ISSN:0003-2654    

DOI:10.1039/AN94772FX017

出版商:RSC    

年代:1947

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94772FP019

出版商:RSC    

年代:1947

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 MAY, 1947 THE ANALYST Vol. 72. No. 854 PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS AN Ordinary Meeting of the Society was held at 6 p.m. on Wednesday, April 2nd, at the Chemical Society’s Rooms, Burlington House, London, W.l. The chair was taken by the President, Mr. Lewis Eynon. The following papers were presented and discussed: “A Note on the Chapman and McFarlane Method for the Estimation of Reducing Groups in Milk Powder,’’ by C.H. Lea, DSc., F.R.I.C.; “The Determination of Carotene in Dried Grass,” by W. A. G. Nelson, B.Sc.,Ph.D. NEW MEMBERS William James Carpenter, A.R.I.C. ; Henry Edward Coornber, BSc. (Lond.) ; Charles Donald Cook, A.R.I.C. ; John Ruff Gwilt, A.R.I.C. ; George Edmund Holmes, M.A. (Cantab.) ; Harold Thomas Islip, BSc. (Lond.), F.R.I.C. ; Alexander Johnston, B.Sc. (Glas.) ; Henry Kenneth Lawton, B.Sc., Ph.D. (Liv.), F.R.I.C. ; Leopold Ferdinand Levy, MSc. (Witwaters- rand), Ph.D. (Lond.) ; Colin Marsden, B.Sc., Ph.D.; Harry Polkinhorne, BSc. (Lond.), A.R.I.C. ; Arthur Henry Snowden, A.R.I.C., Ph.C. ; John Ivor Webb, B.Sc., Ph.D.(Birm.), F.R.I.C. ; William Sydney Durham Wise, B.Sc. (Bris.). DEATH Sura Rajagopal Naidu WE regret to have to record the death of SCOTTISH SECTION THE twelfth Annual General Meeting of the Scottish Section was held in Glasgow on January 15th, 1947. The following is the list of office bearers elected for the year. Chairman-Dr. H. Dryerre. Vice-Chairman-Dr. J. Sword. Hon. Secretary and Treasurer-R. S. Watson. Other Members of Committee-A. R. Jamieson, H. C. Moir, J. Sandilands, A. M. Smith, R. G. Thin and S. L. Tompsett. Hon. Auditors-A. R. Campbell and W. M. Cameron. MICROCHEMISTRY GROUP AT the Annual General Meeting of the Group, held on Friday, January 31st, 1947, at the Sir John Cass Technical Institute, London, E.C.3, Mr. Norman Strafford was elected Chairman in place of Professor H. V. A. Briscoe, who had completed his term of office, Dr. Janet Matthews was elected Vice-chairman and Professor Briscoe, Mr. J. T. Stock and Mr. E. J. Vaughan were elected Ordinary Members of the Committee in place of Miss I. H. Hadfield, Dr. Janet Matthews and Dr. G. H. Wyatt who, having served for two years, were due to retire. After the Annual General Meeting the following papers were read and discussed: “A Review of Electrolytic Methods of Microchemical Analysis,” by A. J. Lindsey ; “The Oxidation of Nitrogen during the Micro-combustion of Organic Substances,” by A. E. Heron (see this Vol., p. 142); “The Micro Separation of Gums from Crystals,” by A. L. Bacharach; “The Microchemical Determingtion of Molybdenum in Steel,” by J. E. Wells and R. Pemberton (see this Vol., p. 185).

ISSN:0003-2654    

DOI:10.1039/AN9477200177

出版商:RSC    

年代:1947

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-ction 178 ANGELL : SOME ANALYTICAL METHODS APPLICABLE TO [Vol.72 Some Analytical Methods Applicable to Furan and its Derivatives BY F. G. ANGELL IN recent years attention has been focussed on the utilisation of waste vegetable material as a potential source of commercial chemicals, notably furfural and other furan derivatives. Little information exists in the literature concerning analytical methods applicable to such compounds, and the present paper deals with quantitative methods that have been employed in the examination of a large range of furan derivatives prepared in the Research Department of Imperial Chemical Industries, Ltd. (Billingham Division), including furfural, furfuryl alcohol, tetrahydrofurfuryl alcohol, furan, sylvan, tetrahydrofuran and tetrahydrosylvan. These methods may be classified under three headings, viz., Oximation, Absorptiometric and Bromination.1. OXIMATIOK- -0 + H,NOH.HCl -+ 0 H : N O H + HCl + H,O 0 0 The extent of the reaction is ascertained by titration of the hydrochloric acid liberated from neutralised hydroxylamine hydrochloride and the method is in general limited to the estima- tion of large amounts of furfural. Various furan compounds (e.g., furfuryl alcohol), when warmed with the reagent, undergo ring opening with the production of aldehydes, and this behaviour seriously limits the applicability of the method. 2. ABSORPTIOMETRIC- The production of a red colour by mixing furfural and aniline acetate has been recognised for a long time as a specific qualitative test for the former compound (and thus for pentosans).By working under carefully controlled conditions on the basis of this test,2 an absorptiometric method has been developed and is of considerable utility in the determination of sub- ordinate amounts of furfural present as impurity in other furan compounds. 3. BROMINATION- “Pyridine sulphate bromide’’ has been found to effect complete saturation of the ring with such compounds as furfuryl alcohol, furan, and sylvan. Little, if any, substitution occurs, for the corresponding tetrahydro compounds are practically inert towards the reagent. It is therefore of great utility in the analysis of such compounds. Certain furan derivatives, e.g., furoic acid and furfural, are unaffected by this reagent although they are attacked by acidified potassium bromide - bromate solution.Furoic nitrile exhibits unique behaviour in that it is inert towards all ordinary bromination reagents. EXPERIMENTAL 1. OXIMATION OF FURFURAL Redistilled furfural (b.p. 162.0” to 162-2” C.) which was pale straw yellow in colour and neutral towards methyl yellow was used in investigating the method. The results in Table I, obtained by the method described below, indicated that oximation did not proceed further than 98.0 per cent. even if the sample was left in contact with the reagent for 1 hour. No increased precision resulted from the use of larger weights of sample involving correspondingly larger titrations. Examination of some solutions whose concentrations were not known to the analyst (Nos.4 to 6 in Table I), on these lines, confirmed that the reaction was not quite stoichiometric. Owing to the intense buffering action of the excess of hydroxylamine hydrochloride, titrations with 0.1 N sodium hydroxide are not recommended, as the end- points so obtained are too indefinite, and in such circumstances larger quantities of sample should be used for analysis or the furfural determined by the aniline acetate method.May, 19471 FURAN AND ITS DERIVATIVES 179 When applied to the determination of furfural in mixtures containing furfuryl alcohol and the like it is essential that the oximation be carried out in the cold, for on being warmed TABLE I Wt. of sample Expt. No. present, mg. 1 528.1 2* 630.4 3 624.8 4 492.2 5 560.9 6 422.0 0.5 N NaOH required, ml.10.75 12.90 12.80 10.10 11-45 8.68 Wt. of furfural found, mg. 5 16.0 619.2 614.4 484.8 549.6 416.6 Mean * 1 hr. standing. Percentage oximation 97-6 98.2 98.3 98.5 98.0 98.7 . . 98*'2&0*6 furfuryl alcohol readily undergoes ring opening with the production of various compounds containing a carbonyl group. Although these compounds will react with hydroxylamine hydrochloride, this reaction is not suitable for the accurate determination of furfuryl alcohol, because variable quantities of dark-coloured polymerised products are often also formed. METHOD- Reagents- (1) A 5 per cent. w/v solution of hydroxylamine hydrochloride in water, neutralised with 0.5 N sodium hydroxide to the orange tint of methyl yellow. (2) Refined methanol (of low aldehyde content).(3) Indicator-a 0-1 per cent. solution of methyl yellow in methanol. (4) Sodium hydroxide solution, 0.5 N, free from carbon dioxide. Procedwe-Weigh 0.5 to 0.7 g. of the sample by difference, from a weighing pipette, into a 250-ml. beaker containing 15 ml. of neutralised hydroxylamine hydrochloride solution (50 per cent. excess) and 15 ml. of methanol. After half an hour titrate the liberated hydro- chloric acid in good daylight with 0-5 N sodium hydroxide to the orange tint of the indicator, using a blank solution containing the same volume of reagents to assist in judging the end- point. 2. ABSORPTIOMETRIC DETERMINATION OF FURFURAL Determination of subordinate quantities of furfural (about 1 mg.) have often been con- ducted by matching the red colour produced with aniline acetate against a series of standards diluted to a convenient volume with methanol in Nessler cylinders.Preliminary experiments indicated that in the presence of methanol the optical extinctions measured on the Spekker TABLE I1 SOLUTION CONTAINED 0.554 MG. O F FURFURAL-EXTINCTIONS I N 1-CM. CELL (El FOR HG LINE 5461~ (CALOREX 503 AND ILFORD 605 FILTERS) 2.5 g. of aniline + 25 ml. of glacial acetic acid and 1 g. of Na,HPO,. 12H20 diluted to 100 ml. with water. f A \ Time (mins.) El cm. 30 0.272 45 0.303 60 0.330 75 0.354 90 0.353 105 0.354 150 0-337 2.5 g. of aniline+ 10 ml. of glacial acetic acid + 1 g. of Na,HPO,. 12H20 diluted to 100ml. with water r A > Time (mins.) El cm. 5 0.014 15 0.077 30 0.169 45 0.159 60 0-147 absorptiometer with an appropriate filter diminished rapidly on standing, and moreover no advantage was gained by substituting aniline hydrochloride for the acetate.Of the various methods proposed in the literature for developing this test on an absorptiometric basis the procedure of Stillings and Browning1 as modified by Duncan,2 seemed the most attractive. The latter author recommended a mixture of disodium phosphate and oxalic acid as a stabiliser, but it was found that disodium phosphate alone was quite satisfactory for this purpose. Further, it seemed desirable to avoid using oxalic acid, because of the sparing solubility of180 ANGELL : SOME ANALYTICAL METHODS APPLICABLE TO [Vol. 72 sodium hydrogen oxalate. A large volume of the mixed reagent prepared according to the directions of Duncan deposited, on standing, a considerable quantity of a crystalline precipi- tate, presumably this salt.The effective time for the maximum development of the colour with aniline acetate and disodium phosphate, the period of stability, and the effect of using lesser quantities of acetic acid were next investigated. As will be seen from Table 11, with less acetic acid the colour was not so fully developed and faded more rapidly, but in presence of 1 g. Na2HP0,.12H20 and 25ml. of glacial acetic acid containing 26g. of freshly distilled aniline the extinction was at its maximum between 75 and 105 minutes, after which time it gradually diminished. METHOD- Reagents- (1) A 10 per cent. w/v solution of freshly distilled aniline in glacial acetic acid (2) A 10 per cent.w/v solution of Na2HP0,.12H,O in water. (freshly diluted each day). Procedztre-Adjust the temperature of d solutions to 20 f 0.5" C. before mixing. Measure an aliquot of the sample solution, containing 0.2 to 1.0 mg. of furfural; it should be neutral to phenolphthalein. Add 10 ml. of 10 per cent. Na2HP0,.12H20 solution, dilute to 70 ml. with water, and tinally add 25 ml. of aniline acetate reagent and adjust the volume to 100 ml. At the same time prepare a blank solution in an identical manner. After the expiration of 14 hrs. measure the extinc- tion in a l-cm. cell for the Hg line 5 4 6 1 ~ , using Calorex 503 and Ilford 605 filters, with the blank solution in No. 2 cell. The results given in Table I11 were obtained in this manner; from them was derived the relation: Mix well and immediately transfer to a dark cupboard.E, cm. x 1.50 = mg. of furfural per 100 ml. of solutions for values of E, below 0.7. TABLE rrI wt. of furfural, mg. 0.156 0.469 0.782 0.940 1.096 1.253 1.409 Elm. 5461 A 0.100 0-314 0.628 0.634 0.726 0.781 0.824 Factor 1.56 1-49 1-48 1.49 1.51 1-61 1.71 The colour is virtually specific for furfural and unaffected by acetone, furfuryl alcohol Table IV gives the results obtained on some typical products or tetrahydrofurfuryl alcohol. containing small quantities of furfural. TABLE IV Furfural % Furfural % Description of sample (absorptiometric) (by oximation) } 1.50 1.58 Distillate obtained by digestion of waste vegetable material (con- taining ketones, etc.) Ditto 1-48 1.54 Redistilled tetrahydrofurfuryl al- cohol (containing 1.3% of fur- fury1 alcohol) Ditto (containing 0.4% of furfuryl Furfuryl alcohol: Sample A 0.66 0.64 I 1 €3 0.69 0.61 *, c 1.10 1.11 Detected 0.022 <0.1 - } Not detected alcohol) } (0.01 3.BROMINATION (1) USE OF PYRIDINE SULPHATE BROMIDE- This reagent * has received considerable application3s4s5sa in the determination of the un- Thus Fitelson7 saturation of hydrocarbons and is stated to produce very little substitution. * For preparation of this reagent see below, p. 182.May, 19471 FURAN AND ITS DERIVATIVES 181 employed it for the determination of squalene, and Wilson and Nisbeta applied it in the analysis of various shale oil fractions. With compounds containing a furan ring, complete saturation usually takes place in accordance with the equation given on p.178. Further work revealed that the nature of the substituent R exerted a very marked effect on the behaviour of the reagent. Thus if R = H, CH, or CH,OH saturation of the ring readily occurred, but if R = CHO, COOH or CN little or no reaction was observed. Moreover, practically no reaction occurred with the corresponding tetrahydro compounds where R = H, CH, or CH,OH, thus affording strong evidence that but little substitution takes place. This reagent proved to be a powerful weapon with which to attack the problem of the analysis of furan compounds, and with its aid methods have been devised for the determination of furfuryl alcohol in admixture with furfural and tetrahydrofurfuryl alcohol and for the deter- mination of furan and sylvan in presence of the corresponding tetrahydro compounds.Details of the method used are given later (p. 182). DETERMINATION OF FURFURYL ALCOHOL-A sample of refined furfuryl alcohol (b.p. 78” to 80” C./20 mm., DSo 1.1337, n:’ 1.4870, furfural 0.24 per cent.) was analysed by the method described below and the furfuryl alcohol content calculated on the assumption that complete saturation of the ring occurred. (I) Time of contact Furfuryl alcohol with reagent found, yo 15 mins. 93.0 30 ,, 97.0 60 ss 100.0, 100.0, 100.0, 100.6, 99.3 Thus quantitative bromination occurred in 1 hour, while furfural gave a “bromine value’’ of 30 to 35 g. of Br per 100 g. (equivalent to 10 per cent. of furfuryl alcohol) and tetrahydro- furfuryl alcohol a value of less than 1 (equivalent to (0.3 per cent.of furfuryl alcohol) under similar conditions. Mixtures of furfuryl alcohol, tetrahydrofurfuryl alcohol and furfural, whose composition was unknown to the analyst, were examined by the method detailed below, with the results given in Table V. Furfural present, ye 0 7.1 6-0 3-5 31.6 48.6 62.2 5.5 68.9 81.2 5.4 90.0 Tetrahydrof urfuryl alcohol present, yo 0 7-6 7-3 32-6 40.4 25.0 20-9 78.9 19.8 10-5 88.9 5.2 TABLE V Furfuryl alcohol present, yo 100.0 85.3 86-7 63.9 28.0 2 6 4 16.9 15-6 11.3 8.3 5.7 4.8 Furfuryl alcohol found, % 98.4 84.4 85.9 63-1 28-6 26-8 18-7 16.1 11-8 10.0 5.9 5-9 Deviation % of mixture - 1.6 - 0.9 - 0.8 - 0.8 + 0-6 + 0.4 + 1-8 + 0.5 + 0.5 + 1.7 + 0.2 + 1.1 Thus, provided that the furfural content of such a ternary mixture does not exceed 20 per cent., furfuryl alcohol can be determined to within f 1 per cent.of the true value and the method is obviously applicable to the determination of small amounts of furfuryl alcohol present as impurity in tetrahydrofurfuryl alcohol. When the method was applied to the analysis of technically pure furfuryl alcohol, inconsistencies appeared in the results and were ultimately traced to the ease with which furfuryl alcohol and some other furan compounds undergo polymerisation. It was found that the furfuryl alcohol had changed after storage for several weeks. Vacuum distillation in a current of carbon dioxide yielded 89.6 per cent. of distillate (b.p. 87” C./20 mm.), which proved to be furfuryl alcohol of purity 99 per cent., 3.2 per cent.of distillate consisting of less pure furfuryl alcohol, and 5-8 per cent. of dark brown sticky residue which became a brittle solid on cooling to room temperature. The results of this experiment are summarised in Table VI. That the low and inconsistent results were attributable to the presence of polymerised substances was finally demonstrated by addition of varying quantities of “heavy ends” to182 ANGELL SOME ANALYTICAL METHODS APPLICABLE TO [Vol. 72 a redistilled sample; in all instances a rapid diminution in bromine value resulted. Thus addition of an equal weight of heavy ends to a sample showing 92.0 per cent. of furfuryl TABLE VI yo Furfuryl alcohol (pyridine sulphate Fraction No. yo of original bromide method) 1 61.2 99-5 2 28.4 98.7 3 3-2 67-7 4 (Residue) 5.3 Loss 1.9 alcohol gave a result of 45.7 per cent.of furfuryl alcohol. The rapidity with which polymeri- sation took place is illustrated by the observation that when 10 g. of freshly distilled sample contained in a platinum dish were evaporated to dryness on a steam bath 2.1 per cent. of hard non-volatile residue remained. Therefore, all subsequent analyses by bromination methods on furan and its derivatives were conducted on freshly distilled samples, DETERMINATION OF SYLVAN AND FURAN-In an identical manner the behaviour of sylvan, tetrahydrosylvan, furan, tetrahydrofuran, furoic acid and furoic nitrile were in- vestigated, freshly distilled material being used for the liquid substances. The results obtained are indicated in Table VII.(11) TABLE VII Apparent % Wt. taken, Bromine of sylvan Compound mg- value or furan 190 396 101.4 sylvan Sylvan Theoretical bromine 19.9 386 98.9 ,, value 391 27.89 394 101.0 ,, 24.13 392 100.6 ,, 7 70 12 3.1 ,, 3) 179 11.6 3 4 I ! t 60.5 4.6 1.2 ,, Tetrahydrosylvan F~ran J Theoretical bromine 1 value 470 15.437 478 101.7 ,, Tetrahydrofuran : Sample A 1780 <0.2 K0.1 ,, 1 3 B 444 4-7 1.0 ,, ,, c 443 5-7 1-2 3, 443 10.0 2.1 I, , I D 20.369 465 98.9 furan { - Furoic acid 260 3.4 ,, nitrile 300 3-9 - The results in Table VII indicate that furan and sylvan react quantitatively with the reagent, but this exerts only a slight action on tetrahydrosylvan, possibly attributable to substitution. With tetrahydro furan, however, independent confirmation of the presence of furan (and possibly sylvan) as impurities has been obtained from phase-rule studies of the system water, tetrahydrofuran and furan (unpublished work) .9 Thus sample A was specially purified by batch fractionation in a high efficiency column and was perfectly miscible with water in all proportions.On the other hand B, C, and D, were miscible with water only over a limited range of concentrations, and phase-rule work indicated about 2 per cent. of furan and sylvan in samples B and C and about 4 per cent. in sample D. METHOD USED FOR THE DETERMINATION OF FURFURYL ALCOHOL, SYLVAN, AND FURAN- Reagents- (1) Pyridine sulphate bromide reagent (approx. 0-05 N with respect to bromine). Into each of 3 dry 500-ml. conical flasks measure 4 4 ml. of glacial aGetic acid.Cool, and add to the first 16.3 ml. of pure pyridine and to the second 10.9 ml. of sulphuric acid (sp.gr. 1.84). When cold, combine these two solutions, with further cooling, and to the third flask add 3.2 ml. of bromine. Finally, add the contents of the third flask to the previous mixed solution, dilute to 2 litres with glacial acetic acid and mix thoroughly by shaking. (2) A 10 per cent. w/v potassium iodide solution. (3) Sodium thiosulphate solution, 0.1 N .May, 19471 FURAN AND ITS DERIVATIVES 183 For unsaturated compounds introduce into a tared oleum bulb an appropriate weight of sample (20 to 25 mg. of furan or sylvan, 30-35 mg. of furfuryl alcohol), seal, and reweigh on a micro balance. Alternatively use larger quantities of sample, dilute to a convenient bulk with glacial acetic acid in a volumetric flask and withdraw an appropriate aliquot for analysis.With saturated compounds use any suitable larger quantity of material. Procedztre-Pipette 50 ml. of the reagent (1) into a 200-ml. stoppered “iodine” flask, introduce the sample via the sealed oleum bulb or otherwise, break the bulk carefully under the surface of the solution by means of a glass rod and wash down the rod with a few ml. of glacial acetic acid. Promptly replace the stopper and seal the neck of the flask with 5 ml. of potassium iodide solution. Allow to stand in the dark for 1 hour, together with a “blank” on 50 ml. of the reagent. Release the stopper carefully, allowing the potassium iodide solution to flow into the flask so that no bromine is lost.Add 10 ml. of potassium iodide solution, shake well and titrate the liberated iodine with 0.1 N thiosulphate, adding a little starch solution when the titrated solution becomes pale yellow. Frequently the titrated solution is pale brown at the end-point , but no difficulty is experienced in recognising the disappearance of the starch iodide colour. If B = bromine value = g. of bromine absorbed per 100 g. of sample, percentage of furfuryl alcohol = 100B/325 1 , ,, furan = 100B/470. ,, ,, sylvan = 100B/391. (2) USE OF ACIDIFIED POTASSIUM BROMIDE - BROMATE SOLUTION- It has been stated by Hughes and AcreelO that if furfural be treated with acidified bromide - bromate solution at 0” C. for 10 minutes, only one double bond is attacked, in accordance with the eauation: 0 This procedure was investigated, both the bromide - bromate solution and the 5 per cent.hydrochloric acid used for acidification being cooled in an ice-bath at 0” C. for 4 hr. preceding the bromination tests. With the same sample of redistilled furfural (assaying 98.2 per cent. by aqueous oximation) the following results were obtained (Table VIII). TABLE VIII TEST SOLUTION CONTAINED 30.9 MG. OF FURFURAL Time of bromi- Furfural Apparent yo nation, mins. found, mg. f u rfural 8 27.4 90.9 10 29.1 94.2 10 28.6 92-6 15 31-9 103.1 These results indicate that bromination for 10 minutes does not proceed beyond 94 per cent. of completion, whereas with 15 minutes reaction time bromination exceeds 100 per cent. on the basis of the above equation. Moreover, the starch iodide end-point of the subsequent titration is frequently fugitive and may well lead to even greater divergencies than result from slight variation in the time of bromination.This method does not appear to have any advantages over the oximation procedure, and in general it seems undesirable to adopt as a standard procedure any method in which the reproducibility of the results clearly depends on a careful counterbalancing of opposing sources of error. However, acidified bromide - bromate solution, with addition of methanol as a solvent for the compound, has been applied to the determination of furoic acid alone or in admixture with tetrahydrofuroic acid. Addition of increasing quantities of methanol to the blank solution diminished its titre, but provided that at least 25 per cent.by volume of methanol was present the blank titration was unaffected. As solutions of suitable concentrations of furoic acid in 25 per cent. methanol could be readily prepared, the method was standardised on this basis. The bromination was allowed to proceed for 15 minutes at room temperature, with the usual Koppeschaar technique. Results obtained for furoic acid alone and in mix- tures with tetrahydrofuroic acid whose composition was unknown to the analyst are shown184 ANGELL: SOME ANALYTICAL METHODS FOR FURAN, ETC. [Vol. 72 in Table IX. Tetrahydrofuroic acid alone gave a bromine value equivalent to 1 per cent. of furoic acid. TABLE IX Furoic acid Nature of sample yo found Furoic acid . . .. .. .. .. 97.5 , I 9 , . ,- .. .. .... 98.0 , I I , - - .. .. .. .. 99.4 Mixture containing 9.8% furoic acid . . 10.2 , J 1 , 48.1% 2 , I , - - 48.2 , J 76.0% ,, ,, . . 77-1 Furoic nitrile was unaffected by this reagent (bromine value = 2) and towards Kauf- mann's reagent (bromine + sodium bromide in methanol) it was equally inactive, yielding a bromine value of 3 to 3.5. That the impure nitrile available was an unsaturated compound was confirmed by hydrolysis with dilute sulphuric acid and extraction with ether, when an acid with m.p. 123" to 125°C. was obtained. (Furoic acid has m.p. 130" to 131"C., and tetrahydrofuroic acid is a liquid.) Thus, of all the furan derivatives investigated, furoic nitrile is unique in its inertness towards bromination agents. SUMMARY- Existing methods for the analytical examination of furan derivatives have been critically examined and, where necessary, improved. 1. Furfural can be determined by aqueous oximation at room temperature, although the reaction is not quite stoichiometric. Small amounts of furfural should be determined absorptiometrically, using the aniline acetate method. 2. Pyridine sulphate bromide is the most useful reagent for the determination of unsaturation in the furan series. Saturation of both double bonds occurs with furan, sylvan, and furfuryl alcohol, and substitution reactions with the corresponding tetrahydro compounds are negligible. On the other hand, furfural, furoic acid and furoic nitrile are but little attacked by this reagent. 3. Acidified potassium bromide - bromate reagent finds limited application as a bromi- nating reagent for furoic acid, but with furfural only approximately quantitative results are obtained. In conclusion, I wish to thank Mr. W. Hutchinson for the experimental data on the method employed for furoic acid. 1. 2. 3. 4. 5. 6. 7 . 8. 9. 10. REFERENCES Stillings, R. A., and Browning, B. L., I n d . Eng. Chem., Anal. Ed., 1940, 12, 409. Duncan, I. J., Ibid., 1943, 15, 162. Rosenmund, K. W., and Kuhnhenn, W., 2. Unters. Nahr. u. Genussm., 1923, 46, 164. Dam, H., Biochem. Z., 1924, 152, 101; 1925, 158, 76. Bolton, E. R., and Williams, K. A,, ANALYST, 1930, 55, 5. Thorbjarnarson, T., and Drummond, J. C., Ibid., 1935, 60, 23. Fitelson, J., J . Assoc. Off. Agr. Chem., 1943, 26, 499. Wilson, G. E., and Nisbet, H. B., ANALYST, 1946, 71, 183. Private communication from Bury, C. R., and Hodgson, M. E. A. Hughes, E. E,, and Acree, S. F., Ind. Eng. Chem., Anal. Ed., 1934, 6, 123. IMPERIAL CHEMICAL INDUSTRIES LTD. RESEARCH DEPARTMENT BILLINGHAM DIVISION BILLINGHAM, Co. DURHAM December, 1946

ISSN:0003-2654    

DOI:10.1039/AN9477200178

出版商:RSC    

年代:1947

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 184 ANGELL: SOME ANALYTICAL METHODS FOR FURAN, ETC. [Vol. 72 Erratum.-December issue, 1946, p. 555, line 17 from the bottom: For “nickel” read “nickelous. ”

ISSN:0003-2654    

DOI:10.1039/AN9477200184

出版商:RSC    

年代:1947

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-ction May, 19471 WELLS AND PEMBERTON: MOLYBDENUM IN STEEL 185 The Microchemical Determination of Molybdenum in Steel BY J. E. WELLS AND R. PEMBERTON (Read at the Annual General Meeting of the Microchemistry Grozlp, January 31, 1947) IN the course of recent investigations it became necessary to determine molybdenum in small quantities of steel. A review of available methods led to the conclusion that the reactions involved were not of sufficient sensitivity for the work in hand. It was known, however, that molybdenum would give a green precipitate with toluene-3 :4-dithiol in acid solution,l and work was initiated to determine the suitability of the reaction for quantitative deter- minations.Preliminary work indicated that the green molybdenum compound produced in cold hydrochloric acid solution could be extracted with amyl acetate. The amyl acetate extract could be rendered clear and free from turbidity by washing with concentrated hydrochloric acid, and the absorptiometric evaluation of its colour bore a linear relationship to the molyb- denum concentration. Under these conditions, that is, in cold hydrochloric acid solution, and in absence of stannous chloride, any tungsten present reacted only slowly, the reaction rate decreasing with decreasing acid concentration. These results suggested the possibility that under suitable conditions interference by tungsten might be eliminated, and a determination of molybdenum carried out.Investi- gat ions were, therefore, put in hand to determine these conditions. EXPERIMENTAL For the purpose of these experiments, “synthetic” steel solutions were made up from a solution of pure iron in sulphuric acid. Aliquots equivalent to four milligrams of metal were used as a test basis, and other elements added in the form of standardised solutions. Preparation of pure iron solution-One gram of pure iron was dissolved in 18 ml. of 10 per cent. sulphuric acid. After oxidation with the minimum amount of nitric acid, the solution was boiled down almost to dryness, taken up with water, and made up to one litre in a graduated flask.Aliquots of this solution containing 4mg. of iron were then taken per test, each containing the equivalent of 0.0012 ml. of free sulphuric acid. Efect of Hydrochloric acid concentration on the extraction of the coloured molybdenum complex-Solutions representing 4-mg. samples of a synthetic 0.70 per cent. molybdenum steel to which the equivalent of 0.05ml. of concentrated sulphuric acid had been added, were boiled down to fuming, and the fumed liquids were taken up in 3-ml. portions of hydro- chloric acid, the concentration of which was varied from sample to sample. The solutions were then cooled, and 3 ml. of a 1 per cent. solution of toluene dithiol in amyl acetate were added to each. After standing for varying periods of time with occasional shaking, the amyl acetate layer of each was separated, washed with 3 ml.of concentrated hydrochloric acid, transferred to a 10-ml. graduated flask and made up to the calibration mark with amyl acetate. The absorption was then measured on the Spekker photo-electric absorptiometer, using Calorex heat-resisting filters H503, spectrum red filters 607, and a l-cm. micro cell. The results obtained, in Spekker units, were as follows: sp.gT. of hydrochloric acid at 15” C. 1 so2 1 1.043 1.051 1-061 1.075 1-082 1.097 1.182 7 6 - 0.295 0-530 0.555 0-560 0-565 0.555 Standing time before separation (minutes) 10 0.130 0-330 0-560 0.560 0.560 0.560 0-560 - 20 0.090 - - 0-560 0-560 0.566 0.560 - 30 - 0.560 0-555 0-560 0.560 0.665 1 40 0.120 0.190 0350 0.560 0-560 0.660 0.560 0.560 These figures show uniform results for all hydrochloric acid concentrations of specific gravity between 1-075 and 1-182, and for all time intervals tested over this range of acidity.Acid of specific gravity 1.075 was selected for further work, as preliminary experiments, on186 WELLS AND PEMBERTON : THE MICROCHEMICAL [Vol. 72 the eff ect of tungsten, had already indicated that this acidity would achieve the best compromise in relation to the suppression of the corresponding dithiol tungsten complex. In such acid concentration, any tungsten present in the steel would tend to separate as tungstic acid, possibly carrying with it some molybdenum, and thus giving low results. Further experiments were, therefore, carried out in order to determine the effect of phosphoric acid on the development of the molybdenum colour.For convenience the phosphoric acid was added as “Spekker” acid (15 per cent. sulphuric acid, 15 per cent. phosphoric acid). A series of test solutions, each containing the equivalent of 4-mg. of synthetic 0-70 per cent. molybdenum steel, were prepared, and different amounts of “Spekker” acid were added to each. The solutions were evaporated to fuming, taken up in 3 ml. of hydrochloric acid of sp.gr. 1.075 and cooled; the dithiol was added, and the separations were carried out as before. Amount of “Spekker” acid used, ml. . . nil 0.26 0.60 0.76 1.00 “Spekker” reading . . . . .. . . 0.666 0.660 0.660 0.666 0.660 These results show that the amounts of “Spekker” acid in the range investigated have no effect on the intensity of the colour due to molybdenum.All further work was therefore carried out in the presence of 0.5 ml. of “Spekker” acid, as this amount was found effectively to prevent the hydrolysis of up to 16 per cent. of tungsten on the sample weights used. E’ect of acid concentration on the formation of the tungsten complex-Most previous work done with toluene-3:4-dithiol has been concerned chiefly with its use for the detection and estimation of tungsten2J and tin.* It was, therefore, thought advisable at this stage of the investigation to ascertain the exact conditions necessary for suppression of the reaction with tungsten. An addition equivalent to 4 per cent. of tungsten was therefore made to a number of solution samples of synthetic 0-70 per cent.molybdenum steel, each containing the 0.50 ml. of “Spekker” acid previously decided upon. The samples were then evaporated to fuming, and taken up in 3 ml. of hydrochloric acid solution, the concentration of which was varied from test to test. After the addition of 3 ml. of dithiol solution the amyl acetate layer was separated and its absorption measured as before: Sp.gr. of hydrochloric acid used . . . . 1.064 1.076 1.083 1.097 1.182 “Spekker” reading . . . . . . . . 0.660 0.666 0.660 0.660 0.806 These readings show that 4 per cent. of tungsten has no effect on the determination of molybdenum provided the reaction is carried out in hydrochloric acid of specific gravity between 1.064 and 1.083. This confirms that the specific gravity previously decided upon, namely, 1.075, is probably the best compromise between the conditions necessary, on the one hand for complete suppression of the tungsten colour, and on the other for complete develop- ment of the molybdenum colour.Efect of dithiol comentrations-The above conditions were applied except for the use of dithiol solutions of differing concentrations, 3 ml. being added in each case. Extractions were made on synthetic solutions of three types of steel containing respectively: (a) 0.70 per cent. of molybdenum. (b) 0.70 ,, J , ,, ,, plus 4.0 per cent. of tungsten. (c) 4.0 ,, ,, ,, ,, Concentration of dithiol solution Sample 0.26% 0.50% 1.0% 2.0% 3.6%‘ “Spekker” readings (a) 0.70% MO . . . . 0.516 0.660 0.660 0.666 0.660 (b) 0.70% MO + 4-00/6W . . 0.520 0.666 0.666 0.570 0.616 0.770 0-776 0.775 0.770 (c) 4.0% Mo (0.26 cm.cell) . . - These figures indicate that 3 ml. of 0.50 per cent. dithiol solution would be adequate, but in order to be sure of a safe excess it was decided to use the 1 per cent. solution. Stability of colour-The amyl acetate solution of the molybdenum complex was found, after separation, to undergo no measurable change in absorption in twenty-four hours. Efect of tem$erature-Tests made on synthetic solutions containing tungsten showed that the formation of the tungsten complex is inhibited only under the conditions previously specified, in which the colour development is allowed to proceed at room temperature. For example, the following figures show for two synthetic samples one of which containedMay, 19471 DETERMINATION O F MOLYBDENUM IN STEEL 187 the equivalent of 4 per cent.of tungsten, the effect on the results of heating for 15 minutes on the water bath before separation of the amyl acetate extract. “Spekker” readings Sample lkOl-IIlal Fifteen mins. on contained treatment the water-bath 0*70~0 MO 0.660 0.670 0.70% Mo + 4.0% W 0.660 0.700 It is clear, therefore, that the selective formation of the molybdenum complex is depen- dent on the use of a relatively low temperature for colour development. Eflect of other elemeutts-The effect of other elements likely to be found in steel, in the procedure evolved, has been examined. No interference is detected when tungsten is present in amounts below 16 per cent., as shown by the following results on a synthetic 0.70 per cent.molybdenum steel containing variable amounts of tungsten : Percentage of tungsten 0.0 2.0 4.0 8.0 16.0 “Spekker” reading . . 0.660 0.666 0.660 0.666 0.660 Cobalt, vanadium, tin, lead, niobium, tantalum, manganese, and aluminium do not interfere when present in amounts up to 10 per cent. Nickel and chromium have shown no interference below 25 per cent. Titanium has shown no interference up to 1 per cent., and selenium and silicon none up to 5 per cent. Iron present in the ferric state is partially extracted by the amyl acetate under the con- ditions used, and accounts for the small “blank” observed, i.e., 0.01 Spekker unit. If 10 per cent. of copper is present, the amyl acetate layer becomes cloudy and black, but rapidly clears when washed with the concentrated hydrochloric acid, leaving a faint cloudiness which invariably gives a reading equivalent to 0.015 per cent.of molybdenum. Zirconium, in amounts up to 10 per cent., gives a pale green colour equivalent to 0.025 per cent. of molybdenum. We may, therefore, conclude that in practical steel analysis this method is specific for molybdenum. REAGENTS- DithioZ soZution-Dissolve 0-5 g. of toluene-3 :4-dithiol in 50 ml. of amyl acetate by gentle warming; the temperature should not exceed 40” C., and the solution should be prepared just before use. “Spekker” acid-Add 150 ml. of sulphuric acid (sp.gr. 1-84) carefully to 600 ml. of water. After mixing, add 150 ml. of phosphoric acid (sp.gr. 1-75), mix, allow to cool and dilute to 1 litre. Hydrochloric acid (sp.gr.1.075)-Dilute 350 ml. of hydrochloric acid (sp.gr. 1.18) with water to 1 litre and adjust the specific gravity to 1.075. Standard molybdenum sohtion for calibfation-Molybdenum content 0.01 mg. per ml. PROCEDURE- Weigh out a 4-mg. sample of the steel, dissolve it in 0.5 ml. of Spekker acid diluted with 1 ml. of water, and oxidise with nitric acid. Alternatively, an aliquot containing the equiva- lent of 4 mg. of the steel and 0.5 ml. of Spekker acid may be taken from a larger bulk of solution from which other samples have been taken for analysis. Evaporate the sample to fuming, take it up in 3 ml. of hydrochloric acid of sp.gr. 1.075 and cool it in a water-bath. Add 3 ml. of 1 per cent. dithiol solution and allow the test to stand for fifteen minutes with occasional shaking.Then wash the mixture into a separating funnel, using a small amount of amyl acetate; shake it, and allow the layers to separate. After removing and rejecting the aqueous layer, wash the amyl acetate layer mth 3 ml. of concentrated hydrochloric acid, which removes the slight cloudiness present in it. Make up the solution to 1 O m l . with amyl acetate in a graduated flask, mix, and measure its absorption on the absorptiometer, using a micro cell of suitable size, together with Calorex H 503 and Spectrum Red 607 filters. The molybdenum content is found by reference to standard calibration curves, produced by applying the above method to pure iron solutions to which known amounts of molybdenum This colour may be due to impurities in the zirconium used.RECOMMENDED METHOD188 WELLS AND PEMBERTON: MOLYBDENUM I N STEEL [Vol. 72 solution have been added. All the Spekker readings given in this paper have been obtained with a tungsten lamp in the absorptiometer, but sufficient work has been done with a mercury vapour lamp to show that similar results would be obtained, the calibration curve being similar to that obtained with a tungsten lamp. TYPICAL RESULTS- With this technique, a number of steels have been analysed for their molybdenum content, with the results shown in the accompanying Table. The figures given for comparison have been obtained by the normal macro thiocyanate method. TABLE OF COMPARATIVE RESULTS Type of steel Plain carbon . . Ld;v alloy . . I 1 ? I * * I 1 - * I1 D l * * 11 I1 * - I 1 I1 * - I 1 I1 * * I > ,I * - #I I * * * I<% TiAgsten' High speed steel 13% Cr, 1:3% Nb 18Cr 8N1 .. I 1 D l I S .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. Molybdenum % Dithiol method 0.04 0.09 0.16 0.06 0.24 0-24 0-30 0.32 0.5 1 0.68 1.7 1 0.56 4.22 0.0 1 1.30 2.72 2.40 3.00 Molybdenum % Thiocyanate method 0.04 0.09 0.16 0.06 0.22 0.24 0-3 1 0.34 0.62 0.68 1.68 0.66 4-19 nil 1.31 2.73 2.42 2-99 CONCLUSION- content of a 4-mg. sample of any steel likely to be examined. SUMMARY- A coIorimetric method for the determination of molybdenum, in milligram quantities of steel, is described. The method involves the use of toluene-3:4-dithiol in amyl acetate solution, and is virtually specific for molybdenum in steel. The method as described above will give reasonably accurate results for the molybdenum We are indebted to Mr. B. Bagshawe, Assoc.Met., for his advice on this problem, and to Dr. C. Sykes, F.R.S., of the Brown - Firth Research Laboratories, for permission to publish this paper. REFERENCES 1. 2. 3. 4. Hamence, J. H., ANALYST, 1940, 65, 152. Miller, C. C., Ibzd., 1944, 69, 109. Vaughan, E. J., and Whalley, C., J. Iron mzd Steel Inst., 1947, 155, 535. Clark, R. E. D., Ibid., 1937, 62, 661. THE BROWN - FIRTH RESEARCH LABORATORIES SHEFFIELD, 4 October, 1946

ISSN:0003-2654    

DOI:10.1039/AN9477200185

出版商:RSC    

年代:1947

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-ction May, 19471 BAGSHAWE AND TRUMAN: TUNGSTEN IN STEEL 189 A Method for the Determination of Tungsten in Steel, using Toluene-3 : 4-Dithiol. The Removal of Molybdenum Interference by Selective Extraction BY B.BAGSHAWE AND R. J.TRUMAN THE traditional methods for the determination of tungsten in steel are based on hydrolytic precipitation of tungstic acid and conversion to the oxide. Such methods are reasonably satisfactory for relatively large tungsten percentages, but below about 1 per cent. of tungsten, hydrolysis from steel solutions is very uncertain and usually incomplete, and in our experience this is still true irrespective of whether precipitation aids such as cinchonine, rhodamine B, etc., are used or not. Tungsten in amounts below about 0.2 per cent. occurring as a residual from scrap contamination in non-tungsten steels is sometimes difficult to detect at all by hydrolysis methods and, in any case, the results are often erratic and usually much below the truth.Attention was first turned to toluene-3 :4-dithiol as the basis of an entirely new principle by Hamencel in 1940, and later by Miller and Lowe,2 and Miller's work gave a preliminary indication of the possible application of the reagent as the basis of a semi-micro method for the element in steel. More recent work on the subject is that of Vaughan and Whalley.6 We have since made a prolonged investigation with a view to devising an accurate quantitative means of determination, of which the method given below is the outcome. It very soon became obvious that the practical application of dithiol reagent to com- mercial steels was severely limited by the interference of molybdenum.Molybdenum interference is serious because (a) the corresponding molybdenum-dithiol reaction is one of high sensitivity, and (b) apart from true molybdenum steels, practically all steels are contaminated with this element as a residual impurity. There is, therefore, no useful scope for the principle of the tungsten - dithiol reaction unless account can be taken of the corresponding molyb- denum effect. Miller claims partial suppression of the molybdenum - dithiol reaction by reduction to the tervalent condition with stannous chloride. Our experience confirms her observation that whilst tervalent molybdenum may not react with dithiol there is interference due to subsequent oxidation resulting in the formation of intermediate brown complexes and, later, of the green molybdenum complex itself.The order of this interference is shown in Table I, giving typical results on steels in presence of quite small amounts of molybdenum. TABLE I Steel Mo % added (a) 18 Cr 8 Ni, W- and Mo-free nil # J $1 0-05 3, # # 0-25 8s 3. 0.10 J , ,# .. 0.05 J , ,D .. 0.10 (b) 18 Cr 8 Ni, low tungsten . . nil 81 # * 0.05 S J J J 0.20 (c) 18 Cr'8 Ni, W steel .. nil W yo found nil 0.04 0.21 0.12 0-15 0-19 0.28 0.78 0.82 0.83 Th advers effect of molybdenum, even in residual amounts, is therefore well marked, and it increases, although in irregular manner, with increasing amounts of molybdenum. We attempted to remove molybdenum together with iron by ethereal extraction of 0.1-g. steel samples as ferric chloride solution containing sufficient phosphoric acid to prevent tungstic acid hydrolysis. It is known that ether extraction of molybdenum approaches 100 per cent.in presence of excess of iron, but our tests showed that the distribution ratio is reduced by the phosphate ion, necessary in this case to fix tungstic acid, with the result that considerable molybdenum is retained in the acid tungsten phase. There was also some loss190 BAGSHAWE AND TRUMAN: A METHOD FOR THE DETERMINATION OF [Vol. 72 of tungsten in the ether phase, but conditions that reduce this effect to a minimum, i.c., increased phosphoric acid concentration , similarly induce increased retention of molybdenum in the acid phase, hence no effective ether separation of the two elements was achieved.A further attempt to apply the ether separation, but after conversion of molybdenum to its oxythiocyanate complex, also failed, and there was additional interference at a later stage from tin salts introduced to reduce molybdenum for the thiocyanate formation. Later work has been concentrated on an adaptation of a preferential formation and ex- traction of the molybdenum - dithiol complex itself, which has been reported in a previous paper from these laboratories' as the basis for a microchemical method for molybdenum. Our observations are summarised as follows : In hydrochloric acid solutions of approximately 1 a06 sp.gr. the molybdenum - dithiol complex alone is formed. If the acid has sp.gr. below about 1.05 the molybdenum complex forms only very slowly, whilst at sp.gr.1.08 its formation is accelerated but there is also some formation of the corresponding tungsten complex, and this increases with increasing acidity and is quantitative in acid of sp.gr. 1-16. Below 20" C. the formation of the molybdenum complex may be retarded, and if this occurs some molybdenum may escape extraction and interfere later when the tungsten complex is formed. At temperatures exceeding 30" C. there is a gradually increasing tendency for partial simultaneous formation of the tungsten complex even in acid of sp.gr. 1.06 or thereabouts, with resultant loss of tungsten in the discarded molyb- denum extract. We now develop the molybdenum complex over a period of fifteen minutes in a bath controlled within the range 20" to 25" C.A prompt and full development of the molybdenum complex is dependent on the use of a freshly prepared solution of the fresh reagent. This is more fully discussed in a later section of this paper. After the amyl acetate extract of the preferentially formed molybdenum complex has been discarded, the residual acid layer containing the tungsten can be concentrated and extracted in hydrochloric acid of sp.gr. 1.16, when further treatment with dithiol reagent on the boiling water bath results in a quantitative formation of the greenish- blue tungsten complex. This reaction is carried out in presence of stannous ion, otherwise high blanks would be obtained due to ferric chloride solubility in the amyl acetate extract of the tungsten complex. The tungsten - dithiol formation is much less sensitive to stale reagent solution than that of the molybdenum complex, probably owing to the influence of stannous ion in reducing oxidation products of the reagent.If the molybdenum separation is im- perfect owing to stale reagent, this will be betrayed by the development of brownish tints along with the tungsten complex, which when pure and free from molybdenum should be bluish-green. From the above observations the method described below has been derived. It is applied to 15-mg. fractions from 06g. steel samples, is suitable for a wide variety of alloy steel types and moreover provides for the first time a ready means of accurately determining tungsten in low ranges, i.e., from 0 to 1 per cent., with which the hydrolytic precipitation methods fail to give quantitative recovery.METHOD REAGENTS- (sp.gr. 1.75) made up to one litre with distilled water. ~p.gr. 1.06. "Spekker" acid-150 ml. of sulphuric acid (sp.gr. 1.84) and 150 ml. of phosphoric acid Hydrochloric acid (s$.gr. 1*06)-Dilute the concentrated acid with water and adjust to Hydroxylamine sulphate solution-10 per cent. solution in distilled water. loluene-3:4-dithiol solution-Open a sealed 1-g. phial of the reagent and dissolve in The solution thus prepared must be used within a few hours of Stannous chloride solution-Dissolve 10 g. of stannous chloride in 100 ml. of concentrated 100ml. of amyl acetate. preparation. * hydrochloric acid.May, 19471 TUNGSTEN IN STEEL, USING TOLUENE-3 : CDITHIOL 191 PROCEDURE- To 0-5 g. of the sample in a 300 ml.flask (Taylor pattern) add 30 ml. of Spekker acid and 10 ml. of concentrated hydrochloric acid. Heat until dissolved, oxidise with concen- trated nitric acid and then evaporate until hydrochloric and nitric acids are expelled and the solution fumes. Extract with 100ml. of water, boil and transfer to a 500-ml. graduated flask. Pipette a 15-ml. aliquot representing 15 mg. of sample into a 50-ml. flask and evaporate to fuming. Cool, add 5 ml. of hydrochloric acid (sp.gr. 1.06) to the fumed concentrate, warm gently until all salts are in solution and then cool to room temperature. Add 5 drops of the hydroxylamine sulphate solution and 10 ml. of the toluene-3 :4-dithiol reagent solution, allow to stand in a bath at 20" to 25' C. for 15 minutes and shake the solution at intervals throughout this period.Transfer to a 25-ml. stoppered cylindrical tap funnel, rinsing 3 or 4 times with small portions of amyl acetate. Shake and allow the layers to separate. Draw off the lower acid layer containing the tungsten and reserve it in the original 50-ml. flask. Wash the remaining amyl acetate layer twice consecutively with 5-ml. portions of hydrochloric acid (sp.gr. 1-06) , separating and withdrawing the acid layer each time as before. Combine the acid wash layers with the original acid layer reserved in the 50-ml. flask. Discard the washed amyl acetate layer, which contains the molybdenum. Evaporate the acid tungsten solution, carefully at first until dissolved amyl acetate is expelled, then add a few drops of concentrated nitric acid and evaporate to fuming.Add a few more drops of nitric acid during fuming to clear up any charring organic matter, rinse the flask with a minimum of water, and re-fume to expel nitric acid and water. Add 5 ml. of the stannous chloride solution to the fumed liquid and heat on a boiling water-bath for 4 minutes. Add 10 ml. of toluene-3 :4-dithiol reagent solution and continue to heat on the boiling water-bath for a further 10 minutes. Shake the solution at intervals throughout this period. Transfer to a 25-ml. stoppered tap funnel, rinsing 3 times with 2-ml. portions of amyl acetate. Shake, separate, draw off the lower acid layer, and discard it. Add 5 ml. of con- centrated hydrochloric acid to the amyl acetate layer in the separator, repeat the extraction and again discard the lower acid layer (see Note below).Draw off the amyl acetate layer, containing the tungsten, into a 50-ml. graduated flask (previously rinsed free from water, first with alcohol and then with amyl acetate), make up exactly to the mark with amyl acetate and mix. Measure the absorption of this solution in the Spekker absorptiometer, using the mercury vapour lamp, 4 cm. cells and Ilford Spectrum Red No. 608, and Calorex H.503 filters. Refer the readings to a calibration curve prepared from spectrographically pure iron to which suitable increments of standard sodium tungstate solution have been added. Note-For steels containing appreciable cobalt further repeated washing is necessary at this stage. After the wash with 5 ml. of concentrated hydrochloric acid, give two further washes with hydrochloric acid (sp.gr.1.06) , and a final wash with concentrated acid. Cool, dilute to the mark with water, and mix. RANGE- The method as specified, i.e., on 15-mg. aliquots from an initial 0.5-g. sample weight, gives a calibration range of 0 to 1 per cent. tungsten = 100 drum divisions, with the 4-cm. cells. The range may be extended +ro rata to cover higher tungsten percentages by using 2-, 1-, or 0.5-cm. cells. For the greatest accuracy in the lowest tungsten ranges, the calibration range may be reduced to 100 drum divisions E 0.5 per cent. of tunsten by making the final reading in a volume of 25 ml. The reading accuracy is then of the order of ~k0.005 per cent. of tungsten. With the calibration range as specified in the method, the reading accuracy is within 0.01 per cent.of tungsten over the range 0 to 1 per cent., and this fulfils all normal requirements within this range. RESULTS- The foregoing method was proved by tests made on austenitic 18 Cr, 8 Ni tungsten bearing steels with and without synthetic additions of molybdenum, and on synthetic pre- parations obtained from 18 Cr, 8 Ni steels (spectrographically free from tungsten) treated with various known amounts of molybdenum and tungsten solutions. Results are given in Table 11.192 BAGSHAWE AND TRUMAN: A METHOD FOR THE DETERMINATION OF [VOl. 72 TABLE I1 Steel Moadded, % nil nil 1.0 2.0 2.0 3.0 nil 3% 18 Cr 8 Ni (spectrographically free from W) 18 Cr 8 Ni steel, 0.78% W Wadded, % nil 0.50 0.02 0.05 0.20 nil 0.10 0.50 W found, % nil 0.60 0.02 0.05 0.21 0.0 1 0.11 0.5 1 0.77 0.78 0.77 0.78 0.77 These results are all accurate to a tolerance of 0.01 per cent.of tungsten, even when abnormally high percentages, e.g., 3 per cent., of molybdenum are introduced. EFFECT OF OTHER ELEMENTS- Of the common steelmaking elements, nickel, chromium , manganese, silicon, vanadium, aluminium, titanium, niobium (columbium), and tantalum do not form coloured dithiol complexes under the test conditions and exert no adverse influence even when present in major alloying amounts. There is a small extraction of iron by the amyl acetate, which imparts a faint yellowish tinge to the ester layer in complete absence of tungsten, and in presence of very small amounts of tungsten modifies the pale bluish-green of the complex to a yellowish-green.It is, however, easy to distinguish between the pale yellow of “blank” iron and the colour introduced by as little as 0.01 per cent. of tungsten, and in any event the reading value of the yellow component is virtually eliminated by the red filters. Thus pure iron spectrographically free from tungsten gives a blank reading of the order of 0.01 Spekker unit, equivalent to about 0.01 per cent. of apparent tungsten. This is compensated by preparing the calibration from a pure iron base with suitable increments of added sodium tungstate rather than from pure sodium tungstate alone. There is no increase of “blank” absorption from nickel or chromium, both these elements being preferentially soluble in the acid phase and rejected with it.Titanium, silicon, niobium (columbium), and tantalum may give insoluble hydrolysis products on fuming with mixed phosphoric and sulphuric acids, but there is no need to remove them. They do not occlude tungsten which is fixed as soluble phospho-tungstic acid, and any precipitate is virtually eliminated in taking the 15-ml. aliquot from the 500-ml. initial test volume. Any residual amount of these elements soluble in the test aliquot is entirely without influence. The method, therefore, provides for the first time a simple means of determining tungsten in alloy steels containing niobium (columbium) , tantalum, and titanium. On a tungsten-free 0.68 per cent. niobium (columbium) steel 0.30 per cent. of tungsten was found after exactly that amount had been added as a standard solution.A sample of heat-resisting alloy (Ni 70, Cr 20, Fe 3, Ti 2-5 per cent.) gave a residual tungsten content of nil by this method and 0.21 per cent. of tungsten after addition of a further 0.20 per cent. as standard solution, whilst British Chemical Standards No. 209 (18/8 steel with 0-59 per cent. of Ti) gave 0.30 per cent. of tungsten after that amount had been added. Copper forms a black precipitate in the ester layer at the molybdenum extraction stage, but there is no interference and there is no corre- sponding formation at the tungsten exti-action stage. If large amounts of cobalt are present partition occurs, resulting in a partial transfer of the element to the ester layer, which becomes coloured greenish-blqe by the cobalt ion.The extent of cobalt interference is indicated by the figures in Table 111. The effect is only important as it applies to cobalt alloy steels; ordinary plain and alloy steels do not contain sufficient residual cobalt to prejudice the tungsten readings. In any event the effect of as much as 10 per cent. of cobalt can be virtually eliminated by repeated acid washing of the ester phase, as described in the Note to the Method, e.g., a plain steel treated with the equivalent of 10 per cent. of cobalt gave no measurable reading, and after addition of the equivalent of 0.5 per cent. of tungsten returned a value for this element of 0-52 per cent.May, 19471 TUNGSTEN IN STEEL, USING TOLUENE-3 : 4-DITHIOL 193 TABLE I11 Cobalt Apparent Steel added, yo tungsten, yo 18 Cr 8 Ni (W nil) .. - nil J I ,a .. 2.0 0-06 ,J ,, .. 4.0 0.10 S J # # .. 6.0 0.16 1 s n s .. 8.0 0.21 J t ,, .. 10.0 0-31 OBSERVATIONS ON THE METHOD OF USING DITHIOL REAGENT- The reagent as normally supplied to us has been obtained in l-g. sealed glass phials and occasionally in 5 g . sealed phials. It was known that its keeping properties were limited once the phials were broken, and with 5-g. lots we adopted the practice of with drawing 1-g. amounts for the preparation of solution and immediately re-sealing the tubes each time. In spite of this we experienced many inconsistencies of performance in the early stages of the investigation. It was observed that satisfactory molybdenum separations were only achieved with new solutions prepared immediately before use and the molybdenum separation became erratic when the dithiol solutions were a few hours old, and sometimes when absolutely fresh solutions were prepared from dithiol obtained from phials that had previously been opened and re-sealed.The effect was to give an incomplete conversion of molybdenum into its dithiol complex, and hence its incomplete extraction and removal, the residual molybdenum giving the characteristic brown tints at the later tungsten stage and consequent high values for tungsten. The effect of stale reagent seemed to be confined to the molybdenum formation, as the corresponding tungsten formation was always complete even when the reagent solution was a week old. We attributed this difference in behaviour to the retarding effect of oxidising decomposition products of the reagent upon the formation of the molybdenum complex, the absence of an a;nalogous effect at the tungsten stage being accounted for by the reducing action of stannous chloride.Stannous chloride is not a suitable reducing agent to have present at the molybdenum separation stage, as tin salts hydrolyse on fuming the extracts, with occlusion of tungsten. After trying several alternative reducing agents we obtained satisfactory results with hydroxylamine sulphate, 5 drops of a 10 per cent. aqueous solution, added immediately before the dithiol addition, being sufficient to restore maximum reagent reactivity with molybdenum, under the conditions specified. With greater amounts of hydroxylamine there is again a tendency to incomplete molybdenum extraction, possibly owing to partial reduction of molybdenum itself. Since introducing hydroxylamine we have not experienced any difficulty in achieving complete extraction of molybdenum, but as an additional safeguard we prefer to use freshly prepared reagent solutions. Surplus reagent solution can conveniently be reserved for the tungsten extraction stage and used over a period of several days. SUMMARY- A method is described for the determination of tungsten in steel, using the reagent toluene-3 :4-dithiol. Interference from the corresponding molybdenum - dithiol complex is prevented by forming it preferentially in cold dilute acid solution, and removing it by amyl acetate extraction. The residual acid layer is treated for formation of the tungsten - dithiol complex, which develops quantitatively in hot concentrated acid medium. The complex is extracted with amyl acetate and tungsten determined absorptiometrically. There is little or no interference from other elements and the method is applicable to practically all types of alloy steel, being particularly useful for determinations in residual and other low ranges, where the usual gravimetric methods give poor performance. We are indebted to the directors of Messrs. Thos. Firth and John Brown, Limited, and in particular to Dr. C. Sykes, F.R.S., of the Brown - Firth Research Laboratories, for permission to publish this paper. REFERENCES 1. Hamence, J. H., ANALYST, 1940, 65, 162. 2. Miller, C. C., and Lowe, A. J., J . Chem. SOC., 1940, 1268. 3. Miller, C. C., Ibid., 1941, 792. 4. - Ibid., 1943, 72. 6. - ANALYST, 1944, 69, 109. 6. Vaughan, E. J., and Whalley, C., J . Iron and Steel Inst., 1947, 155, 635. 7. Wells, J. E., and Pemberton, R., ANALYST, 1947, 72, 185. THE BROWN - FIRTH RESEARCH LABORATORIES SHEFFIELD, 4 Januavy, 1947

ISSN:0003-2654    

DOI:10.1039/AN9477200189

出版商:RSC    

年代:1947

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 194 RAMASARMA, HAKIM, AND RAO : A CHROMATOGRAPHIC ADSORPTION [Vol. 72 A Chromatographic Adsorption Method for the Estimation of the Provitarnin-A Content of Foodstuffs* BY G. B. RAMASARMA, D. N. HAKIM, AND S. D. RAO A NUMBER of methods have been proposed by various authors for estimating the provitamin-A content of plant materials; these have been critically reviewed by Moon: Seaber? Petersons and, very recently, 300th.~ Essentially all the methods consist of four steps: (1) extrac- tion of the pigments from the material, (2) saponification to remove oils and hydrolyse xanthophyll esters, (3) separation of the provitamins, collectively termed “carotene,” from the associated pigments, and (4) estimation of the carotene by colorimetric or spectrophoto- metric methods of comparison.The present investigation deals mainly with the third step, which until recently consisted in the application of the Willstatter - Stoll phase partition between light petroleum and 90 per cent. methyl alcohol. This procedure is known to have some serious drawbacks; in particular, (a) the separation of kryptoxanthin is not sharp, the pigment being found in both the phases, and (b) the inactive lycopene is epiphasic and therefore contaminates car0 tene .Further, recent investigations in this laboratory6 have shown that the partition between light petroleum and methyl alcohol is unsatisfactory in that some coloured but biologically inactive degradation products also remain in the epiphasic layer and are incorrectly estimated as carotene. The presence of such carotene-like artefacts has been observed by some earlier workers also: by Kemmerer and Fraps6 in the excreta of rats and chickens, by Wiseman and his co-workers‘ in market hays and silages, by Quackenbush et aL8 in A.I.V. silage and by Whitnah et aL9 in the faeces of cows. Various treatments have been suggested for the removal of these interfering pigments, e.g., washing the light petroleum solution with diace- tone, passing it through calcium carbonatelo or shaking it with a small amount of specially prepared magnesium carbonate.u Seaber2 proposed a chromatographic method, using Brockmann’s alumina as adsorbent and light petroleum containing 3 per cent.of acetone as developer. Mooreu reported that a column of dicalcium phosphate adsorbs all the xantho- phylls and interfering pigments but allows carotene to pass down unadsorbed. An additional drawback in the phase separation method is that no distinction is made between 13-carotene and the other provitamins, which are only half as active as the former. Neither the inactive lycopene nor the “low-grade” provitamins (mostly cc-carotene and kryptoxanthin) appear to be of such rare occurrence or in so negligible an amount as was hitherto supposed.This fact seems to have been realised only in the case of yellow corn and yellow maize, as can be seen from the work of Buxton,13 Fraps and Kemmerer,l* White et aE.,16 and Sadana and Bashur Ahmad,16” who have determined both carotene and kryptoxanthin in order to find out the provitamin-A activity. In a critical application of the chemical method for assessing the provitamin-A activity of any plant materia1,t it is necessary to estimate the individual provitamins and calculate the activity by using the following formula which is based on the definition of the International Unit: pg. of other provitamins. 1.2 Provitamin-A activity in Internat. Units = Chromatographic adsorption, which offers the only means of separating the individuaI pigments, has been used extensively in qualitative and preparative work, but not for purposes pg.of 13-carotene 0.6 + ~ * This investigation was completed in February, 1943, but owing to unavoidable circumstances it could not be presented for publication earlier. A preliminary note, however, was published in Current Science, 1943, 12, 21. -f It is to be admitted, however, that with certain foodstuffs serious discrepancies have been observed between the chemically determined activity and that obtained by biological assay. Some of these anomalies may be due to imperfections in the chemical methods already referred to, but there are other important factors influencing the biological availability-via. , the extent of digestion and absorption and the presence of varying amounts of anti-oxidants (Hickman ef aZ.ls; Guggenheiml’).It has been suggested that a rela- tively high figure should be fixed for the daily requirements if all the vitamin-A activity is to be derived from vegetable sources, for the activity of the provitamins is relatively low at the higher levels of intake, probably owing to inefficient absorption (Guilbert et aZ.18; Vitamin-A Sub-committee of the Accessory Food Factors Committee, Lister Institute and Medical Research Council1*). Although from a practical point of view a unit of provitamin A is not the same as a unit of vitamin A, the need for further improvements in the chemical and biological methods of assay cannot be denied.May, 19471 METHOD FOR THE ESTIMATION OF PROVITAMIN-A CONTENT OF FOODSTUFFS 195 of quantitative estimation, because considerable amounts of the pigments, varying with their adsorptive affinities, may be lost owing to incomplete elution.Thus, if a mixture of pig- ments is chromatographed to give a sharp separation of the constituents the loss of xantho- phylls and other inactive pigments would be immaterial, but the loss of variable amounts (70 to 90 per cent.) of the provitamins would introduce a factor of uncertainty which makes the procedure unsuitable. It is obvious, therefore, that the elimination of the non-carotene pigments and the separation of the individual provitamins for quantitative estimation are not possible in one and the same chromatographic operation. It was thought, however, that a close approximation to the objectives in view might be achieved if the chromatographic adsorption were carried out in two stages; the first to estimate the “total carotene” (including lycopene, if any) and the second to estimate the relative proportions of the individual pigments in this “total carotene.” Dicalcium phosphate prepared according to Moore12 has been found to fulfil the requirements of the first stage, in which xanthophylls and artefacts should be retained completely and the hydrocarbon pigments allowed to pass down un- adsorbed.In the second stage, satisfactory resolution of the pigment mixture was obtained by use of Brockmann’s alumina or activated magnesia. Throughout this paper the two stages are referred to as the “first chromatography” and the “second chromatography” respectively .EXPERIMENTAL PREPARATION AND PURIFICATION OF THE REAGENTS- Dicalcium phos$hate-Dicalcium phosphate was prepared precisely according to Moore.= AZumina-On account of the scarcity of Brockmann’s alumina, it was found necessary to activate the adsorbent and use it over and over again. The used adsorbent was repeatedly washed by heating under reflux with light petroleum (b.p. 60” to 75” C.) containing 3 per cent. of alcohol, until the extract was practically colourless. The adhering solvent was removed, finally by drying at 100” C., and the alumina was heated in a nickel dish over a Meker burner (at a temperature ranging between 200” and 250” C.) for a number of hours and stirred fre- quently with a glass rod meanwhile. There was an initial darkening due to carbonisation of traces of organic matter, but on continued heating the adsorbent became practically white.It was allowed to cool in a desiccator over sulphuric acid and soon after transferred to glass- stoppered bottles. Light petroleum (“$etroZeum ether”)-As purified light petroleum was not available, ordinary automobile petrol was distilled and the fraction boiling between 60” to 75” C. was collected and purified according to Castille and Henri20 by treatment with sulphuric acid and alkaline permanganate. Methyl alcohol-Methyl alcohol was purified by heating under reflux with aluminium turnings (10 g. per litre) and potassium hydroxide (10 g. per litre) and then submitted to fractional distillation. In order to obtain a 92 per cent.v/v methyl alcohol for the phase separation, 90 ml. of purified alcohol were mixed with 10 ml. of water. Ethyl alcohol free from aldehyde-This was prepared by treating rectified spirit in a manner similar to the methyl alcohol. CHROMATOGRAPHIC TECHNIQUE- The procedure was practically the same as that described by Moore,12 except that smaller adsorption tubes (1.3 x 12 cm.) were employed. The chromatogram was developed under a vacuum of 40 cm. of mercury instead of the 65 cm. recommended by Moore, in order to avoid excessive loss of solvent under tropical conditions. In order to determine the extent of the loss that may occur during the first chromato- graphy, solutions containing 10 to 60 pg. of /3-carotene were passed through identical columns of dicalcium phosphate; estimation of the carotene content of the filtrates showed that the losses of /&carotene rarely exceeded 1 per cent.This is well within the range of errors in- herent in visual spectrophotometric determination. The need for care in the preparation of the phosphate has been stressed by Mo~re.~*l~ Preliminary experiments showed that both xanthophylls and xanthophyll esters axe retained by a column of dicalcium phosphate. Hence, in this method, both the saponification and the phase separation could normally be dispensed with, thus simplifying the procedure considerably. Nevertheless these operations have been retained in the present investigation, in order to demonstrate the existence of non-carotene pigments in the epiphase.196 RAMASARMA, HAKIM, AND RAO: A CHROMATOGRAPHIC ADSORPTION [vole 72 Some of the early trials, in which no saponification was performed, showed that the presence of oil in the extract may adversely affect the chromatographic separation.No difficulty was experienced with rich sources of carotene, e.g., leafy material, the xanthophylls and artefacts from which formed sharply defined and firmly held bands on the dicalcium phosphate column, but the extracts of poor sources, such as spices, cereals, and nuts, gave rise to diffuse overlapping bands, which showed a tendency to come down on continued washing. This difficulty could be easily overcome by preliminary saponification of the light petroleum extract and removal of the soaps. That the adverse effect was due to the presence of oil was confirmed by the following experiment. Aliquots of an oil-free solution containing carotene, lycopene, xanthophylls, and artefacts were mixed with varying amounts of coconut oil and passed over identical columns of dicalcium phosphate.The pigment that flowed down unadsorbed was in each instance estimated as carotene. When the oil contents were 0, 10 and 20 mg., the carotene values were 37, 37-4, and 37.5 pg. respectively. When the oil contents were 50 and 100 mg., higher carotene values, viz., 40.5 and 40.3 pg. respectively, were obtained, showing that some other pigment besides carotene was washed down. When 200 and 500 mg. of oil were used, the bands were irregular and diffuse. These results indicate that, under the experimental conditions employed, the presence of oil to the extent of about 20 mg.in the extract does not seriously interfere with the adsorption. With larger amounts, however, saponification is necessary. Generally speaking, saponification seems to be essential when the material under test is rich in oil or poor in carotene con tent . PROCEDURE- Extraction of pigments-Preliminary treatment depended upon the nature of the material. Dried materials like cereals and pulses were ground thoroughly in a porcelain edge-runner mortar to pass an 80-mesh sieve and a sample of the powder was taken for analysis. Fresh materials such as fruits and vegetables were cut into small bits and ground with acid-washed sand; this grinding was preferably repeated after the first extraction with alcohol. The quantity of material taken for analysis was largely dependent upon its carotene content; 0-5 to 5 g.of rich sources were sufficient, while 30 to 50 g. were necessary with cereals and pulses; according to the quantities taken, the volumes of alcohol and ether used for extraction were varied. Typical example of extraction procedzcre-30 g. of a powdered sample were weighed into a 5OO-mI. Erlenmeyer flask, 100 ml. of aldehyde-free ethyl alcohol (95 per cent.) were added and the mixture was heated over a water-bath under a reflux condenser for half an hour. The alcoholic extract was decanted, preferably through a wad of cotton wool, into a separating funnel. The residue was extracted similarly with another 100 ml. of alcohol and the extract was added to the first. The residue was further extracted by heating under reflux for 15 minutes with 100 ml.of a mixture of 2 volumes of light petroleum (b.p. 60" to 75" C.) and 1 volume of alcohol. Finally the residue was washed with 50 ml. of a similar petroleum - alcohol mixture. By this time the provitamins were completely extracted. The extracts were combined and sufficient water was added to bring the alcohol concentration to 75 to 80 per cent. The lower, aqueous alcoholic, layer was drawn off and extracted in a separating funnel with three 50 ml. lots of light petroleum (b.p. 60" to 75' C.). Further extraction was found to yield only xanthophylls. SaponiJication and phase partition-The combined light petroleum extract was washed once with water and saponified by heating under reflux for 15 minutes with 25 ml.of 10 per cent. alcoholic potash solution. The chlorophyllins, soaps and excess of alcoholic potash were removed by careful washing. The light petroleum extract was then shaken with an equal volume of 92 per cent. methyl alcohol in a separating funnel and the lower, alcoholic, layer, containing xanthophylls, was drawn off. The epiphase was washed repeatedly with smaller portions of 92 per cent. methyl alcohol until the washings were practically colourless. The combined methyl alcoholic solutions were washed with a small volume of light petroleum, which was added to the epiphasic solution. The combined light petroleum solution was washed free from alcohol, dried over anhydrous sodium sulphate and made up to a suitable volume. The pigment concentration was determined by spectrophotometry and the carotene content of the material calculated.This is the value obtainable by the usual methods employing Willstatter - Stoll phase separation. First chromatography-An aliquot of this solution (or all the solution, if the carotene content was low) was concentrated under reduced pressure in an atmosphere of nitrogenMay, 19471 METHOD FOR THE ESTIMATION OF PROVITAMIN-A CONTENT OF FOODSTUFFS 197 to about 5 to 10 ml. and passed through a column of dicalcium phosphate. The xanthophylls and artefacts were held strongly at the top, while carotene passed down practically un- adsorbed. Lycopene (when present) showed little separation from carotene ; its presence could, however, be suspected when the top portion of the carotene band, as it approached the lower end of the tube, appeared dark red in colour.It was found convenient to collect the carotene solution in a separate test tube, which could be suspended in the flask just when the carotene reached the lower end of the column and before any pigment was washed down. The solution was made up to a suitable volume and the gross “carotene” content was estimated by spectrophotometric means. In some experiments it was observed that a distinct, pale yellow band moved down the column soon after the carotene on continued washing of the column; this was found to be kryptoxanthin. Since, under these conditions, the xanthophylls and artefacts do not move down at all, this offers a means of separately estimating kryptoxanthin in any material. Second chromatography-The “gross carotene” solution (filtrate from the dicalcium phosphate column) was then concentrated to a small volume under reduced pressure and in a current of nitrogen and was passed through a suitably sized column of Brockmann’s alumina.The chromatogram was developed with light petroleum, which separated the constituent pigments into sharply defined bands. The bands were carefully scooped out by means of a spatula and separately eluted with light petroleum containing 3 to 5 per cent. of ethyl alcohol. The eluates were made up to suitable volumes and examined in the spectrophotometer for identification and estimation. The total pigment in the eluates did not account for all that was chromatographed. Usually the recovery was about 90 per cent., but since the three common hydrocarbon pigments-a-carotene, p-carotege and lycopene-diff er but slightly in their adsorptive affinities, it was assumed that the losses were shared by them equally.The amounts of individual pigments present in the original solution were calculated accord- ingly. S@ctro#hotometry-In order to identify and estimate the different pigment fractions, their solutions in purified light petroleum (b.p. 60” to 75” C.) were examined in a Gaertner Visual Spectrophotometer. The photometer drum readings were taken at &my. intervals over the range 430 to 550 mp. and the extinction (E) values were read off from conversion tables (Brode%). The pigments were identified by their characteristic absorption maxima and the concentrations calculated on the basis of the extinction coefficients (Et& = 2440 at 450 mp., 2020 at 470 mp., and 2140 at 480 mp.; solvent light petroleum, b.p.60” to 75” C.) obtained for a sample of pure p-carotene isolated from Badami mango fruit.= The average of the values obtained for the three wavelengths was taken as the correct figure. For the sake of simplicity, all estimations were made in terms of p-carotene, irrespective of the identity of the particular fraction. Having thus found the amounts of different provitamins present in the material, the total provitamin-A content expressed in International Units was calculated according to the formula given on p. 194. Results for a number of food materials found by this procedure areshownin the accompany- ing Table.For comparison, values given in the Health Bulletin. No. 23, Third Edition (1941), published by the Government of India, have also been included in the table; most of them were determined by De,% by means of a phase separation method. DISCUSSION Our results clearly show that plant materials that have been dried and stored for some time contain appreciable amounts of epiphasic artefacts. These are wrongly estimated as carotene by the usual phase partition methods. By chromatography on a column of di- calcium phosphate the impurities can be removed without loss of carotene. Analysis of a sample of dehydrated carrots (supplied by Messrs. Parry & Co.) indicated that over 20 per cent. of the epiphasic pigment consisted of destruction products showing no definite absorption spectrum.Our work shows that more reliable results will be obtained if the chromatographic method is employed for such dehydrated foods. Another interesting fact brought out is the multiplicity of epiphasic pigments. It is generally assumed that most of the carotene of plant materials consists of p-carotene and that lycopene and kryptoxanthin are of rare occurrence. Among the materials tested, more than half the “apparent carotene” of coriander seeds and nearly 90 per cent. of that of mace Sekhon25 found that loss of carotene on dehydration of carrots was small.198 RAMASARMA, HAKIM, AND RAO : A CHROMATOGRAPHIC ADSORPTION POI. 72 seems to be lycopene. The carotene of chillies and carrots contains nearly 25 per cent. of the a-isomer. Again, the provitamin A occurring in papaya fruit is almost entirely krypto- xanthin.’The few results presented here clearly indicate the need for similar detailed analyses of the common Indian foodstuffs. Owing to the exigencies of the war, there has been a considerable increase in the con- sumption of dehydrated foods, while processed and canned foods promise to come into a more extensive use than ever before. Various investigators have studied the carotene losses when foodstuffs are subjected to different cooking processes. It is highly probable that in all this work the observed provitamin-A values were vitiated by interference from non-carotene pigments. A re-investigation employing improved chromatographic methods seems to be desirable. PROVITAMIN-A CONTENT PER 100 G.OF MATERIAL Material Bengalgram . . Greengram . . Redgram .. Horse gram . . Lentil . . .. Whole wheat . . Cholam .. Fenugreek seeds Mace . . Red chillies (diy) Pistachio nut . . Gingelly seeds Mustard . . Coriander seeds .. .. .. .. .. a . .. .. .. .. .. .. * . .. Mango fruit (Badami) Carrots (dehydrated) Papaya fruit . . .. Determined by the authors r A \ Second Health First chromato- Vitamin-A Botanical No. 23 partition graphy (calculated) (calculated) Bulletin Phase chromato- graphy activity name C(g4”II.U.) Pg- Pg. WE. I.U. I1 I11 Cicer arietinum Phaseolus radiatus Cajanus indicus Dolichos bijlorus Lens esculenta Triticum vulgare Sorghum vulgare Trigonella f oenugraecum Myristica fragrans Capsicum annuum Pistacia Vera Sesamum indicum Brassica juncea Coriandrum sativum Mangifera indica Carica papaya Daucus carota 316 158 220 119 450 108 136 160 I 676 240 100 270 1570 4800 2020 - 224 109 125 74 70 21 20 660 3580 11200 176 21 178 230 - - 37800 162 26 100 17 25 6 13 260 2150 6230 140 12 149 100 5000 1280 29800 ’IV V b=162 270 b=24; ?=2 42 b=100 166 b=17 28 42 10 22 b=240; ?=20 420 * * * L= 1976; b = 174 b = 4420 U= 1620; ?= 190 b=126; a=14 - b=141; ?=8 L(?)=55; b=45 b = 5000 C= 1150; b= 130 b = 22350 a = 7450 290 8870 220 20 242 73 8330 1175 43460 ? = doubtful identity; a = a-carotene; b = ,%carotene; L = lycopene; c = kryptoxanthin; * = not analysed, assumed to be all /3-carotene.The differences between I and I1 are mostly due to differences inherent in the samples analysed. Note:-Column I: Values reported in the Health Bulletin No.23. Column I1 : Values obtained by the authors, employing a similar phase-separation method. Column I11 : Values obtained by subjecting I1 to chromatography over dicalcium phosphate. (11)-(111) : Non-carotene pigments wrongly estimated as carotene by the phase-separation method. Column IV: Composition of I11 in terms of individual pigments (calculated from the results Column V: Activity in International Units calculated from IV. obtained by subjecting 111 to chromatography over Brockmann’s alumina). Finally, a word of caution is necessary with regard to the first chromatography. There are many variables in the experimental procedure-the adsorptive power and particle size of the dicalcium phosphate, the size of the column and the manner of packing, the vacuum applied during chromatography, and so forth; unless due care is taken, considerable errors may be introduced.At the outset, all these experimental conditions should be standardised to give quantitative recoveries of carotene and the details strictly adhered to subsequently. It is further recommended that every new lot of adsorbent should be tested for its proper performance before it is brought into use. In the second chromatography (over Brockmann’s alumina) which seeks to estimate the relative proportions of the individual pigments, it is not quite correct to suppose that the losses due to incomplete elution are shared equally by the constituents. By analysis of “synthetic” mixtures, it has been found, as might be expected, that larger amounts of the more strongly adsorbed pigment are lost.The consequent errors are not high, but improve- ments in this direction are desirable. Subsequent to the completion of this work (February, 1943), several groups of ~orkers~6-30 have proposed chromatographic methods for the estimation of the true carotene content ofMay, 19471 METHOD FOR THE ESTIMATION OF PROVITAMIN-A CONTENT OF FOODSTUFFS 199 processed foods, feeding stuffs, and the like. It should be mentioned, however, that few of these methods, with the exception of those of Kemmerer and co-w0rkers,~~~2 go beyond the estimation of the total carotene content. The large number of investigations of a similar nature that have been reported during recent years shows the extent to which the subject is deservedly attracting the attention of workers interested in nutrition.SUMMARY An improved method for the estimation of the provitamin-A content of foodstuffs has been described. It involves application of chromatographic adsorption in two stages , using suitable adsorbents: the first to estimate the total “carotene” and the second to ascertain the relative proportions of the constituent pigments. This permits the estimation of the individual provitamins and therefore a more precise estimate of the total provitamin-A activity of the material under test. A few food materials have been analysed by this improved method and the results are presented. The results indicate that large errors might be introduced in the analysis of dried and stored materials, owing to the presence of certain modified carotenoid pigments which are devoid of any provitamin-A activity, but are estimated as carotene by the usual methods employing the Willstatter - Stoll phase separation.These impurities can be re- moved by chromatographic adsorption over dicalcium phosphate , the carotene recoveries being quantitative. The possible formation of epiphasic non-carotene pigments during the course of storage, cooking, canning or dehydration of foodstuffs has been discussed and the need for a thorough re-investigation by improved chromatographic methods has been stressed. In order to eliminate errors due to the presence of lycopene and the “low grade” provitamins, the second chromatography should be carried out and the individual pigments estimated. One of us (G. B.R.) is grateful to the Lady Tata Memorial Trust for the award of a scholarship. The authors wish to thank Prof. V. Subrahmanyan and Sir J. C. Ghosh for their keen interest in this work. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. REFERENCES Moon, F. E., J . Agric. Sci., 1939, 29, 295. Seaber, W. M., ANALYST, 1940, 65, 266. Peterson, W. J., Ind. Eng. Chem., Anal. Ed., 1941, 13, 212. Booth, V. H., J . SOC. Chem. Ind., 1945, 64, 162. Ramasarma, G. B., and Hakim, D. N., Nature, 1942, 149, 611; Ann. Biochem. Exp. Med., 1942, Kemmerer, A. R., and Fraps, G. S., J . Nutrition, 1938, 16, 309. Wiseman, H. G., Kane, E. A., Shinn, L. A., and Cary, C. A., J . Agric. Research, 1938, 57, 635. Quackenbush, F. W., Steenbock, H. E., and Peterson, W. H., J . Amer. Chem. Soc., 1938,60, 2937. Whitnah, G. H., Peterson, W. J., Atkeson, F. W., and Cave, H. W., J . Agric. Research, 1939,58, 343. Hegsted, D. M., Porter, J. W.. and Peterson, W. H., Ind. Eng. Chem., Anal. Ed., 1939, 11, 256. Fraps, G. S., Kemmerer, A. R., and Greenberg, S. M., J . Assoc. 08. Agric. Chem., 1940, 23, 659. Moore, L. A., Ind. Eng. Chem., Anal. Ed., 1940, 12, 726; Abst., ANALYST, 1941, 66, 169. Buxton, L. O., Ibid., 1939, 11, 128. Fram. G. S.. and Kemmerer. A. R.. Ibid., 1941, 13, 806. 2, 181. White, J. W.., Brunson, A. M., and Zscheile, F. P., Ibid., 1942, 14, 798. Hickman, K. C. D., Kaley, M. W., and Harris, P. L., J . Biol. Chem., 1944, 152, 303. Guggenheim, K., Biochem. J., 1944, 38, 260. Guilbert, H. R., Howell, C. E., and Hart, G. H., J . Nutrition, 1940, 19, 91. Vitamin A Sub-committee of the Accessory Factors Committee, Lister Institute and Medical Research Council, Nature, 1945, 156, 11. Castille, A., and Henri, V., quoted by Weissberger, A., and Proskauer, E., “Organic Solvents: Physical Constants and Methods of Puri$cation,” Oxford University Press, 1935. Moore, L. A., Ind. Eng. Chem., Anal. Ed., 1942, 14, 707. Brode, W. R., “Chemical Spectroscopy,” John Wiley & Sons, Inc., New York, 1939. Ramasaxma, G. B., Rao, S. D., and Hakim, D. N., Biochem. J., 1946, 40, 657. De, N. K., et al., a number of papers in the Indian J . Med. Research, 1935-38. Sekhon, N. S., Ibid., 1942, 30, 528. Kemmerer, A. R., J . Assoc. 08. Agric. Chem., 1943, 26, 7 7 . Mackinney, G., Aronoff, S., and Bornstein, B. T., Ind. Eng. Chem., Anal. Ed., 1942, 14, 391. Mann, T. Barton, ANALYST, 1944, 69, 34. Wall, M. E., and Kelly, E. G., Ind. Eng. Chem., Anal. Ed., 1943, 15, 18. Charkey, L. W., and Wilgus, H. S., Ibid.. 1944, 16, 184. Kemmerer, A. R., J . Assoc. 08. Agric. Chem., 1944, 27, 542. Kemmerer, A. R., Fraps, G. S., and Meinke, W. W., Food Research, 1945, 10, 66. INDIAN INSTITUTE OF SCIENCE 15a. Sadana, J. C., and Bashur Ahmad, Indian J . Med. Research, 1946, 34, 59. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. DEPARTMENT OF BIOCHEMISTRY BANGALORE, INDIA February, 1947

ISSN:0003-2654    

DOI:10.1039/AN9477200194

出版商:RSC    

年代:1947

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 200 NELSON: THE DETERMINATION OF CAROTENE IN DRIED GRASS pol. 72 The Determination of Carotene in Dried Grass BY W. A. G. NELSON (Read at the Meeting of the Society on April 2, 1947) A NEW method for the determination of carotene in dried grass is being put forward by a Carotene Committee,* which was originally formed through the Crop Driers Association, and in 1941 proposed a tentative method of analysis.1 This was called Method B, two other methods, A and C, having been under consideration at that time.In order to point out the defects of this old method and show the progress that has since been made, it is necessary to give an outline of the tentative method as published in 1941. METHOD B OF 1941- The sample of dried grass is ground to a fine powder with sand and extracted with a 3 : l mixture of light petroleum of b.p. 40" to 60" C. and acetone, in a Soxhlet or drip-type extractor. The extract is shaken up with a concentrated solution of potash in methyl alcohol to convert the chlorophyll present into potassium chlorophyllin, which is removed with water. The remaining extract now contains carotenoids and xanthophyll, and the xanthophyll is removed by means of a 9:l mixture of methyl alcohol and water.The amount of carotene in the light petroleum solution thus obtained is then estimated colorimetrically. From the work of Seaber,2 Kon and Thompson: Moore4 and MannD6 it was demonstrated by chromatography that there is in grass a petrol-soluble carotenoid that does not exhibit the properties of /3-carotene and has no biological activity. It was believed that this par- ticular "carotene" forms on the average 30 per cent. of the total carotenoids in grasses and therefore analysis of a grass meal by Method B gives an untrue picture of its biological worth. Furthermore, it was shown that it is not always possible to remove all the chlorophyll as potassium chlorophyllin, and a trace of chlorophyll in the final solution makes the colour estimation fallacious.Any method which would give the true /%carotene content of a grass meal would, there- fore, have to embody the following three important features: (1) It must be capable of separating p-carotene completely from the non-active caro- tenoids of grass. (2) It must yield for the final colorimetric estimation a solution entirely free from any forms of chlorophyll. (3) It must be a method in which there is no likelihood of isomerisation taking place. Points (1) and (2) have been mentioned above, and for (3) it is necessary to consider the work of Zechmeister.6 He showed that /3-carotene was capable of spontaneous isomerisation in solution and gave molecular extinction curves of the all-trans compound and mixtures of its stereoisomers (see Fig.1). Table 'I gives the Et,& values of /?-carotene over the wavelength range 451 to 447 mp., calculated from the above molecular extinction curves. TABLE I Wavelength mP* 451.0 all trans 450.5 450.0 449.5 449.0 448.5 448.0 447.5 447.0 much isomerisation EE. 2575 2505 2435 2365 2295 2225 2155 2085 2015 When a solution is being analysed colorimetrically for p-carotene the E:h. value is usually taken to be 2500 at 450 mp. From the figures in Table I it is obvious that, if isomeri- sation has taken place and the E:& at 450mp. is assumed to be 2500, inaccuracies will be incurred in determining the /3-carotene present. * Members of the Carotene Committee-Mr. R. 0. Davies (Chairman), Dr. V. H. Booth, Dr. A. Green, Mr. J. Green baum, Mr.A. W. Hartley, Mr. T. Barton Mann, Dr. F. E. Moon, Dr. W. A. G. Nelson, Mr. W. M. Seaber, Mr. H. H. Ward, Dr. H. Wilkinson, Mr. R. F. Wright.May, 19471 NELSON: THE DETERMINATION OF CAROTENE IN DRIED GRASS 201 Zechmeister has postulated the possibility of the existence of twenty isomers of /3-carotene within the range from all trans to all cis (see Fig. 2) and he has been able to identify several of them. WAVE LENGTH IN Mp FIG. 1. Molecular extinction curves of p-carotene in hexane: -, fresh solution of the a!-tvuns compound : - - - , mixture of stereoisomers after heating under reflux in darkness for 46 min. ; - . -, mixture of stereoisomers after iodine catalysis at room temperature in light. (From J . Amer. Chem. SOC., 1943, 65, 1523. Bearing in mind the facts mentioned above, Mann, Seaber, Green and Hartley (who are members of the present Carotene Committee) collaborated with a view to finding an improved method for the determination of carotene in grasses. As a result of their investigations a chromatographic method called Method D was suggested.METHOD D- One g. of the sample is ground to a fine powder with sand and extracted with a 3:l mixture of light petroleum of b.p. 40” to 60” C. and acetone, as in Method B. The mixed solvents axe removed almost completely by evaporation on the water bath and the last traces are blown off with a stream of carbon dioxide to minimise oxidation. The dry residue is dissolved in light petroleum (b.p. 40” to 60” C.) and then passed through a column of bone meal (Mann’s findings on the use of bone meal as an adsorbent have already been recorded6).The filtrate is then examined for /3-carotene colorimetrically in the usual way. The salient points emerging from the analysis of grass meal by Method D were: (1) The filtrate from the bone meal column contained carotene which had the full biological activity of p-carotene, whilst the “carotene” fraction retained by the bone meal had no biological activity. (2) The filtrate contained no chlorophyll. (3) The absorption spectrum of the carotene in the filtrate coincided with that of all-trans- /3-car0 t ene . It was now clear that a method had been found which gave a much more accurate deter- mination of /3-carotene in grass than the previous ones. By the combined efforts of the whole Committee, it was shown that Method D gave more reproducible results than those obtained by Method B.202 NELSON: THE DETERMINATION OF CAROTENE IN DRIED GRASS Pol.72 I II II I V XI VI d VI I 6 - 2 Vlli s-p XVI 0 XVI I XI x dvtp FIG. 2. Skeleton models of the twenty possible stereoisomers of 8-carotene : all-trans- 8-carotene, three mono-cis- ,$carotenes, six di-cis- ,&carotenes, six tri-cis- 8 carotenes, three tetra-cis- 8- carotenes, and all-cis- 8-carotene. After this stage had been reached, an improvement in the method of extraction was brought about through the work of the Lever Bros. team consisting of Wilkinson, Edisbury and Gridgeman. The process of grinding with sand, followed by extraction with a 3:l mix- ture of light petroleum of b.p. 40" to 60" C. and acetone, was replaced by extraction with light petroleum of b.p.80" to 100" C. alone, without any initial grinding. This is now adopted in the method finally recommended by the Committee-Method E-which is described below.May, 19471 NELSON: THE DETERMINATION OF CAROTENE IN DRIED GRASS METHOD E-Now RECOMMENDED 203 Boil from 1 to 2 g. of grass meal with 50 to 60 ml. of light petroleum of b.p. 80" to 100" C. under reflux for 1 hour on a steam bath, Cool the flask and contents and filter the extract through sintered glass or any other suitable type of filter, or merely decant directly, on to a 2-inches by l-inch column of bone meal. Rinse the flask and residue with small quantities of light petroleum (light petroleum of b.p. 40" to 60" C. may be used at this stage, for ease of subsequent removal if this happens to be desirable).Apply suction to the bone meal column, elute with light petroleum of b.p. 40" to 60" C. and concentrate if necessary. Estimate the carotene in the eluate, colorimetrically. NOTES- Boiling can be done in large Kjeldahl flasks, which have been found to provide sufficient condensing effect . The bone meal should be extracted before use with a 3:l:l mixture of petrol, acetone, and ether. The bone meal should be of particle size passing a 120-line sieve but retained by a 200-line sieve. (Arrangements are being made for the preparation of a standard bone meal which can be supplied to anyone interested in this type of work.) The bone meal column can be used for a large number of determinations.After repeated use it may be washed with acetone, which removes the bulk of the pigments. A further wash with light petroleum prepares the column for further tests. The whole Committee carried out from 60 to 70 analyses on a sample of dried grass by Method D and an equal number by Method E. The average results by these two methods for all practical purposes can be considered to be identical. For this particular sample the average figures were: By Method D: 335 mg. per kilo. By Method E: 330 mg. per kilo. Further comparative average figures for a large number of tests were as follows: By Method D: 129mg.-perVkilo. By Method E: 135mg. per kilo. ,f ,> Y , 275 ,, ,, 9 , , J Y , J , 279 9 , 9 , $ 3 It has been shown that light petroleum of b.p. 80" to 100" C., without preliminary grinding of the sample with sand, is as efficient for the extraction of carotene as any other solvent or mixture of solvents.Its efficiency is only equalled by that of soaking the sample in the dark and in the cold for 48 hours with light petroleum of b.p. 40" to 60" C. This latter method, of course, is undesirable if an analysis is required quickly, as is usually the case. Previously, attempts to extract with boiling light petroleum of b.p. 40" to 60" C. had been made, but had been found to be inefficient. It seems that the light petroleum of b.p. 80" to 100" C. is much superior because of the higher temperature attained during ex- traction. As mentioned previously, it was believed that about 30 per cent. of the so-called "carotene" obtained by Method B was not p-carotene. As a matter of academic interest as well as commercial importance, the Committee set out to get a more definite figure.For this purpose, 42 samples were analysed by Methods B and E, and it was found that the results by Method E were only 69 per cent. as great as those by Method B. Again this is an average figure, some meals giving, say, 60 per cent. and others 80 per cent., depending on the age of the meal and certain other factors. From this work the following conclusions can be drawn: (1) Light petroleum of b.p. 80" to 100" C. is an efficient solvent for the extraction of the carotenoids of grass. (2) Bone meal is an efficient adsorbent for the separation of /3-carotene from the other pigments in grass. (3) Method E can be carried out more rapidly and easily than any other method.1. Carotene Committee of the Crop Driers Association, ANALYST, 1941, 66, 334. 2. Seaber, W. M., Ibid., 1940, 65, 266. 3. Kon, S. K., and Thompson, S. Y., J . Agric. Sci., 1940, 30, Pt. IV, 636. 4. Moore, L. A., Ind. Eng. Chem., Anal. Ed., 1940, 12, 726. 6. Mann, T. Barton, ANALYST, 1944, 69, 34. 6. Zechmeister, L., Chem. Revs., 1944, 34, No. 2, 267. REFERENCES204 THE DETERMINATION OF CAROTENE IN DRIED GRASS: DISCUSSION [VOl. 72 DISCUSSION Mr. W. M. SEABER said that in the past the estimation of carotene had been lengthy and tedious. He had been connected with this problem for a long time and had been interested to see the method develop in the direction of simplicity. He had tried the new method, not only on dried grass but also in general work, and had found it convenient and rapid.They owed a great deal to Mr. Barton Mann for bringing to light the advantages of bone meal as an adsorbent of non-carotene substances, and to the chemists a t Messrs. Lever Brothers for introducing the use of light petroleum of higher boiling-point range than that previously used for the extraction. Mr. N. T. GRIDGEMAN said that he had recently, on behalf of the Carotene Committee, statistically analysed the results of the final collaborative experiment in which methods D and E were compared. It had emerged that the reproducibility of the two methods was substantially the same (coefficient of variation = 4), and that method E yielded slightly, yet significantly, higher results (by about 3 per cent.) than method D.As in so many analytical techniques, reproducibility was found to be better within laboratories than between laboratories, and there may be good reason to believe that inter-laboratory differences (coefficient of variation = 8) were largely due to non-uniformity of instruments. Many laboratories perforce used "abridged" spectrophotometers, e.g., photoelectric absorptiometers dependent upon optical filters and absorption standards. In ,%carotene estimation potassium dichromate solution enjoyed an undeserved popularity as a suitable calibration medium-perhaps by false analogy with its undoubted virtues as a visual standard. The steepness of the slope of the absorption curve of potassium dichromate in the region of 450 mp. rendered i t highly unserviceable, and the position was worsened by the fact that most types of nominally identical optical filters exhibit marked variations in their transmission characteristics.He hoped that eventually a wholly satisfactory standard would be found ; meantime perhaps the best expedient was to use petrol solutions of pure p-carotene. Mr. K. A. WILLIAMS said he would like to support in the strongest possible terms Mr. Gridgeman's strictures on the use of potassium dichromate as a yellow colour standard. Whilst its use in visual colori- metry was defensible because of the limits of sensitivity of the human eye, it could not be defended for more accurate work. In spectroscopy or photo-electric measurements any standard must have an absorption curve very closely approximating to that of the test colour; it was but rarely that the curve of potassium dichromate did this.Mr. T. BARTON MANN said that from the point of view of spectroscopy one would naturally take readings at the peak of absorption. In photo-electric instruments employing filters he had found potassium dichromate relatively insensitive in so far as variations in concentration near that recommended, i.e., 0.0158 per cent. (= 1 pg. of carotene per ml.) did not appreciably affect the graph. There was little differ- ence between 0-0158 and 0.0164 per cent. solutions. He agreed that search should be made for an alter- native standard, preferably a dye the colour of which would not be affected by change of PH. Dr. C. H. LEA asked if differences in exposure to light in the course of analysis might cause a variable amount of change of the carotene.Dr. NELSON pointed out that in method E there was no evaporation of solvent from the extract, as there was in method D. Mr. BARTON MANN said that oxidised carotene would be adsorbed on bone meal and not pass into the solution to be measured. The use of the higher-boiling light petroleum reduced risk of oxidation, because the higher temperature enabled the carotene to be extracted without previous grinding of the dried grass with sand. It would seem that the higher temperature removed the moisture of the grass meal and permitted the solvent to penetrate more readily. Mr. SEABER remarked that light petroleum of b.p. 80" to 100°C. was apt to be rather variable in character and composition. Mr.WILLIAMS suggested that perhaps n-heptane might prove more satisfactory. It had a boiling- point range of 98" to 100" C., and to ensure freedom from aromtic constituents it could be washed with sulphuric acid. Mr. BARTON MANN said that on the use of various petroleum fractions of lower or higher boiling-point ranges he would particularly like to draw the attention of analysts to a point that had arisen in the collabora- tive work of the Committee, viz., that with change of solvent from one of lower to one of higher boiling-point there was a concomitant shift of peak absorption from a lower to a higher wavelength. For example, with light petroleum of b.p. 40" to 60" C. the E max. was 447 to 448 mp., but with that of b.p. 80" to 100" C. it was 452 to 464 mp. Dr.J. R. Edisbury had very kindly checked these findings and had furnished the speaker with the refractive indices of two such petroleum fractions, viz., one of b.p. 40" to 60" C., 1-3656 and one of b.p. 80" to 100" C., 1.4002. These differences in absorption and refractive index were significant, perhaps not so much for users of spectrophotometers, by whom the extinction would normally be obtained at peak absorption, but certainly with colorimeters and instruments employing filters, where a change of wavelength would automatically introduce a change of colour. Pending further work along these lines it would seem advisable to adhere to the estimation "carotene in light petroleum of b.p. 80" to 100" C." There could be no question that the method proposed did produce a solution containing the true carotene of grass meals and that intra-laboratory concordant results could be obtained.The question of inter-laboratory concordance appeared to be entirely a matter of instrument calibration, and it was to be He was pleased to have taken part in the work of the Committee.May, 19473 NOTES 205 hoped that the Committee would tackle this problem, possibly along the lines of a master reference instru- ment of the photo-electric spectrophotometer type to which the owners of colorimeters could refer. Dr. E. C. WOOD asked if the accuracy of the new method had been checked by “recovery” experiments with known added amounts of pure p-carotene, and also if the method could be adapted to the analysis of substances containing vitamin A as well as carotenoids.He had read recently of’an organic dyestuff, forming a stable solution, with an absorption spectrum sufficiently similar to that of carotene to make it a satisfactory standard instead of potassium dichromate. Perhaps one of the investigators could comment on this. Mr. BARTON MANN said he had no knowledge of any work on the recovery of carotene added to grass meals. He had determined the efficacy of recovery of /3-carotene from fat, using the bone meal treatment. A freshly prepared 0.03 per cent. standard, after saponification and extraction with ether, was subjected to the whole process of bone meal chromatography, and the figure returned was 0.0283 per cent. Having regard to the severity of the manipulation and the inherent errors of visual spectrophotometer estimation, one could conclude that the loss by such chromato- graphy was nil or negligible. With regard to vitamin A, Dr. T. W. Goodwin had found from his work with cod liver oil that vitamin A ester passes bone meal and vitamin A alcohol is adsorbed by it. If Dr. Wood had in mind the application of the method to biological material, for which saponification is usually necessary, then carotene would pass into the filtrate and vitamin A, as the alcohol after saponification, would remain adsorbed. He would refer Dr. Wood to “The separation of vitamin A from xanthophyll” (Mann, ANALYST, 1943,68,233) ; “A Chroma- tographic Method for Separating Free and Esterified Vitamin A” (Glover, Goodwin, and Morton, Biochem. J. , 1947, 41, 94); “Relationship between Blood Vitamin A Level and Liver Stores in Rats” (Ibid., 97). Mr. GRIDGEMAN said that the yellow substance referred to by Dr. Wood was methyl orange in aqueous solution, which had been suggested as a standard for /3-carotene by R. J. Taylor in a recent paper (ANALYST, 1946, 71, 566). But it applied to 8-carotene only in chloroform solution, in which the peak absorption occurred a t about 460 mp. No “control” experiments of the type Dr. Wood had in mind had been carried out, nor did he think they would be very valuable, as the separation problem was the extraction of carotene from grass cells. In reply to a question by Mr. Bacharach, as to whether statistical analysis had isolated any inter- personal variations within laboratories, the speaker said that the inter-personal error had been studied in one laboratory and found to be negligible; but with colorimetric (in contrast with absorptiometric) methods some observational disagreements would almost certainly have to be reckoned with. Later in the discussion Mr. Gridgeman deprecated the use of nitrogen for the removal of final traces of solvent, on the ground that it often contained some oxygen. Carbon dioxide was objectionable because of frosting of the cylinder valves. Hydrogen was always used in his laboratory and seemed to be themost suitable of the common gases for the purpose. The difficulty of such work would be very great.

ISSN:0003-2654    

DOI:10.1039/AN9477200200

出版商:RSC    

年代:1947

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-ction May, 19473 NOTES 205 Notes THE DETERMINATION OF LEAD AS IODATE IN GLASS ANALYSIS WE have recently carried out determinations of the lead content of three samples of lead glass (Si02 56%, PbO 30%, A1,0,1%, CaO 0*5%, K20 7*5%, Na,O 5%) by the gravimetric iodate method described by C. H.R. Gentry and L. G. Sherringt0n.l In every instance the lead iodate precipitate obtained showed a yellow discoloration, and a subsequent spectro- scopic examination of one precipitate showed the presence of iron and titanium. The results obtained are shown in Table I, together with results obtained in parallel determinations in which the lead was determined by separating and weighing it as sulphate. TABLE I Sample PbO as iodate PbO as sulphate Difference Per cent. Per cent. Per cent. A 29.66; 29-53 28.98; 28.94 0.6; 0.59 B 30.07; 29.98 29.48; 29-44 0.59; 0.54 C 30.42; 30.18 29.87; 29.75 0.55; 0-43 With sample A, the lead iodate precipitates, after being weighed, were dissolved through the sintered glass crucibles with warm dilute caustic soda solution, 20 ml.of hydrochloric acid were added and the solutions evaporated to small volume to eliminate iodic acid. Ten ml. of sulphuric acid were then added to each beaker and the contents evaporated to strong fuming. The determination of the lead by weighing as lead sulphate was completed in the usual manner. By this method the PbO content was found to be 29.07 and 28-94 per cent., compared with 28.98 and 28.94 per cent. found by the direct determination as sulphate.206 NOTES [Vol. 72 The yellow coloration of the original lead iodate precipitates, together with the spectro- graphic evidence, suggested that iron might be present as an impurity. To explore further the influence of small amounts of iron on the determination of lead as iodate a series of standards was prepared containing known added quantities of iron.The iron was added in the form of ferric nitrate to a solution of pure lead nitrate of which the PbO content was approximately that of a l-g. sample of the glasses under examination. The lead content was determined gravbetrically a s iodate, as before. In Table I1 are given the results, together with the lead content determined as lead sulphate. Assuming that the iron is completely co-precipitated with the lead as ferric iodate, the presence of 0.07 per cent. of iron (expressed as Fe203) in a glass should theoretically give rise to a positive error of 0.20 per cent. (Fe(I03), x 0.1374 = Fe,O,; Pb(IO,), x 0.4005 = PbO.) The actual difference found was 0.25 per cent.TABLE I1 PbO as sulphate Fe,O, added PbO as iodate Difference Per cent. Per cent. Per cent. Per cent. 0.0 29.91 0.11 0.07 30.17 0.37 0.14 3042 0.62 0.28 30.92 1.12 0.26 29.80 0.26 0.50 The iodate method has also been tried on glasses containing both barium and strontium in addition to lead; the results are shown in Table 111. TABLE I11 PbO after conversion Sample PbO as iodate of iodate to sulphate Per cent. Per cent. A 19.4; 19.4 18-5; 18.5 B 21.2; 21.2 19.6; 19-7 These precipitates also were badly discoloured and obviously contained iron. However, the iodic acid precipitation is a valuable method for effecting a preliminary separation of lead from barium and strontium. Gentry and Sherrington point out that ferric iron precipitates with, the lead but state that “the traces of iron in lead glasses are too insignificant to interfere with the lead deter- mination.” Our results indicate that the iodate method for the determination of lead in glass can be applied only to samples known not to contain more than very small amounts of iron; 0.07 per cent. of Fe203, for example, can give an increase of 0.25 in the percentage figure for PbO. If the lead iodate precipitate shows a yellow discoloration it is advisable to redissolve it and to reprecipitate the lead as sulphate. REFERENCE 1. Gentry, C. H. R., and Sherrington, L. G., ANALYST, 1946, 71, 31. P. M. C. PROFFITT R. C. CHIRNSIDE RESEARCH LABORATORIES, January, 1947 THE GENERAL ELECTRIC Co. WEMBLEY NOTE ON THE PREPARATION OF CYCLOHEXANE FOR SPECTROSCOPIC WORK IN a number of analytical processes involving the use of absorption spectroscopy cyclohexane is commonly employed as a solvent.Its suitability for this purpose depends on the absence of absorption bands, and for this reason traces of benzene, from which cyclohexane is prepared by hydrogenation, must be removed. By the method of Dolinl it was found that a recent delivery of cyclohexane contained 0.4 per cent. of benzene. Traces of benzene are usually removed by sulphonation, a process that involves repeated shaking with oleum followed by successive washes with water, perrnanganate solution and water. The cyclohexane is then dried over calcium chloride and redistilled.May, 19471 MINISTRY OF FOOD: STATUTORY RULES AND ORDERS 207 This process of purification is time- and labour-consuming, and it has been found that the benzene can be completely removed by adsorption on passing the cyclohexane through a column of silica gel.This method has the merit of simplicity, it requires no attention, and the operation is conveniently allowed to run overnight. The apparatus consists of a glass tube approximately 11OOmm. long, with an internal diameter of 10mm. To one end is fused the cone portion of a B14 standard joint, and a sintered glass disc is sealed into the tube at a position approximately 20 mm. from the other end. A reservoir is made from a glass tube, 300 mm. long and 45 mm. wide, tapered at the bottom and fitted with the socket portion of a B14 standard joint. The tube is packed with powdered silica gel, of a particle size which passes a 30-mesh sieve but is retained on a 150-mesh sieve.The packing is done by small additions, after each of which the tube is gently shaken by tapping on a pad of filter papers. Approxi- mately 100 g. of silica gel are required to pack the tube, which is then fixed in a vertical position. The cylindrical glass reservoir is attached to the top of the tube and charged with 350 to 400 ml. of cyclohexane. The liquid percolates slowly through the column, the cyclohexane going forward and the benzene remaining behind in accordance with their relative adsorba- bilities. At the end of 24 hours, benzene-free cyclohexane may be collected from the bottom of the column at the rate of 16 ml. per hour. If the operation is continued overnight the rate of collection very slowly drops to 14 ml.per hour by the following morning. The purified cyclohexane collected during the night is tested for freedom from benzene by the formolite reaction, which consists in adding 1 drop of the sample to a mixture of 10 ml. of concentrated sulphuric acid containing 0.5 ml. of 40 per cent. formaldehyde solution. In presence of traces of benzene a yellow to red coloration at once appears. Thereafter the cyclohexane coming from the column is collected in 20-ml. portions, each being tested for ffeedom from benzene by the formolite reaction. The first fraction to show traces of benzene indicates the “break point” of the column and the end of the run. Using the conditions and apparatus described above, a test run was started at 12 noon, and by 4 p.m. the following day 320 ml. of benzene-free cyclohexane had been collected. The result of a spectroscopic test confirmed the absence of benzene and hence the suitability of the sample. In this run the “break point” occurred after 350ml. of cyclohexane had been collected. Silica gel is an inexpensive adsorbent and a fresh 100-g. charge has been used for each run. There would, however, appear to be no difficulty in reconditioning the silica for further use. I wish to thank the Government Chemist for permission to publish this note, REFERENCE 1. Dolin, Ind. Eng. Chem., Anal. Ed., 1943, 15, 242. DEPARTMENT OF THE GOVERNMENT CHEMIST THE GOVERNMENT LABORATORY LONDON, W.C.2 S. A, ASHMORE February, 1946 * Obtainable from H.M. Stationery Office. Italics signify changed wording.

ISSN:0003-2654    

DOI:10.1039/AN9477200205

出版商:RSC    

年代:1947

数据来源: RSC