilute as I unit per ml.One disadvantage of this method is its indirectness and lack of specificity; there is the risk that it might respond to breakdown products of penicillin and other sulphur-containing impurities in crude penicillin; obviously it cannot be used for fermentation liquors. The other disadvantage is that it is more laborious than methods developed subsequently an April 1948- FOR PENICILLIS ASSAY ISTRODUCTORT SCKVEY 199 indeed rather more so than routine biological methods. Statistical examination of adequately replicated determinations on a number of samples showed that the accuracy is of the same order as that of the plate method of biological assay. COLORIMETRIC AND FLUORIMETRIC METHODS-This depends on the fact that amines react under suitable conditions with penicillin the p-lactam ring opening to yield a substituted amide of penicilloic acid.Scudi utilised this phenomenon in a verv ingenious fashion by using a coloured amine namely N-( l-naphthyl-4-azobenzene)-ethylene-diamine. The penicillin is extracted into chloroform from acidified aqueous solution (about 10 i.u. per ml,), and the extract is left standing for 3 hours with a benzene solution of the reagent containing a trace of acetic acid which catalyses the reaction. The condensation product being acidic by virtue of the carboxyl group of the penicillin is separated from excess of the basic reagent by extraction with 0.055 sodium hydroxide. After acidification the red product is extracted into butanol - benzene mixture to separate it from any remaining traces of reagent.The extract is finally diluted with alcoholic hydrochloric acid for colorimetric measurement. This method is very sensitive and is almost specific for penicillin. It can be used for fermenta-tion liquors provided a blank determination is included on the same sample after inactivation of the penicillin with penicillinase. It suffers from the disadvantage that the numerous manipulations involved are time-consuming and can give rise to serious errors unless great care and skill are exercised. The fluorimetric method4 depends on exactly the same principle the only difference being that the coupling agent 2-methoxy-6-chloro-9-(~-aminoethyl)-aminoacridine is fluorescent. Thus the manipulations are practically the same except that the condensation requires 1 hour only and the final estimation is done fluorimetrically.The sensitivity is thereby increased so that blood and urine samples containing 0.1 i.u. or even less per ml. may be assayed but the other disadvantages remain. A colorimetric method,5 based on the reaction between ninhydrin and the penicillamine liberated on acid hydrolysis does not appear to have been much used. A very rapid colorimetric method has recently been publishede; it depends on the reaction between penicillin and hydroxylamine to form a hydroxamic acid which gives a purple colour with ferric salts. The reactions are complete in 10 minutes a period that must be timed accurately because the colour fades quickly. The method is not specific for penicillin, but the effect of interfering substances can be eliminated by a blank determination after inactivation of the penicillin with penicillinase.The method then becomes applicable directly to fermentation liquors. HYDROLYTIC METHODS-The /?-lactam ring of penicillin can be opened by dilute aqueous alkali or the enzqme penicillinase liberating the potential second carboxyl group. This permits estimation of penicillin by what is virtually a saponification value determination. The reaction is complete in a few hours a t room temperature and the excess of alkali merely has to be titrated back. This method is of the utmost simplicity is specific in absence of esters and is accurate. Its main disadvantage is that it requires more penicillin than the previous methods.I t s capabilities are described more fully in another paper (p. 207). Alternatively the hydrolysis can be accomplished with penicillinase provided adequately pure specimens of the enzyme are available the resulting increase in acidity can be titrated directly,' or assessed mano-metrically* by performing the reaction in bicarbonate solution. It has been proposed to estimate penicillin by oxidation with hydrogen p e r ~ x i d e . ~ IODIMETRIC METHQD-This methodl0*l1 depends on the observation that penicilloic acid but not penicillin itself, will react with iodine. The precise course of the reaction is somewhat obscure and appears to depend on reaction conditions. Complete reaction presumably involves oxidation of the sulphur atom to the sulphonic acid state and oxidation of the potential aldehyde group of the thiazolidine ring to the carboxylic acid state involving in all a total of 8 atoms of iodine per molecule of penicillin.On this account and because iodine can be estimated accurately in dilute solution the method is much more sensitive than the direct hydrolytic method, The colorimetric method developed by Scudi3 came next. The coupling is effected in a chloroform solution of penicillin (free acid) 200 LESTER SMITH CHEMICAL ASL) PHYSICAL METHOD5 "i70l. 73 is more rapid and is applicable to strongly buffered solutions which is not true of the direct hydrolytic methods. It is also more selective because the blank determination on a portion of the solution that has not been treated with alkali eliminates interference by most other oxidisable bodies.The method has been adopted officially in the United States and is regarded with increasing favour in this country. The Ninistry of Supply laboratories have introduced a useful modification in which the iodine solution is buffered thus reducing greatly the temperature coefficient of the reaction and obviating the need for a thermostat. To 5 ml. of the penicillin solution containing not more than 6000 units is added 1 ml. of &V sodium hydroxide. The solution is neutralised after standing for 30 minutes and treated with 10 ml. of 0.01 AT iodine buffered at pH 6-24. After another 30 minutes the solution is titrated with 0.01 -1' thiosulphate. A blank is done omitting the alkali treatment and allowing only 5 minutes standing with iodine.POLARIMETRIC METHOD-amounts of optically active impurities. dextro-rotatory and to the same degree. that the penicillin in such samples could be estimated polarimetrically. SPECTROSCOPIC METHOD-by heating a t pH 4.6 is described in another paper (p. a l l ) . Commercial penicillins of 800 i.u. or more per nig. appear to contain no significant The penicillins on the other hand are strongly Accordingly it has recently been suggested12 A spectroscopic method13 for total penicillins based on the absorption a t 322 mp. induced ESTIMATIOX OF INDIVIDUAL PEKICILLINS We turn now to an entirely different aspect of the subject namely the determination of particular individual penicillins present in mixtures as distinct from the estimation of total penicillin irrespective of variety.The methods available for this purpose can be divided roughly into chemical physical and bio-physical methods. CHEMICAL METHODS-Since the penicillins differ only in the nature of their side-chains it is clear that only these side-chains are available for differential chemical attack. The benzene ring of benzyl penicillin can be nitrated and the determination made by adapting methods14J5J6 based on the estimation of phenylalanine in this way. In the method of Page and Robinson the penicillin is nitrated reduced with zinc dust diazotised and finally coupled with X-(1-naphthyl) ethylenediamine to yield an azo dye suitable for colorimetric measurement. Unfortunately the method is by no means specific and will respond for instance to phenylacetic acid an impurity liable to be present in yellow penicillin.It should be possible to determine P-hydroxybenzyl penicillin (S) by taking advantage in one way or another of its phenolic hydroxyl group; for example the determination of acetyl value might be used or advantage be taken of the fact that this type of penicillin will take up iodine. In practice penicillin X is more easily determined by partition methods. The differing unsaturation in the side-chains of the various penicillins has been suggested as a basis for differentiation. It would be advantageous if some mild hydrogenation technique could be found that would reduce only the aliphatic double bond in penicillin F (or flavicidin) ; but such methods or indeed others that might be devised depending on the peculiar reactivity of aliphatic double bonds do not appear to have been described.Mention has been made in confidential reports1' of a vigorous hydrogenation technique that reduces in addition the aromatic double bonds of penicillins G and X. This method would obviously only dis-criminate between two groups of penicillins namely the fully saturated heptyl and amyl penicillins and all the others. A method has been published that purports under favourable conditions to separate benzyl penicillin from all other penicillins by precipitation as the ethylpiperidine salt.ls As this method is described in another paper (p. 205) I will only remark that it would be very useful if only it were as specific as its authors claim. PHYSICAL METHODS-and will be described in another paper (p.211). Methods involving ultra-violet and infra-red spectroscopy have been p u b l i ~ h e d l ~ ~ ~ iipril 19.181 FOR PENICILLIS ASSAY IITTHODUCTORI- SCRVET 20 I The possibilities of X-ray crystallography for analysing mixtures of pure crystalline penicillins have been considered in more than one laboratory but no results have yet been published. A great deal of work has been done on the separation of penicillins by taking advantage of the differences in their partition behaviour between buffer solutions and organic solvents. For the most part these differences are small but roughly quantitative methods for p-hydroxy-benzyl and heptyl penicillins (X and K) have been devised depending on “bulk partition” as distinct from counter-current techniques.Thus penicillin X is virtually not extracted by chloroform from acidified aqueous solutions under conditions that remove other penicillins nearly quantitatively. Penicillin K is largely extracted by chloroform from a buffer at $H 5.5 while other penicillins are extracted only to a small degree. This partition separation can be made more nearly perfect by using multiple counter-current partitions. This can be done with the Craig apparatus,21 a machine designed to apply without too much mechanical effort a total of 20 or 25 “theoretical plates.” Vastly more “theoretical plates” can be applied by using a partition chromatogram in which the stationary phase is silica gel impregnated with a strong buffer solution a technique adapted by I.C.I. chemists from that originally developed by Martin and Synge for the separation of acetyl amino acids.The penicillin fractions arising from the Craig machine or from chroma tog ram^^^^^^ can obviously be estimated either biologically or chemically. There is however an ingenious modification of the chromatographic technique also elaborated by I.C.I. ~ o r k e r s ~ ~ @ ~ ~ in which buffer-impregnated filter paper strips form the stationary phase This micro separation is of necessity followed up by biological estimation of the separated penicillins as described in further detail in a later paper (p. 203). Some attempts have been made to separate the penicillins by adsorption chromatograph!-on alumina charcoal and other adsorbents. Vigorous hydrolysis will split the amide linkage in the side-chains of the penicillins, liberating the corresponding acids R.COOH.These have been used for identification of individual penicillins and we have been experimenting lately (as doubtless have other laboratories) on methods of fractionating these acids by the Craig apparatus or by partition chromatography as a means of indirect analysis of mixed penicillins. B r o d e r ~ e n ~ ~ . * ~ has recently described a technique based on measurements of the rate of inactivation by acid. On plotting the logarithm of penicillin concentration against time, changes of slope in the curve are observed due to the presence of penicillins of differing lability. A rather complicated geometrical analysis permits calculation of the percentage of penicillin G present and of the more labile penicillins S F and K which cannot be differentiated A number of samples were found to contain traces (under 1 per cent.) of a less labile penicillin IT.Each method has its advantages and its disadvantages and probably no single method provides the perfect solution to this difficult problem of the accurate assay of penicillin mixtures. To make matters worse it has been claimed that the clinical efficacy of penicillin is enhanced by impurities of unknown constitution that are present in some samples of crude penicillin. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 1 1 . 12. 13. 14. 15. 16. REFERENCES Committee on Medical Research (Ofice of Scientific Kesearch and Development Washingtoc; and the Medical Research Council (London) Nature 1946 156 766.Hems B. A, Page J. E. and Robinson F. A. C.P.S. 225 290 and 384. Scudi J . V. J . Biol. Chem. 1946 164 183. Scudi J. V. and Jelinek V. C. Ibid. 1946 164 195. Allinson 11. J. C. PYOC. SOC. Exp. BioZ. ilfed. 1945 60 293. Ford J. H. Anal. Chem. 1947 19 1004. Murtaugh J. J. and Levy G. B. J . -4ntev. C h e w Soc. 1945 67 1042. Henry R. J. and Housewight R. D. J . B i d . Chem. 1947 167 559. Colon A. A, and Frediani H. h. Bol. Col. Quinz. P ~ e v t o Rico 1947 4 20 ( c j . C ~ E I ? ~ . A h . 1947, Alicino J . F. I n d . Eitg. Chew. Anal. Ed. 1946 18 619. Mundel %I. Fischbach H. and Eble T. E. J . Awev. Phaviii. Assoc. 1946 35 373. Grenfell T. C. Xeans J. A. and Brown E. V. J . Bid. Cheiiz. 1947 170 627. Hemott R. M. Ibid. 1946 164 725. Page J.E. and Robinson F. A, Natuve 1946 158 910. Del Vecchio G. and Argenziano R. Bolt. SOC. Ital. Biol. speriw. 1946 22 1190. Canback T. Fnuiit. Reo. 1947 46 97 (Chevz. Abs. 41 3258). 41 7662) [Vol. 73 202 BOOS THE I)ETEKMISATIC)\ OF 1SDIVII)UAL PESICILLISS : l i . 18. 19. 20. 21. 32. 23. 24. 25. - - ANALYST 1947 72 277. 26. 27. Brodersen R. Acta Pharwiacol. 1946 2 1. 28. - Ibid. 1947 3 124. Eli Lilly Inc. C.P.S. 472.* Sheehan J. C. Mader W. J. and Cram D. J. J . Amer. Chew. SOC. 1946 68 2407. Philpotts A. R. Thain W. and Twigg G. H. Nature. 1947 159 839. Barnes R. B. Gore R. C. Williams E. F. Linsley S. G. and Petersen E. M. Anal. Chew., Craig L. C. Hogeboom G. H. Carpenter F. H. and Du Vigneaud V. J . B i d . Chew. 1947, Fischbach H. Mundell &I.and Eble T. E. Science 1946 104 84. Fischbach H. Eble T. E. and Mundell &I. J . Aazer. Pharwi. Assoc. Sci. Ed. 1947 36 220. Goodall R. R. and Levi A. A. Nature 1946 158 675. \Vin&en W. A. and Spark A. H. Sczence 1947 106 192. 1947 19 620. 168 668. GLAXO LABORATORIES LTD. GREENFORD MIDDLESEX The Determination of Individual Penicillins : A Critical Review of Some Proposed Methods BY W. R. BOON THE problem of determining individual penicillins varies with the nature of the particular sample to be examined and also with the sort of information required. Thus one may wish to know at one extreme the relative amounts of the various penicillin species in a sample that may contain say six different penicillins as well as a quantity of inert material and at the other extreme the amount of a particular penicillin present in a substantially pure sample.In this paper the different methods that have been proposed from time to time to deal with this problem will be examined briefly and an attempt will be made to indicate what are the particular advantages and disadvantages of each. Spectroscopic methods will not be dis-cussed as they are dealt with by Dr. Twigg (p. 211). One of the earliest methods that found any extended application was the so-called difierential assay. In this method the biological activity of the sample under investigation was determined by means of two different test organisms usually Staphylococcus auyeus and Bacillus subtilis and a single standard substance. Obviously in this simple form it is only possible to determine the composition of a two component mixture; with more complex mixtures the figures can only be interpreted in terms of a large number of possible combina-tions.It has been suggested from time to time that the method can be extended by the addition of a test using a further organism for each additional penicillin present. Whilst this is theoretically possible there is the practical difficulty that one seldom knows how many penicillins are present in a mixture. Kevertheless the method still has some value in the control of manufacturing operations where the previous history of any sample under examination is known. Since all the penicillins have very similar chemical properties methods for their estimation in complex mixtures containing much inactive material must necessarily involve separation, partial or complete of the different individuals by physico-chemical methods followed by measurements of the penicillin content of the various fractions by biological assay by a chemical method e g .the iodimetric titration method of Alicino,l or by a physical means such as light absorption or optical rotation.2 At the present time the most useful method of separating the penicillins is undoubtedly by distribution between two liquid phases. Distribution between a liquid and a solid phase, as in adsorption chromatography is not nearly so satisfactory as no suitable adsorbent has yet been found for this purpose. Owing to the small differences in partition coefficient and dissociation constant of the different penicillins simple solvent extraction is of little use in effecting a separation and resort must be had to counter-current methods.There is one exception however to this general statement since p-hydroxybenzyl penicillin is virtually insoluble in chloroform and may be estimated by extracting the other penicillins with this solvent from an acidified aqueous solution. Of the counter-current extraction procedures the oldest is the silica - buffer - solvent chromatogram introduced in our laboratories in the middle of 1942 and since then used * Progress reports of the Committee for Penicillin Synthesis are available for inspection at the places listed in Nature 1947 159 565 -1pri1 19481 A CRITICAL REVIEW OF SOME PROPOSED METHODS 203 extensively elsewhere. In the method which is an adaptation of the partition chromatogram of Martin and Synge,s one of the liquid phases a phosphate buffer solution is held stationary absorbed on silica gel while the other mobile phase moves past it.It was by this method that in 1943 we were able to demonstrate conclusively the existence of more than one penicillin by separating what are now known as benzyl penicillin and A2-pentenyl penicillin from one another.3 We also used it somewhat later to estimate the composition of the crude penicillin produced by various combinations of mould strain and m e d i ~ m . ~ The method although very effective for preparative purposes is rather cumbersome as an analytical tool. Unless the amount of penicillin put on to a column is very low in proportion to the amount of silica employed there is often considerable overlapping of the bands and in order to obtain a complete separation in the less favourable cases it is necessary to analyse fractions from the first column on one or more further columns.Furthermore it is necessary to determine the total penicillin activity in a large number of samples either of eluate or of portions of the column material in order to obtain a measure of the distribution of activity. For rapid approximate determinations the polarimeter is of considerable help for the penicillins are strongly dextro rotatory. Care should be exercised however in the interpretation of results obtained by this method since some batches of crude penicillin contain optically active hut biologically inert material both dextro and laevo rotatory.Recently Fischbach Eble and Mundel16 have written a paper on the use of this method for the analysis of mixed penicillins. Their technique differs little from that developed by us some five years previously except that they estimate the penicillin content of their fractions by means of the iodimetric method of Alicino. From the results given in this paper which may be taken as typical it would appear that n-heptyl penicillin can be estimated fairly readily for it moves so much faster through the column than any other of the penicillins that there is no overlapping. The picture given by Fischbach et al. of the distribution of activity is in accord with this supposition for the shape of the band is characteristic of a pure substance having a sharp front edge a zone of constant concentration and then a gradual fall-off at the tail.There is a possibility that this happy state of affairs in which only one penicillin migrates faster than the others will not always hold for we have evidence that in some batches of crude penicillin there may be more than one active substance present in the zone normally occupied by n-heptyl penicillin. Fischbach et al. claim that by this method they are able to estimate n-heptyl penicillin with a reproducibility of -+2 per cent. They make no claim for the determination of other penicillins although they state that they were able to isolate some sodium A2-pentenyl penicillin. Judging by the shape of the curves given in their paper it appears that there is considerable overlapping between the different zones of activity which would render the method of little value for the estimation of penicillin other than n-heptyl penicillin.Perhaps the most generally useful method for determining the composition of a complex mixture of penicillins is the micro-chromatographic method of Goodall and Levi.' This method is similar in general principle to the partition chromatogram discussed above the main difference being that the inert support for the phosphate buffer solution is a strip of filter paper instead of silica gel. In addition the distribution of activity between the various fractions is determined in one operation by placing the paper strip containing the developed chromatogram on a sheet of nutrient agar that has been inoculated with a suitable penicillin-sensitive micro-organism.After incubation the nature of the penicillins and the amount of each present may be estimated from the position and size of the inhibition zones. The main advantages of this method are as follows-(i) It is fairly readily adapted to routine use because the manipulations involved are simple and easily learned by the average laboratory assistant though strict attention to detail is necessary. iii) It employs only a very small amount of material the actual amount applied to a strip being a few micrograms. (iii) Replication is easy a series of six replicates on one sample being easily run on one plate. (iv) All the penicillins are estimated at one time. (v) The efficiency of separation of one penicillin from another is extremely high.Thus it is possible to separate benzyl penicillin (11) from A2-pentenyl penicillin (I) the ratio of whose partition coefficients is only 1.5. More difficult is the separatio 204 (vi) (vii) BOON THE DETERMINATION OF INDIVIDUAL PEXICILLINS [Vol. 73 of A2-pentenyl penicillin from what in our laboratories we call penicillin 117, but even in this case where the ratio of the partition coefficients is less favourable, a complete separation can be effected. This complete separation of penicillins I and IV is not shown in the illustrations in the paper of Goodall and Levi,‘ but recent slight changes in technique have rendered it possible though it is usually necessary to develop the K group of penicillins off the strip to achieve it The amount of inert material in the sample to be analysed is unimportant provided the sample is not so impure that it is impossible to obtain a solution of the required concentration 10,000 units per millilitre.The method indicates the presence of any novel penicillins that may be present in the sample subject to the proviso that sufficient resolution has been obtained during development. Although it is not possible to say categorically that the method will permit of the separation of all penicillins it can be said with confidence that the resolution obtained is much greater than with any other method available at the present time. Against the many advantages indicated above some defects of the method must be set. The chief one is that results can only be expressed as a proportion of the total penicillin activity measured in terms of the particular test organism and standard that are used.Translation of these into either percentage of total weight of penicillin or of sample is theoretically possible but is only likely to be accurate if the activity of the individual penicillins in the pure state is known. Unfortunately this is not always so at the present time. Calculation of the relative proportions in terms of total activity is based on an empirical equation whose constants vary somewhat from plate to plate and probably also from one penicillin to another and with the total amount applied to the strip. These weaknesses the effect of which it is impossible to assess accurately do not detract from the general utility of the method since it enables consistent and reasonably reliable results to be obtained on complex mixtures that cannot be analysed by any other technique available at the present time.It has also proved useful for the examination of nearly pure and reputedly pure, samples of individual penicillins for small quantities of other penicillins are readily detected. Results obtained by this method for the benzyl penicillin content of commercial crystalline sodium penicillin are usually in good agreement with those obtained by the N-ethylpiperidine salt method or by infra-red spectroscopy. There is one other method depending on distribution that remains to be considered. That is the method introduced by Craig at the Rockefeller Institute using an ingenious piece of apparatus which is in effect a series of tubes or separating funnels so arranged that the top layer in one funnel may be transferred to the next one while at the same time fresh top layer is brought in from the one on the other side.s By this means it is possible to submit a solute to a number of counter-current distributions.If the solute is a pure substance and if its partition coefficient is constant over the range of conditions met with in the experi-ment the total amount of solute present in each tube is given by the successive terms in the expansion of . I * (1) 1 K n [Wl+K+1] * . where K is the partition coefficient and n is the number of “plates” in the distribution. If the solute contains two substances that do not interact and whose partition coefficients are K and K‘ constant throughout the conditions of the experiment and the fractions of each present initially are $ and 1-9 respectively then the amount in any given tube will be the corresponding;term in the expansion of Provided the difference between K and K’ is sufficiently great there will be two maxima in the distribution and it is possible to estimate accurately the relative amounts of the two solutes present from the shape of the curve and the positions of the maxima.The method has been applied to penicillin by Craig Hogeboom Carpenter and du Vignea~d,~ using ether and a 2N phosphate buffer solution as the two immiscible solvents. These authors’ results show that it is fairly easy to separate n-heptyl penicillin an -1pri1 19481 A CRITICAL REVIEW OF SOME PROPOSED METHODS 205 p-hydroxybenzyl penicillin from benzyl penicillin by this method but very little separation was achieved with a mixture of benzyl penicillin and A2-pentenyl penicillin.The penicillin in each tube was determined by transferring all the material to the ether layer evaporating to dryness and weighing or by a spectrophotometric procedure. This method although very ingenious appears to be far too cumbersome and insensitive to be useful as a routine analytical method. There is also a weakness in it which does not seem to have been appreciated by Craig who assumes that the partition coefficient is constant over a wide range of conditions. This is not true in general for organic acids and penicillin is no exception. The effective partition coefficient of penicillin is in fact a function of several variables the most important of which have been found by my colleagues Mr.Greenhalgh and Dr. Pryce to be as follows. (i) The nature of the organic solvent. (ii) The hydrogen ion concentration in the aqueous phase. (iii) The salt strength of the aqueous phase. (iv) The concentration of penicillin particularly in the solvent phase. Under the conditions of Craig’s method (i) and (iii) can be kept constant and (ii) is approximately constant for in order to obtain a partition coefficient of unity it is necessary to work at a $H value very near the limits of the buffering range of the phosphate system employed. The most important factor is undoubtedly the last since owing to association in the solvent phase the effective partition coefficient is higher at higher concentrations, q.at the beginning of the distribution or at the peak than it is at low concentrations e.g., at the tails of the distribution. The effect of association is probably not of much importance when ether is used as the organic solvent as then the association constant of benzyl penicillin is less than 10; with other solvents it is much higher being about 20 for amyl acetate and at least 600 for chloroform. I t will be realised that the use of solvents such as these which might be considered on grounds of greater convenience is to be avoided since with them the inathematical expressions used by Craig for interpreting the results are no longer valid. If we assume all factors other than the concentration in the solvent layer to be kept constant the effective partition coefficient is given to a first approximation by the expression .. * * (2) 1 K = 2 1 -I- q/8~rC + 1 ” [ 2 where KO is the true partition coefficient at zero concentration u is the association constant (association into double molecules) and C is the concentration in the solvent phase in gram molecules per litre. Then assuming an association constant of 10 an effective distribution coefficient of 0.989 at a concentration of 0.0175 g.-mol./litre in the solvent in the first tube a calculation, term by term for a twenty-four plate distribution shows that the maximum will occur one tube sooner than would be expected from Craig’s expression. If on the other hand the “observed” partition coefficient at the maximum is used a “theoretical” curve in much better agreement with the “observed” one is obtained; the agreement is still better if one fits the maximum of the “theoretical” curve to the maximum of the “observed” one using the method of Williamson and Craig.lo These effects are illustrated in the figure.To sum up Craig’s method is too cumbersome and insufficiently sensitive for the routine examination of complex mixtures. It is probably of use for detecting heterogeneity in “pure” samples of individual penicillins though it is unlikely to be of much use in detecting, say a trace of A2-pentenyl penicillin in benzyl penicillin. In addition Craig’s theoretical treatment is too simple to be applied indiscriminately to all systems though it is probably adequate under the conditions actually employed by Craig et al.in their examination of penicillin. In a later paper by Sato Barry and Craig1* on the distribution of fatty acids the effect of association on the theoretical treatment is realised and an attempt is made to find a system in which the partition coefficient does not change with concentration. Of the purely chemical methods for the estimation of individual penicillins only that of Sheehan Mader and Cram,l’ involving the precipitation of the N-ethylpiperidine salt of benzyl penicillin has been used to any extent. This method is official in the United States.12 In the original paper it was claimed that it could be used to determine the benzyl penicillin in a mixture provided this penicillin represented at least 50 per cent. of the total penicillin and that the potency was over 800 units/mg.This claim was based on the melting point, specific rotation ultra-violet absorption and elementary analysis of the precipitated salt 206 BOON THE DETERMINATION OF INDIVIDUAL PENICILLINS p o l . 73 Unfortunately these measurements are all such as would be altered only slightly by contamina-tion with several per cent. of another penicillin and are therefore useless as criteria of homo-geneity. Some time ago my colleague Dr. Dobson examined this point critically by analysing the starting material and the precipitate by the micro-chromatographic method and by re-analysing the precipitated salt of supposedly pure benzyl penicillin. Thus a sample of calcium penicillin of potency 1320 u./mg. and containing 65 per cent.of benzyl penicillin, 10 per cent. of A2-pentenyl penicillin 1 per cent. of $-hydroxybenzyl penicillin and 15 per cent. of penicillin IV gave a precipitate equivalent to 57 per cent. of benzyl penicillin in the sample. This precipitate on micro-chromatographic analysis was found to contain only 83 per cent. of benzyl penicillin together with 7 per cent. of A2-pentenyl penicillin 1 per cent. of $-hydroxybenzyl penicillin and 9 per cent. of penicillin IV. This N-ethylpiperidine salt was then analysed and gave a 90 per cent. recovery of a salt containing 90 per cent. of benzyl penicillin by micro-chromatographic analysis and only small amounts of other penicillins. It is now generally accepted in this country that the method should only be applied to samples substantially free from inert material and containing at least 90 per cent.of their penicillins as benzyl penicillin. Even with this limitation the method is still rather tricky and the analysts of the main producers together with a representative of the Ministry of Supply are endeavouring to standardise details of procedure so that results obtained from different laboratories will be in as good agreement as those that can be obtained by any one of them One of the biggest sources of variation has been found to be the N-ethyl-piperidine used. This is probably due to the fact that piperidine as usually available contains several other substances notably partially reduced pyridines and higher homologues. If, however the reagent is carefully purified in a precision still more concordant results can be obtained.Page and Robinsonl4 have suggested a colorimetric procedure for benzyl penicillin in “purified ” penicillin involving nitration reduction with zinc diazotisation and coupling with N-( 1-naphthy1)-ethylenediamine. This method does not appear to have found any very extensive use. There is of course the broad division into percentage on total weight and percentage on total penicillin. The first presents little difficulty other than the fact that penicillin is sold not by weight but in terns of a biological assay. If the result is expressed in terms of total penicillin then the figures will vary with the method of assay employed. This is perhaps best illustrated by an example. Suppose we have a sample of sodium penicillin of which 90 per cent.by weight of the total Finally a few words about methods of expressing results April 1948; A CRITICAL REVIEW OF SOME PROPOSED METHODS 20; penicillin is benzyl penicillin and 10 per cent. by weight is n-heptyl penicillin; if the penicillin activities are determined by the usual assay procedure using S . aweus the benzyl penicillin will appear as only 85 per cent. of the total penicillin but if the total penicillin is determined by the iodimetric method of Alicino or by optical rotation then the correct result will be obtained because the molecular weights of these two penicillins are almost identical. 4 fair comment on the methods discussed above would be that there are no methods available that are entirely adequate for the determination of individual penicillins but that the two most generally useful are the micro-chromatographic analysis of Goodall and Levi because of its range of application and simplicity and for the determination of benzyl penicillin in nearly pure material the ethyl piperidine salt method of Sheehan et al.REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. Alicino J. F. I n d . Eng. Chew. Anal. Ed. 1946 IS 619. Grenfell. T. C Means 1. rl. and Brown E. V. 1. Biol. Chem. 1947 170 527. Boon. W. R Calam. C."T Gudgeon H and L e 6 A. A,. Biochem. 1. In the press. " . . C.P.S. Report No. 49 12.4.44. Fischbach H. Eble T. E. and Mundell M. J . Amer. Pharm. Assoc. 1947 36 220; Preliminary Martin A. J. P. and Synge R. L. M. Biochein. J. 1941 35 1368. Goodall R.R. and Levi A. A. ANALYST 1947 72 277. Craig L. C. J . Biol. Chem. 1944 155 519. Craig L. C. Hogeboom G. H. Carpenter F. H. and du Vigneaud V. Ibid. 1947 168 665. Williamson B. and Craig L. C. Ibid. 1947 168 687. Sheehan J. L. blader W. H. and Cram D. J. J . Amer. Chew. SOL. 1946 68 2407. United States Federal Registev 1946 11 13905. %to Y. Barry G. T. and Craig L. C. J . Bid. Chem. 1947 170 501. Page J. E. and Robinson F. A. Nature 1946 158 910. note in Science 1946 104 84. IMPERIAL CHEMICAL INDUSTRIES LTD. RESEARCH LABORATORIES HEXAGON HOUSE MANCHESTER 9 The Determination of Penicillin by Alkaline Hydrolysis BY STELLA J. PATTERSON AND W. B. EMERY ABRAHAM and Chain1 reported that penicillin was inactivated by alkali and record that electrometric titration of an aqueous solution of the barium salt with alkali gave evidence of a reaction occuring between pH 11 and 12.It was later stated by Lester Smith (private communication) that alkaline hydrolysis took place quantitatively in a manner analogous to the saponification of oils; he demon-strated that theoretical results could be obtained on pure penicillin but that for the low potency material then generally available the results were high because impurities present also consumed alkali. The reaction is represented thus-'CH' + NaOH+ I I \H' 'CO CH-COONa NH.CO.R Id I NH.CO.R The product formed is sodium penicilloate; the radical R differs in the different forms of penicillin. A report2 received later from the research laboratories of Chas.Pfizer and Co. New York, gave details of a quantitative method for penicillin estimation based on alkaline hydrolysis. Their procedure was as follows. Pipette 10ml. of a penicillin solution coritaining from 60,000 to 150,000 units into a 50-ml. beaker equipped with the usual glass and calomel electrodes connected to a pH meter 208 PATTERSOX ASD EMERY THE DETERMINATIOS O r [YOL 73 and a motor-driven stirrer. Add dropwise stificient 0.1 X sodium hydroxide to bring the PH to 8.0. Add exactly 10.0 ml. of the standard alkali which will bring the $H to approxi-mately 12. Stir the solution at room temperature for 10 minutes and then titrate back to PH 8.0 with standard 0.1 N hydrochloric acid and note the volume of acid consumed. Calczrlation-Units of penicillin = (10 - ml.of hr HCl) x 594,000. We have found a modification of this method very useful for routine assays on solid penicillin of high potency. In order to avoid the use of a $H meter we tried several indicators, singly and in combination and found cresol red to be satisfactory. I t gives at the required PH a colour change that is sharp even in presence of the yellow pigment of commercial penicillin. The technique we finally adopted is as follows. REAGEws-Cresol red solution4.1 per cent. solution of cresol red in 70 per cent. alcohol neutralised with 0.1 .iV sodium hydroxide. Carboa dioxide free water-Boil distilled water for $ hour stopper the flask with a rubber bung fitted with a soda-lime tube and allow to cool. PROCEDURE-weigh between 0.1 and 0.2 g. to the nearest mg.into a small dry conical flask taking all precautions necessary to minimise absorption of moisture. Add 50 ml. of cold carbon dioxide free water and 1.0 ml. of cresol red solution followed by 0.1 N sodium hydroxide slowly from a micro-burette until a red coloration is obtained (a 5-ml. micro-burette delivering drops of from 0.02 to 0.03 ml. is suitable). Add from a pipette 10 ml. of 0.1 N sodium hydroxide; stopper the flask with a rubber bung and allow to stand at room temperature for 3 hours. After this period add 10 ml. of 0.1 IV hydrochloric acid and immediately titrate the excess of acid with 0.1 A' alkali to the red colour obtained on initial neutralisation of the penicillin solution (a ml.). Carry out a blank ( b ml.) on 50 ml. of the carbon dioxide free water with 1 ml.of indicator solution treated in the same way (usually this requires about 0.13 ml. of 0.1 N alkali). Penicillin i.u.,/mg. = (a - b) x 59,340/weight of sample taken in nig. An alternative procedure used by one of us (W. B. E.) on production material is as follows. Weigh out the sample as before and dissolve in 50 ml. of cold carbon dioxide free water. -4dd 10 drops of a 0.1 per cent. solution of a-naphtholphthalein in 50 per cent. alcohol and add 0.01 N sodium hydroxide until a pee-n (with yellow penicillin) or blue colour (with white penicillin) is obtained. Add 10 ml. of 0.1 N sodium hydroxide stopper the flask with a rubber bung and allow to stand at room temperature for 3 hours. Then titrate back with 0-05 2\' hydrochloric acid to a pale greenish-yellow colour (with yellow penicillin) or to almost complete absence of colour (with white penicillin).OBSERVATIONS OX THE METHODS-1. The use of water free from carbon dioxide was found to be essential but we found it unnecessary to prepare carbon dioxide free standard acid and alkali. 2. Some workers find no great advantage in using standard acid and alkali more dilute than 0-1 N as the end-point then becomes less distinct. Using 0.1 Ar solutions with cresol red a sharp end-point is obtained with 1 drop from a micro-burette unless the penicillin solution is strongly buffered ; this represents a possible titration error of approximately & 1 per cent. when the above quantities are taken for assay. 3. We normally find it convenient when carrying out several assays at the same time, to dissolve the penicillin in 50ml.of water and allow the solution to stand for 3 hours to complete the inactivation after addition of the sodium hydroxide. Lester Smith (private communication) however has pointed out that the reaction can be completed in a shorter time by reducing the total volume of the solution with 20 ml. (including the 10 ml. of 0.1 A-sodium hydroxide) 1 hour's standing is sufficient; with a total volume of 30ml. 14 hour's standing is sufficient. 4. The temperature of the solution during inactivation is not critical. Inactivation is completed in the stated time at temperatures above 4" C. 5. The statement of the equivalence of 1 ml. of 0.1 N sodium hydroxide is derived from the molecular weight of sodium penicillin G (356) and the fact that 1 mg.has a potency of 1667 i.u. Clearly also 1 ml. of 0.1 N sodium hydroxide E 59,340 i.u. of penicillin G present as the calcium or any other salt. Thus 1 ml. of 0.1 N sodium hydroxide = 35.6 x 1667 = 59,340 i.u .\pril 1948 PENICILLIB BY ALKALINE HYDROLYSIS 209 For penicillin K with a molecular weight of 364 and a potency of 2300 i.u./mg. 1 ml. of 0.1 N sodium hydroxide is equivalent to 83,720 i.u. Thus in the analysis of commercial samples of penicillin G containing some penicillin K the use of the 59,340 factor will give results approximately 3 per cent. lower than the true biological potency for every 10 per cent. of penicillin K present. Appreciable quantities of the other penicillins if present will also affect the accuracy of the results.6. Although the chemical assay cannot in all circumstances have the same value as a biological determination of potency it is nevertheless very useful where assays are required, both in production control and on various penicillin products. The bio-assay is the more consuming of time and the number of these assays that can be carried out is often restricted : there is therefore a great advantage in having available a quick chemical method with a known degree of reliability. The method just described has been of great use in investigations into the stability of penicillin and some of its preparations; thus a considerable bulk of information has become available from the results of many hundreds of keeping tests which could not have been carried out by biological assay alone.LIMITATIONS OF THE M E T H O P 1. Since 1 ml. of 0.1 N sodium hydroxide is equivalent to 59,340 i.u. of penicillin G, it is clear that the method as described is not of use in the examination of products of low levels of potency such as the official ointment (500i,u./g.) and lozenge (5OOi.u.). It is useful however in the routine examination of bulk penicillin powder having a potency greater than 900 i.u./mg. vials containing from 0.1 to 1 x 106 units penicillin in oil and beeswax suspension high-potency lozenges and ointments and certain other special phar-maceutical preparations. The penicillin must normally be first extracted before the hydrolysis can be carried out ; we give later in this paper the method we have adopted for the suspension of penicillin in oil and beeswax.2. While carrying out an investigation into the effect of boiling on penicillin solutions, some wide discrepancies between the results of chemical assay and those of the biological method were observed.s On boiling the biological potency fell more quickly than the apparent potency found by alkaline hydrolysis. After about 10 minutes boiling in some instances an unbuffered solution initially of 50,000 i.u./ml. showed no biological activity but the chemical assay still indicated a considerable potency. It was clear that the penicillin itself had been completely destroyed but some alkali-consuming substance remained. Lester Smith and Page (private communication) postulated that some of the loss of activity was caused by a breakdown of the penicillin molecule owing to cleavage of the sulphur-containing ring as follows:-\C+H.COOH CH, I ‘Cd ‘co CH,/ J I S N ‘\ /’ CH I , NH.CO.R CH 8-Cr.COOH I SH I N / \ HO.CH CO “ C d I NH.CO.R That this is so has been partially confirmed by the results of polarographic experiments.Since this (or something similar) occurs or may occur when penicillin decomposes it follows that the use of the chemical method for the assay of solutions or preparations that have partially lost potency must necessitate occasional checks against bio-assay to establish the reliability of the chemical results in the particular circumstances. Samples of freeze-dried (yellow) penicillin were kept at 100” F. for about 12 to 14 months and were examined to see whether decomposition had occurred in the solid substance over this long period.The samples (21) were assayed chemically and biologically; on the average the chemical were 10 per cent. higher than the biological results. The average loss of biological potency over the period was 25 per cent. It must be pointed out that the samples were of loose powder in stoppered vials i.e. not in the normal commercial freeze-dried vial pack 210 PATTERSON AND EMERY THE DETERMINATION OF [Vol. 73 it is not claimed that the experimental conditions were carefully controlled particularly in respect of moisture content. It is likely however in view of the higher chemical results, that the type of decomposition that occurs on boiling the solution had been slowly taking place.In the interpretation therefore of chemical assay results on old samples of solid penicillin, it will be necessary to bear this phenomenon in mind. ASSAY OF PENICILLIN OIL AND BEESWAX SUSPENSIONS-The B.P. oily injection is a suspension of calcium penicillin in a mixture of arachis oil with 4.5 per cent. of beeswax; it contains 125,000 i.u./g. The penicillin may be extracted for assay by dissolving the mixture in chloroform and shaking out with water; good recoveries have been obtained by this method but emulsions are readily formed. These may be avoided by using a large excess of chloroform but several extractions with water are then necessary; the layers take several minutes to separate completely and the procedure is tedious. TABLE I Batch Input i.u./g.Found i.u./g. 1 272,000 276,000 2 136,000 136,000 3 113,000 112,000 4 120,000 118,000 6 130,000 130,000 It was originally hoped to apply the chemical method of assay to these suspensions without previously removing the oil and beeswax; a number of solvents were used but in our experience some degree of saponification of the oil always took place results being con-sistently high. We realised that it would be necessary to separate the penicillin from the oil and beeswax and the following method depending on the negligible solubility of calcium penicillin in anhydrous ether was finally adopted. PROCEDURE-weigh between 1 and 2 g. of the sample to the nearest mg. into a dry 50-ml. centrifuge tube; add 50 ml. of dry ether to dissolve the oil and beeswax leaving the calcium penicillin undissolved and centrifuge for 3 minutes.Decant the ether layer carefully and as completely as possible; centrifuge with a further 50 ml. of dry ether and to the residue in the tube add 50 ml. of carbon dioxide free water proceeding with the chemical assay in the manner described above. Alternatively the penicillin recovered in this way can be dissolved in buffer solution and assayed biologically if necessary. TABLE I1 Original potency i.u./mg. Batch 8 9 12 14 16 17 20 26 34 37 62 64 3 7 9 11 12 16 Biological Chemical 149,000 136,000 142,000 137,000 145,000 134,000 166,000 146,000 141,000 126.000 144,000 136,000 268,000 264,000 276,000 284,000 276,000 278,000 Age months 11 11 11 11 11 11 11 11 10 10 7 7 10 10 10 9 9 9 Re-assay i.u./mg.Biological Chemical r c \ 169,000 140,000 144,000 117,000 162.000 127,000 122,000 131,000 - 144,000 138,000 127,000 iin.noo 116.000 ~ ~ ~ . 114,000 106,000 118,000 106.000 i0i:oOO 112,000 146,000 123,000 222,000 23 1,000 249,000 236,000 282,000 292,000 270,000 281,000 - 266,000 223,000 249,000 Storage temperature Room ,I $1 9, 9 " 100' F. I, ,, 100' F. " n 1, , The dry ether used in the above extraction is prepared by shaking anaesthetic ether with Table I gives the results on five experimental batches; they show that the extraction powdered calcium chloride for 1 hour followed by filtration and distillation.process is for all practical purposes satisfactory -2pri1 19483 PENICILLIN BY ALKALINE HYDROLYSIS 211 Similarly the method has been found adequate for the control of large-scale production batches both of the B.P. product and of oil and beeswax suspensions of higher potencies. STABILITY OF OIL AND BEESWAX SIJSPENSIONS-at 100" F. and others at room temperature. products considering the readiness with which penicillin itself can be destroyed. The figures in Table I1 were obtained on routine samples taken from stock some stored These figures indicate that the oil and beeswax suspensions are remarkably stable SUMMARY 1 I The alkaline hydrolysis method for quantitative determination of penicillin originally reported by the Pfizer research laboratory has been adapted to the routine examination of large numbers of samples.2. Reference is made to certain limitations of the method. 3 . Some applications of the method are described; they include a particular reference to a rapid method for the extraction of penicillin from suspensions in oil and beeswax. The authors are indebted to Miss H. B. Johnson and Mr. G. Norris for most of the chemical and biological assays respectively and to Mr. A. F. Lemgo for direction and advice. REFERENCES 1. 2. 3. GREENFORD MIDDLESEX Abraham E. P. Chain E. and Holiday E. R. Brit. J . Exp. Path. 1942 23 103. Committee for Penicillin Synthesis Report No. 602. Johnson H. B. and Lerrigo A. F. Quart. J . Pharm. 1947 20 3 183. G~axo LABORATORIES LTD. The Spectroscopic Estimation of Penicillin BY G.H. TWIGG THE complexity and uncertainty of the biochemical methods used in the estimation of penicillin and especially in the estimation of the different penicillins has led to the develop-ment of chemical and physical methods one of which is the use of ultra-violet and infra-red spectroscopy. With this technique the aim is to discover in the absorption spectrum a band which is characteristic of each penicillin molecule as a whole. In practice this is an ideal unlikely to be realised and use has to be made of absorptions arising from the separate parts of the molecule. While such a procedure may with little ambiguity be made to provide an estimate of total penicillin it leads to a fundamental difficulty in assaying individual penicillins. Impurities and deactivation products containing similar molecular groupings may have bands almost identical with those of the penicillins.It seems probable that the spectroscopic estimation of individual penicillins is applicable only to pure materials but more work is necessary to find out how far this is true. 1. ULTRA-VIOLET ANALYSIS OF TOTAL PENICILLIN-One of the first applications of spectroscopic methods was made by Herriottl for the determination of total penicillin. The method depends on the fact that an absorption band develops at 3220 A. on treatment of aqueous penicillin solution with acid. The band is due not to the end product of acid deactivation but to an intermediate. The absorption band, therefore disappears in time and the analysis thus depends on an empirical technique designed to catch this band at its maximum intensity.In practice the sample which may contain as little as 35 units is heated in a 0.4 M acetate buffer solution at $H 4.6 for 15 minutes and cooled rapidly. Using a Beckman ultra-violet spectrophotometer measure-ment is made of the increase in absorption at 3 2 2 0 ~ . compared with a blank in the same buffer but kept at room temperature. The penicillin concentration is then obtained from a calibration chart. This method can be used with impure material as it depends on an increase in absorption. .in accuracy to within 6 per cent. is claimed. Since the development of this technique 212 TWIGG THE SPECTROSCOPIC ESTIMATIOX OF PENICILLIX [Vol. 73 other methods have been found for the estimation of total penicillin and it is doubtful whether this method can compete with any of the chemical methods of assay for speed and accuracJ-.2. ULTRA-VIOLET ANALYSIS OF PENICILLIN c It is in the estimation of the individual penicillins that spectroscopic methods offer greater promise. Two methods have been developed; they depend on the absorption bands in the ultra-violet due to the phenyl group in penicillin G. In the first of these (Philpotts, Thain and Twig@) the ultra-violet spectrum of a solution of the sodium penicillin sample in water - ethanol (1 30) is photographed several times on a plate using a series of path-lengths which are varied by means of a Hilger micrometer cell. Alongside each exposure is recorded the spectrum of a standard penicillin G solution using the same path-length each time.The path-length at which the spectrum of the unknown solution matches that of the standard is estimated by eye with interpolation between spectra when necessary. The relative concentrations of the two solutions are then given by the inverse ratio of these path-lengths. As an alternative to penicillin G an alcoholic solution of phenyl acetamide can be used as a sub-standard. Its spectrum is not identical with that of penicillin G since the unspecific absorption of the penicillin molecule overlies some of the phenyl absorption bands but matching is possible at the longer wavelength bands at 2685 A. and 2645 A. This method appears to be accurate to -+2 per cent. for pure samples of penicillin. Certain impurities produce a continuous unspecific absorption so that direct matching of the intensities of the bands will give an incorrect result.However if this absorption is not too strong Ihatching can be effected by the pattern and width of the bands. With more impure samples an oxidation with permanganate was carried out and the benzoic acid produced estimated by the same method of matching spectra. The chief limitation of this method is that since it is based on the absorption produced by the phenyl group it will include all phenyl-containing substances whether active penicillin or not. This is particularly true of the estimation via benzoic acid. The result however, may be a useful guide in setting a maximum value to the penicillin G content of a sample. A further limitation is the possible presence of penicillin X which has a broad and strong absorption band; its presence to the extent of more than 1 per cent.will invalidate the analysis. This analytical method appears to hold for any salt of penicillin a correction for molecular weight only being necessary. One advantage of photographing the whole spectrum is that it is easily seen whether the sample has suffered any acid degradation by the appearance of a band a t 3220 A. A method similar in principle to the above has been devised by Grenfell Means and Brown3 for the estimation of penicillin G. Using a Beckman ultra-violet spectrophotometer, the optical density of an aqueous solution is measured at 2630 A. where there is a phenyl absorption band. Pure penicillin G has almost no absorption at 2800 A.; decomposition products and other impurities however have. To correct for these the optical density at 2800 A. is subtracted from that at 2630 A. Both penicillin K and F show some absorption at 2 6 3 0 ~ . and to take account of this all measurements of optical density are made with solutions of a constant total penicillin content (1.8 mg./ml.). A graph of the optical density difference (E,,, - EZ8,,) plotted against percentage of penicillin G in the sample is then found to give a straight line; analyses are evaluated from this calibration curve. The authors state that this method becomes inaccurate when the optical density at 2800 A. is greater than 0.1. This is similar to what was found by Philpotts Thain and Twigg.2 Grenfell Means and Brown overcome this difficulty by a purification of the penicillin.To the aqueous penicillin solution is added 30 per cent. of ammonium sulphate the mixture is cooled to -5" C . and the precipitate separated and analysed as before. It is stated that for fairly pure samples there is no change in the ratio of the penicillins in this process and that the recovery is over 90 per cent. With very impure samples this purification may not be adequate; it is then repeated and if a change in penicillin G content is found it is corrected for by a linear extrapolation to 100 per cent. purity. There appears to be nothing to choose between either of these two methods of using ultra-violet absorption for the estimation of penicillin G. Both suffer from similar defects, particularly in respect of phenyl-containing inactive material although the purification technique of Grenfell Means and Brown probably circumvents this source of trouble.It should be noted that in both methods the presence of pencillin X in quantities greater than 1 per cent. will invalidate the results. Grenfell Means and Brown detail a method of estimating the amount of penicillin X present April 19481 TWIGG THE SPECTROSCOPIC ESTIMATION OF PESIC ILLIX 213 Theoretically infra-red analysis should be the ideal method as the infra-red spectrum of any substance is unique. In practice there are serious difficulties. One of these may arise through the penicillin containing impurities or inactive materials that have absorption bands in the same position as the bands used for analysis. Another arises through penicillin being chiefly in the form of a salt (usually the sodium salt) which is insoluble in all the solvents that are of use in infra-red measurements; conversion of the salt to the free acid and transfer to a suitable dry solvent is not easy and may result in degradation.Barnes Gore Williams Linsley and Petersen4 claim to have overcome most of these and other difficulties in a method which uses the solid sodium salt. The salt is ground with a small quantity of Nujol and pressed to a suitable thickness between two rock-salt plates; the spectrum is recorded and these authors use a Perkin - Elmer spectrometer. A qualitative examination of the whole spectrum is always made and may reveal the presence of impurities I t should show a band at 1770 cm.-l which is common to all the penicillins.From an examination of pure samples of the five known penicillins Barnes et al. show that each has a characteristic band which is usually free from interference by the bands of the other penicillins. One difficulty in the analysis of solids is to know the thickness of the absorbing layer of the substance under examination. This has been overcome by the use of an internal standard in known concentration and for this purpose the authors recommend dl-alanine. Weighed amounts of penicillin and dl-alanine are ground together a drop of Nujol is added and the mixture is squeezed between rock-salt plates. Most of the work described was on the analysis of penicillin G which has a characteristic band at 703 cm.-l For comparison the alanine band at 851 cm.-l was used and the ratio R = log (Io/I),03/log (Io/I)851 was determined.(I and I are respectively the intensities of the incident and transmitted radiation.) A calibration curve of R against percentage of penicillin G was made up by dilution of pure penicillin G with magnesium oxide; it was claimed that by means of this curve analysis of unknown mixtures could be made accurate to 1 2 per cent. A similar method was used for the analysis of the other penicillins; characteristic bands used were penicillin F 971 cm.-l F (amyl) 1166 cm.-l K 1330 cm.-l and X 831 cm.-l. There are many technical difficulties in this method of analysis. The effect of crystal structure is not known and a separate calibration may be necessary with amorphous material. I t is not easy accurately to measure I, the intensity of the incident radiation; in the present work it was measured by interpolation of the background intensity a procedure which may be inaccurate especially if impurities are present having absorption bands close to the band being measured.One of the most serious difficulties and one that may limit the technique to crystalline penicillin of high purity is the possible presence of substances such as deactivation products that have absorption bands at the same wavelength as the characteristic bands of the penicillins. For example the band used in the analysis of penicillin G is one associated with the presence of phenyl groups; deactivation products as well as substances such as phenyl-acetic acid will thus interfere with the analysis.I t is true as Barnes et al. point out that such impurities may be detected by the additional bands they produce at other wavelengths, e.g. those of phenylacetic acid at 682 cm.-l and 728 cm.-l It is possible though unlikely, that a unique band characteristic of the active penicillin may be found. In their work on the quantitative analysis Barnes et al. have used only pure specimens of the penicillins, and it is obvious that further investigation is required before the validity of this method of analysis is completely established. One samplt. of penicillin G was found to give an anomalous result on analysis. Microscopical examination revealed that the crystals were in the form of flat plates that had become oriented on squeezing the Nujol mull between the rock-salt plates; the intensities of absorption along the different crystal axes are not equal.The practical difficulty caused by this could be overcome by a more complete grinding of the sample and the production of a thoroughly random distribution of the crystals. The effect if present can be detected by observing whether the apparent penicillin concentration (as measured against the alanine) is altered when the sample is rotated in the beam of radiation. 3. INFRA-RED ANALYSIS OF INDIVIDUAL PENICILLINS-This characteristic band is used for quantitative analysis. An interesting effect due to crystal orientation was found by Barnes et al 214 [Vol. 73 From the foregoing it may be concluded that the application of spectroscopic methods to the analysis of penicillin has been moderately successful the limitations being imposed mainly by impurity of the material.In a sample consisting very largely of active penicillin, the G content can be determined accurately by means of ultra-violet absorption and the technique is fairly quick and simple. It appears possible to extend the analysis to less pure samples by making a purification under standard conditions. Infra-red measurements can be applied to the determination of the other penicillins but here the technique is more com-plicated and further exploratory work appears to be necessary to put the method on a sound basis. SUMMARY DISCUSSIOS PHYSICAL AXD CHEMICAL METHODS FOR PENICILLIN ASSAY The applications of ultra-violet and infra-red spectroscopy to the estimation of total and individual penicillins are reviewed and the limitations of the methods are discussed.1. Ultra-violet analysis of total $enicillin-Total penicillin can be measured by the absorption band at 3220 A. which develops when an aqueous penicillin solution is treated with acid under standard conditions. 2. Ultra-violet analysis of $enicillin G T h e analysis depends on the absorption bands due to the phenyl group. In one method using a photographic technique the spectrum of the unknown is compared with that of a standard. In another method using a spectro-photometer the difference in optical densities at 2630 A. and 2800 A. gives a measure of the penicillin G concentration. Penicillin X in more than 1 per cent. concentration invalidates these methods. The effect of impurities and de-activation products is discussed.3. Infra-red anaEysis of individual penicillins-Spectra are recorded of the penicillin in the form of its solid sodium salt. The individual penicillins each have characteristic absorption bands which are substantially free from interference by each other and can be used for quantitative analysis. For estimations a suitable solid internal standard is mixed with the penicillin. Some of the difficulties of the method are discussed. The author thanks the Directors of the Distillers Company Limited for permission to publish this paper. REFERENCES 1. 2. 3. 4. Hemott R. M. J . Biol. Chem. 1946 164 725. Philpotts A. R. Thain W. and Twigg G. H. Nature. 1947 159 839. Grenfell T. C. Means J. A. and Brown E.V. J . Biol. Chem. 1947 170 627. Barnes R. B. Gore R. C. Williams E. F. Linsley S. G. and Petersen E. M. Arzal. Chem., 1947 19 620. THE DISTILLERS COMPANY LTD. RESEARCH AND DEVELOPMENT DEPARTMENT GREAT BURGH EPSOM SURREY DISCUSSIOS 0s THE PRECEDING FOUK PAPERS ON PHYSICAL AND CHEMICAL METHODS OF PENICILLIN ASSAY Dr. J. E. PAGE gave some particulars about the polarographic determination of penicillin. The procedure depends on the observation that penicillamine in an ammoniacal cobalt buffer solution forms a catalytic step similar to that given by cysteine (cf. Brdicka CoZZ. Czech. Chenz. Comm. 1933 5 148). A fresh solution of pure penicillin does not give a catalytic step but if the buffer solution is allowed to stand in the polarograph cell in the presence of the dropping mercury electrode hydrolysis takes place and the catalytic step slowly develops.For analytical work the penicillin is inactivated with 0.1 N sodium hydroxide hydrolysed by warming with 1.0 N hydrochloric acid and dissolved in BrdiEka's ammoniacal cobalt buffer solution. The hydrolysis of the penicillin and preparation of the buffer solution must be carried out under carefully controlled conditions ; the final solution must be polarographed immediately. Small changes in pH value have an appreciable effect on the height of the catalytic step. If a trace of gelatin is added to the solution the maximum on top of the cobalt step is suppressed but the height of the catalytic maximum is not affected. The vertical distance from the top of the cobalt step to the characteristic catalytic minimum provides a measure of the penicillin originally present.The results for purified penicillin solutions listed in the Table show that the accuracy of the polaro-graphic method is of about the same order as that of the biological procedure. In these experiments, 2 ml. of each penicillin solution were inactivated hydrolysed and diluted to 60 ml. for polarographic examination. The method is not suitable for metabolism solutions since any substance containing a free sulphydryl group will interfere with the assay and certain amino acids such as tryptophan histidine and arginine exert a suppressive action on the height of the catalytic step. Some typical polarograms for hydrolysed penicillin are reproduced in Figure 1 April 19481 DISCUSSIOS PHYSICAL AiKU CHEMICAL METHODS FOR PENICILLIN ASSAY 216 'i 0 -08 -1.2.-16 -2ovo Ammoniacal cobalt buffer solution - 0.8 -1,2 -1.6 -2.0 V O ~ 1.0 I.U. of sodium penicillin per ml. of buffer solution No. of replicate.; 11 12 10 9 11 9 8 8 -0.8 -1.2 -1.6 -2.0 V( s 0.6 I.U. of sodium penicillin per ml. of buffer solution t5 2.0 I.U. of sodium penicillin per ml. of buffer solution OF RESULTS OF POLAROGRAPHIC AND BIOLOGICAL ASSAYS Percentage Mean coefficient of Biological assay polarographic assay variation of in i.u./ml. in i.u./ml. polarographic values 20 20 25 40 42.5 8 50 57.5 9 100 95 8 150 155 7 200 210 4 300 300 5 300 510 4 In reply to Dr. G. E. Foster Dr. PAGE said that the polarographic method was not suitable for the determination of penicillin in samples contaminated with hydrolytic decomposition products but that i t could be used to study the nature of such products.Mr. L. J. BELLAMY asked Dr. Lester Smith for information on the hydrolysis of penicillin with alkali. He suggested that as temperature seemed to influence the rate and possibly the degree of hydrolysis the simple opening of the p-lactam ring might not be the only reaction involved. From the practical point of view sufficient evidence had been presented by Patterson and Emery to show that the hydrolysis was quantitative enough to give results in reasonable agreement with the biological method, bearing in mind the uncertainty of the conversion factor when dealing with mixed penicillins. From personal experience with the chromatography of penicillins he agreed with nearly all Dr.Boon's comments. With silica gel columns 80 per cent. recovery of penicillin seemed as much as one could expect and the claims of some American workers to get nearly quantitative recovery (except with amyl penicillin) seemed rather remarkable. Some other American workers described a modification of the paper strip method said to be applicable directly to fermentation liquors. The strips are buffered at pH 6.0 and developed Dr. LESTER SMITH said he had no further information on the alkaline hydrolysis of penicillin 216 BRITISH STANDARDS INSTITUTIOX [Vol. 73 for a few hours only at room temperature using amyl acetate This method revealed some new penicillins called S and S near the top of the strip but did not give good separation of penicillins F and G.The I.C.I. method however was capable under favourable conditions of completely separating penicillins 11, I and IV (in the I.C.I. nomenclature). The Craig apparatus had proved rather cumbersome and laborious in use and appeared incapable of doing anything more than separating penicillin K from all the others. Noreover some destruction of penicillin was observed during the protracted manipulations. Dr. Lester Smith said that his colleague hlr. Hickman had measured the partition coefficient for pure penicillin G between various solvents and buffer solutions and found hardly any changes in the values over the concentration range of 60 to 5000 i.u. per ml. On the other hand the partition coefficient zi,us influenced by other acids such as those present in crude penicillin.As to the ethyl piperidine method he had also demonstrated by the paper strip method the presence of penicillins other than G in the precipitate and in addition the presence of a substantial part of the original penicillin G in the filtrate. The method for purification of crude penicillin by precipitation with ammonium sulphate referred to by Dr. Twigg did not appear satisfactory with some penicillin samples. Some batches rich in penicillin K and assaying 600 to 800 i.u. per mg. had given no precipitate a t all with saturated ammonium sulphate solution. Dr. W. R. BOON said that from the results obtained by Mr. Greenhalgh and Dr. Pryce it was clear that in some solvents penicillin was markedly associated. This effect was most important with chloroform. It also appeared that there was cross association between different species of penicillin and impurities such as phenylacetic acid. This might explain the difficulty of separating individual penicillins on the micro-chromatogram when solvents other than ether were employed. He also agreed with Dr. Lester Smith that the ammonium sulphate precipitation method did not always work within the limits set by American workers. Many samples that should have been satisfactory gave either no precipitate or a sticky brown mess. Mr. C. W. +MUNDAY had found that the infra-red method could be used for the analysis of penicillin provided that the total penicillin content was greater than 90 per cent. Two-component mixtures of sodium penicillin G and sodium penicillin F had been examined and the infra-red results were in fair agreement with those obtained by Goodall and Levi's micro-chromatographic method. The difficulty of mixing the sample and internal standard could be overcome by suitable experimental technique. Infra-red spectroscopy was of considerable value for following the changes that take place in penicillin during storage. Mr. K. A. BROWNLEE said that it was perhaps not generally realised that the iodimetric method could give seriously erratic results compared with biological assay. He had found that the difference betweer, iodimetric and biological assay for freeze-dried penicillin varied appreciably according as the penicillin solution was freeze-dried in 0-1 or 0.2 mega unit vials. Dr. PAGE asked Dr. Twigg if he had any information about the X-ray method for penicillin (cf. I d . Eng. Chew. 1947 November p. 14~). Dr. TWIGG said that he did not know about the method but he thought that such a technique could only be applied to crystalline penicilli

ISSN:0003-2654    

DOI:10.1039/AN9487300197

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction

ISSN:0003-2654    

DOI:10.1039/AN948730216b

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

A4prii 19481 ABSTRACTS F001) ASD DRUGS 217 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS Food and Drugs Determination of the Moisture Content of Cereals by Measurement of Specific Inductive Capacity. L. G. Groves and J. King (1. SOC. Chem. Ind. 1946 65 320-324)-The apparatus uses well-established principles and is easily constructed in the laboratory. The circuit is similar to that of Groves and Sugden ( J . Chern. SOL 1934 1094) and consists of a high-frequency oscillator loosely coupled to a valve voltmeter receiver. The tuned circuit of the latter contains a measuring condenser cell into which the sample is introduced. A calibrated variable condenser, C7, connected across the cell allows the electrical capacity change thus produced to be compensated and the receiver to be kept in resonance with the oscillator.Resonance is indicated by a maximum reading of the galvanometer in the anode circuit of the receiver. The apparent specific inductive capacity is given by the ratio of the capacities of the cell when filled with the sample and when empty. When moisture is the only variable there is a straight-line relationship between moisture content and specific inductive capacity. However each cercal requires its own calibration curve. WIFING CILHDLH / I i 1 ! a< LEM 3 MMS. EKUITL ' + ERISS REINFORCWC FOR RICID(1Y. The cell consists of two concentric brass cylinders forming an annular space 3 mm. wide. The outer cylinder is connected to the earthed side of the system is let into a stout ebonite base plate and has a t the upper end a detachable ebonite filling sleeve.The inner cylinder is connected to the grid of the receiver triode and is driven on to an ebonite plug. The latter is reinforced with brass a t the lower end and fits into a hole in the base plate. An appropriate weight of sample is fed into the filling sleeve; after each small addition, a brass tamping cylinder is inserted rotated and withdrawn helically. To empty the cell the plug is withdrawn when the cereal either falls or is brushed through the hole in the base plate. The nature of the sample must allow packing of uniform density from a standard weight. Sieving is usually necessary and biscuit tapioca and the like require grinding before sieving. The method is not applicable to cereals that contain angular starch grains (e.g.maize) and form tight aggregates. Uniform packing of fine powders such as flour requires considerable practice. The prepared sample must be kept in a stoppered bottle until equilibrium is attained. Its conductivity must be low and its specific inductive capacity high so that the tuning curve is sharp. The apparatus is suitable for the rapid examina-tion of numerous samples. It should be possible to estimate the moisture content to within 0.25 to 1 per cent. Measured over the range 0" to 30" C., the temperature coefficient of the apparatus is much smaller than the experimental error. J. T. STOCK Determining the Presence of Olive Oil extracted from Oil-cake or of Arachis Oil, in Olive Oil obtained by Pressing.G. Loew (Id. y Quim. 1947 9 9-12)-The method of detecting the presence of oil-cake oil depends on the observation of Dorta (Atti X" Congr. intern. Chin%. 1939 4 517) that the oil extracted from oil-cake contains a greater proportion of un-saponifiable matter and also contains waxy substances and their polymerisation and oxidation products. These substances are stated to be unaffected during refining and therefore appear in the final product together with the unsaponifiable matter normally present in olive oil; the presence of these substances causes a rise in the m.p of the unsaponifiable matter and a determination of the m.p. permits an estimate of the proportion of oil-cake oil present even in presence of arachis oil. Procedure-The unsaponifiable matter is separated by a modification of the method of Spitz and Hoenig.Distil off the ether used for extraction in several stages using a small flask; when the volume has been reduced to 5 ml. transfer the solution to a test tube of 12-mm. diameter and remove the remaining solvent by carefully immersing the tube in boiling water for 5 min. Immediately transfer the test tube to a 250-ml. flask containing water a t 50" C. fixing tb tube in place by means of a cork, and arranging in the tube a thermometer graduated in 0.1" up to 50" C. Note the temperature a t which the entire contents of the tube become turbid (separation of crystals at temperatures below 25" C. is not characteristic of the non-saponifiable matter from oil-cake olive oil). This temperature is the "turbidity point" Pe.The determination of the turbidity point must be carried ou 218 ABSTRACTS OF CHEMICAL PAPERS [Vol. 73 immediately after the elimination of the ether its partial polymerisation of the unsaponifiable matter will otherwise lead to a rise in the solidification point. It is essential that the temperature should drop slowly during the determination of Pe and a surrounding temperature of 20" C. is recom-mended; if necessary the flask should be immersed in a water-bath a t 20" C. After determining Pe allow the temperature to fall further tilt the flask frequently and record the temperature at which the contents of the test tube become gelatinous and cease tp drain down the walls of the tube; this temperature is the solidjfica-tion point Ps.Unrefined oil obtained by pressing is said to contain not more than 0.9 to 1.2 per cent. of un-saponifiable material which remains clear and drains well a t 20" C.; after long standing small crystals separate. Refined olive oil contains about 1 per cent. of unsaponifiable matter which, in general behaves in the same way as that from the unrefined oil though it may become opalescent at 26" to 25"C. but without becoming turbid; it drains down to 22" to 20" C. If before refining, the oil is of very poor quality and contains much acid such as the "washed" or "infierno" oils, the unsaponifiable matter may become turbid at 30" C. and solidify at 25" C. A refined oil-cake oil has Pe between 45' and 40°C. and Ps between 44' and 38' C.and the content of unsaponifiable matter is about 2 per cent. Table I shows the variation of Pe and Ps with different proportions of oil-cake oil and pressed oil. that this content may increase greatly especially during brewing. Differences in brewing conditions may thus account for most of the variations found in the riboflavine content of malt extract. The fluorimetric assay applied t o barley and malted barley gave figures for the riboflavine content ranging from 72 to 89 per cent. of those obtained microbiologically; and sometimes the fluorimetric result was even lower. These differences do not affect the above conclusions. J. ALLEN Colorimetric Determination of Morphine. D. C. M. Adamson and F. P. Handisyde (Quart. J . Phavm. 1946 19 350-359)-The method based on the colour produced by treating a solution of morphine with nitrous acid and making the mixture alkaline has been examined and details of an improved photometric technique employed are given.Procedure-Transfer a volume of a solution of the alkaloid in 0.1 N hydrochloric acid such as might be expected to contain not more than 1 mg. of morphine to a 50-ml. Nessler cylinder and dilute to 20 ml. with 0.1 N hydrochloric acid. Add 8 ml. of a 1 per cent. aqueous solution of sodium nitrite mix well with a plunger .and allou-to stand for exactly 15min. Then add 12ml. of 10 per cent. aqueous ammonia solution immediately dilute to 50 ml. with distilled water and measure the extinction by means of a Spekkez absorptio-meter using 4-cm. cells and Ilford 601 (spectrum violet) and €3.503 heat filters.Read off the quantity of morphine present in the volume of I TABLE I Oil obtained by Oil-cake oil, - 100 pressing per cent. per cent. Pe Ps 100 clear at 22"-20" C. clear at 22"-20" C. turbid at 45O-40" C. gelatinous at 44"-38" C. 99 42'41" C. . 9) 43"-42"C. 50 60 70 80 90 50 40 30 20 10 97 99 I 9 ) 40.5"-40" C. 38"-37" C. 39 39"-38.5" C. 36*8"-36.5' C. 93 38"-37°C. I 9 35"-33.8' C ! Y9 36"-33.8" C. 3lo-3O0C. f The method recommended for detecting arachis oil in olive oil obtained by pressing is that of Jaffe (Annuli di Chimica Applicata 1928 18 368) and depends on the very slight solubility of the lithium salt of arachidic acid a characteristic component of arachis oil.The test is not invalidated by the presence of oil-cake olive oil. E. M. POPE Riboflavine in Malt Extract. C. Klaztkin, F. W. Norris and F. Wokes (Quavt. J . Pharm 1946 19 376-387)-Fluorimetric assays have been conducted on 25 samples of malt extract and malt preparations made by 10 differeot manufacturers. The results indicate wide variations ranging from 0.09 to 0.3 mg. per fl. 02 in riboflavine content. With one exception which is being further investi-gated the figures obtained are in good agreement with those derived from microbiological assays, being on the average 103 per cent. of the latter. A study of the effect of malting and brewing on the riboflavine content of malt extract showed solution used by referring to a curve correlating known quantities of the alkaloid with the extinction produced by the same procedure.The colour is adequately stable a diminution of about 1 per cent. during 1 hr. being observed when the final solution is exposed to artificial light. The stability is much less in daylight. The morphine and nitrite standard described in the 7th Supplement to the B.P.C. 1934 is shown to be unsatisfactory in that no time of standing before alkalising is specified and no age limit for the reagent is given. The absorption curve of the ammoniacal nitroso-morphine has three maxima at 235,342 and 442 mp., the corresponding extinctions based on the morphine content being 360 169 and 124 respec-tively. The presence of a comparatively high peak in the ultra-violet region may prove of value in detecting small amounts of morphine.Several samples of papaveratum have been examined by the official procedure and by the proposed method ; the results are quoted. The compensating '' blank April 19481 BIOCHEMICAL 219 technique of Nicholls ("Aids to the Analysis of Food and Drugs," London BailliBre Tindall & Cox, 1942 p. 371) was used and the agreement obtained was about f2 per cent. The proposed method is not specific for morphine (see Garratt Quart. J . Pharm. 1937 10 467) since i t is a general reaction for most phenols. In injection of papaveratum, B.P.C. 2nd Supplement there is 0.2 per cent. of chlorocresol for 1 per cent. of morphine. In such a preparation the morphine content as determined by the proposed method would be subject to a positive error of not more than 1-5 per cent.When subjected to the proposed method both phenol and chlorocresol give a colour but this is not directly proportional to the concentration over the range studied. J. ALLEN Simple Colour Reaction for Piperazine. R. D. Barnard ( J . Amer. Pharm. Assoc. Sci. Ed 1947 36 224)-To about 5 ml. of test solution add dropwise sufficient of a 5 per cent. aqueous solution of potassium ferricyanide to produce a permanent pale yellow tint add a droplet of mercury and shake well. In presence of piperazine, a lilac colour that fades after 10 min. is developed, but i f an excess of solid sodium bicarbonate be first added to the test solution a permanent red colour is produced on completing the test. Solu-tions containing proteins become turbid when shaken with the mercury although the colours can still be detected whilst if polyphenols are present they must first be removed by extracting the acidified sample with ether.A. H. A. *\BBOTT Determination of Barbituric Acid Deriva-tives. H. A. Mangouri and L. Milad (Quart. J . Pharm. 1947 20 109-113)-Critical investiga-tion of the available methods for the determination of barbituric acid derivatives revealed in each sources of error not easy to control. The following technique which trials showed to be the most suitable set of conditions for utilising the property of these derivatives of forming silver salts was evolved as an alternative. Procedure-Suspend about 0.17 to 0.25 g. of the material in 20 ml. of water add 10 ml.of 10 per cent. sodium acetate solution warm gently and add dilute aqueous ammonia dropwise until the suspension is dissolved. Boil off the excess of ammonia add a known volume of 0.1 N silver nitrate and 0.1 g. of pure calcium carbonate boil the solution for 2 to 3 min. cool filter and wash the precipitate with 5-ml. quantities of freshly boiled cooled water until free from silver. Acidify the combined filtrate and washings with dilute nitric acid and titrate the excess of silver nitrate with 0.1 N ammonium thiocyanate using ferric ammonium sulphate as indicator. CaZcuZation-From the volume of 0.1 N silver nitrate consumed calculate the quantity of the barbituric acid derivative from the following data 1 g.-molecule of the barbituric acid derivative reacts with 2 g.-equivalents of silver if it is one of the acid derivatives or their sodium salts with 4 g.-equivalents if i t is one of the thiobarbituric acids or their sodium salts and with 1 g.-equivalent i f it is one of the N-methylated derivatives or their sodium salts. For thiobarbituric acid derivatives the boiling period should be increased to 5 to Gmin. but for sodium N-methylated derivatives warming to 60" to 70" C. is sufficient to coagulate the silver com-pound. The addition of ammonia is not necessary when the two imido hydrogen atoms in the nucleus of the derivative are replaced by a metal and a radical respectively. A. H. A. ARBOT

ISSN:0003-2654    

DOI:10.1039/AN9487300217

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE.By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time.The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years.The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion.The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on.Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp.15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C.Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner.He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE.By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time.The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years.The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions.After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction

ISSN:0003-2654    

DOI:10.1039/AN9487300219

出版商:RSC    

年代:1948

数据来源: RSC