ISSN:0003-2654    

DOI:10.1039/AN94772FX045

出版商:RSC    

年代:1947

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94772BX047

出版商:RSC    

年代:1947

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94772FP057

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 DECEMBER, 1947 THE ANALYST VOL. 72, No. 861 PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS A JOINT meeting of the Society with the Food Group of the Society of Chemical Industry was held at 7 p.m. on Wednesday, December 3rd, 1947, at the Chemical Society’s Rooms, Burlington House, Piccadilly, London, W.1.On the invitation of the Chairman of the Food Group, Dr. E. €3. Hughes, the Chair was taken by the President of the Society, Mr. Lewis Eynon. The general subject of the meeting was “ The Occurrence, Physiological Importance and Estimation of Metallic Contaminants in Foodstuffs,” and the following papers were presented and discussed:--“ The Occurrence of Metallic Contaminants in Foodstuffs,” by G. E. Forstner, M.Sc., A.R.I.C. ; “The Public Health Aspect of Metallic Contaminants in Foodstuffs,” by G. W. Monier-Williams, O.B.E., M.C., M.A., Ph.D., F.R.I.C. ; “Trace Metals in Human Nutrition,” by W. F. J. Cuthbertson, B.Sc., A.R.I.C. ; “The Estimation of Metallic Con- taminants in Foodstuffs,” by N. L. Allport, F.R.I.C., and D. C. Garratt, B.Sc., Ph.D., F.R.I.C.NEW MEMBERS Kyle Campbell, B .Sc., F.R.1 .C. ; Samuel Manoranjan Chanmugan, B.Sc. (Lond.) , A.R.I.C. ; Edward Watson Clark, B.Sc. (Leeds) ; Arthur William Hartley, A.M.C.T., A.R.I.C. ; Herbert Makin, A.M.C.T. ; George Rippon Nellist, F.R.I.C., M.1nst.F. ; John Gerard Reynolds, F.R.I.C. ; Leslie Singleton; Reginald Smart, B.Sc. (Lond.), A.R.I.C. ; Emrys Islwyn Williams, B.Sc. (Lond.), A.R.I.C.; Ernest Raymond Willott, A.R.I.C. DEATH Sir Bernard H. Spilsbury, Honorary Member. WE regret to have to record the death of PHYSICAL METHODS GROUP THE Third Annual General Meeting of the Physical Methods Group was held at 6 p.m., on Tuesday, November 26th, 1947, in the Rooms of the Chemical Society, Burlington House, London, W.1. Mr. R. C. Chirnside, the Chairman of the Group, presided. The Officers and Members of Committee for the forthcoming year are as follows:- Clmivman : Dr. J. G. A. Griffiths. Vice-Chairman: Mr. B. S . Cooper. Hon. Secretary ; Dr. J. E. Page, Glaxo Laboratories, Ltd., Greenford, Middlesex. Members of the Group Committee : Dr. W. Cule Davies, Dr. J. R. Edisbury, Dr. W. F. Elvidge, Mr. J. Haslam, Mr. R. A. C. Isbell and Mr. D. M. Smith and, ex ojicio, the President, the Hon. Treasurer and the Hon. Secretary of the Society and the Editor of THE AKALYST. Mr. C. A. Bassett and Dr. D. C. Garratt were re-appointed Hon. Auditors, The meeting passed a vote of thanks to the retiring members of Committee, Mr. R. C. Chirnside, Dr. S. Judd Lewis and Dr. F. Wokes, for their services to the Group, and especially thanked Mr. Chirnside for his services as Chairman since the inauguration of the Group. Following the Annual General Meeting, an Ordinary Meeting of the Group was held, at which Mr. B. S. Cooper delivered a lecture on “Electron Microscopy.” 603

ISSN:0003-2654    

DOI:10.1039/AN9477200503

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-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 504 RANSLEY: A PROCEDURE FOR GAS ANALYSIS [Vol. 72 A Procedure for Gas Analysis at Low Pressures* By C . E. RANSLEY THE methods available for the micro-analysis of gas mixtures may be classified broadly into two groups, in which the sample is manipulated (a) at approximately atmospheric pressure and ( b ) at very reduced pressures, usually less than 0.1 mm.of mercury. In the first group the analytical procedure usually follows orthodox chemical methods and the constituent gases of the mixture are removed one by one with a series of specific reagents. Various ingenious techniques have been evolved for the handling of very small volumes of gas; most of them involve the use of capillary burettes at constant pressure, and the manipulation of the reagents either as solids or in the form of impregnated glass beads. Suitable apparatus and procedures have been described by Blacet et alial and Sutton2; a modified apparatus for analysis at constant volume, in which the gas is circulated through reagents contained in loops of capillary glass tubing, has been suggested by Spen~e.~ With care, the accuracy of such analysis can be comparable with that obtained in ordinary macro-analysis, but it is difficult to deal with samples smaller than about 0.1 ml.The feasibility of analysing minute quantities of gas by a relatively simple procedure at low pressures was first demonstrated as early as 1912,by LangmuirJ4 who found such a technique of great value in his work on gas reactions at solid surfaces. In this type of analysis the gases are usually confined in a fixed volume, and the pressure changes resulting from a series of physical or chemical processes are followed by means of a McLeod or other suitable gauge.The sensitivity possible is very much greater than that of the orthodox chemical methods, and it is estimated that 0.001 ml. of gas may be analysed in this way. The great sensitivity is due to the fact that there are high-vacuum gauges available for measuring pressures down to mm. with considerable accuracy, so that a pressure difference corresponding, for example, to g. of hydrogen can be measured with some precision. The number of papers published on applications of the low-pressure method is not large. R ~ d e r , ~ in 1918, described an apparatus for dealing with gases evolved from heated metals, and outlined an analytical procedure suitable for the analysis of mixtures containing water vapour, carbon monoxide and dioxide, hydrogen , nitrogen and oxygen.More elaborate apparatus for similar work on gas - metal systems was developed by Norton and Marshall6 and by Smithells and Ransley.’ A simplified type of equipment, such as one described by Chipman and Fontana,* has been designed for analysing the gases evolved in the vacuum fusion method now widely used for the determination of the total oxygen contents of steels. In a more recent paper, Prescott and Morrisong give details of an apparatus and technique for the rapid analysis of samples with a total volume of 1 to 25 x 10-3ml. of gas, with a probable error for each component of about 5 per cent. of the total sample. The apparatus is a refined version of one described previously1° and has been applied by them to problems arising from a study of the behaviour of thermionic cathodes.This procedure can be used for mixtures consisting of water, carbon dioxide, hydrogen, carbon monoxide and oxygen or alternatively methane; and as far as we know, it is the only one published that gives a specific method for the determination of methane. An important contribution to low-pressure technique was made in 1921 by Campbel1,ll who introduced a method for the identification of gases and vapours by means of their characteristic vapour-pressure curves, which can be determined quite simply with the aid of the .Pirani gauge. This is an extremely useful method of analysing mixtures of gases that can be condensed out by liquid oxygen, and some applications have been described by Ransley12 and Wooten; l3 it has also been used successfully for the analysis of complex hydrocarbon mixtures, by Sebastian and Howard.l* Micro gas analysis at low pressures has also been employed for investigating the gases evolved by heated glasses, and contained in “seeds” in glass, and an account of the special technique required for this kind of work will be found in a paper by Shadduck and Van Zee,15 which should also be consulted for earlier references in this field.The gases evolved from glass or * Contribution from The Research Laboratories of The British Aluminium Co., Ltd., Chalfont Park, Gerrard’s Cross, Bucks.Dec., 19471 AT LOW PRESSURES 505 usually contain a high proportion of condensable gases such as carbon dioxide and sulphur dioxide, and the Campbell method of low-temperature distillation can therefore be used with considerable advantage in such investigations. The apparatus described in the present paper has been developed primarily for work on gases in metals, and is used for the measurement and analysis of the gases evolved from heated aluminium.The gas-content of aluminium has an important influence on the properties of both cast and wrought products, and we have recently been investigating the extraction of gases from the heated metal in both solid and liquid states. The gas evolved is a mixture of hydrogen, nitrogen, carbon monoxide, carbon dioxide and methane, and although the bulk of the gas is normally hydrogen it has been necessary to develop an analytical technique to deal with mixtures of these gases.Oxygen is not usually present, but must be looked for. A certain amount of water vapour is also collected, which is desorbed from the oxide skin present on the metal; it cannot be measured accurately in the present apparatus without fairly elaborate precautions and its determination will not be discussed here. The apparatus is similar to one previously described,l2 but incorporates certain important modifications which ensure greater accuracy and, in particular, enable methane to be determined. This was not possible with the earlier apparatus. PRINCIPLES OF THE ANALYTICAL METHOD General Consideratio?z-There is a tendency, in many of the methods that have been proposed for micro-gas analysis at low pressures, to make use ,of certain chemical reagents in a fairly orthodox manner.For example, in the method described by Prescott and Morrison copper oxide is used for the oxidation of hydrogen and carbon monoxide, magnesium per- chlorate for the absorption of water vapour, and soda-lime to remove carbon dioxide. These reagents are used in the form of small plugs containing only a fraction of a gram of powder through which the sample gases are circulated by means of automatic Toepler or miniature diffusion pumps. It is necessary, of course, to bake out each of the reagent tubes before beginning an analysis. We have not used this type of procedure, and have endeavoured instead to make the fullest possible use of physical methods of separation, so that chemical reaction is limited to simple combustion, if possible at a neutral surface, with added oxygen.The use of powdered reagents in a vacuum system we consider undesirable for the following reasons. (1) The relatively large specific surface of the reagents may result in general absorption of the constituents of the sample. (2) The necessity for circulation of the gases by Toepler pumps complicates the apparatus and increases the possibility of contamination of the sample. (3) The absorption by reagents, such as soda lime, is irreversible for practical purposes, so that re-measurement, which is so convenient a feature of the physical methods, is not possible. The most desirable procedure would be one which gave complete separation of the sample into the constituent gases, so that they could then be measured individually. This ideal can nearly be achieved, since condensable gases and hydrogen are separated by the procedure to be described, and nitrogen is left as a residue; the oxidation products from the combustion of carbon monoxide and methane are also collected separately, and can be measured subse- quently.Some of the principles involved in the procedure for individual gases are given below :- Condensable gases-Condensable gases, i.e., those that have a vapour pressure of less than lW5 mm. at the temperature of liquid oxygen (- 183" C . ) , can in many instances be deter- mined very rapidly by immersing the tip of a small side-tube on the system in a suitable refrigerant and noting the fall in pressure. For example, freezing acetone (- 95" C.) will condense out water but not carbon dioxide, and liquid oxygen will condense out carbon dioxide but not the permanent gases.Since water vapour cannot be measured accurately because of strong adsorption effects it is usually convenient to keep acetone on throughout the analysis and substitute liquid oxygen whenever carbon dioxide is to be measured or removed. These are the only two condensable gases present in the mixtures we are considering here; if others are thought to be present, it may be necessary to resort to the method of low tempera- ture distillation, which can be readily carried out without any modification to the apparatus. The procedure has been described elsewhere.12506 RANSLEY: A PROCEDURE FOR GAS ANALYSIS [vol. 72 Hydrogen-The specific and rapid diffusion of hydrogen through palladium provides a very simple method for the determination of hydrogen, which is to be preferred to the more general procedure of oxidation, because of the avidity with which water vapour is adsorbed by glass.The possibility, however, of interaction at the palladium surface, in addition to the outward diffusion of hydrogen, must not be ignored. Two reactions are known to occur at ordinary pressures, and temperatures above 300" C.16 2 co + c + CO2 .. .. - . (2) CO + 3H2 + CH, + H,O .. These reactions do not appear to take place to any appreciable extent at low pressures (k, less than 0.1 mm.). Since liquid oxygen is usually kept on one of the freezing traps when the palladium tube is used, both reactions would be encouraged to go to the right, but tests have-shown that both carbon monoxide and methane are in fact completely stable in presence of hydrogen, even when temperatures of 700" to $00" C.are used. In the earlier form of the apparatus only one palladium tube was used, and diffusion of the hydrogen into the air was effected in about five minutes by heating to approximately 700" C. Test analyses with known mixtures prepared from coal gas have indicated that some breakdown of carbon monoxide in accordance with equation (1) can take place when unsaturated hydrocarbons are also present, presumably because the reaction is promoted by carbon deposited when the hydrocarbons are cracked. Ethylene, which is not completely condensed out by liquid oxygen, is a possible source of trouble in this respect. To guard against the possibility of error from this cause, a palladium filament can be added to the system, and the stability of the sample tested by running this for a few seconds at about 700" C.prior to switching on the palladium tube. This test will also indicate whether oxygen is present in the gas or not. A palladium tube can be used with complete confidence, if in addition to measuring the drop in pressure in the system a direct measurement is made subsequently of the hydrogen separated by diffusion. This can be done quite readily, and the new apparatus has been modified to make it possible. An interesting point that may be mentioned here is that when free oxygen is present in the sample, hydrogen can be admitted to the system by momentarily heating the external palladium tube with a reducing gas flame, without any appreciable reaction taking place at the hot surface of the tube.Advantage can be taken of this fact when it is desired to introduce hydrogen for the purpose of determining oxygen by reaction at the platinum filament. Carbon Monoxide and Methane-The residual gases after removal of water vapour, carbon dioxide and hydrogen are carbon monoxide, methane and nitrogen. All the methods available for the separation of carbon monoxide and methane at low pressures involve differential oxidation. The procedure for carbon monoxide and methane together described by Prescott and Morrison is the only one that has been published so far. In their method the carbon monoxide is oxidised by two or three passages over powdered copper oxide heated to 300" C., and the carbon dioxide formed absorbed by soda-lime.The residual gas is then mixed with 2Q to 3 times its volume of oxygen and then compressed by a Toepler pump into a small explosion pipette and sparked at a pressure of about 17 cm. The oxidation products are determined by absorption in magnesium perchlorate and soda-lime. Since we wished to avoid this type of procedure we have investigated the conditions necessary for the determination of carbon monoxide and methane by simple combustion with oxygen at a platinum filament. If methane is known to be absent the procedure is quite straightforward. The reaction of carbon monoxide with a slight excess of oxygen is very rapid, e.g., with the filament at 700" C.,* and with liquid oxygen on one of the freezing traps to condense out the carbon dioxide formed, the oxidation is complete in a fdw seconds.The oxidation of methane is very slow at 700" C. and is incomplete after one hour. If the filament temperature is reduced to about 500" C., the oxidation of carbon monoxide is still so rapid that reaction is complete within two minutes, whereas the methane reacts only to a negligible extent in this time. This procedure is therefore suitable for the first step in this stage of the analysis, i.e., the separation of the carbon monoxide. * The filament temperatures cited are true temperatures obtained by applying the appropriate brightness correction to temperatures observed with a disappearing-filament pyrome ter.Dec., 19471 AT LOW PRESSURES 607 In order to obtain a sufficiently rapid oxidation of methane, it is necessary to raise the filament to somewhere in the neighbourhood of 1000" to 1200" C., but at this temperature a complication arises in the form of a reaction between the platinum and oxygen.This has been remarked upon by Prescott and Morrison, who state that "contrary to expectation,(the filament) is readily attacked by oxygen above 700" C., to an extent sufficient to limit its use to the combustion of oxygen with an excess of hydrogen or carbon monoxide." We have not been able to find any other references in the literature to this behaviour of platinum. We have, however, carried out a certain number of tests which indicate that :- (1) When a carefully decarburised platinum filament is heated to temperatures around 1000" to 1200" C.in a'low pressure of oxygen there is a rapid and complete dis- appearance of the gas. For example, at 1150" c. 7-8 p. of oxygen in the analytical system (volume 540 ml.) cleaned up completely in 10 minutes. The rate of reaction is quite negligible a t 700" C., but increases rapidly with rising temperature. (2) The normal thermal evaporation of platinum atoms from the filament is much too small t o account for the clean-up of oxygen by a gettering action. The bulb con- taining the filament does, however, show a slight blackening after several runs. (3) The oxygen can be recovered slowly by subsequently baking out the bulb at 350" C. (4) The cleaned-up oxygen is quantitatively reduced by introducing hydrogen into the system and reheating the filament.These results are consistent with the theory that the disappearance is due to formation of a volatile platinum oxide which deposits on the walls of the bulb, where it is fairly easily decomposed or reduced. The precise mechanism has not, however, been elucidated. If a sample of gas containing only methane and nitrogen is mixed with rather more than double its volume of oxygen and allowed to react at a platinum filament heated to about 1150" C., the pressure drops rapidly, until after five minutes it has reached a constant final value. The methane is completely oxidised, as may be checked by measurement of the carbon dioxide formed, which can be quantitatively recovered from a side tube in which it has been condensed out during the reaction. The excess of oxygen is cleaned up by the filament, and the residual gas is thus nitrogen.This method (oxidation at a platinum filament first at 500" then at ll5OoC.) can be used quite successfully for the analysis of mixtures containing carbon monoxide, methane and nitrogen. Although sufficiently accurate results are obtained in this way and no cumulative effects can be detected after repeated tests, the rather obscure nature of the oxygen clean-up makes the procedure possibly undesirable. An alternative method for the determination of methane was therefore sought. Some preliminary tests indicated that by using an alumina- coated platinum filament, prepared in a manner which will be described later, a high rate of oxidation of methane could be achieved, whilst the protective layer on the platinum reduced the disappearance of oxygen to negligible proportions.With this filament at 1150" C., oxidation is complete in 3 to 4 minutes, and the amount of oxygen used in the reaction can be determined accurately if desired, by measuring the residual oxygen in the usual way. APPARATUS A diagram of the apparatus that we have constructed in accordance with the principles discussed in the preceding section is given in Fig. 1. It contains a two-stage mercury diffusion pump (pump A) which collects the sample and delivers it into an analytical system. The latter can be evacuated by a second, three-stage pump (pump B) which is located belowthe table level and is backed by a general laboratory vacuum line at a pressure of 2 to 5 mm. of mercury.High vacuum technique is followed throughout, and it should be emphasised that successful results can only be obtained when the whole system is so constructed that a find pressure of about mm. can be rapidly attained, and then held when the system is isolated from the pump. Except for certain special applications, greased taps are eliminated in favour of mercury cut-offs; four, marked a to d in Fig. 1, are used in the present apparatus. All measurements are made at constant volume, and the pressure changes resulting from a series of operations are read on both a Pirani gauge (P) and a McLeod gauge (M). The McLeod gauge and the cut-offs are constructed so that changes in atmospheric pressure do not appreciably alter the mercury levels in the system. It will be noticed that the volume of the system in which the sample is first collected is dependent upon the action of pump A.With certain types of jet, the volume defined by a pump in this way can vary quite markedly508 RANSLEY: A PROCEDURE FOR GAS ANALYSIS [Vol. 72 with the pressure of gas collected in the system;” the second stage of pump A, however, consists of a short “parallel” jet which tests indicate to be relatively insensitive to backing pressure, so that the volume of the system is constant over the range of pressures normally used. We find that a total sample pressure of 1 to 30 microns, in an analytical system of 300 to ciao ml., is usually suitable for an analysis. It has been demonstrated that no reaction occurs between the gases present in a normal mixture, during transmission through the collection pump.I 1 SAMPLE TABLE: LEVEL Fig. 1. Diagram I I C - apparatus. The final pressure measurements at each stage of the analysis are taken on the McLeod gauge, which is compensated for atmospheric variations and requires no adjustment. The single gauge on the present apparatus reads up to about 0.07 mm. of mercury, but for certain experiments it is convenient to use a double gauge with an additional “coarse” bulb capable of reading up to 1 or 2 mm. Such an arrangement is very useful when carrying out determina- tions of minor constituents. The Pirani gauge is extremely useful for taking continuous readings, and is normally operated in addition to the McLeod. It consists of two identical bulbs, each containing two coiled tungsten filaments of as nearly as possible the same resistance.One bulb is highly evacuated and sealed off, and the other is connected to the system. The method of using this gauge is shown in Fig. 2 ; the filaments are arranged as a bridge circuit, and a small variable resistance enables any zero adjustment to be made and the bridge balanced. A constant voltage is maintained across the bridge, and the out-of-balance voltage resulting from the pressure of gas in bulb B is measured on a high resistance (2000ohm) millivoltmeter. This is a very convenient way of operating the gauge, since the continual adjustment required in the more usual null method is avoided. Typical calibration curvesDec., 19471 AT LOW PRESSURES 509 for hydrogen and oxygen are given in Fig.3, and show that the response is linear over the range of pressures normally used. The response is also additive and, since the common gases give calibration curves very close to that of oxygen, the gauge readings can provide useful information during the analysis, particularly in operations involving addition or sub- traction of hydrogen. Also condensable gases, such as water, sulphur dioxide and ammonia, which cannot be measured on a McLeod gauge, can be measured by means of the Pirani gauge. 1 1 I I 1 1 I I I f I. I I f I I Pirani Gauge. Electrical arrangement for deflection method. Fig. 2. Two palladium tubes (Pd 1 and Pd 2 in Fig. 1) are incorporated in the present apparatus. They are both of 1 mm. inside diameter and 0.15 mm. wall thickness, with an over-all length of 50 mm. One end is closed by welding and the other is soldered with gold into a platinum thimble, which is in turn joined to the glass of the system.The tube Pd 1 can be used for admission of hydrogen to, or its extraction from, the analytical system. Hydrogen is admitted by flicking the tube with a soft blowpipe flame, or diffused out by heating it with a miniature electric furnace. Fig. 3. Pd2 is arranged so that hydrogen extracted through this tube can be collected and measured separately. I t is therefore sealed internally into the analytical line and protrudes into an extension of the line which is wound externally with nichrome wire and insulated with asbestos cement. This section of tubing is made of a special glass that will withstand 700" C.under vacuum. The temperature attained by the palladium tube is previously calibrated (under vacuum conditions) against the current passed through the furnace winding. It is normally operated at 450" C. and at this temperature the extraction of hydrogen is complete in 15 to 20 minutes. As will be seen from Fig. 1 the outside of Pd 2 is pumped continuously by a very small but fast single-stage mercury pump (pump C) ; this delivers any hydrogen510 RANSLEY: A PROCEDURE FOR GAS ANALYSIS [vol. 72 diffusing through the tube into the bulb B which is evacuated before starting an analysis and then isolated from the main system by means of cut-off d. The tube Ag in Fig. 1, is used to admit pure oxygen into the system. It is a fine silver tube 2 mm. in diameter, 0.2 mm.in wall-thickness and about 100 mm. long, closed a t one end and silver-soldered into a platinum thimble. A radiation fin is clamped on the lower end to prevent overheating of the thimble and the joint to the glass. By heating the end of the tube with a miniature electric furnace running at about 750" C. a controlled volume of oxygen can be allowed to diffuse in from the air. The three filaments used (Fl, F2 and F3) are housed in separate lead-glass bulbs of about 30 ml. capacity. The lead-in wires in each bulb are of 1-mm. diameter platinum. Fl is a 3cm. loop of very thin palladium strip, and F, a similar length of 0.1-mm. diameter platinum wire. F, is the platinum.filament coated with alumina. It is prepared by repeatedly dipping a short spiral (0-1-mm.wire coiled on a 0.5-mm. mandrel) into a dilute dispersion of a-alumina in Nicoloidine, with intermediate firing to about 1600" C. in a gas flame; in this way a dense and coherent layer is sintered on to the wire. The bulb containing this filament is off-set from the line of the system to localise any clean-up effects. The small glass side tubes x and y are used for freezing out condensable gases. Any gas condensed out in x can be isolated from the main system by raising cut-off c. The latter can also be used if necessary to isolate the silver tube during the admission of oxygen. PROCEDURE If the analytical system has been open to the atmosphere for any length of time it is advisable to flash the filaments and heat the palladium and silver tubes prior to starting an analysis.The platinum and palladium filaments are heated to 800°C., and the platinum- alumina filament to 1200°C. for 1 or 2 minutes in vacuum. The internal palladium tube should also be "flushed" by allowing some hydrogen to diffuse through it at the normal operating temperature. After this hydrogen has been pumped away, cut-off d is raised t o shut off the bulb B from the system. The sample is introduced via pump A, and the pressure in the analytical system, if greater than required, is reduced to 10 to 20p by manipulation of cut-offs a and b. The sample is finally confined by cut-off b. Pressure readings are then taken after each of the following steps- Apply freezing acetone and then liquid oxygen to side-tube x, and raise cut-off c. Run the palladium filament (FJ at 700" C.for a few seconds. If the sample is not stable, run the filament for as long as a pressure change occurs and then re-trace the the operations of step (1). Heat the internal palladium tube Pd 2 at 450" C. for 15 to 20 minutes. Introduce oxygen equivalent to rather more than half the total pressure, by heating the silver tube (with cut-off c raised during the diffusion). Heat the platinum filament (F,) a t a current giving an extrapolated temperature of 500" C., for two minutes, with liquid oxygen on y. Determine the carbon dioxide produced in step ( 5 ) by replacing liquid oxygen by freezing acetone. Determine the residual oxygen by admitting excess of hydrogen through Pd 1, re-heating the filament and finally heating Pd 1 with a miniature furnace at 700" C .Introduce further oxygen, equivalent to rather more than double the residual sample pressure. Run the platinum-alumina filament at 1150" C. for 3 to 4 minutes with liquid oxygen on y again. Determine the carbon dioxide produced in step (8). Determine the residual oxygen by the procedure in step (7). Pump away the residual gas (nitrogen) and re-determine the carbon dioxide produced in the oxidation steps, and originally present in the sample. Determine the hydrogen extracted originally, by lowering cut-off d, thus expanding the gas collected in bulb B into the analytical system. procedure is more complete than is usually necessary, and enables the carbon monoxide and methane contents to be cross-checked in three ways. For normal rapid analysis it is simpler to introduce initially sufficient oxygen to consume both gases, and then calculate their respective percentages from the fall in pressure when the two filaments are burned.Dec., 19471 AT LOW PRESSURES 61 1 ANALYTICAL RESULTS The accuracy of the method has been tested for the single pure gases, and for binary synthetic mixtures prepared in the analytical system. For more complex mixtures we have followed the practice of carrying out low-pressure analysis of samples taken simultaneously with large samples suitable for orthodox chemical analysis (e.g., Orsat).The normal accuracy is such that constituents are determined with Bn approximate inaximum error of 2 per cent. on the basis of the total sample. This was illustrated in the earlier paper12 for mixtures containing carbon dioxide, carbon monoxide, hydrogen and nitrogen. To test the accuracy of the procedure for mixtures containing methane, a sample of coal gas, freed from carbon dioxide and unsaturated hydrocarbons, was collected in a bulb suitably equipped for introducing very small doses of gas into the analytical system.Another sample, taken at the same time, was analysed on an Orsat apparatus. The results obtained by macro- analysis and low-pressure analysis are given in Table I. TABLE I ANALYSIS OF TREATED COAL GAS SAMPLE Volume of system 540 ml. , Method Volume taken, ml. H, co CH4 Nz Composition per cent. 7- L I Orsat . . . . .. 100 44.3 13.9 21.3 Rest Low pressure . . . . 0-0050 44.0 14.3 22.6 (a) ,, 0.0091 46.9 15-2 19.7 (a) ,, 0.0118 45.0 12.0 23.1 (a) ,, 0.0122 44.8 12.6 22.4 ( b ) ,, 0.0113 46.0 12.1 21.7 (b) ,, (a) Using bare platinum filament.(b) Using platinum - alumina filament. The accuracy illustrated is ample for work on gas extraction from metals, and is, in fact, quite adequate for most micro-analytical purposes. MINOR CONSTITUENTS In certain circumstances a high degree of accuracy can be obtained in the determination of minor constituents by low-pressure methods; this is specially so when a large sample (e.g., about 1 ml. or so) can be taken initially to give in the analytical system a pressure of about 1 mm. which is measured on a “coarse” McLeod gauge. If the constituent can now be extracted or retained either in its original state or after oxidation or reduction, while the main gases are pumped away, it may then be measured very accurately on the fine McLeod gauge.We have used this type of procedure to measure the carbon dioxide and carbon monoxide contents of samples of au taken near a large gas-fired furnace. In this instance the carbon dioxide is measured very simply by freezing it out in one of the side tubes, pumping away the permanent gases, and then measuring the increase in pressure when freezing acetone is substi- tuted for the liquid oxygen. For the determination of carbon monoxide a similar sample is taken and the carbon dioxide frozen out and isolated in a side-tube by means of a cut-off ; the carbon monoxide is then oxidised by running a platinum filament for a few minutes, and the carbon dioxide produced is measured in the same way as before.Prolonged pumping of the condensate must be avoided, as the vapour pressure of carbon dioxide at - 183” C. is not sufficiently low to be ignored. The low-pressure method for carbon determinations is based on this type of manipulation, and has a much greater sensitivity than the normal chemical methods. For example, an accuracy within f- 10 per cent. can be obtained on samples containing only 0.001 per cent. of carbon .18 When the minor constituent to be measured is hydrogen, it is very conveniently extracted by means of the internal palladium tube, and then measured after the other gases have been pumped away. Table I1 gives typical results obtained on some mixtures of hydrogen with inert gas which were analysed in this way. A brief review is given of the development of micro-gas analysis at low pressures, and a new procedure is described for the analysis of mixtures containing carbon dioxide, carbon512 RANSLEY: A PROCEDURE FOR GAS ANALYSIS Pol.72 TABLE I1 ANALYSIS OF HYDROGEN - INERT GAS MIXTURES Sample Percentage of hydrogen a b C 1.00 1-02 1.00 3.30 3-25 3.30 4.16 4.20 4-05 4.22 SUMMARY monoxide, hydrogen, methane and nitrogen. The apparatus is particularly suitable for the collection and analysis of the gases evolved from heated metals, and similar applications. When the volume of the sample is of the order of 0.005 ml., the accuracy of analysis is such that constituents are determined to within f 2 per cent. of the total sample. REFERENCES 1. Blacet, F. E., and Leighton, P.A., Ind. Eng.Chem. Anal. Ed., 1931, 3, 266; 1933, 5, 272. Blacet, F. E., Leighton, P. A., and MacDonald, G. D., Ibid., 1934, 6, 334. Blacet, F. E., and Volman, D. V., Ibid., 1937, 9, 44. 2. Sutton, T. C., Rev. Sci. Instr., 1938, 15, 133. 3. Spence, R., J . Chem. SOC., 1940, 1300. 4. Langmuir, I., see e.g., Ind. Eng. Chem., 1915, 7 , 348. 5. Ryder, H. M., J . Amer. Chem. Soc., 1918, 40, 1656. 6. Norton, F. J., and Marshall, A. L., Amer. Inst. Min. Met. Eng., 1944, 156, 351. 7. Smithells, C. J., and Ransley, C. E., Proc. Roy. SOC., A, 1935, 155, 175. 8. Chipman, J., and Fontana, M. G., Ind. Eng. Chem., Anal. Ed., 1935, 7 , 391. 9. Prescott, C. H., and Morrison, J., Ibid., 1939, 11, (4), 230. 10. Prescott, C. H., J . Amer. Chem. Soc.. 1928, 50, 3237. 11. Campbell, N. R., Proc.Phys. SOC., 1921, 33, 287. 12. Ransley, C. E., G.E.C. Journal, 1940, 11, (2), 1. 13. Wooten, L. A., Amer. SOC. Test. Materials, Bull., 1941, No. 108, 39. 14. Sebastian, J. J. S., and Howard, H. C., Ind. Eng. Chem., Anal. Ed., 1934, 6 , 172. 15. Shadduck, H. A., and Van Zee, A., J . Amer. Cer. SOC., 1942, 25, 69. 16. Fleiger, A. G., Ind. Eng. Chem., Anal. Ed., 1938, 10, 544. 17. Naughton, J. J., and IJhlig, H. H., Ibid., 1943, 15, 750. 18. Wooten, L. A., and Guldner, W. G., Ibid., 1942, 14, 835. DISCUSSION Mr. A. F. WILLIAMS asked whether a mixture of condensable gases could be separated into the con- stituent gases. How would a mixture of carbon dioxide, sulphur dioxide and hydrogen sulphide be separated. Dr. RANSLEY, in reply, said that if the condensation temperatures of the constituent gases of a mixture are sufficiently widely separated, so that on warming the condensate tHe first gas, attains 'its full partial pressure before the temperature rises to the condensation temperature of the second, and so on, the pressure- temperature curve of the mixture will show a distinct plateau between one gas and the next.When this is so, separation of the gases can be achieved fairly readily. A cut-off can be used to isolate the small side tube in which the gases are condensed, and by raising the mercury in this when the condensate has reached a suitable temperature, the most volatile constituent, which has completely evaporated to fill the main system, can be separated from the remaining gases still retained as solids in the side tube. This procedure was illustrated by reference to slides showing typical vapour pressure - temperature curves of CO, -SO, and CO, -NH, mixtures. . The method will not work if the gases form solid solutions when frozen out. In some instances a freezing agent can be selected to effect a direct separation of two gases ; for example freezing acetone (- 95O C.) is used to differentiate between water vapour and carbon dioxide, the difference between the condensation temperatures of which is about 90' C . ; but where the difference is not so great it may be difficult to find the precise freezing agent for separation. Regarding the separation of hydrogen sulphide, carbon dioxide and sulphur dioxide, the last two can be separated successfully, but the vapour pressure - temperature curve of hydrogen sulphide is very similar to that of carbon dioxide, and low-temperature distillation cannot be used to separate them. Wooten (A.S.T.M. Bulletin, 1941, No. 108, 39) describes a test to distinguish between these two gases, which involves passing the gas over silver oxide a t 100" C. ; hydrogen sulphide reacts to form water vapour and silver sulphide, but carbon dioxide does not react at this temperature. Dr. P. L. ROBINSON queried whether a true separation of two gases could be effected in this way. When dealing with a mixture of carbon dioxide and water, for example, would not the carbon dioxide be adsorbed on the separated ice ?Dec., 19471 AT LOW PRESSURES 513 Dr. RANSLEY replied that the effect suggested by Dr. Robinson was not sufficiently large to interfere with a practical separation. The side tube in which the gases are condensed has a very small area compared with the remainder of the wall of the analytical system. Mr. F. POPPER enquirecl if the micro-fractionation technique had been used for the analysis of hydro- carbon mixtures. Dr. RANSLEY said that the method had been applied successfully in this field, e.g., Ify Sebastian and Howard (Ind. Eng. Chem., Anal. E d . , 1934, 6, 172). Mr. H. N. WILSON asked whether water vapour adsorbed in the oxide film on aluminium would react with the metal on heating and cause fictitiously high Galues for dissolved hydrogen. Dr. RANSLEY’S reply was that there was a real danger that misleading results might be obtained for the true hydrogen content of aluminium if this important factor was not taken into account. The very high values obtained by earlier workers were due to the fact that thin sheet with a large surface area was fre- quently used, and the surface was not usually prepared in any way. The evolution of some surface gas, originating from this reaction with adsorbed water, is inevitable, but by the adoption of a standard method of preparing samples an appropriate and consistent correction could be made for this spurious gas and the true hydrogen content calculated. He used cylindrical specimens of approximately 1 cm. diameter and 4 or 5 cm. long, which are turned dry on a lathe, washed in benzene, and introduced into the vacuum system as rapidly as possible. With specimens prepared in this way, the correction on a normal gas content is not more than about 10 per cent.

ISSN:0003-2654    

DOI:10.1039/AN9477200504

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-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 Dec., 19471 AT LOW PRESSURES 513 The Analysis of Hydrocarbon Gases by Low Temperature Distillation BY J. H. D. HOOPER INTRODUCTION THE chemist concerned with the quantitative analysis of gases likely to be encountered in the petroleum industry is faced with a highly specialised problem which is moreover complicated by the wide diversity of gaseous mixtures that he may be called upon to examine.Such gases will vary from simple binary systems, for example mixtures of isobutane and %-butane, to complex paraffin - olefin mixtures containing perhaps a dozen or even twenty constituents Five typical gas mixtures are shown in Table I. TABLE I COMPOSITION OF TYPICAL HYDROCARBON GASES Expressed in molecular percentages Refinery Gases. Natural Gases. 7- * Constituent A B C D E Hydrogen . . 8-6 Methane .. . . . 13.6 Ethane . . . . 8.3 Propylene . . . . 23-6 Isobutane . . . . 7-8 Isobutene . . . . 9.7 n-Butenes . . . . 15.7 n-Butane . . . . 3.2 Pentanes . . . . Trace Carbon Dioxide . . - Oxygen . . .. Nitrogen . . . . Ethylene .. . . 4.3 Propane . . . . 5.3 - - - 2-0 70-7 - 26.8 0.5 - 82.3 5.3 1.6 0-2 - - - - 0.4 0-4 Nil Nil 9.8 - 42.2 12.7 6.4 0.2 - - - 0-6 0.3 0.2 0.4 38-1 For simple gas mixtures, it is often possible to effect an analysis by straightforward chemical means, for example, by absorption of specific components such as olefinic gases in suitable liquid reagents ; alternatively, combustible gases may be oxidised by passage over heated copper oxide or a platinum spiral, or by explosion after admixture with oxygen. Analytical techniques employing such procedures are well established and form the basis of the well-known Orsat, Bone and Wheeler, G.L.C. (Gooderham) and Haldane types of apparatus, and many others. Certain gas mixtures lend themselves to analysis by direct physical methods, e.g., by by measurement of dew pressure, vapour pressure or thermal conductivity.Recently,514 HOOPER: THE ANALYSIS OF HYDROCARBON GASES BY [Vol. 72 spectroscopic methods involving the measurement of absorption of infra-red or ultra-violet radiation have proved valuable tools in the hands of the gas analyst. In America, much progress has also been made in the development of the Mass Spectrograph for the analysis of gases. Nevertheless, with the possible exception of the Mass Spectrograph, the methods indicated here cannot give a complete analysis of a complex multi-component hydrocarbon gas mixture sGch as sample A in Table I. They can, however, be employed with advantage when such a mixture has been split up into a number of simple fractions, each containing relatively few constituents.If the boiling points of the lighter hydrocarbons are considered, (Table 11) it will be seen that the limited number of possible hydrocarbons, containing between one and five carbon atoms per molecule, are spaced over a boiling-point range of nearly 200 degrees Centigrade : this fact therefore, provides an obvious basis for the physical and analytical separation of the hydrocarbon gases. TABLE I1 BOILING POINTS OF SOME GASEOUS HYDROCARBONS Hydrocarbon Methane .. Ethylene . . Ethane .. Propylene . . Propane . . Isobutane . . Isobutene . . Butene-1 . . Butadiene . . *-Butane .. Butene-2 (Trans.) Butene-2 (Cis.) Isopentane . . n-Pentane .. Boiling Point, .. .. .. - 161.4 .. .. .. - 103.9 .. .. .. - 88.9 .. .. .. - 47.7 .... .. - 42.2 .. .. .. - 11.8 .. .. .. - 6.8 .. .. .. - 6.3 .. .. .. - 4.5 .. .. .. - 0.5 .. .. .. + 0.9 .. .. .. + 3-65 .. .. .. + 27-95 .. .. .. + 35.95 O C . During the past 15 to 20 years much work has been carried out along these lines and numerous pieces of equipment for the fractional distillation of condensed gases have been described in the literature. The best known apparatus is undoubtedly that due to Podbielniak,ls2v8 and several versions of his apparatus are available commercially. GENERAL DESCRIPTION OF APPARATUS Basically, an apparatus for the low-temperature distillation of gases comprises the following main features. (a) A distilling bulb, generally of capacity from 10 to 100 ml., and fitted with an electric heater. ( b ) A glass column of small bore (3 to 5 mm.), containing a wire packing. (c) A sleeve-type vacuum jacket enclosing the column and either internally silvered or provided with an internal metal reflector.( d ) A condenser at the column head for providing liquid reflux, liquid air or preferably liquid nitrogen being used as a refrigerant. (e) A stopcock manifold, for the transfer of gaseous distillate to the receivers, to which are connected manometers for measurement of column and receiver pressures. (f) Distillate receivers. Two forms are commonly used- (i) Large graduated burettes in which the distillate is collected (and directly measured) by displacement of a suitable confining agent such as mercury or brine. (ii) Vacuum bottles, normally of capacity between 4 and 15 litres, maintained in a water-bath at constant temperature.This type of receiver, in which the quantity of distillate collected is assessed by measurement of rise in pressure, is employed in the apparatus described in this paper. (g) Miscellaneous items such as a scrubbing train to remove carbon dioxide and water vapour from gases prior to entry into the distilling bulb, a vacuum pump and a Topler pump to enable gas samples to be withdrawn from the receivers. A thermo- couple is provided for measurement of column-head temperature. A simplified diagram of an apparatus incorporating these features is shown in Fig. 1.Dec., 19471 LOW TEMPERATURE DISTILLATION 515 OUTLINE OF DISTILLATION PROCEDURE Although many details of distillation proced~re~1~1~ will vary according to the type of gas sample under examination, a general account of the method may be given briefly, as follows.The apparatus is first evacuated and tested for leaks. If these are absent, the column head and distilling bulb are cooled by means of liquid nitrogen, the degree of cooling depending on the nature and boiling-point range of the sample. The hydrocarbon gas sample, free from moisture and carbon dioxide, is then cautiously admitted to the cooled distilling bulb, where it condenses. If gases such as air or hydrogen are present, however, these will not be condensed, and the pressure in the system, as indicated by the column manometer, will rise rapidly. Such gases are therefore bled off into one of the receivers, while the remainder of the sample is being liquefied.The quantity of gas charged to the apparatus will depend on the composition of the sample. An average figure would be 2 to 3 litres; if, however, the proportion of “unconden- sable” gases is high, as in example B, Table I, four or five times this amount of gas would have to be passed into the apparatus to allow an * adequate fiquid charge to- accumulate in the distilling bulb. It is in fact, normally desirable to collect at least 10 ml. of liquid in this bulb. When sufficient gas has been condensed, the sample inlet tap is closed and the receiver mani- fold is isolated from the column. Excess of refrigerant is removed from the Dewar vessel enclosing the distilling bulb, and current to the heater windings is switched on. The pressure in the column tends to rise as the charge becomes warm, and is restored to atmospheric by taking off uncondensable gases into the receiver, or by cooling the column head if liquid reflux has appeared on the packing.When the column is in equilibrium under conditions of total reflux and the temperature indicator is recording the boiling point of the lightest hydrocarbon present in the mixture, take-off of distillate is begun. The overhead temperature and the receiver pressure are recorded at frequent intervals to allow an accurate distillation curve to be plotted. The rate of removal of distillate will again depend on the nature of the sample; where the distillation curve shows a long “Dlateau.” due to the mesence of a large FINE 6ORE METAL LEADS TAKE-OFF LINE Fig. 1. General layout of simple low- temperature distillation apparatus.I v proportion of a single component, relatively high take-off rates, say, from 20 to 50ml. per minute, may safely be employed. At “breaks” between two components, and particularly where these have boiling points that are not widely separated, it is necessary, for good fractionation, to operate at a high reflux ratio and hence a very low take-off rate, possibly only 2 to 5 ml. or less, per minute. For hydrocarbons in the methane - butane boiling-point range, it is usual to maintain the column at atmospheric pressure, but for higher-boiling materials it is necessary to reduce the pressure in the column to a value sufficiently low to ensure that liquid hydrocarbon will not tend to condense in the manifold. Thus a convenient distillation pressure for pentanes is 300 mm.and for hexanes 100 mm. of mercury (absolute). In addition, pressure in the distillate receiver must not be allowed to rise above certain limiting values (approx. 300 mm. Hg. for C, to Cp hydrocarbons, and correspondingly lower for pentanes and hexanes), otherwise errors due to the deviations of the various hydrocarbons from the ideal gas laws become significant. If such errors can be neglected, the calculation of results is greatly simplified, as it can be assumed that the rise in receiver pressure for each fraction is proportional to the volume of that fraction present in the total gas sample. The latter quantity is deduced from the total recorded pressure rise, after due allowance has been made for difference in size516 HOOPER: THE ANALYSIS OF HYDROCARBOX GASES BY [Vol.72 between the receivers used. It is then a simple matter to calculate the volume percentage of each fraction present. If the fractions contain constituents that cannot be quantitatively estimated from the distillation curve, for example, gases such as nitrogen, hydrogen, or unsaturated compounds, it will be necessary to withdraw samples of these fractions from their individual receivers for further analysis by absorption, combustion or spectroscopic methods. It will be seen from the typical distillation curve shown in Fig. 2, that it is convenient to divide the gas into groups of hydrocarbon fractions containing 1, 2, 3, 4 and 5 carbon atoms per molecule respectively. If we consider the gas denoted by A in Table I, the fractions taken will contain the following constituents :- Fraction 1-Hydrogen, methane (and uncondensibles, if present).Fraction 2-Ethylene, ethane. Fraction 3-Propylene, propane. Fraction 4-1~0 bu t ene , 92- but enes , isobu t ane, 31 -butane. Fraction &Pentenes, pent axles. Analysis of these fractions in subsidiary apparatus thus allows the ultimate composition of the gas sample to be determined. - 20- 0 - -20- -40 - V UJ a -60- 5 fi -80- 5 I- -too- -120 - -140 - Fig. 2. Example of low-temperature distillation. TYPICAL LOW-TEMPERATURE DISTILLING COLUMN ASSEMBLIES Most of the earlier low-temperature distillation columns employed a relatiyely simple form of packing, often just a single wire helix, because designs of this nature allowed reasonable fractionating power without causing excessive liquid hold-up.In view of the small charge employed, this latter factor is, of course, a matter of some importance. Details of two typical columns are given in Table 111. Numerous types of this form of packing have been suggested from time to time ; packings have been constructed from wire of all gauges and from ribbon and have been wound in a variety of pitches. Double helices have been used, and the addition of a straight wire former down the centre of the helix has also been recommended, As an example of the latter, a design by McMillan' may be described. This comprised a 6-turn-per-inch 15-gauge brassDec., 19471 LOW TEMPERATURE DISTILLATION 517 spiral with a straight central insert of 23-gauge wire.As a matter of interest it might also perhaps be mentioned that the author once experimented with an empty tube, 4mm. in diameter, containing no packing at all, and achieved reasonable separation of a mixture of isobutane and n-butane. Columns of the general type so far described were satisfactory for the separation of many hydrocarbon mixtures, but were not adequate for the fractionation of compounds boiling much closer together than 8 degrees Centigrade. The majority were perhaps equivalent to about 7 to 15 theoretical plates. TABLE I11 SIMPLE LOW-TEMPERATURE DISTILLIXG COLUMNS Column (1) ( 4 Type of packing . . .. .. . . Single Helix. Single Helix. Internal diameter oi column, mm. . . 3.7 3.0 Gauge of wire (S.W.G.) . . .. .. 23 26 Turns per inch . . .... . . 6.7 3.8 Length of packing, cm. . . .. . _ 108-6 99 Two further packings will be mentioned briefly. First, the low-hold-up twisted gauze design described by Bower and Cooke,s when used in a column 5 mm. in internal diameter, has been found very suitable for this type of work; secondly, reference must be made to the Heli-Grid column introduced by P~dbielniak.~ This is of complex construction, and consists of a number of sector-like coils of fine wire, wound around each other and also round a straight central core. This column has, of course, a much higher hold-up than the simple helix, but this is offset by the greatly increased fractionating efficiency. It is, in fact, claimed by Podbielniak to be equivalent to 50 or more theoretical plates. It is certainly the author's experience that it can be used to separate such close-boiling components as isobutane (b.p.-11.8" C.) and isobutene (b.p. -6.8" C.), or methylethylethylene and n-pentane. Typical separations achieved with a Heli-Grid column are shown in Table IV. TABLE IV The figures are expressed in molecular percentages EXAMPLES OF SEPARATIONS OBTAINED WITH HELX-GRID " TYPE COLUMN Mixtures !.P. Componedt C. r I I1 I11 IV V V i 27.950 J blended - - 47.5 2.3 31-4 38-9 47.2 2-85 31.85 38.6 - - Iyafound - lsopentane . . .. - blethylethylethylene . . 31.1' . 1% % found 13.' 14.7 8.05 6'95 52.8 52.5 - blended 86.1 93.05 - 97.7 68.6 61.1 "/o found 86.3 91.95 - 97-15 68.15 61.4 u-Pentane . . .. 35.950{ Many improvements have also been made to the design of the vacuum jacket and the condenser unit.It should be appreciated that during a distillation the temperature of the reflux zone will slowly rise from - 190°C. to almost room temperature. It is therefore important to be able to maintain the condenser at any required constant temperature within this range. At the same time the heat capacity of the condenser must not be excessive, otherwise the delays incurred at cut-points, when the reflux zone temperature rises from the boiling point of one component to that of the next highest, will lead to unduly prolonged distillations. The simplest form of condenser is an annular metal tank, concentric with the upper portion of the column,l and supplied with refrigerant as necessary. A more elaborate design proposed by McMillan' consists of a layer of aluminium pellets which are packed round the column and can be cooled by liquid nitrogen trickling down from a small copper sprinkler tank.The earlier vacuum jackets were often subject to breakages owing to contraction of the inner wall on cooling to a temperature some 200 degrees below that of the outer wall. This difficulty can be overcome by the use of flexible glass bellows. Another modification has been the enlargement of the lower portion of the jacket to accommodate the whole of the distilling bulb in addition to the column. The Podbielniak Super-Cool type of jacket incorporates both these feature~.~,lO The complete jacketing of the distilling bulb eliminates the atmospheric weathering of the charge, often encountered with the older, external bulb, and permits more518 HOOPER: THE ANALYSIS OF HYDROCARBON GASES BY Fol.72 rigid control of heat input, and hence greater column stability. Another feature of this jacket is the inclusion of a free vapour space between the column and the inner walls of the jacket. This allows liquid nitrogen vapour from either the condenser or the distilling bulb compart- ment to gain access to the entire length of the column and is of great assistance during the preliminary process of cooling the apparatus, saving both time and refrigerant. Similarly, dry air, warmed if necessary, may be passed up over the column walls during the course of a distillation. This air current tends to overcome the heat capacity lag of the column and reflux cooling unit, particularly at “breaks,” and is also of much value towards the conclusion of a distillation when the bulb is empty and it is desired to distil off the residual liquid reflux adhering to the packing.AUTOMATIC DEVICES It will be clear that the carrying out of a low-temperature distillation requires con- siderable skill and attention on the part of the operator. Frequent readings of temperature and receiver pressure must be taken and recorded, heat input and gas take-off rates must be carefully adjusted to suit the fraction being distilled, and column pressure must be maintained at as constant a level as possible to allow a smooth distillation curve to be obtained. Careless operation, or perhaps even only a moment’s inattention, may lead to poor fractionation, “flooding” in the column COMPUE9SED or the “blowing” of manometers.Much thought therefore has been devoted to the use of automatic devices that will relieve the task of the operator. Perhaps the greatest boon in this respect has been the development of means for the automatic control of column pressure. The mode of operation of a typical system is indicated in Figure 3. It is con- trolled by contact wires dipping into the open limb of the column pressure manometer. A rising mercury level, due to increase in column pressure, completes an electrical circuit and by means of any convenient relay system, opens a solenoid valve on a com- pressed-air line connected to a liquid nitrogen storage vessel. Refrigerant is thus displaced from this vessel into the reflux cooling unit, and this causes the columii pressure to fall again.Similarly, if the column pressure should drop below a predetermined level, the falling mercury in the manometer breaks a circuit, and take-off of gas distillate is stopped by the closing of ‘a very simple shut-off valve, until the pressure builds up once more. This valve consists of a short length of flexible tubing resting between two metal jaws : the lower jaw is fixed, and on operation of the valve the upper jaw is forced downwards by the action of a solenoid, thus gripping the tubing tightly and preventing passage of gas. A further refinement is the incorporation of an additional contact wire in the manometer, which will cause a buzzer to sound and draw the operator’s attention to any unusually high pressure rise, caused, perhaps, by exhaustion of the liquid nitrogen in the storage vessel.Podbielniak has introduced an almost entirely automatic distillation a p p a r a t u ~ , ~ ’ ~ ~ which is even capable of plotting its own distillation curve. This is achieved by means of an ingenious device whereby a contact point at the base of a thin movable rod, dipping into the atmospheric limb of the receiver pressure manometer, is automatically raised by a motor- driven rack-and-pinion mechanism each time it is touched by the rising mercury. The motor that operates this mechanism is coupled to the drum carrying the chart on which the column head temperature is plotted by means of a recording potentiometer. The forward movement of the chart is therefore directly proportional to the rise in pressure in the receivers and hence THERMQCOUPLe MANOMETER Fig.3. Semi-automatic low-temperature distillation apparatus.Dec., 19471 LOW TEMPERATURE DISTILLATION 519 to the quantity of gas distilled. In this apparatus, column pressure is automatically controlled by means similar to those already described and, in addition, take-off rate is automatically varied as the distillation proceeds. On plateaux, distillate will be admitted to the receivers at a reasonably fast rate, but as a cut point is approached the take-off rate is progressively reduced, in order to improve fractionation at the breaks. This rate-control device responds to the smallest tendency towards rise in overhead temperature as detected by the potentiometer galvanometer, and also to falls in column pressure : either effect causes (by means of suitable relays) a solenoid valve to open and inject water into a hydraulically operated needle-valve which reduces the flow of gas through the distillate manifold.An apparatus of this nature, although elaborate and expensive, does nevertheless relieve the operator of many tasks and, by carrying out such tasks automatically and mechanically, results in greater standardisation of procedure and hence in increased accuracy of analysis. Moreover, with automatic distillation apparatus it is possible for an operator to carry out two or even three distillations simultaneously. Finally, the author would like to express his thanks to Dr. D. A. How- and the Directors of the Anglo-Iranian Oil Company for permission to present and publish this paper, and to Mr. C.A. Miller for his assistance in the preparation of much of the material. REFERENCES 1. Podbielniak, W. J., Ind. Eng. Chem., Anal. Ed., 1931, 3, 177. 2. Podbielniak, W. J., Ibid., 1933, 5 , 119. 3. Podbielniak, W. J., Ibid., 1933, 5, 172. 4. Savelli, J. J., et al.: Ibid., 1941, 13, 868. 5. “Liquefied Gases Panel,” J . Inst. Pet., 1945, 31, 16. 6. Natural Gasoline Association of America, Publication 1146. “ Recommended procedure for analysis of saturated hydrocarbon gases by low-temperature fractional distillation,” 1946. 7. McMillan, W. A., J . Inst. Pet., 1936, 22, 616. 8, Bower, J. R., and Cooke, L. M., Ind. Eng. Chem., Anal. Ed., 1943, 15, 290. 9. Podbielniak, W. J., Ibid., 1941, 13, 639. 10. Podbielniak, W. J ., “Analytical Determination and Testing.” (Podbielniak Co.brochure). RESEARCH STATION THE ANGLO-IRANIAN OIL COMPANY SUNBURY-ON-THAMES DISCUSSION Mr. F. POPPER enquired what was the advantage of gas collection with pressure measurement over collection with volume measurement. Mr. HOOPER replied that both systems had been used in low-temperature distillation apparatus for assessment of gas quantity, and both have their own advantages and disadvantages. (a) For pressure measurement, the gas must be collected in evacuated receivers, and the slightest leak is a major source of error. (b) With volume measurement, there is less risk of leakage, but it is necessary to collect the gas over a confining liquid. For small fractions, mercury can be used for this purpose, but this is olhiously imprac- ticable where quantities of the order of a litre or more are involved.It is therefore generally necessary to use brine or some other aqueous confining agent in which the various hydrocarbons are not readily soluble. Even then, it is not convenient to use graduated burettes much above 2 litres in capacity, and this is a disadvantage when large fractions of, say, 10 litres in size have to be collected, unless the apparatus is equipped with a considerable number of receivers. Since each burette requires two taps the use of such equipment means a multiplicity of taps, and consequent additional time must be allowed for their main- tenance, i.e., greasing, etc. Control of gas take-off rate can, of course, be readily achieved by control of out-flow of liquid, and gas volume can be measured directly by observations of liquid level. This advantage, however, is offset by the fact that, since volume measurements are made at atmospheric pressure, gas law deviations become significant, particularly for hydrocarbons in the butane range, and it is necessary to apply suitable corrections to observed volume readings: in addition the vapour pressure of the confining solution must also be taken into account. Finally, i t is not easy to use such a volume measurement system when operating the column a t reduced pressure for the distillation of pentanes and heavier hydrocarbons. It is possible under such conditions to withdraw the confining solutions from the burettes by attachment of these to an evacuated reservoir, but this does not permit ready control of the column pressure a t a constant value. For the above reasons, the speaker was inclined to favour the system of gas collection using pressure measurements. Mr. R. E. DODD said that,, given that i t would be possible to use Mr. Hooper’s procedure to separate, say, C, and C , fractions and examine by infra-red spectroscopy, was the separation sufficient to avoid the strong ethylene band a t 12 p , obscuring the C, spectrum ?520 GOODERHAM: A NEW APPARATUS FOR GAS ANALYSIS [Vol. 72 Mr. HOOPER replied that the boiling points of the C, and C, hydrocarbons are sufficiently widely spaced to permit clear-cut fractionation of such a mixture into two fractions, one containing ethylene and ethane only and the other containing propylene and propane. With careful fractionation, no C, component should be present in the C, fraction, and vice versa, particularly if the Heli-Grid type column was used. If, as a result of unsatisfactory operating technique, a poor “cut” was made, with the result that a small quantity of C, hydrocarbon did appear in the C, fraction, this would be ethane rather than ethylene, since the latter, which has the lower boiling point, would already have been distilled off before the C,-C, cut point was reached. Thus the risk of ethylene interference in the C, spectrum during spectroscopic analysis of the C, fraction would appear to be slight.

ISSN:0003-2654    

DOI:10.1039/AN9477200513

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 520 GOODERHAM: A NEW APPARATUS FOR GAS ANALYSIS [Vol.72 A New Apparatus for Gas Analysis by the Soap Film Method BY W. J. GOODERHAM A NEW method of gas analysis was describedl and demonstrated2 by the author in 1940, when it was pointed out that “given a series of accurate gas meters, which do not appreciably absorb gas or cause loss of pressure, the simplest form of gas analysis can be obtained by passing gas through a meter, a reagent to remove completely one constituent of the gas, another meter, another reagent, another meter and so on.” The meters used were soap films, whose rates of travel were measured over calibrated volumes with a stop-watch. Since then, a new type of soap film meter has been developed, which enables the complete analysis to be obtained practically directly in percentages without the use of a stop-~atch.~ NEW METER One form of the new meter is shown in Fig.1. Gas enters at A and normally passes into the top of the cup R, which contains Aerosol soap solution,l~4 and upwards through tube 1; and the calibrated parts of the meter to the point H and out to the scrubber. By raising tube C or D, it becomes possible to push up the wire E, so that tube F is sealed in the soap solution and gas can no longer pass up the length of the meter. When F is sealed, however, the tube G becomes unsealed and gas flows through G out to the-point H and to the scrubber as before. The soap cup, R, thus acts as a two-way valve, which does not stop the flow of gas but deflects it either past the calibrations (cup down) or through the by-pass (cup up).The mercury seal serves the double purpose of sealing the bottom of the soap cup and sealing the whole tube from air and thus facilitates the removal of the bottom of the apparatus by cutting away the single rubber connection. The soap film meter can then be washed through with water from the top on the rare occasions when this becomes advisable. Alternative forms of fitting the soap cups have been used, such as those shown in Figures 1 ( a ) , 1 ( b ) , and 1 (c), and another form of the meter has been described for proving gas meters.* The soap film is broken at the top of the meter by a tightly-rolled spill of blotting paper. This absorbs the thin centre of the film and the remainder drains back into the cup.The blotting paper is held by a loose piece of glass tubing, which rests on the top of the standard ground-glass joint. Both soap solution and blotting paper can be introduced by removing the cap and piece of glass tubing, but the cup should be left up when soap solution is being added, to d o w for adequate drainage, otherwise a succession of films will appear. A soap film is made by raising and lowering the cup R, whereupon the gas travelling up F pushes the film along. The travel of the film can be stopped by raising R and so diverting the flow of gas through G. APPARATUS FOR ANALYSIS OF COAL GAS* An apparatus for the analysis of coal gas is shown in Fig. 2, which is drawn to scale except that the head, h,, for operating the reagent flow is normally only a few inches.The gas should be freed from all tar fog, and preferably partially dried over lump calcium chloride. If it is at a pressure greater than 2 in. water gauge, the gas is dowed to flow in at J and to bubble slowly out to air at K, with the three-way tap, L, turned * Messrs. Griffin & Tatlock have been granted a licence to make these apparatuses under B.P. 550,323 and B.P. 489,117.Dec., 19471 BY THE SOAP FILM METHOD 521 (a) JOINT AT BOTTOM. 6) SEALEDI JOINT AT TOR Fig. 1522 GOODERHAM: A NEW APPARATUS FOR GAS ANALYSIS [Vol. 72 as shown in Fig. 2. If the pressure is less than 2 in. water gauge, the clean gas again flows in at J, but passes through the electrically-driven pump with the tap L turned round the other way.The by-pass tap, M, is partially closed in such a way that gas bubbles gently through the blow-off. The blow-off and by-pass should be connected to burners. Whichever way gas is entering the apparatus, part of it, under the small constant head, h, of butyl phthalate, flows through the control capillary at about 20 to 30 ml. per min. to the saturator, which consists of a folded strip of blotting paper dipping into water. Gas, saturated with water vapour, passes through the first soap film meter and then through the first scrubber, which, as described earlier,l consists of a glass spiral continuously wetted with 15 per cent. w/w caustic potash solution, having a negligible back pressure. The gas thereafter flows in series through a second soap film meter, a scrubber continuously wetted with activated sulphuric acid (not the activated nitrating mixture described in 19401), a water saturator, soap film meter No.3, chromous chloride, meter No. 4, copper oxide made from heavy gauge wire and maintained at a temperature of 270” C., meter No. 5, 15 per cent. caustic potash solution, meter No. 6, Arneil catalyst at about 600” C., meter No. 7, 15 per cent. caustic potash solution and finally meter No. 8. Water, formed in the combustion tubes, flows into cylinders, Q, where it can be measured, if desired. The gas, therefore, has the following constituents removed fi om it in the following order-carbon dioxide, unsaturated hydrocarbons, oxygen, hydrogen, carbon monoxide and paraffin hydrocarbons, until only nitrogen (and other inert gases) are left flowing in the last soap film meter (No.8). The reagents, except for 15 per cent. potash solution in lieu of 25 per cent. solution, are the same as those used on the constant volume gas analysis apparat~s.~ The rate of flow of a liquid reagent is about 30 ml. per hour, but is not critical, the flow being controlled in the manner already described.l All the tubes D (Fig. 1) are connected to a single shaft which can be turned to and fro and thus the eight soap cups raised and lowered together. To carry out a gas analysis, gas is turned on to the apparatus with all reagents in operation. Soap films are sent up the meters from time to time until all the glass walls are wetted with soap. This action also flushes out the bottom connections.When all the air has been swept out an analysis can be made. The eight soap cups are raised and lowered and a soap film moves upward in each of the eight meters. When the film in the first meter is at the top of the lower scale, the cups are sharply raised and left in this-position. The eight soap films stop and readings can be taken, for example Meter No. . . 1 2 3 4 5 6 7 8 Reading.. . . 7-4 7.1 6.8 6.4 2-3 0.6 0-5 1.5 The cups are then lowered sharply and flow continues up the main length of the meters until the first film is stopped at 107.4, whereupon the positions of all the other films are read. If the previous figures are subtracted from these readings it becomes possible to obtain the analysis immediately, as can be seen by continuing the example.Meter No. . . 1 2 3 4 5 6 7 8 Readings: end . . 107-4 104.2 100.9 99.6 48.3 31.8 32.9 10.5 start . . 7.4 7.1 6.8 6.4 2.3 0-6 0.5 1.5 Difference . . 100.0 97.1 94.1 93.2 46.0 31-2 32.4 9.0 - - ~ - - - _ _ _ _ _ _ _ Thus, while 100 volumes of the initial gas were passing in meter No. 1, only 97.1 volumes were travelling in meter No. 2, after carbon dioxide had been removed. The percentage of carbon dioxide is thus 2.9 per cent. ; similarly, the percentage of unsaturated hydrocarbons is 3.0 per cent., of oxygen 0.9 per cent., of hydrogen 47.2 per cent., and of carbon monoxide 14.8 per cent. The nitrogen concentration is 9.0 per cent. and that of paraffin hydrocarbons (C,,Hzn+,J, 31.2 - 9.0 or 22.2 per cent. The value of n in (C,H,,+,) is (32.4 - 9.0)/(31.2 - 9.0) or 1.054.If ethane or higher homologues are present in the paraffin hydrocarbons, combustion over the copper oxide - iron oxide pellets will naturally produce an expansion in volume, as the volume of carbon dioxide produced will be greater than that of the hydrocarbon. If the paraffins are presumed to be only “methane” and “ethane” the expansion will be equivalent to the “ethane,” whilst the “methane” will be equivalent to the carbon dioxide produced less twice the volume of “ethane,” Le., in the above example, “ethane” would be 32.4 - 31.2 or 1.2 per cent. and the “methane” 32.4 - 9.0 - 2-4 or 21.0 per cent. Apart from the calculation of n in the paraffins, each analysis is a simple subtraction and, once the apparatus has been flushed out, an analysis, complete in percentages, can be obtained in twoDec., 19471 BY THE SOAP FILM METHOD a0 i I 0 Y -A I I I I Nl 0- ( 0 0 u ;t"y ?* tD fp tJ0lrnQS- 1 I 0 Y c m 1 523524 GOODERHAM: A NEW APPARATUS FOR GAS ANALYSIS [Vol.72 to three minutes. If the concentration of nitrogen is below about 5 per cent. it is necessary to make a film in meter No. 8 first by raising C - and not D - before making the other films. In this way, a film can be got up on to the graduations in meter No. 8 for a reading, whereas the normal method of operation will leave the film below the calibration marks. Making a film in one meter independently of the others is sometimes useful in other circumstances, such as when seven meters are wet with soap, but one is not; hence the independent movement of tubes C and D is useful and necessary.It will be realised that there are no temperature or pressure corrections. All the soap film meters are in a cabinet together and if the temperature varies it alters all volumes equally: Similarly, the whole apparatus is specifically designed to have a negligible pressure drop of about 0.2 in. (water gauge) across the whole series of meters, scrubbers and oxide pipettes . The cups should be held Srmly in the same “up” or “down” positions. When the cup is moved up, the gas in the calibrated part of the meter is displaced a little forward by the volume of soap solution. This displacement occurs twice, however, and thus cancels out when one volume is subtracted from the other, provided the cup is in the same position on each occasion.The cups must fall readily; if not, they should be weighted by addition of mercury. It is preferable to have only the operating films present in each meter during an analysis. If, however, other films are present it should be remembered that the film being measured is always the one above the last frlm, since the latter is inevitably made as the film under measurement is stopped. A useful feature of the apparatus is that, once it has been flushed out, analyses can be repeated quickly. Two or more analyses can be obtained in a few minutes before changing over to another gas stream. Other advantages of the apparatus aregreater freedom from solubility and adsorption errors, avoidance of errors due to absorption of gases by rubber joints, which can thus be freely used, less danger of breakages, no pressure or temperature corrections, no dead spaces and no taps or mercury to be cleaned.Some of these advantages are inherent in a streaming system, which, however, has disadvantages in needing more gas for analysis and in lacking the flexibility of the constant-volume and other static gas analysis apparatus. The speed and accuracy with which a gas can be analysed directly in percentages outweigh the latter disadvantages. By photographing the films in the top and bottom positions it is possible to obtain a permanent record of an analytical result. When analyses have been completed, the reagents are stopped from flowing by taking off the caps, P, and thus breaking the syphons. Air should then be passed through the whole apparatus with the tap, N, by-passing the control capillary, wide open and with the cups up so that plenty of air passes through to reoxidise the copper without evaporating the soap solution.It has been found to be most convenient to carry out the revivification overnight. SIZES OF METERS- By suitable choice of meter sizes, apparatus can be made to cover all kinds of gas analysis. In the apparatus shown in Fig. 2 for the analysis of coal gas, the meters have the following approximate sizes and are based on 50 ml. = 100 per cent. Bottom stem: K o l No 2 NO. 3 X o . 4 KO. 3 No.6 No.7 No.8 Intern. diam., mm. . . 8 8 8 8 8 8 8 5 Graduations % . . O t o 8 Oto8 Oto8 Oto8 Oto4 straight tubes* Intern. diam., mm. . . 8 8 8 8 8 8 8 5 Graduations, yo .. 90to115 85to110 85to110 80to105 25to60 Ot040* Oto40* Oto20* * Over total length of tube.Top stem: These sizes are intended to give a reasonable accuracy together with a relatively short time for flushing out the apparatus. It will be realised that, with a gas containing, for example, 5 per cent. of nitrogen, the rate of flow in meter No. 8 is only 1 ml. per min. if the initial rate of flow through meter No. 1 is 20 ml. per min. ; so that, if the volume of meter No. 8 were not reduced from 50rnl., the gas would take 50 minutes to flow through it. By reducing the vqlume to 1Oml. (Le., 20 per cent.), the time to flush out the eighth meter is decreased to 10 minutes. It will be seen that all meters are progressively reduced in size in an attempt to get approximately equal rates of flow of the films longitudinally.The apparatus is, however,Dec., 19473 BY THE SOAP FILM METHOD 625 capable of wide variations and with a second apparatus having the following sized meters, for the analysis of producer and waste gases, it becomes possible to analyse most types of manufac- tured fuel gases or waste gases. Stem. int. diam. = 8 mm. ; 50 ml. EZ 100 per cent. ; bottom stems, 0 to 8 per cent. ; top stems-meter No. 1, 90 to 115 per cent. ; Nos. 2 to 6, 75 to 100 per cent.; Nos. 6 and 7, 50 to 80 per cent.; No. 8, 45 to 75 per cent. It would, of course, be possible to manufacture an apparatus containing eight similarly sized and similarly calibrated meters which would analyse any type of gas. Accuracy--or convenient size-would, however, have to be sacrificed and a longer time would be necessary to flush out the apparatus before an analysis could be made.With gases low in nitrogen content this time might be excessive. Other units have been made for special purposes. A portable apparatus for the deter- mination of carbon dioxide, oxygen and carbon monoxide was based on the following dimen- sions :-33 ml. = 100 per cent. ; bottom ca3ibrations 0 to 8 per cent. ; top calibrations for the four soap film meters, 80 to 110 per cent., 74 to 104 per cent., 71 to 101 per cent. and 71 to 101 per cent. A small portable apparatus for the determination of carbon dioxide was based on 25 ml. = 100 per cent.; so were small forms of the apparatus for the determination of oxygen and of nitrogen. In the last one, the gas, after passing through the first meter, passed over Arneil catalyst at 600” C.and soda asbestos, so that only nitrogen remained to flow in the second and much smaller meter. The solid reagent for the removal of carbon dioxide was packed in sizeable pieces (3 to 8 mesh) to avoid back pressures in a U-tube or similar vessel fitted with ground-glass tops so as to be readily removable for recharging. An attempt was made to increase the accuracy of a simple apparatus for the determination of oxygen, by having large bulbs with narrow stems so that 0.1 per cent. was equivalent to about 7 mm. It was thus possible to obtain a second decimal place in the analytical results. The holders described earlier (ref.1 Figs. 4 and 5) have been found effective, but not long- lived.The thickness of the rings should be greater than the 32 s. W. G. previously specified USE OF APPARATUS- TIME 9.50 11.12 11.27 11.21 11.37 12.16 12.21 12.26 12.30 1.40 1.45 1.49 2.50 3.64 2.58 3.2 3.55 4.0 4.3 4.6 4-31 4.39 4.45 4.53 4.58 5.3 5.10 Start on gas from No. 1 Retort House 3.2 1-9 0.2 57.9 14.9 3-2 1.9 nil 58.0 1 5 1 3-1 2.0 0-1 68.0 15.0 1.8 2.0 1.3 55.7 10.2 2-0 1.9 1-2 55.8 9-7 1.9 2.1 1.1 55.8 9.8 2.4 2.0 0.9 53.2 10.7 2-6 2.1 0-6 53.3 10.6 2.1 1.8 1-1 49-0 7.1 2.3 1.9 1.0 48.5 6.9 2.2 1-8 1.0 48-5 6.8 3.0 2-2 0.4 41.2 6.0 2-8 2.2 0.4 41.3 6.1 2.8 2.3 0.5 41.2 6.4 3.0 1-9 0.6 52.6 9.2 9.8 1-8 0.7 53.0 10-4 3-1 1-7 0.8 52.9 10-6 2.8 1.9 0.7 62.9 10.7 3.8 2.0 0.9 52.9 10.5 3-2 5.0 0.8 52-7 10.9 changed over to gas from No. 4 Retort House changed over to District Gas changed over to gas from No. 3 Retort House changed over to gas from No.5 Retort House changed over t o gas from “inlet holders” shut down “C,H,” % 2.5 2-4 9.0 2.7 3.1 3-0 2.5 2.5 2.6 2.3 2.2 3-2 3.0 3.2 3.0 8.9 3.0 2.9 2.7 2.8 “,€I;’ % - 14.6 15.2 19.5 194 19.4 21.0 “-0 33.1 23.2 33.5 I 24.0 23.2 16.3 16.4 16-2 19.9 20.7 20.4 N, % - 4.8 4.6 6.8 6.9 6-9 7-3 7.4 13-22 13-9 14.0 - 20.2 20.4 13.4 12.0 10-7 8.2 7-5 7.2 and the outside edges should be effectively and heavily soldered. The governor (&d, Fig. 6) tended to choke on the smaller sintered-glass filter and it was found better to have no filter, but to have the capillary above the variation in mercury levels. The governor has not been used much, however, as the works samples of gas were readily available in small 10 cu.ft. holders used primarily for calorimetry, while another, more conventional type of governor526 GOODERHAM: A NEW APPARATUS FOR GAS AXALYSIS pol. 72 was used to control the flow of gas from diaphragm holders to the gas analysis apparatus. The latter has been extensively used and it is regretted that although the modifications described above were first made in 1940, the war prevented the commercial development of the apparatus and only “home-made” models have been produced. One such model has, however, been in use in a works laboratory since November, 1941, and is still working well. As many as six different analyses have been made in one day, each analysis being repeated : the following figures give the results exactly as obtained for the analysis of six gas streams.Another “home-made” model of an apparatus for the analysis of producer gas was effectively used in a wartime study on the production of producer gas for use in motor cars. It was the practice in this work to take certain readings of temperatures, pressures, gas flow, etc., every quarter of an hour, when, in addition, a gas analysis was made. It was thus possible to obtain many complete analyses over a long test period. These forms of apparatus have also been used with considerable success in research work on catalysts in streaming systems. Part of the gas at the outlet of a catalyst vessel was made to flow through a soap film apparatus and, despite the fact that no nitrogen was present and thus soap films remained stationary in the last meter, successful gas analyses were con- tinuously obtained.Other smaller forms of soap film apparatus have been used for the analysis of carbon dioxide from exhausts of internal combustion engines and in the C.A.B. Test for the combustibility of coke, for the determination of carbon dioxide, oxygen and carbon monoxide in waste gas and for the determination of oxygen. The types of apparatus mentioned above have been fully tested by analysing known gas mixtures, by checking analyses with the constant-volume and other apparatus and by calibrating the meters with air while water flowed down the scrubbers and while the furnace tubes remained unheated. SUMMARY The method of gas analysis described in 1940 has been further developed. A new type of soap-f‘ilm gas meter has now made it possible to obtain the results, with repeats, of gas analyses directly in percentages within a few minutes after an initial period necessary to flush out the apparatus. REFERENCES 1. 2. 3. 4. 6 . Gooderham, W. J., Ibid., 1938, 57, 388. Gooderham, IV. J., J . SOL. Chem. Ind., 1940, 59, 1. Gooderham, W. J., Che~nistry and Industry, 1940, 18, 368. The Gas, Light & Coke Co. and Gooderham, W. J., B.P. 550,323 (1943). Gooderham, W. J., J . SOC. Chew. Ind., 1944, 63, 351. THE FULHAM LABORATORY THE GAS LIGHT & COKE Co. DISCUSSION Mr. A. F. WILLIAbfs asked how in the apparatus described provision was made for different times of contact necessary for different reactions, e.g., the oxidation of hydrogen takes longer than the absorption of carbon dioxide. Mr. W. H. C. SIMMOXS asked if the apparatus had been applied to the analysis of flue gases from boilers. Mr. E. W. MUDDIMAN enquired as to the accuracy of the apparatus and asked if any particular form of soap solution was used in it. Mr. H. N. WILSON enquired how much gas would be necessary to bring the apparatus to equilibrium and sweep out. Mr. T. A. RYSON asked if it would be of any use to dilute the gas analysed with nitrogen in order to speed up the sweep-out time. Mr. E. BISHOP enquired whether the time required for sweeping out the apparatus could be conveniently reduced by temporarily increasing the through-put of the sample. Mr. GOODERHAM, replying to these questions, stated that the combustion pipettes were of sufficient size to allow the oxidation of hydrogen, carbon monoxide and paraffins to be complete. The time necessary for sweeping out the apparatus and reaching equilibrium conditions could, in an emergency, be reduced by opening temporarily the tap by-passing the control capillary, and the agreement between results of repeat analyses would show if purging was complete. One to one and a half litres of gas were usually sufficient to complete a full analysis, with several repeats. The accuracy of the apparatus demonstrated was 0.2 per cent. on each constituent, but it might be possible to get greater accuracy with a larger ratio of bulb to stem. Apparatus for the determination of carbon dioxide, oxygen and carbon monoxide in waste gases had been made and used. A special acidic soap solution was to be preferred.

ISSN:0003-2654    

DOI:10.1039/AN9477200520

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 Dec., 19471 HILDITCH AND SHRIVASTAVA: LINOLENIC ACID IN FATS 527 The Spectrophotometric Determination of Small Proportions of Linolenic Acid in Fats BY T.P. HILDITCH AND IZ. K. SHRIVASTAVA THE determination of linolenic acid in a mixture of fatty acids, from the extinction-coefficient for ultra-violet absorption at 268 mp after isomerisation with alkali under standardised conditions of concentration, time and temperature (180" or 170" C.), has been described by Mitchell, Kraybill and Zscheilel and by Hilditch, Morton and Riley.2 The latter authors recommended isomerisation with alkali at 170" C. for 15 minutes in the determination of linolenic acid, and in subsequent papers Hilditch, Gunstone and Riley3s4s5 showed further that, in mixtures of saturated, oleic, linoleic and linolenic acids, the precision of the spectrophoto- metric analysis is increased if the mixture is first resolved by crystallisation from acetone or from ether at low temperatures into a series of fractions, in each of which either the saturated, oleic, or polyethenoid acids are concentrated. Meanwhile the application of this method has been reported by several investigators to reveal the presence of slight absorption (E:& of a few units, usually not exceeding 10) at .268 mp after the standard isomerisation with alkali in fats and fatty acids in which hitherto the presence of linolenic acid has not been recorded (cf., e.g., Brice, Swain, Schaeffer and Ault).6 It would appear that in some instances the occurrence of such small absorption has been credited arbitrarily to linolenic acid. We ourselves also have observed the presence, after isomerisation with alkali, of slight absorption at 268 mp in fatty oils such as cottonseed and sunflower-seed oils, but have felt uncertain as to the propriety of calculating this to linolenic acid in the absence of independent proof that traces of the triethenoid acid were indeed present. It seemed possible either that, in presence of a large concentration of linoleic acid, the intense band at 234 mp might be responsible for the presence of very slight absorption as far as a wave-length of 268 mp, or alternatively, that the latter slight absorption might be caused by traces of non-fatty components (either present as such or produced by the treatment with alkali).We have therefore examined a group of seed fatty oils, (i) by observing the value of E :L.at 268 mp after isomerisation of their total fatty acids, and (ii) by submitting the mixed fatty acids to crystallisation from 10 per cent. solutions in acetone at - 60" C. and then isomerising the soluble portion with alkali and determining its extinction-coefficient at 268 mp. In general we have found that the apparent values for linolenic acid obtained by these two procedures were in close agreement. The apparent concentration of linolenic acid in the fraction of acids soluble in acetone at - 60" C. was, however, usually sufficient to warrant its detection as hexabromostearic acid ("linolenic hexabromide ") by addition of bromine to an ethereal solution of this fraction of the total acids: but, of the oils examined, only soya-bean and niger-seed oils responded positively to this test.We are disposed to conclude, therefore, that linolenic acid is not, in fact, present in detectable quantity in the other oils, and to suggest that small values, of the order of less than 10, of E:$. at 268 mp on the total fatty acids of an oil, should not be calculated to linolenic acid unless positive identification of the latter acid has been obtained by other means. That the identification of linolenic acid, present to the extent of only 0-3 per cent. of the total fatty acids, can in fact be achieved by means of concentration of the acid into the portion soluble in a suitable solvent (acetone) at low temperatures is illustrated by the example of palm oil, recently studied in this laboratory by Hilditch, Meara and Roels.' The mixed acids of a plantation palm oil (iodine value of the oil 52.9) left 13.4 per cent.of their weight as a fraction soluble in acetone (10 ml. per g.) at - 40" C. This soluble fraction had iodine value 151.0 and, after isomerisation with alkali at 170" C. for 15 minutes, gave Ei&. 13 at 268 mp, corresponding to 2.4 per cent. of linolenic acid in the fraction and to 0.3 per cent. of linolenic acid in the total fatty acids of the palm oil. On treatment of an ethereal solution at 0" C. with bromine, a very small quantity of crystalline bromo-adduct was deposited, which melted at 174" C. and, when mixed with authentic hexabromostearic acid (m.p. 180°), melted at 176" C .528 HILDITCH AND SHRIVASTAVA THE SPECTROPHOTOMETRIC Pol. $2 EXPERIMENTAL The fatty oils studied were cottonseed, maize, sunflower-seed, sesame, groundnut (Indian and Nigerian), niger-seed, and soya-bean oils.The last-named was included since it is already accepted that linolenic acid is one of its minor components. The mixed acids from each oil were isomerised with alkali under the conditions specified by Hilditch, Morton and Riley2 and then examined in a Beckman spectrophotometer; the results are given in Table I. TABLE I Ei& AT 268 m p Fatty oil Cottonseed . . .. Groundnut (Indian). . Maize . . .. .. Sesame . . .. Sunflower seed . . I D (Nigerian) Niger seed . . . . Soya bean . . .. AFTER ALKALI-ISOMERISATION OF MIXED FATTY ACIDS . I .. .. .. .. .. . . .. Iodine value : Oil Mixed acids 103.0 93.0 86.3 112.6 136.4 113-4 132.6 135.7 106.5 96.5 90.8 117.8 139.7 116-0 136-7 140.7 8.8 1.1 3.4 23.5 3.5 50-1 3.4 - Calculated to linolenic acid 1-7 0.2 nil 0-6 4.4 0.7 9-4 0.6 % The mixed acids from each oil were then crystallised from 10 per cent.solution in acetone at -60" C., for five hours, after which the deposited crystalline acids were removed by filtration and the weights and iodine values of both this insoluble and the soluble fractions determined. Portions of each fraction were also isomerised with alkali under the standard conditions at 170" C. for 16 minutes and at 180" C. for 60 minutes, followed by spectrophoto- metric determination of E:L. at 268 mp and 234 mp respectively. Further, a portion of the soluble fatty acid fraction, in 10 per cent. solution in ether at 0" C., was treated with bromine until a faint yellow colour persisted ; if any crystalline bromo-additive compound separated, it was filtered and its melting-point determined.The data for apparent linolenic acid contents thus obtained are shown in Table 11, except those for niger-seed, soya-bean and sunflower-seed oils, which are dealt with in Table 111. TABLE I1 APPARENT LINOLENIC ACID CONTENTS AND IDENTITY TESTS OF SOLUBLE FRACTIONS FROM MIXED FATTY ACIDS Acids soluble in 10% acetone solution at -60" C. Yo E :2. Calculated to I & \ Fatty oil (of total acids) 268 m p linolenic acid Bromination In fraction On total acids test % % Cottonseed .. . . 33.7 23.9 4.5 1.5 Negative ,, (Nigerian) . . 18.2 0.9 0.2 Trace > I Maize . . .. . . 31.3 9-5 1.8 0.6 ,, Sesame . . .. . . 36.1 9.0 1.7 0.6 I 1 Groundnut (Indian) .. 26.3 3.3 0-6 0.2 I 1 Both the insoluble and soluble fractions of the mixed acids of niger-seed and of soya-bean oils showed absorption at 268 mp after isomerisation with alkali. The sunflower-seed mixed acids behaved differently from the rest in that on crystallisation from 10 per cent. solution in acetone at - 60" C., for five hours, acids of higher iodine value (127.1) than in other instances were deposited. The portions insoluble and soluble at -60" C. were therefore separately crystallised again from 20 per cent. solution in acetone at -60" C . , and two further insoluble fractions (A and B) obtained. The portions left in solution from these separations were combined and finally crystallised from 20 per cent. solution in acetone at -70" C.for five hours, when a fraction (C) was deposited leaving in solution a small amount of most soluble acids (D). The iodine value of this most soluble fraction (147.2) was considerably lower than that of fraction B (17143) or C (1674). It would seem that the high linoleic acid content of sunflower-seed oil resulted in high concentrations of linoleic acid appearing in the original portions left in solution at -60" C., and that further low-temperature crystal- lisation of these caused deposition of acids in which linoleic acid was still more highlyDec., 19471 DETERMINATION OF SMALL PROPORTIONS OF LINOLENIC ACID IN FATS 529 TABLE I11 APPARENT LINOLENIC ACID CONTENTS AND IDENTITY TESTS (Niger-seed, soya-bean and sunflower-seed oils) Fatty acid fractions separated by low-temperature cry stallisation r A 1 Fatty oil Niger seed , .Insoluble Soluble Soya bean . . Insoluble Soluble Sunflower seed . . A* B" C* D' % Iodine E;&. Calculated to tion acids (of total acids) value 268 mp linolenic acid Bromination In frac- On total test 01 'O J Positive % 76.0 134.7 10.1 1.9 24-0 155-8 58-2 10.9 } l(rn.p.. 176-177') 52.3 101.1 47.7 178.0 51.1 117.7 19.8 171.8 4.7 23.5 167.8 6.6 5 6 147-2 20.8 17-2 85.6 1::; } 9'4 { (LFGo) - Negative Negative Negative * See text above. TABLE IV COMPONENT FATTY ACIDS OF THE OILS Fatty acid fractions obtained by low-temperature crystallisation Fatty oil % (of total acids) Cottonseed . . Insoluble 66.3 Soluble 33.7 Groundnut (Indian) Insoluble 73-7 Soluble 26.3 Groundnut (Nigerian) Insoluble 81.8 Maize .. Niger seed . . Sesame . . Soya bean . . Sunflower seed Fatty oil Cottonseed Soluble . . Insoluble Soluble . . Insoluble Soluble . . Insoluble Soluble . . Insoluble Soluble .. (Mixed acids) 18.2 68-7 31-3 76-0 24-0 63-9 36.1 52.3 47.7 100.0 Composition % % % % 80.8 - 234.0 36-5 37-7 25.a - Iodine EiP. Ei& r A \ value 368 m p 234 m p Satd.* Oleic Linoleic Linolenic 155-8 neglected 737-9 9.6 8.9 81-5 - 156.2 neglected 677.2 2.3 22-9 74.8 - 153.0 neglected 656.3 3-5 24-0 72-6 - 76.9 - 133.4 30.7 54.6 14.7 - 76.7 - 69.2 22-7 69.7 7.6 - 95.7 - 237.5 20.3 53.5 26.2 - 166.9 neglected 735-8 - 18.8 81.2 - 134-7 10.1 633-5 24-2 5.2 6a.7 1.9 155-8 58.2 658-2 16-1 7-2 65.8 10.9 96.6 - 274.6 23.5 46.2 30.3 - 149.2 neglected 636.9 6-7 24.0 70.3 - 101.1 17.2 335.3 29.9 31.9 35.0 3.2 178.0 85.6 720.3 5.6 8.9 69-4 16.1 140.7 neglected 610.1 12-2 20-5 67.3 - Composition of total fatty acids in each oil (% by wt.) r A \ Saturated* Oleic Linoleic Linolenic ... . .. 27.4 28.0 44.6 - Groundnut (Indian) . . .. 23.2 ,, (Nigerian) . . . . 19-2 Maize . . .. .. . . 14.0 Nigerseed . . .. .. . . 22-2 Sesame . . .. .. .. 17.1 Soya bean . . .. .. . . 18-3 Sunflower seed . . .. .. 12.2 46.3 61-4 42.6 5.7 38-2 20.9 20.5 30.6 19.4 43.4 68.0 44.7 51.4 67-3 * The figures (obtained by difference) for saturated acids include also any unsaponifiable matter present in the fatty oils.530 HILDITCH AND SHRIVASTAVA THE SPECTROPHOTOMETRIC [Vol. 72 concentrated. The data for niger-seed, soya-bean and sunflower-seed oils are summarised in Table 111.DISCUSSION AND CONCLUSIONS In spite of the fact that in all cases the spectrographic evidence from the mixed acids (Table I) and from the more soluble unsaturated concentrates (Tables I1 and 111) is closely accordant, negative “ hexabromide ’’ tests were obtained with the concentrates of unsaturated acids from cottonseed, groundnut, maize, sesame and sunflower-seed oils. We therefore consider that linolenic acid cannot occur in more than minute traces in these oils, and that the small proportions indicated by spectrographic analysis should in these and similar instances be ignored. Contrariwise, there was no difficulty in confirming the presence of linolenic acid (already, of course, well established by isolation of hexabromostearic acid by many previous workers) in soya-bean oil.Finally, the occurrence of some linolenic acid, hitherto reported only in one instance (Pye*), in niger-seed oil was similarly proved. We recommend, as stated earlier in this communication, that small proportions of linolenic acid should not be credited to fatty oils on the evidence of small absorption at 268 mp after isomerisation with alkali, unless their presence can be supported by production of crystalline hexabromostearic acid from a concentrate of the unsaturated acids. Moreover, for minor proportions of linolenic acid (e.g., less than 10 per cent. of the total fatty acids), we feel that the spectrophotometric method of analysis may tend in any case to record values somewhat higher than the truth, although the error is unlikely to exceed 0-5 to 1 unit per cent.of the total fatty acids. COMPONENT FATTY ACIDS OF THE FATTY OILS From the iodine values and spectrophotometric data of the acids obtained by low- temperature crystallisation during this investigation we have determined the proportions of saturated, oleic, linoleic and (when shown to be present) linolenic acids, with the results shown in Table IV. The sunflower-seed and niger-seed oils were specimens the component acids of which had been examined some years previously in this laboratory by lead salt separation followed by fractional distillation of the methyl esters of the respective “solid” and “ liquid’’ acids, unsaturated C,, esters being calculated as mixtures of oleate and linoleate from the iodine values of the ester fractions, with the following results :- Saturated Oleic Linoleic Yo % % Sunflowerseed .. 10.5 22-0 67.5 (Hilditch and Rile?) Niger seed . . 11-9 17.0 71-1 (Hilditch and !%mes) The sunflower-seed oil figures agree fairly closely, but Hilditch and She’s datag for niger-seed oil require amendment to allow for the small proportion of linolenic acid now shown to be present. Of other reports on niger-seed oil, only the recent (1945) study by Pye,* who determined the component acids from the iodine and thiocyanogen values of the oil, discloses the presence of linolenic acid :-saturated acids 9.6, oleic 16.3, linoleic 72.4, linolenic 1.7 per cent. The specimens of the other seed oils used in this investigation were not examined by the more detailed ester-fractionation technique, but the values for their component acids (Table IV) recorded from the spectrophotometric examination of the insoluble and soluble acids obtained by crystallisation from acetone at - 60” C.are very similar to thoserecorded by various workers who have at different times applied the more detailed procedures to the respective fatty oils.l0 The groundnut oils used in the present study were of some interest in that they represented approximately the extreme limits of iodine value encountered in genuine Indian or West ,4frican groundnut oils. It is interesting to note that the component acids observed for the two specimens lend further support to the view11 already held that groundnut oils cover the following general range in their component acids:- % % Saturated .. .. 16-18 18-23 Oleic . . .. . . 66-60 56-50 Linoleic . . .. 19-22 25-27 When the proportion of oleic acid is lower, that of linoleic as well as that of the total saturated acids is generally higher, the increase being, however, somewhat more marked in the case of linoleic acid.Dec., 19471 DETERMINATIOK OF SMALL PROPORTIONS OF LINOLENIC ACID IN FATS SUMMARY I. Although spectrophotometric analysis discloses small absorption at 268 mp after isomerisation of polyethenoid C,, acids by alkali, no evidence has been obtained of the presence of linolenic acid (as revealed by formation of ether-insoluble hexabromostearic acid, m.p. 180’) in unsaturated acid concentrates from cottonseed, groundnut , maize, sesame and sunflower- seed oils. It is concluded that linolenic acid is present, if at all, only in minute traces in these fatty oils.2. It is recommended that small spectrophotometric values (after alkali isomerisation) not exceeding Ei,%,. 10 at 268 mp should not be calculated as linolenic acid in a fatty oil, unless confirmed by production of crystalline hexabromostearic acid from a concentrate of the unsaturated acids of the oil. 3. Owing to extraneous absorption, linolenic acid proportions dependent upon small values of Ei&. at 268 mp probably tend in any case to be somewhat higher than the true figures. 4. In njger-seed oil, the procedure recommended in this paper has established the presence of small proportions of linolenic acid (probably of the order of 3 4 per cent. of the total fatty acids of niger-seed oil). We are indebted to Messrs. J. Bibby & Sons, Ltd., for the provision of the two groundnut oils and certain of the other seed oils used in this work; and we wish also to thank Professor R. A. Morton for placing a Beckman spectrophotometer at our disposal for the spectrographic measurements. One of us (R. K. S.) thanks the Government of India for a grant held by him during the progress of the work. 531 REFERENCES 1. Mitchell, J. H., Kraybill, H. R., and Zscheile, F. P., I n d . Eng. Cham.., A n a l . Ed., 1943, 15, 1; 2. Hilditch, T. P., Morton, K. A., and Riley ,J. P., AnaZyst, 1945, 70, 68. 3. Hilditch, T. P., and Riley, J. P., J . Soc. Chew. Ind., 1945, 64, 204. 4. Hilditch, T. P., and Gunstone, F. D., Ibid., 1946, 65, S. 5. Hilditch, T. P., and Riley, J. P., Ibid., 1946, 65, 74. 6. Brice, B. A., Swain, M. A., Schaeffer, B. R., and Ault, W. C., Oil and Soap, 1945, 22, 219. 7. Hilditch, 1’. P., Meara, M. L., and Roels, 0. A., J . SOG. Chem. Ind., 1947 (in the press). 8. Pye, C. R., Paint Tech., 1945, 10, 113. 9. Hilditch, T. P., and Sime, I. C., J . SOC. Chem. Ind., 1944, 63, 112. 10. cf. Hilditch, T. P., “The Chemical Constitution of Natural Fats,” 2nd edition, Chapman & Hall, London, 1947; pp. 159, 160 (sesame, niger seed, sunflower seed, Table 50), 173 (cottonseed, Table 52), 177 (maize, Table 53), 188, 189 (groundnut, soya bean, Table 57). 11. cf. Hilditch, T. P., Ibid., p. 187. Beadle, B. W., and Kraybill, H. R., J . Awzer. Chem. SOC., 1944, 66, 1232. DEPARTMENT OF INDUSTRIAL CHEMISTRY THE UNIVERSITY OF LIVERPOOL June, 1947

ISSN:0003-2654    

DOI:10.1039/AN9477200527

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-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 Dec., 19471 DETERMINATIOK OF SMALL PROPORTIONS OF LINOLENIC ACID IN FATS 531 The Determination of the Composition and Constitution of Ammonium Phosphornolybdate and the Conditions affecting its Precipitation BY W.P. THISTLETHWAITE (Read at the meeting of the Society 0% February 5th, 1947) AMMONIUM phosphomolybdate was first prepared by Berzelius, and it is almost exactly a hundred years since it began to attract the attention of chemists. It was recognised from the first that phosphorus was necessary to the formation of the yellow precipitate, but the very small proportion of the element present (about 1.7 per cent.) caused some chemists to doubt whether it was an essential constituent of the pure compound1s2; after about ten years it was generally agreed to be ~ 0 . ~ ~ 4 The next twenty-five years were devoted to attempts to establish the exact atomic ratio of molybdenum to phosphorus : this was finally accepted as 12 to 1, but more through faith in the Law of Definite Proportions than from reproducible experimental r e ~ u l t s . ~ - ~ In the 1880’s were published the two classical contributions to the subject.lOsu Henry Pemberton became the father of a long line of very popular volumetric methods based on The history of the compound may be divided into a number of periods.5 32 THISTLETHWAITE : THE DETERMINATION OF THE COMPOSITION AND [Vol.72 ammonium phosphomolybdate, while Fritz Hundeshagen, studying the compound in a more academic way, expressed his belief in the constancy of composition of the substance under the most varied conditions of precipitation. He put forward two formulae, (NH,),PO,.12Mo0,.2HNO3.H2O for the precipitate dried over calcium chloride and potassium hydroxide for a few days and (NH4!,P04.12Mo0, for the precipitate dried at 130" to 150" C.; these have been accepted by practically all subsequent workers. There is a kind of paradox about the great influence exerted by these two chemists on their successors, for Pemberton was by no means a precise experimenter, and Hundeshagen gave no definite experimental evidence in support of his two formulae. From that time forward, progress in this field has followed two streams. Practising analysts have constantly improved the old methods and techniques and invented new ones,12-18 and their work includes much incidental study of some of the factors involved in precipitation and subsequent treatment but with much disagreement on details, for example the influence of chloride i ~ n ~ ~ - ~ ~ and organic a~ids.~,-~' At intervals during the same period there have been a few more fundamental investigations of the chemical processes in~olved.28-~6 In these a serious attempt has been made to decide how many experimental factors influence the course of precipitation and the composition of the precipitate, followed by experiments in which these conditions were varied in a systematic manner.The work of Chesnea~,~~ Claren~,~~ Clennell,= and Kitajima36 deserves special mention. Recent workN on this and similar compounds, using X-ray crystallographic methods, has shown that the compound is really- (NHJ3 P (Mo,~O,,,) and is more correctly named ammonium molybdophosphate. The old formulae and name are retained in this paper as being more famiIiar.OBJECTS OF THE INVESTIGATION-A weakness of nearly all previous researches, even the most thorough, has been to neglect full analysis of phosphomolybdate precipitates and to place too much reliance on the weight of the precipitate or on alkalimetric titration. It has been the aim of the present work to investigate the precipitation under a variety of conditions, altering one factor at a time while maintaining others constant ; and to analyse all precipitates by determination of molybdenum, phosphorus, and ammonium. chief difficulty encountered was due to the great disparity between the proportions of molyb- denum (about 60 per cent.) and those of phosphorus and ammonium (1.7 and 1 to 2-4 per cent. respectively) present in the dried ammonium phosphomolybdate precipitates.In view of the fact that these are hygroscopic, it was thought best to dissolve the whole and use aliquot portions of the same solution for all determinations; this procedure involved the use of semi-micro methods for phosphorus and ammonium. Phos@zorus-There is a paucity of good methods for determination of phosphorus even on the macro scale. The most famous, using magnesium pyrophosphate, suffers in accuracy from the small molecular weight of this compound as well as from other causes. For this reason, Dyer, fifty-five years ago, could already speak of "this old-fashioned method." Search was made in the literature for less common methods, and that of Cattelain and Chabrier37 was tried. In this method lead phosphate is precipitated and washed and then dissolved in a measured quantity of N nitric acid.Pb,(PO,), + 6HN03 + 3Pb(NO,), + 2H,PO, The authors state that this is a balanced reaction, but it is carried to completion by addition of N sulphuric acid, lead sulphate being precipitated. The excess of strong acids and the first stage of the liberated phosphoric acid are titrated with 0.1 N sodium hydroxide to the methyl orange end-point and titration is then continued to the phenolphthalein end-point, giving the second phosphoric stage. After much work, and substitution of bromocresol green and mixed phenolphthalein and a-naphtholphthalein for the older indicators, it was finally concluded that the method is not accurate on this scale (if, indeed, it is on the usual scale).The second end-point is quite indefinite, doubtless owing to metathesis between the lead sulphate precipitate and the sodium phosphate in solution. Though this line of attack failed, it suggested the determination of phosphorus gravi- metrically as lead phosphate, which is probably the least soluble of all phosphates and certainly one of the heaviest. Conditions of precipitation were investigated and it was found that the theoretical amount of lead acetate reagent added to a given amount of KH2P04 solution gave less than the theoretical amount of precipitate expressed as Pb,(PO,),. Addition of excess CHOICE OF METHODS FOR AKALYSING THE PRECIPITATES-In the choice Of methods the This method was tried first on a scale one-tenth that described.Dec., 19471 CONSTITUTION OF AMMONIUM PHOSPHOMOLYBDATE 533 of reagent incFeased the amount of precipitate up to a maximum at about 33 per cent.excess. This maximum does not seem to correspond to any simple stoicheiometric proportion, and the use of an empirical factor was adopted. Molybdenum-For determination of molybdenum the Jones reductor method was tried first, dissolving precipitates in ammonia and acidifying with sulphuric acid. This involves reduction of MoVI to Mom by passage of the acid solution through a specially packed column of amalgamated zinc into a ferric iron solution; an amount of iron equivalent to the Mom is reduced to the ferrous state and determined by titration against standard permanganate or dichromate. In spite of claims to the contrary by other analysts, the method appeared to be unsatisfactory. By the use of weaker acids it was found that while the highest pH that allowed satisfactory reduction without side-reactions was 1.6," reprecipitation of phosphomolybdate began when its ammoniacal solution was brought to $H 1.7" by addition of acid.Determination of molybdenum by means of 8-hydroxyquinoline ( o ~ i n e ) ~ ~ , ~ ~ was found to be completely satisfactory, and was adopted. Ammonium-Determination of ammonium by addition of sodium hydroxide, distillation, and micro-titration was finally rejected after very extensive trials. The precision was not satisfactory and much trouble was experienced through puncturing of the micro-still by the hot alkali. In spite of the criticisms of Kolthoff and other~,~O-~~ the hypobromite method was found to be completely satisfactory, even in presence of molybdenum ; it is also rapid and convenient.The ammonium is oxidised to nitrogen by the hypobromite and the excess of this caused to liberate iodine, which is titrated with thiosulphate.& A semimicro-scale version of the method was worked out and used in the analysis of phosphomolybdate precipitates (see p. 534). The various methods of analysis adopted were shown to be accurate when applied to known test-solutions (see Table I). Their aplication to the analyses of phosphomolybdate precipitates is described in detail in the following section. I TABLE I TESTING OF ANALYTICAL METHODS MOLYBDENUM-(" Oxine " gravimetric method)- Tested on ammonium molybdate solution (10 ml.) : Mo present: 0-1370 g.39 found: 0-1367 to 0.1369 (seven determinations) mean value 0.1368. AMMoNIun&-(Oxidation by hypobromite, volumetric method)- Tested on ammonium chloride solution (5 ml.) : Tested on ammonium molybdate solution (6 ml.) : found: 98.8, 98.4, 98-7, 97.8; mean 98.4% of the theoretical value. found : 99.0, 99.6 ; mean 99.3% of the theoretical value required by (NH,),Mo,O,~.~H,O. PHOSPHORUS-(" Lead phosphate " gravimetric method)- Tested on potassium dihydrogen phosphate (0.0160 g.) : mean 0.0517 g. i weight of precipitate: 0-0516 g. 0.0518 0-0519 0.0519 0-0515 empirical factor based on this mean value:- P/" Lead phosphate " = 0.07045. Several incidental investigations were involved in this search for analytical methods and are here briefly mentioned.The time and temperature needed to dry Gooch crucibles to constant weight, the conditions of use of desiccators of various kinds, and several methods of washing phosphomolybdate precipitates, were investigated with some care. Although the acidimetric methods for ammonium and phosphorus were finally rejected, considerable time was spent in a search for the most suitable indicators. * Calculated values.534 THISTLETHWAITE: THE DETERMINATION OF THE COMPOSITION AND pol. 72 PROCEDURE USED FOR THE ANALYSIS OF PHOSPHOMOLYBDATE PRECIPITATES In most of the experiments recorded in Tables I1 to IV the phosphomolybdate precipitates were obtained from the same quantity of potassium dihydrogen phosphate, 0.0320 g., and in the procedure described below the quantities of reagents mentioned are, except where other- wise stated, those found convenient for that quantity of precipitate.The precipitate, contained in a Gooch crucible, was dissolved in 20ml. of Nsodiunl acetate (pH 8.7) by standing the crucible in a filter funnel in the neck of a 100-ml. graduated flask and allowing portions of the acetate solution, alternating with water, to drain through, dissolution being assisted by stirring and scrubbing the walls of the crucible with a thin glass rod. The solution was then diluted to the mark, mixed and filtered (Solution A). For the determination of ammonium, a buffered hypobromite solution was prepared, twice daily, by adding to 10 ml. of 0.1 N bromine, or the equivalent acidified potassium bromide and bromate solution, sufficient sodium hydroxide solution to give a lemon-yellow colour, and after 1 hour adding 25 ml.of a borate buffer solution of pH 8.8 (prepared by dissolving 87.5 g. of boric acid and 14.6 g. of sodium hydroxide in 800 ml. of water, boiling for half hour to remove any trace of ammonia and diluting to 1 litre). After addition of the borate buffer the hypobromite solution was diluted to 100ml. with water freed from carbon dioxide. Ten ml. of this buffered hypobromite reagnet were added to 5 ml. of Solution A in a 100-ml. stoppered bottle, and after standing for 10 minutes in the dark, the mixture was treated with 1 g. of potassium iodide and 5 ml. of 2.5 N hydrochloric acid and the liberated iodine was titrated with 0.01 N sodium thiosulphate in presence of starch indicator. With each batch of tests a blank determination was carried out with 5 ml.of water containing the same amount of sodium acetate, in place of 5 ml. of Solution A. Results obtained by this method on standard solutions of ammonium chloride and ammonium molybdate are shown in Table I. One ml, of 0.01 N thiosulphate = 0~0000601 g. of NH,. For the determination of molybdenum and phosphorus, 50 ml. of Solution A were diluted with 50 to 75ml. of water and heated just to boiling. The flame was then removed and molybdenum was precipitated by dropwise addition, with continuous stirring, of a 2 per cent. oxine reagent prepared by dissolving 5 g. of 8-hydroxyquinoline in 22.3 ml. of glacial acetic acid diluted with a little water, adding a solution of 17.0g.of sodium acetate and diluting the mixture to 250ml. with water. The dropwise addition of the reagent was continued until a slightly yellow colour was imparted to the liquid and then about 0-5 ml. of the reagent was added in excess. The total volume of oxine reagent required for most of the phospho- molybdate precipitates analysed was 21.7 ml. After the addition of the reagent, the liquid was boiled gently for 3 minutes, with stirring, and the precipitate was collected in a tared Gooch crucible, washed 6 times on the filter with hot water and dried to constant weight at 130" to 140" C. Some results obtained on standard solutions of ammonium molybdate are shown in Table I. The filtrate and washings from the molybdenum precipitate were adjusted to approxi- mately @H 5.8 by addition of N sodium hydroxide. The volume required was 30 ml., pro- vided that 21.7 ml.of the oxine reagent had been used for'the molybdenum precipitation. When, owing to lower molybdenum contents, the volume of oxine reagent used was less than 21.7 ml. it was found convenient to make up the difference between the volume used and 21.7 ml. by addition of an " oxine buffer solution " similar in composition to the oxine reagent except that it contained no oxine. This ensured the presence of the same amount of acetate whatever the volume of oxine reagent used, so that the filtrate from the molybdenum precipi- tate could always be adjusted to $H 5.8 by addition of 30 ml. of N sodium hydroxide. After this adjustment had been made, the liquid was filtered and, at a volume of about 300 ml., heated to incipient boiling in a beaker.The flame was then removed and the phosphate was precipitated by addition of a solution containing 3 g. of AnalaR lead acetate in a litre of 0.01 N acetic acid ; the addition was made dropwise from a burette, with continuous stirring, over a period of 10 to 15 minutes. Where, owing to low phosphate content, less than 30 ml. of the lead acetate solution was used, the deficiency was made up with 0.01 N acetic acid, so that the $H during precipitation would always be the same. After precipitation, the liquid was heated at 90" to 100" C. for about half an hour and set aside overnight, and then the precipitate was collected in a Gooch crucible, washed 6 times with hot water and dried to constant weight at 130" to 140" C .Weight of precipitate x 0.07045 = weight of phosphorus. This is an empirical value. The quantity of lead acetate solution used for precipitation is about 33 per cent. greater than the amount calculated for the formation of Pb,(PO,), (cf. p. 533). Weight of precipitate x 0.2305 = weight of molybdenum.Dec., 19471 CONSTITUTION OF AMMONIUM PHOSPHOMOLYBDATE 535 FORMATION AND TREATMENT OF PHOSPHOMOLYBDATE PRECIPITATES The methods of analysis outlined above were used in a study of the conditions suitable for the formation and treatment of phosphomolybdate precipitates with a view to their determination by weighing ; among the factors investigated were the influence of the quantity of precipitant used, the temperature of precipitation, the nature of the washing solutions used and the conditions of drymg.TABLE I1 PHOSPHOMOLYBDATE PRECIPITATES Obtained from the same weight (0.032 g.) of KH,P04 by precipitation with different amounts of reagent Washed with acid potassium nitrate solution Expt. N O . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Reagent volume ml. 10 15 n 93 9) n 20 3) 93 ?9 n 9Y 25 Y Y Y Y 30 n 93 35 7) Y? n 40 n 9 ) 73 7) n 45 Y Y n 50 Mo/P moles, taken 9.4 14.0 33 ?7 71 9, 18.7 >Y Y Y ? ? 5, Y Y 23.4 99 Y7 28.1 n n 32.8 n n YY 37.4 %Y >Y Y Y Y ? Y7 42-1 n Y Y 46.8 PPt. obtained g- 0.0063 0.0932 0.1722 0.2770 0.3326 0.4521 0.4512 0.4475 0.4486 0.4554 0-4559 Analysis of precipitates h \ Mo ppt., P ppt., Mo/P €5 g. moles no precipitation occurred 0.0220 0.0279 0.0253 0.0220 0.2232 0.1567 0.1433 0.1511 0.0916 0.4535 0.4303 0-4420 0.4501 0.5776 0.5674 0.5714 0.5716 0-5776 0.5736 0.5801 0.5543 0.5668 0.5842 0.5740 0.5829 0.0026 0.0039 0.0194 0.0124 0.0118 0-0151 0.0091 0.0395 0.0367 0.0401 0.0397 0.0506 0.0501 04502 0.0508 0.0507 0.0502 0.051 1 0-0490 0.0499 0.0526 0*0500 0.0509 (mean value of five precipitates) 10-7 6-0 12.4 134 12.8 10-6 10.6 12.1 12.4 11.6 12.0 12.1 12.0 12.0 11.9 12.0 12-1 12.0 11.9 12.0 11.7 12.1 12.1 NW4 thio., ml.0.12 0.13 0.19 0.17 1-71 1.35 1.25 1.21 0.72 3-00 2.86 3.57 3.44 3.50 3-45 3-12 3.58 4.08 3.90 3.74 3.60 3-51 3.47 3.66 3-69 Mo/NH, moles 13.3 15-5 9.6 9.4 9.4 8.4 8.3 9.0 9.2 10.9 10.9 9.0 9-5 11.9 11.9 13-2 11.6 10.2 10.6 11.2 11.1 11.7 12.2 11.7 11.6 Theory = 4 Formation of phosfihomolybdate precipitates-The method of precipitation was in the first place chosen arbitrarily after a thorough study of the best known methods; it was modified somewhat in the light of experience but its main features were justified by the results obtained.AnalaR potassium dihydrogen phosphate was used as the source of phosphorus. Being subject to mould growth, its solutions were prepared afresh every 2 or 3, weeks. The acid ammonium molybdate reagent was prepared in accordance with a formula kindly supplied by Dr. A. D. Mitchell (see Appendix). It is very stable and develops no turbidity on being heated for several hours at 57" C., even in presence of molybdic acid nuclei. Precipitation was carried out in a large water bath maintained at constant temperature.The phosphate solution mixed with 8ml. of concentrated nitric acid, 100ml. in all, was536 THISTLETHWAITE : THE DETERMINATION OF THE COMPOSITION AND [Vd. 72 contained in a beaker and the reagent (50ml.) was added in a fine stream from a burette, with continuous stirring. The time of outflow was 7 minutes. The mixture was kept at the bath temperature for 75 minutes and then allowed to cool for 60 minutes. Filtration and washing-The precipitates were washed three times by decantation, collected in Gooch or sintered-glass crucibles and washed six times more in the crucibles. In the earlier experiments, including all those summarised in Tables I1 and 111, the washing solution used was one containing 0.5 per cent. of nitric acid and 1 per cent. of potas- sium nitrate; as ammonium was to be determined in the precipitates it was not considered advisable to have an ammonium salt in the washing solution. The results indicated, however, that the potassium in the washing solution displaced most of the ammonium from the precipi- tate.' In later experiments, therefore, a washing solution containing 0.5 per cent. of nitric TABLE I11 PHOSPHOMOLYBDATE PRECIPITATES Obtained from the same weight (0-032 g.) of KH,PO, by precipitation at various temperatures Washed with acid potassium nitrate solution Analysis of precipitates f A Expt. No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Pptn. temp. O c. 15 >I It 30 I* tt 40 It It 50 It 19 It I9 It 61 I9 I¶ 70 I9 I t 77 n I* PPt. ob tamed €5 0.4342 0.4374 0-4488 0.4568 0.4650 0.4560 0-4564 0-4550 0.4622 >!lo ppt., g .0-5570 0-5154 0.5279 0.5701 0-5801 0.5806 0.5795 0.5861 0-5824 0-5832 0-5831 0.5836 0.5824 0-5869 0.5839 0.5833 0.5865 0.5867 0.5916 0.6085 p PPt.8 g . 0.049 1 0.0436 0.0455 0.0501 0.0513 0.0504 0.0507 0.051 1 0.0503 0.0506 0.05 10 0.0516 0.0505 0.0516 0-0513 0.0507 0.0504 0.0506 0.0520 0.0518 Mo/P moles 12.0 12.5 12.3 12.0 12.0 12.2 12.1 12.1 12.2 12.2 12.1 11.9 12.2 12.0 12.0 12.2 12.3 12.3 12-0 12-4 NH, thio., ml. 3-76 2.86 2-81 3-17 2.91 3.49 3.66 3.86 3.46 3.47 3.86 3.61 3.88 3-22 3.40 3.77 4-13 4.26 4.54 4.6 1 *Xo/NH, moles 10.7 13.0 13.3 13.0 14.4 12.0 11-8 11.0 12.2 12.1 10.9 11.7 10.9 13.2 12.4 11.2 10.3 10.0 9.4 9.5 Mean ratios (all) .. .. .. 12.15 .. .. . . 11.7 ,, ,, (50°C.) .. .... 12.1 . . .. . . 11-5 acid and 0.8 per cent. of ammonium nitrate was used, and a final wash was given with a 1 per cent. solution of nitric acid. This method of washing was used in the experiments summarised in Table IV and is recommended in the Appendix. Estimations of the solubility of freshly prepared phosphomolybdate precipitates in various possible washing liquids were made. In each test, the precipitate from 0.032 g. of potassium dihydrogen phosphate, after being washed with the particular solution under test, was transferred to a large volume of similar solution and left for several days, with occasional shaking. The clear filtered extract was evaporated to small volume and, if acid, neutralised with sodium hydroxide solution. After buffering with 10 ml.of N sodium acetate, deter- minations were made of molybdenum and phosphorus by the methods described on p. 534. From the molybdenum values the weights of phosphomolybdate dissolved by 100 ml. of theDec., 19471 CONSTITUTION OF AMMONIUM PHOSPHOMOLYBDATE 537 solutions tested were calculated. replicate results. They are as follows and are averages of closely concordant Solution containing 1 yo *of HNO,--26-2 mg. per 100 ml. > J J Y ,, ,, 0.5% of HNO, and 1% of KNO,--6.9 mg. per 100 ml. 0.5y0 of HNO, and O.SyO of NH,NO3--O.8 mg. per 100 ml. J J ,, O.SyO of NH,NO,--6.2 mg. per 100 ml. An attempt was made to estimate the losses actually incurred in washing with the acid ammonium nitrate and nitric acid solutions as recommended in the Appendix. The washings (except the first) from 30 precipitates, 2560 ml.in all, were evaporated to 60 ml. and the molyb- denum and phosphorus present were determined as before. The former indicated 26.5 mg. and the latter 32 mg. of phosphomolybdate, i.e., a loss of about 1 mg. of precipitate (= 0-016 mg. of phosphorus) per determination. Drying of jwecipitates-Seven methods of drying were used, five at room temperature in desiccators, with or without evacuation, and two in an electric oven, at 115" C. or at 130" to 140" C. The oven method at 130" to 140" C. was adopted for most of the determinations. Sintered-glass crucibles were dried for 29 hours and Gooch crucibles for 8 hours at this tempera- ture, and the Same times were used in taring the empty crucibles. Both kinds were allowed to cool for 25 minutes in small desiccators containing sulphuric acid, one crucible to each desiccator.The main results of the investigations outlined above are summarised in Tables I1 to IV. Weighing was as rapid as possible , with pre-selected weights. TABLE IV PHOSPHOMOLYBDATE PRECIPITATES Obtained under various conditions Washed with acid ammonium nitrate solution -4. Air-drying at 130" C. Analysis of precipitates KH2P04 Upt. ,- A \ taken obtained Moppt., Mo Pppt., P Mo/P NH,thio., NH, €5 g- g. Y O g. yo moles ml. % (7) 0.032 0.4401 0.5853 61-32 0.0522 1-67 11-85 8-89 2-41 Mo/NH4=4.8 (4) 0*032* 0.4401 0.5844 61-23 0.0517 1-65 11.95 8.88 2.41 }Theory = 4 (3) 0.016 0.2213 0.2961 61.68 0-0270 1.72 11.6 4-32 2.35 (4) 0.0064 0.0882 0.1206 63.0 (3) 0.0032 0.0446 0.0621 64.3 B.Drying in vacuo at room temperature 0.033 g. of KH,P04 taken in all cases Desiccant (1) H,SO, 04415 0-5865 61.26 0.0522 1-67 11.9 8-79 2.39 (2) P,O, 0.4414 0.5854 61-14 (4) H2S04 0.4413 0-5842 61-08 0.0517 1.65 11.95 5.81 2-40 & KOH Precipitate allowed to stand overnight at room temperature before filtration. STATEMENT AND DISCUSSION OF RESULTS Tabb II-These results were obtained with varying mounts of molybdate reagent, They show: (a) the necessity for at least 3.5 times the theoretical amount of molybdate for complete precipitation ; (b) that although precipitation is incomplete with less than this amount, the molybde- num/phosphorus ratio in the precipitates remains practically constant. (c) that washing with potassium nitrate solution causes base exchange ; apparently two of the three ammonium ions are replaced by potassium ions.Table 111-The only variable here is temperature of precipitation. The following points emerge : (a) precipitation is incomplete below 50" C . ; (6) the ratio molybdenum /phosphorus in the precipitates is constant for all temperatures of precipitation within the range examined; (c) decomposition of the reagent and co-precipitation of molybdenum occur above 70" C . ; ( d ) the base exchange phenomenon noted previously is confirmed. all other conditions remaining the same.538 THISTLETHWAITE : THE DETERMINATION OF THE COMPOSITION AND [vol. 72 Table IV @)-this shows the effect of decreasing the amount of phosphorus to be pre- cipitated while maintaining constant the amount of molybdate reagent and other factors.The bracketed numbers on the left indicate the number. of replicate determinations made. The results show : (a) that although the extreme variation in the molybdenum content of the precipitates is about 5 per cent., the variation in weight of the precipitates is much less (not more than 1.5 per cent.) ; ( b ) that the mean weight of precipitate obtained from 0.032 g. of KH,PO, is close to the theoretical value, 0.4412 g., calculated from Hundeshagen’s second formula, and that the weighted mean of all the 21 results shown is 0.4415 g. calculated to the same basis; (c) that the mean weight of molybdenum oxinate corresponding to 0.032 g. of KH,PO, is 0.5850 g. (theoretical value 0-5873 g.) ; ( d ) that although the precipitates were washed with acid ammonium nitrate solution the amount of ammonium ion found in these precipitates is only about 5/6th of the theoretical, suggesting that the precipitate may be (NH4)3P04.(NH4),HP0,.24MoO, ; this is surprising in view of the apparent agreement with Hundeshagen’s formula in (b) and (c) above ; (e) that a longer time of standing has little or no influence on the amount or composition of the precipitate (second line of Table). Table IV (23)-This gives a few results obtained on precipitates dried by various desiccator methods : the results are close to those obtained by heat-drying, any slight differences being too small to be of stoicheiometric significance. This raises the question whether Hundeshagen’s first formula, including the nitric acid and water addenda, is correct; the point has not yet been tested directly. CONCLUSIONS Taking theoretical aspects first, the data obtained cast some doubt upon the correctness of Hundeshagen’s famous formulae, but in view of the readiness with which base exchange occurs during washing with quite dilute solutions, it is impossible to speak with certainty on this point.The practical conclusions are that phosphorus can be accurately determined gravi- metrically as ammonium phosphomolybdate if precipitation is carried out at 50” C., using at least 3-5 times the theoretical amount of molybdate reagent, and if suitable methods of wash- ing and drying are employed; and that determination of the molybdenum in the precipitate as oxinate provides a check which is superior in convenience, speed and accuracy to the usual magnesium pyrophosphate method. Attempts have also been made to find a method more economical of molybdenum, but so far without success.The influence of foreign substances on precipitation has not yet been investigated. APPENDIX PROCEDURE RECOMMENDED FOR THE DETERMINATION OF PHOSPHATE IN AN UNKNOWN SOLUTION Reagents- 1. Concentrated nitric acid (AnalaR) . 2. Acid molybdate solution-Dissolve 35. g. of finely powdered AnalaR ammonium Dilute 168 ml. Pour the molybdate Very Allow to stand at least 24 hours, dilute to 9OOml. Preserve in wax-lined bottles to prevent formation of silicomolybdate. 3. Acid ammonium nitrate wash liquid-Dissolve 20 g. of AnalaR ammonium nitrate in 4. Nitric acid wash liquid-Dilute 25 ml. of concentrated nitric acid with water to 2.5 Filter crzlcibles-Use either the finest grade sintered glass crucible or a Gooch crucible Half fill with the usual asbestos suspension, well-fixed; drain slowly molybdate in a mixture of 50 ml.of “04380” ammonia and 50 ml. of water. of concentrated nitric acid with water to 360ml. and allow to cool. solution into the nitric acid in a thin stream and with constant stirring or swirling. little or no precipitation should occur. with water and filter. If any precipitate develops later, filter immediately before using. water, add 12.5 ml. of concentrated nitric acid and make up to 2.5 litres. lit res. prepared as follows.Dec., 19471 CONSTITUTION OF AMMONIUM PHOSPHOMOLYBDATE 539 and apply gentle suction. Relax the suction and pour in a little more of the suspension, after allowing the coarser particles to settle; apply strong suction.In this way a filter surface of fine grain is obtained. Wash five or six times with the nitric acid wash liquid, wipe the outside of the crucible and dry to constant weight at 130" C., cooling in a sulphuric acid desiccator 25 minutes before weighing. To prepare sintered-glass crucibles, wash once or twice with the nitric acid and dry as above. Both kinds of filter are readily cleaned with dilute ammonia after use. Procedure-The phosphate solution should contain not more than 0.007 g. of phosphorus and its volume should not exceed 90 ml. Add 8 ml. of concentrated nitric acid, dilute with water to 100 ml. and heat to 50" 3- 1" C. in a water bath.If this is large enough and if a shielded flame is used there is no need for thermostatic control. Add the molybdate reagent (5O.ml.) from burette slowly (time of outflow 7 to 10 minutes), with constant stirring. This allows for at least 3-5 times the theoretical amount of molybdenum. Allow the mixture to remain in the water bath at the same temperature for 75 minutes. Remove, stir once, and allow to stand in a cool place for at least 1 hour. Decant the mother liquor into the filter as completely as possible. Add to the precipitate about 15ml. of the ammonium nitrate wash liquid and allow to stand about 5 minutes, stirring 4 to 5 times during that period; allow to settle and decant again. Wash by decanta- tion twice more with 10-ml. portions, allowing short periods of standing and stirring. Transfer the precipitate to the filter, wash 6 times with the same wash, filling the crucible half-full each time and using gentle suction.Wash once with the nitric acid wash liquid, again filling about half full, and finally with about 1 ml. of the same solution. Suck dry, wipe the outside of the crucible, and dry at 130" to 140" C. for at least 4 hours (8 hours if a Gooch crucible is used) , cool for 25 minutes in a sulphuric acid desiccator and weigh as rapidly as possible. Heat again until constant weight is attained, pre-selecting the weights to ensure rapidity of weighing ; the precipitate is very hygroscopic. The weight of precipitate multiplied by 0.01654 gives the weight of phosphorus present in grams. N.B.-The acid in the desiccator must be kept concentrated and colourless.This is not difficult if the times of opening to insert or remove crucibles are kept as short as possible. Suck as dry as possible after the last wash. The work recorded in this paper was carried out in the Frankland Laboratories at the University of Birmingham. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. BIBLIOGRAPHY Svanberg, L., and Struve, H., J . pyakt. Chem., 1849,44, 257. Rose, H., Pogg. Ann., 1849, 76, 1. Sonnenschein, L., J . prakt. Chem., 1851, 53, 339. Seligsohn, M., Ibid., 1856, 67, 470. Debray, Comptes rend., 1858, 46, 1098. Rammelsberg, Ber., 1877, 10, 1776. Finkener, Bey., 1878, 11, 1638. Pemberton, H., Chem. News, 1882, 46, 4 . Gibbs, W., Amer.Chem. J.. 1882, 3, 317. Pemberton, H., J . Arner. Chem. Soc., 1893, 15, 382; 1895, 17, 178. Hundeshagen, F., 2. anal. Chem., 1889, 28, 141. Lorenz, N. von, Landw. Versuchs-Stat., 1901, 55, 183. Naumann, A., 2. physiol. Chem., 1902, 37, 15. Woy, R., Chew.-Zeit., 1897, 21, 441, 469. Brearley, H., and Ibbotson, F., Chem. News, 1900, 82, 55; 1901, 83, 122. Richards, M. B., and Godden, W., ANALYST, 1924, 49, 565. Cameron, A. M., and DOW, W. T., Ibid., 1927, 52, 576. Birnbaum, N., and Walden, G. H., jun., J . Amer. Chew?. Soc., 1938, 60, 66. Pemberton, H., Chem. News, 1882, 46, 4. Meineke, C., 2. angew. Chem., 1888, 1, 68. Charpy, G., 2e. CongrBs. Intl. de Chim. ApPl. 111, 379. Hibbard, P. L., J . Ind. Eng. Chem., 1913, 5 , 998. Kilgore, B. W., J . Amer. Chem.Soc., 1899, 17, 950. Feigl, F., 2. anal. Chem., 1928, 74, 386. Dinan, M., Monit. scient., 1905, 4, 19, 94. Schindler, C., 2. anal. Chem., 1888, 27, 142. Lipowitz, Ann. Phys. Chenz., 1860, 109, 135. Baxter, G. P., Amer. Chern. J., 1902, 28, 298. Baxter, G. P., and Griffin, R. C . , Ibid., 1905, 34, 204.540 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. THISTLETHWAITE AMMONIUM PHOSPHOMOLYBDATE Gregerson, J . P., 2. physiol. Cheaz., 1906, 53, 463. Chesneau, G., Revzte de Me'tall., 1908, 5, 237. Clarens, J., Bull. SOC. Chim., 1918, 23, 147. Clennell, J. E., MiningiMag., 1921, 24, 151. EndrCdy, A. von, 2. anorg. Chen?., 1930, 194, 239. Kitajima, S., Sci. Papers, Inst. Phys. Chem. Reseavch, Tokyo, 1931, 16, 286. Illingworth, J. W., and Keggin, J. F., J .Chem. SOL, 1935, 575-80. Cattelain, E., and Chabrier, P., Cowzpfes wnrl., 1937, 205, 19. Berg, F., Z. anal. Chein., 1937, 71, 23. Balanescu, C., Ann. Chin?. dnalyt., 1!330, [2], 12, 470. Artmann, P., and Skrabal, A., Z. anal. Chew., 1907, 46, 5 . Kolthoff, I. M., and Laur, A., Ibid., 1938, 73, 177. Kolthoff, I. M., and Stenger, V. A, l n d . Eng. Chewt., Anal. Ed., 1935, 7, 79. Ostwald and Kaich, Z. physikal Chenr., 1888, 2, 125. [Vol. 72 MERCHANT VENTURERS TECHNICAL COLLEGE BRISTOL, 1 DISC u ss I o x The PRESIDENT congratulated the author on a very useful piece of work dealing with one of the most widely used of analytical methods. He asked the author what advantages the weighing of the phospho- molybdate precipitate had over its determination by a volumetric method. Mr. A. H. EDWARDS said that during the standardisation of a method, now accepted as a British Standard, for the determination of phosphorus in coal and coke ash, he had determined the factor required to convert ml. of 0.1 N sodium hydroxide to phosphorus. The factor, 1 ml. of 0.1 N sodium hydroxide = 0.000135 g. P, which was found by precipitating ammonium phosphomolybdate from disodium hydrogen phosphate, agreed with that calculated from the equation The phosphomolybdate precipitate was washed with 1 per cent. potassium nitrate solution and it seemed that under these conditions no exchange of potassium for ammonium radicals occur, otherwise a different conversion factor would have been obtained. Hundeshagen's formula for ammonium phosphomolybdate, (NH4),P0,.12Mo03.2HN03.2H,0, was, therefore, probably correct, and during washing with neutral potassium nitrate solution the nitric acid and water were removed from the precipitate. Mr. THISTLETHWAITE, in reply to the President, claimed that alkalimetric methods involve more variable factors-for example, uncertainty as to the exact number of phosphoric hydrogen ions replaced, possible loss of ammonia, interference by carbon dioxide-than his gravimetric method. 2[(NH4),P0,.12M00,] + 46NaOH -+ 2Na,HPO, + 21N+MoO, + 3(NH,),Mo04 + 22H,O. In reply to Mr, Edwards, he pointed out that the equation- 2 [K,NH,P04.12M00,] + 46NaOH --> 2N&HP04 + 21N&MoO, + 2K,Mo04 +'(NH,),MoO, + 3dIi,O, which assumes the base exchange indicated by his own results (Tables I1 and 111) would give exactly the same conversion factor as Mr. Edwards's equation. In other words, alkalimetric titration of this type could not decide the question of base exchange, though an alkalimetric titration of the Neumann type (where the ammonium ions are replaced by sodium and the ammonia boiled off) could do so. Regarding Hundeshagen's equations, Mr. Thistlethwaite emphasised again that these could not be regarded as sacrosanct. Although the first one (without the nitric acid and water addenda) was based on full analysis by methods which Hundeshagen described in great detail, strangely enough he did not give any actual results of these analyses. It was really incredible that chemists ever since should have accepted this formula in the absence of the all-important experimental evidence. As t o the second formula, the existence of the 2HN03 was inferred solely from alkalimetric titrations, in which the number of equivalents of NaOH used varied from 23.14 to 23.46 for the heat-dried compound and from 25-28 to 25-43 for the desiccator-dried compound. Surely no chemist to-day would accept figures of such lon- precision and so far from whole numbers as definite proof of any formula.

ISSN:0003-2654    

DOI:10.1039/AN9477200531

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 Dec., 19471 SOTES 641 Notes THE ZINC URATE OXIDATION REACTION: A SELECTIVE TEST FOR ZIXC MANY samples of normal urine, when made slightly alkaline and oxidised by iodine, develop a red-purple colour that is deepened and stabilised by zinc.The chromogen has been found to be associated with the urochrome complex (Godfriedl). In the course of a study of this reaction, the existence of a second chromogen that developed a blue colour was observed. It proved to be uric acid, and the reaction to which it gave rise was found to provide a delicate and selective test for zinc. TEST CONDITIONS-About 20 mg. of finely-powdered uric acid are suspended in 4 ml. of a dilute (0.1 to 0.2 per cent.) zinc solution, and made moderately alkaline by addition of 2 to 4 drops (not more) of 20 per cent. sodium hydroxide solution. The mixture is well shaken, and then oxidised by gradual addition of 2 per cent. iodine in iodide solution, until the colour of the halogen just persists.The presence of Zn" is shown by the appearance of a pure blue colour, which remains when sufficient of the osidiser has been added. I t will not work in alkaline solutions at $H values below 12, and its delicacy is impaired by excess bf strong hydroxides, which immobilise the metal as a zincate. When the unoxidised uric acid is in excess the colour fades, but can be restored by addition of more oxidiser, to which it is remarkably stable. The test will shorn Zn" in concentrations down to about 1 in 10,000. Below this, the pale yellow of the iodine is apt to obscure the reaction, and hypochlorite is then preferable as an oxidiser. In concentrated solutions, the pigment separates out along with the zinc hydroxide. It is insoluble in all the common organic solvents, is reversibly bleached by mild reducing agents (including uric acid in alkaline solution) and is irreversibly discharged by weak acids.The test is of interest in being selective for uric acid and for zinc ; no other substances have as yet been found capable of replacing either of the reactants. EARLY HISTORY-In 1908, Ganassini2 observed that when a strongly alkaline solution of uric acid is saturated with potassium persulphate and treated with a slight excess of 10 per cent. zinc sulphate solution until the precipitate no longer redissolves, it gradually acquires a blue-green colour. In this form, the test will reveal uric acid down to 0.01 per cent., and may be applied to urine by filtering off the pigmented zinc precipitate. Exposure to bromine, chlorine or sunlight hastens colour development on the moist precipitate.Vitalis reported that sodium peroxide was the only oxidiser capable of replacing the persulphate, and that zinc was the only metal that gave a blue pigment, although colours ranging from green to violet were given by Cu", Co", and Ni". MECHANISM-The component of the pigment provided by the uric acid is elusive. Ganassini obtained negative results with all the other common purines, and some other nitrogenous compounds, namely : adenine, guanine, xanthine, hypoxanthine, heteroxanthine, paraxanthine, 3-methyl xanthine, 1 : 7-dimethyl xanthine, caffeine, theobromine, theophylline, nuclein, nucleic acid, alloxan, alloxanthin, allantoin, creatine, creatinine, glycine, tyrosine, leucine, hippuric acid and urea.The form of the reaction with iodine as oxidiser was found to be negative with these compounds (excluding the substituted xanthines, which were not available), and with the recognised products of uric acid oxidation and related compounds, namely : 4: 5-dihydroxy- 4 : 5-dihydro-uric acid (uric acid glycol), dialuric acid, carbonyl diurea, cyanuric acid, cyame- lide, allantoxanic acid, allantoic acid, allophanic acid, parabanic acid, violuric acid, barbituric acid, uracil, 5-amino uracil, biuret, arginine, guanidine, histidine, cyanate and carbamate. The uric oxidation derivatives were prepared according to the methods of Venables and Application of the test at various stages during the oxidation of uric acid by liver uricase failed to show any production of the blue pigment, in absence of an external oxidiser.When adsorbed on the zinc precipitate, and washed free from contami- nants, the pigment is stable indefinitely to light and air, and in some respects resembles a metallo-porphyrin type of compound. When it is decomposed by acid, urea is the only nitrogenous product so far identified. This suggested that the pigment might be a zinc allophanate, but allophanate prepared by mild alkaline hydrolysis of the ethvl ester failed to give any colour with zinc, under a variety of conditions. Incidentally, of all the compounds tested, only two reacted chromatically, namely dialuric acid and uric acid glycol, both of Bromine water or hypochlorite is equally effective. The test is tricky. and Biltz and Klemm.5542 NOTES [Vol.72 which in neutral or alkaline solution gave with zinc a yellow colour that, unlike the blue pigment, was reversibly bleached by acidification. In its present form, the test is selective for zinc. No colour reactions were obtained with uric acid and any of the other common metallic cations, including: Al, Ba, Be, Ca, Cd, Ce, Fe, Hg, La, Li, Mg, Pb, Se, Sn, Sr, Ti, U and Zr. Some samples of cadmium gave a slight blue reaction, but this was traced to contamination with zinc. The colour reactions recorded by Vitali for Cu, Co, and Ni belong to a different category in that they are given by alkaline urate directly, without the need for an added oxidiser, and they are reversibly discharged by acidification. Silver and manganese also undergo characteristic colour changes, involving reduction, when added to alkaline urate. REFEREXES 1.2. 3. 4. 5. DEPARTXENT OF BIOCHEMISTRY W. R. FEARON TRINITY COLLEGE, DUBLIN May, 1947 Godfried, E. J., Biochem. J., 1935, 29, 1340. Ganassini. D., Boll. chim. Farm., 1908, 47, 715. Vitali, D., Ibid., 1911, 50, 799. Venables, C. S., and Moore, F. J., J . Amer. Chem. Soc., 1917, 39, 1750; 1918, 40, 1099, 1120. Biltz, H., and Klemm, W., Annalen, 1926, 448, 134. A MICRO FILTER THIMBLE ALTHOUGH paper is the most widely employed filtering material1 its use in the form of a thimble appears to have been suggested only by Mack and Hecht,* who describe the method of preparing a small thimble by folding ordinary filter paper. In view of the difficulty of folding a paper in this way, we have designed a micro thimble which may be manufactured as a seamless cvlinder of Whatman paper closed at one end Fig.1. I:! as shown i n Fig. I.* The thimble is 10 mm. long and 5 mm. in diameter and weighs about 0.02 g. The thimble may be employed to filter small amounts of liquid by inserting it in a cylindrical funnel as shown in Fig. 2. For the filtration of solutions by suction, the thimble is fitted over the end of quill or capillary tubing so that the arrangement can be used as an immersion filter or “filter-stick.” To avoid tearing of the paper, the end of the glass tube should be ‘ I fire-polished,” and the thimble worked on with a rotary motion. The curved bottom of the thimble affords additional strength, and solutions .Fig. 2. may be filtered very rapidly without dakaging the paper.Provided the dry thimble fits tightly on the glass, the slight swelling which occurs in water ensures that there is no passage of the solid particles between the glass and the paper. The thimble is easily removed from the end of the tube and can be used several times. A micro thimble of this kind has many other applications in microchemical, biological and general laboratory work. REFERENCES 1. Wyatt, G. H., ANALYST, 1946, 71, 124. 2. Mack, M. v., and Hecht, F., Microchem. Acta, 1937, 2, 228. UNIVERSITY COLLEGE S. T. BOWDEN CARDIFF February, 1946 THE FORMATION OF RACEMIC CALCIUM TARTRATE IN WINES IN the course of studies on the formation of crystalline deposits in wine, it was observed that when old wines were being examined the crystalline deposit was usually composed almost entirely of calcium tartrate, and that this salt was not dextrorotatory as is the rest of the tartaric acid content of wines, but was optically inactive racemic calcium tartrate.Various anomalies have been observed in the past, and the laws governing the deposition of crystallisable substances from solution, when applied to wines, seemed not to hold ; these anomalies were ascribed to the phenomena of “seeding” and supersaturation. When it is appreciated that the dextrorotatory tartaric acid of the wine gradually changes to the optically * Made to the above design by arrangement with Messrs. H. Reeve, Angel & Co., Ltd., 9, Bridewell Place, Lqndon, E.C.4.Dec., 19471 MINISTRY OF FOOD 543 inactive compound and that the solubility of the calcium salt of this acid is very low, the anomalies are rationally explained. The solubilities of the various isomers are given as: Dextro calcium tartrate .. 0.023 g. per 100 ml. Laevo ,, ,, . . 0.025 ,, ,, ,, ,, Racemic ,, > t . . 0.003 ,, ,, ,, ,, The differences between the solubilities of the various optical isomers of potassium hydrogen tartrate are not sufficiently large to have any effect on the production of crystalline deposits; although this substance is usually of importance in this connection, it behaves normally. The typical crystalline form of racemic calcium tartrate can be reproduced by adding racemic tartaric acid to a wine, and the crystals then formed resemble those found naturally in the older wines. The racemic salts can be easily made by heating the dextrorotatory salts with excess of potassium hydroxide in an oven at 150" C.for 2 hours. The rate of formation of racemic tartaric acid in wines is dependent in the majority of cases almost exclusively on the temperature at which the wine is stored and the amount of tartrate radical present. The salts of racemic tartaric acid are less soluble at low temperatures, and their concentration can be reduced by Tefrigeration. If the wine is cooled to O O C . , as is normal practice for wineries using refrigeration methods, the concentration of racemic calcium tartrate is reduced by precipitation. If the wine is subsequently stored at a low temperature the rate of formation will naturally be small, and if it is stored at normal temperatures the time taken to produce enough of the optically inactive acid to raise the concentration of the calcium salt higher than the limit of its solubility, is between 6 and 9 months. Summary-The natural dextrorotatory tartaric acid of wines undergoes auto-racemisation to produce the optically inactive acid, whose calcium salt is sparingly soluble and forms crystalline deposits. Certain solubilities are given and the practical implications discussed. THE LABORATORIES VINE PRODUCTS LIMITED A. CAMB~TZI KINGSTON ON THAMES April, 1947 Official Appointments OFFICIAL AGRICULTURAL ANALYST APPOINTNENTS NOTIFICATION of the following appointments has been received from the Ministry of Agriculture and Fisheries since the last record in THE ANALYST (1947, 72, 397). Ojicial Agricultuval Analyst A ppointniants HERON, Neil (Deputy) . . County Boroughs of Birkenhead, Blackburn, Bootle and Southport.

ISSN:0003-2654    

DOI:10.1039/AN9477200541

出版商:RSC    

年代:1947

数据来源: RSC