ISSN:0003-2654    

DOI:10.1039/AN94772FX005

出版商:RSC    

年代:1947

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94772BX007

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 FEBRUARY, 1947 THE ANALYST Vol. 72, No. 851 PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS PHYSICAL METHODS GROUP THE Second Annual General Meeting of the Group was held at 6 p.m. on Tuesday, November 26th, 1946, in the rooms of the Chemical Society, Burlington House, London, W.l. The Group Chairman, Mr.R. C. Chirnside, presided, and 32 members were present. The Com- mittee’s Report and the Financial Statement were presented and adopted. The Officers and pembers of Committee for the forthcoming year are as follows. Chairman, Mr. R. C. Chirnside. Honorary Secretary, Dr. J. E. Page.* Committee, Mr. B. S . Cooper, Dr. J. R. Edisbury, Mr. J. Haslam, Dr. S. Judd Lewis, Mr. D. M. Smith, Dr. F. Wokes and, ex-oficio, the President, Honorary Treasurer and Honorary Secretary of the Society and the Editor of THE ANALYST. Mr. C. A. Bassett and Dr. D. C. Garrett were reappointed Honorary Auditors. Vice-chairman, Dr. J. G. A. Griffiths. POLAROGRAPHIC DISCUSSION PANEL The Chairman said that the Group Committee had decided to form a Polarographic Discussion Panel, the objects of which would be to hold and sponsor informal discussions on polarographic analysis.Draft rules of the panel had been approved by the Committee of the Group and the Council of the Society. The following members were elected to serve on the Committee of the Panel: Dr. W. Cule Davies, Mr. J. Haslam and Mr. J. T. Stockt (Honorary Secretary) , with Dr. J. E. Page as the representative of the Group Committee. ORDINARY MEETING Immediately following the Annual General Meeting, an Ordinary Meeting of the Group was held, at which about eighty members and visitors were present. The following papers on the subject of Polarographic Analysis were presented and discussed : “Amperometric Titrations,” by J. T. Stock, M.Sc., F.R.I.C. ; “The Rotating Platinum Electrode,” by C. J. 0. R. Morris, B.Sc., Ph.D. ; “The Application of the Cathode Ray Oscillograph to Polarography,” by J. E. B. Kandles, M.A., B.Sc., and L. Airey, B.Sc., who demonstrated their apparatus. SCOTTISH SECTION A MEETING of the Scottish Section was held at the N.B. Station Hotel, Glasgow, on Friday, November 29th, 1946. Mr. James A. Hunter presented a paper on “A Semimicro-Method for the Determination of Magnesium,” which he hopes later to submit for publication in THE ANALYST. Dr. C. W. Herd, B.Sc., F.R.I.C., presented “Some Observations on the new Ice Cream Order” as a basis for discussion on the subject of the Order. DEATHS Joseph John Blackie Robert Selby Morrell WE regret to record the death of * Address : Glaxo Laboratories Ltd., Greenford, Middlesex. t Address : Chemistry Department, L.C.C. Norwood Technical Institute, Knight’s Hill, London, S.E.27. 35

ISSN:0003-2654    

DOI:10.1039/AN9477200035

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-ction 36 OBITUARY: W.H. ROBERTS Obituary PROFESSOR W. H. ROBERTS WILLIAM HENRY ROBERTS was born in Liverpool on January l l t h , 1877. He was educated a t Liverpool College and University College, Liverpool, where he studied under Professor Campbell Brown. Having taken his B.Sc. degree at Victoria University he proceeded to the M.Sc. a t Victoria and Liverpool University, and in 1902 he passed the examination for the Associateship of the Institute of Chemistry. On leaving the University, Roberts became assistant to Campbell Brown, who was not only Professor of Chemistry but also Public Analyst to the County of Lancaster. On the death of Campbell Brown the County appointment was given to Mr.Collingwood Williams-still with us-who had held the Liverpool City Analyst’s post and, as the City was contemplating the building of new City Laboratories, considerable discussion took place as to who was able to undertake satisfactorily the duties of City Analyst to Liverpool. Eventually, despite expressed doubts, Roberts was chosen and he was given as his Deputy the late Mr. E. Gabriel Jones. One of his first tasks was to plan and equip the new laboratories, which were, and are, the admiration of everyone privileged to inspect them. Those who had doubted the wisdom of the appointment were speedily converted when they saw the amazing administrative ability that the new Analyst possessed. Roberts soon gathered round him a loyal band of able young chemists, by whom he was affectionately known as “The Chief ,” an appellation that later generations sometimes expanded to “The Great White Chief.” The laboratories were in a new building which housed also the School of Hygiene and the City Bacteriological Laboratories, and qualified medical men reading for the D.P.H.diploma attended lectures there. I t was almost in- evitable that Roberts should be asked to lecture on Public Health Chemistry, and the University regularised the appointment by making him an Associate Professor. He was allowed to use the laboratories for Public Analyst work-for other towns and boroughs and held the appointments of Public Analyst for the County Boroughs of Barrow- in-Furness, Birkenhead, Blackburn, Bootle, Preston and Southport and the Boroughs of Crosby, Kendal and Widnes. He was also permitted to undertake analytical and consultative work for private firms and individuals, and the assistance that he gave to commercial enter- prises still further enhanced his influence and gained a desirable publicity for the laboratories.In 1934 he was made a Vice-president and in 1938 President. This was the proudest moment in Roberts’s life. The writer saw him just after he received the news and can record that this recognition by fellow workers of work well done was, to him, the highest honour which could be conferred on any chemist. From the time he.passed the examination of the Institute of Chemistry, Roberts was one of the Institute’s stoutest supporters and fought for the highest standards of professional conduct.Even at the time of his retirement he was planning an attack on what he considered a reflection on the integrity of the profession. From the year 1915, with one break, his name appeared in the list of the Institute’s Council, and from 1933 to 1936 and again from 1944 to 1946 he was a Vice-president; from 1925 to 1929 he acted as the Institute’s examiner in Branch E (Food and Drugs). He was for many years Treasurer to the Liverpool and North- Western Section, at whose meetings he was almost invariably present and which he served zealously, being Chairman i‘n 1921. His interest in the Society of Chemical Industry dated back to the time he served under Campbell Brown, but naturally his influence was chiefly expended on the Liverpool Section.Even when his name did not appear on the official lists as member of Committee or Chairman of the Section, his private rooms were always at its disposal and he afforded every facility to the officers of the Section. His advice on matters of policy was greatly valued, and he was looked upon as the Father of the Section. He encouraged any young chemist who wished to start in practice and gave every possible assistance, even allowing him to work in the Laboratory to familiarise himself with methods and apparatus, but always with the proviso that the newcomer should never attempt to cut fees or otherwise degrade or disgrace the Profession. Thus on January lst, 1912, Roberts entered upon his real life’s work. In 1917 he served on the Council of the Society and again in 1927 and 1936.FIELLER : SOME REMARKS ON THE STATISTICAL BACKGROUND IN BIO-ASSAY 37 It would be impossible to enumerate his many benefactions, for he was the soul of generosity, and, apart from his former assistants who now hold responsible positions as Public Analysts, and managers and directors of business undertakings, hundreds of chemists have been helped and inspired by him.He was at his best in the witness-box, and it is not too much to say that he revelled in this part of his duties. He was a lover of humanity who tried, vainly, to hide his sympathies behind a mask of austerity. Hence he was popular with all sorts and conditions of men, from judges to criminals and from leading medical specialists to laboratory boys. Criminals have even been known to tell him a joke after he had given damning evidence against them.Socially he was what is known as a “success,” but this was, to him, merely much-needed relaxation and. 110 more He was due to retire, under an age limit clause, in January, 1942, but the Corporation felt that his services were too valuable to lose and requested him not only to retain his post but to add to his duties those of supervision of all the preparations for war-gas identification, gas damage, other damage by enemy action, water and food preservation, and so forth, “for the duration. ” The death of Mrs. Roberts, a gracious and gifted lady, whose appearances a t the summer meetings of the North of England Section were hailed with delight because of the atmosphere of sociability that she unconsciously diffused, and who “mothered” every member of the laboratory staff, affected Roberts profoundly.She had been his helpmeet and counsellor, restraining his impetuosity and encouraging him in his more ambitious schemes, and, with her passing, in 1942, something in Roberts died. Though he bravely tried to carry on his work as usual, those nearest to him realised how difficult he found it and how heavy was the strain under which he laboured. He felt himself failing physically, and, from a chance remark, the writer is under the impression that he wished to “die in harness.” This he nearly achieved, for during his brief period of retirement he was involved in several cases, some of which are still pending, but which he handed over to chosen confreres. Among the large concourse that attended his funeral were representatives of the Univer- sity, the City Constabulary, the Health Department and other departments of the Corporation, the legal profession, his Masonic Lodge, the Royal Institute of Chemistry, the Chemical Society, the Society of Chemical Industry, and other local Societies. The staff of the City Laboratories and a number of Public Analysts from the North also attended. Mr. S. E. Melling (Past President) officially represented the Society. His one interest in life was his profession. F. ROBERTSON DODD

ISSN:0003-2654    

DOI:10.1039/AN9477200036

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 FIELLER : SOME REMARKS ON THE STATISTICAL BACKGROUND IN BIO-ASSAY 37 Some Remarks on the Statistical Background in Bio-Assay BY E.C . FIELLER (Read at the Annual General Meeting of the Biological Methods Group, February 25th, 1946) 1. In properly conducted biological assays (and this is now well recognised) the experimenter has a dual aim-firstly, to estimate the activity of a test preparation in terms of that of a standard, and secondly, to derive an objective measure of the reliability of his estimate. The task of evolving an assay procedure is a joint one for the biochemist and the statistician, but it is unwise, as well as increasingly difficult, to attempt any precise definition of their respective fields ; they can collaborate effectively only through mutual adaptation.Broadly speaking, however, it is impossible to conceive of a rational assay-procedure for which there is an experimental technique without an accompanying arithmetical technique, and it is with the latter that I shall be concerned. 2. Like Mr. Gridgeman,lz T shall restrict myself mainly to the last of the three assay-types that he distinguishes, that in which the response to any particular dose is regarded as a continuous variate whose mean value is linearly related, throughout the effective dosage- range, to the logarithm of the dose. This assumption of linearity is not in itself sufficient to provide a basis for deriving, by a rigid mathematical argument, the formulae by which such assays are usually interpreted.We need two further assumptions, that the distributions of responses about their mean values follow the normal law of errors, and that the variances of these distributions are, over the effective dosage-range, equal. If these three conditions38 FIELLER SOME REMARKS ON THE STATISTICAL BACKGROUND IN BIO-ASSAY of linearity, normality and stability of variance are assumed to be satisfied, the design and interpretation of an assay become relatively simple. The safest procedure is to have experi- mental groups on at least three different dose-levels both of the standard and of the test preparation. The assay then becomes self-contained: in order to interpret it we need not appeal to previous experience for estimates of the log (dose) - response line* or of the variance of individual responses, and we can, moreover, check what for the time being I shall take for granted-the adequacy of the assumptions that we have made.3. Let us suppose now that in an assay in which the experimental groups have been chosen at random from the laboratory stock, the doses of standard (measured on a logarithmic scale) the numbers of individuals responding to them, and their average responses are respectively . . . . . . . . x11 x12 x13 ........ n11 n12 n13 ........ Yll Yl2 Y13 while the corresponding quantities for the test preparation are ........ x21 x22 x23 n21 fl22 23 Y2l Y22 Y 2 3 . . . . . . . . ........ If we write n, = n,, + n,, + n,, + ...... XI = =wi/%, P = Pl + P2, activity of test = Zn,,, y1 = Cn,,y,Jn,, 4 = 41 + q 2 , p , = Cn,,(x,, - 41 = Z n l d ( x l , - xl)(yl, - yl)B with similar meanings for n2, x2, y2, p2, q2, and finally then we estimate 18, the slope of the log (dose) - response line, as b = q / p , and the activity of the test preparation from the familiar f o r m ~ l a ~ ~ J ~ ~ L = (xl - x2) - Y '1 -Y2 = x - b , say... (1) log activity of standard b The estimate L is subject to sampling variations, since both the numerator and the denomi- nator of the fraction Y/b are; if the protocols of the assay supply an estimate s2 of the common variance o2 of individual responses, then in assays of the unrestricted design under considera- tion Y and b are di2tributed normally and independently with variances that we can estimate as S2 V ( b ) = - P - Suppose now that t is, say, the 5 per cent.point of the Student-distribution1° with the same number of degrees of freedom as s2. Then as long as [b2 - t2V(b)] is positive, the 95 per cent. fiducial limits for h - X, where h is the true logarithm of the activity ratio, are given by the quadratic equation ( 6 9 7 9 9 ) It follows easily, on solving this equation, that if h2[b2 - t2V(b)] + 2hbY + [Y2 - t2V(Y)] = 0 . . C = b2/[b2 - t2V(b)], L' = X - CU/b and .. .. then the fiducial limits for A are L' f tsl. A numerical illustration is Specification No. 9115: the calculation of limits set out there might possibly replacing (3) by the equivalent formula t2 s;2 = (C - l)rp(&+ i) + C(;)'I . . L . . .. .. - * (3) given in B.S.I. be simplified by . . * - (4) 4. It may conveniently be remarked at this stage that although the assumption of normality is necessary for a rigid derivation of the above formulae, its failure in practice entails * I.e., the line showing the relation between x and 7, where 71 is the mean response in a large group of animals each receiving a dose the logarithm of which is x .FIELLER : SOME REMARKS ON THE STATISTICAL BACKGROUND IN BIO-ASSAY 39 little loss.This is in keeping with the general fact, established by many practical and theoretical investigations (e.g ., Welch2,), that statistical tests based on the analysis of variance remain stable even when the parent population departs quite widely from the normal form. In particular, the part played by the assumption of normality in the mathematical argument of paragraph 3 is only a minor one; it consists principally in ensuring the normality of the sampling distributions of the estimates Y and b, but since these estimates are weighted means of all the responsesy observed in the assay, their distributions will in any case be effectively normal if each y has the same error-variance 0,.Accordingly, we can regard the argument of paragraph 3 as dependent only on the assumptions of linearity and stability of variance. The fiducial-limit formulae in the form given above hold whenever, as in completely balanced litter-mate assays, Y and b are uncorrelated. I have indicated elsewhere6 two other methods by which they may be established; one of them, the geometric approach suggested by Fisher’s accounts of the work of Working and Hotelling and by Bliss,3 is very clearly elaborated by Irwin in his well-known 1943 paper.14 The present method is to be preferred, since it can be adapted immediately to the calculation of limits for assays in which Y and b are not estimated independently. This is, in general, the position in the twin cross-over test,21 for example, and in litter-mate assays in which some of the “responses” have to be estimated.All that is necessary in such instances is to replace the second term in (2) by 6. In a self-contained assay carried out on an assigned number of animals (or other test organisms), in which the assumptions of linearity and stability of variance are sufficiently realistic working hypotheses, we shall achieve maximum precision by minimising sC2.This entails four requirements, which can conveniently be considered in turn,-minimising 5 . + 2h[bY - t*COV(bY)]. (k+ $) and (:),, and maximising p and b2/s2 (which will incidentally minimise C). , . It is easily seen that, if (n, + n,) is fixed, is least when n, and n,, the numbers of responses to test and standard, are equalised. In practice, if there is any great doubt about the activity of the test preparation, it may pay to have more dosage groups on test than on standard, to allow for the possibility that the extreme ones may eventually be rejected as falling beyond the range of linearity. More generally, in a multiple assay in which k test preparations are being compared simultaneously with standard, we need to minimise kl+ &) subject to (n, + klz,) being fixed; the solution is nl = n,\/T (ii) (iii) To minimise ( Y / b ) 2 , it is necessary-assuming for the moment that the slope To maximise 9, we need to maximise both 9, and 9,.is fixed-to minimise Y2, i.e., to aim at equalising the average responses to test and standard. If with each preparation we are willing to sacrifice the test for linearity, and can determine the extreme doses between which the log (dose) -response line is straight, it is most economical to put equal groups on these doses. (iv) We may regard b2/s2 as an approximation to p2/a2 (1/X2 in the notation of Bliss and C.attel14), where ,l3 and o2 are, as above, the true slope of the log(dose) -response line, and the true residual variance about it. Maximising P2/a2 is primarily a matter’for the biochemist rather than the statistician, since /I2 increases with the sensitivity of the test- organisms to changes of dose, and l/a2 with the uniformity of their responses; the fact that the precision of the assay depends on the ratio of P2 to o2 is worth stressing-it implies that it is pointless to steepen the slope /3 if so doing entails a proportionate, or more than proportionate, increase in 0.There is, however, one contribution that the statistician may make to the reduction of p2/u2. In many assays the response of the individual animal can be shown to depend not only on the dose it receives, but also on the value of some characteristic, such as its weight or blood-sugar level, at the tinie it is dosed. This may well happen, in particular, when the metameter is obtained by comparing the final value of the characteristic with its initial value, and is provisionally calculated by the arbitrary device of taking a difference or a per- centage.In such instances, the disturbing effect of differences in the initial values can, as Gridgeman has mentioned,12 be estimated and removed by Fisher’s technique of covariance analysis, which produces a modified metameter, uncorrelated with the initial readings, for which a2 is reduced but /I2 unaltered. Many examples kill be found in the work of Bliss and 7.40 FIELLER : SOME REMARKS ON THE STATISTICAL BACKGROUND IN BIO-ASSAY his associates. In this connection one computational point may be mentioned, since it is frequently overlooked. If we estimate the covariance correction from the internal data of an assay, the logarithm of the activity ratio is estimated not as in the second member of (l), but as where h is the estimated residual regression of the responses y on the initial readings z , and 2 and b, are calculated from the recorded values of z by the same steps that produce Y and b, from the recorded values of y.This method. of allowing for initial differences thus intro- duces a covariance Zb,V(h) between Y’ and b’, and to calculate fiducial limits correctly we must modify the quadratic equation (2) in the way described in paragraph 4. The necessity for this modification vanishes, of course, if we can estimate h from previous experience, as proves possible in the assay of insulin by the rabbit method.8*21 8. The ratio p2/02 gives the best indication of the reliability of an assay method of the type we are considering, because it is inversely proportional to the number of animals needed, on the average, to give any assigned degree of accuracy. If a laboratory is repeatedly carrying out routine assays by the same technique, the estimate b2/s2 is the most appropriate single quantity to watch in a control chart, although it may be profitable to run subsidiary charts of b2 and s2 as well.17 If rival assay-methods are available for the same purpose, as are the line-test and the bone-ash test for vitamin D,, and if the reliability of each method is sub- stantially constant, then the respective values of P2/o2, divided by the cost per animal, provide an appropriate criterion for judging between the methods.If their reliability may change from time to time (which is what we assume may happen, when we insist that each assay should be self-contained) then we must judge between the rival methods by judging between the respective distributions of j12/02, divided by the cost per animal. In this latter case it is open to debate whether we should decide solely by the mean values of the criteria, and if not, how far we should be influenced by their stability about their mean values. 9. The considerations of paragraph 8 can profitably be extended to any assay in which the response is a continuous variate. Let us suppose that doses are still measured on a logarithmic scale, but that the mean response to any particular dose x is now a non-linear function jj(x) of x.and the variance of individual responses another function V{y(x) ] of x . In place of the slope j? of the straight log (dose) - response line, it is natural to consider the x - (Y‘/b’) = x - (Y - hZ)/(b, - hb,), . . .. * - (5) d d X gradient - jj(x) of the log (dose) - response curve, and in place of the single criterion of reliability j?2/a2 (= 01, say), we can consider the Local criterion of reliability* which will in general vary with x . If we knew a(x) precisely, we should choose, as the most economical one in which to carry out assays, the region of x in which a(%) is greatest; if the conditions of linearity and stability of variance are exactly satisfied over some range of x , then a(%) must be constant over that range. To the first order of approximation at any rate- and this is in keeping with the last two remarks--+) is independent of the scale on which we choose to measure the response.To demonstrate this, consider the effect of the transfor- mation on the group of responses to some constant dose. typical response as As we move from one response to another within the group, f(7) and its first derivativef’(9) remain constant, and on the average (y - j j ) is zero, so that whence we derive immediately the familiar result . . * (7) . . - - (8) 2 =f(Y) .. .. .. If 7 is their mean, we can represent the + (y - j j ) , and its transform by .. z =f@) + f’(y)(y - y) approximately. .. 2 =f(y), and z - i =f’(jj)(y - j j ) , . . . . - - (9) 0; =f‘(jj)a, . . .. * The sense in which we can regard a(x) as a local criterion of reliability becomes apparent if we consider the idealised case in which an assay is carried out on very large dosage groups, the successive doses of test and standard lying so close together that over their range the variations in the numerator and denominator of a(%) are negligible.If we interpreted the protocols of this imaginary assay by the formulae of paragraph 3, we should expect to find b2/sZ approximating to a@).FIELLER: SOME REMARKS ON +THE STATISTICAL BACKGROUND IN BIO-ASSAY 41 or, in Since the notation of equation (6), dx’(x) v(z(x> 1 = { d-) 2( 1’ \ J dz^(x) --=- ay(x) dz(x), it follows that approximately @(x) dx dx . . (10) i.e., K ( X ) is unaffected by the transformation (7). 10. The scale of measurement on which responses can conveniently be recorded in the laboratory is not necessarily the one on which the arithmetic of the assay should be per- formed.By transforming the response, it is frequently pcssible to bring within the scope of the familiar formulae of paragraph 3 an assay-procedure that at first sight seems to lie outside it. The considerations of paragraph 9 imply that if a metameter can be found that satisfies the two conditions of linearity and stability of variance, and if the recorded responses are transformed so that they fulfil one of these conditions, then they will automatically fulfil the other. I believe that usually this procedure will in fact reveal a sufficiently wide range of doses over which the curve relating responses to logarithms of doses may be taken as linear, and in which, for maximum precision, assays should be planned; even if it does not, it is not difficult to see how to allow for curvature in estimating the logarithm of the activity ratio and calcu- lating its fiducial limits6 It seems likely, on the other hand, that to allow for real changes in the variance, as we move along the dosage range, would inevitably entail more complicated arithmetic, the results of which, moreover, could only be regarded as approximate.11. The transformation required to stabilise the variance follows immediately from equation (9). Let us suppose that by plotting the standard deviation against the mean, for different dosage groups, we find them to be connected by the relation The transformation (7) will produce a metameter z for whkh and 0, will therefore be constant if f’(7) $(y) is, so that we must take f(y) proportional to Nevertheless, it seems preferable to aim primarily at stabilising the variance.Ua, = $(y). .. .. . . .. . . (11) 0 2 =f’(P) W), . . (12) z =j-&. . . . . .. .. I t may be useful to draw attention, in particular, to the logarithmic and square-root transformations. The former should be applied if 0, is proportional to y, the latter if it is - proportional to djj, since J$ = logy, j$ = 2 q j . 12. As examples of the use of these two transformations, we may refer to the assay of vitamin D, by the radiographic technique, 1 9 3 and to the assay of vitamin B, by. the rat- bradycardia method. Olsson2* gives details of a typical D, assay in which, with the tarso- metatarsal distance as metameter, the observed mean responses and estimated standard deviations within dosage-groups of 28 to 30 chicks were as follows (Table I): TABLE I 7 Group NO.1 2 3 4 5 OLSSON’S VITAMIN D, ASSAY DATA (Metameter y = TMT distance) Cod liver oil I Cod liver oil II -A- 7 Dose Mean S.D. Group Dose Mean 0.20 2.06 0.68 1 0.25 2.14 0.40 1-63 0.4 1 2 0.50 1.70 0.80 1.22 0.39 3 I *oo 1.2G 1-60 0.96 0.19 4 2-00 1.00 3-20 0.96 0.22 5 4.00 0.98 * Per kilogram of fo6d. L &5* ?J SY NO. 8-* Y 7 S.D. SY 0.74 0-62 0-53 0.16 0.1842 FIELLER: SOME REMARKS ON THE STATISTICAL BACKGROUXD IN BIO-ASSAY In the early assays carried out in this country in 1039 and 1940 by the same method, it was observed that 0, decreased with f in a similarly rapid manner, but that the use of the logarithmic transfornation usually reduced the differences between the group variances to insignificance.2 100 log,, (10 x TMT distance in mm.) should be used as metameter.5 Jones and EllioP later found, for their own assays, that in many instances the calculations of activity and of fiducial limits produced virtually identical results, whether carried out on the observed distance or on its logarithm.This does not imply that there is no need to transform the distance, since in other instances the results are not identical, and since in the laboratory in question the variance of the untransformed distance is by no means stable,16 but it does suggest that the topic might bear re-esamination. 13. The square-root transformation is of course particularly easy to handle, since the recorded responses are themselves the squares of the metameter used in the arithmetic, and it appears to apply with remarkable fidelity in the rat-bradycardia assay of vitamin Bl. Table 11, based on Table I1 of Baker and Wright's survey1 of assays carried out during 1037-9, shows that with the duration of cure as metameter the mean response was almost exactly proportional to the group variance.(Pooling the data is legitimate because, as has been TABLE TI 1937-9 Data: Mctampter y = duration of cure in days Dose No. of Mean Variance Ratio mg.* responses I bS Sly2/Y 15 50 1 3-10 1 n . 5 9 0.50 2,: 487 4.4 9 2. ' 0 0.55 40 4.5 5-97 3 24 0-54 * Old International Standard (acid-clay adsorbate). reported elsewhere,l* the log (dose) - response line for the laboratory in question undergoes little variation in slope or position.) The use of the square-root transformation is clearly indicated; Table 111 shows the extent to which it succeeded in stabilising the variance when applied to tests carried out, six years later, in the summer of 1945.TABLE HI 1945 Data: Metameter y =duration of cure in days In B.S.I. Specification No. 91 1 it was accordingly recommended that MEAS RESPONSES AND GROUP VARIASCES IN RAT-BRADYCARDIA ASSAYS FOR VITAMIN B, MEAN RESPONSES AND GROUP VARIASCES IN RAT-BRADYCARDIA ASSAYS FOR VITAMIX Bl Dose No of Mean Variance * responses ?i sYa 3 41 1-61 0.057 6 41 1 -89 0.063 9 41 2-24 0.064 * New International Standard (crystalline vitamin BJ. 14. The well known result expressed by equation (12) could easily be applied (although as far as I know it never has been) without the intervention of formal mathematics.From the experimental records we could plot on a graph one point for each separate dosage group, the abscissa of the point being the mean response in the group, and the ordinate the reciprocal of the estimated standard deviation. A smooth curve drawn through the swarm of points thus obtained would approximate to the graph of I/+(>!), and the transformed value of any particular response y could be obtained mechanically as the arca enclosed by this cwve, the axes of I t would thus be possible to build up empirically what we finally require for application-a table showing the values of z corresponding to selected values of y. ACKYOWLEDGMEKT- I am indebted to the directors of Vitamins Limited for permission to quote paragraph 13 above from an unpublished survev of the rat-bradycardia method of assaying vitamin B1, and. more generally, for affording me from 1912 onwards the opportunity to remain in touch with a subject that my war-time duties would otherwise have compelled me to abandon. and s,, and the ordinate at jj = y.1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 1.5. 16. 17. 18. 19. 20. 21. 28. MILTON, LIDDELL AND CHIVERS : ESTIMATION O F FLUORINE REFERENCES 43 Baker, A. 2. and Wright, M. D., Biochem. J., 1939,33, 1370. -- , ANALYST, 1940, 65, 326. Bliss, C. T., A n n . Appl. Biol., 1935, 22, 134, 307. - and Cattell, McK., Ann. Rev. Physiol., 1943, 5, 479. “British Standard Method for the Biological Assay of Vitamin D, by the Chick Mefhod,” B.S.I. Fieller, E. C., Supp. J . Roy. Stat. SOL, 1940, 7, 50. - Quart. J . Pharm., 1944, 17, 117. - Irwin, J. O., Marks, H. P. and Shrimpton, E. A, G., Ibid., 1939, 12, 724. Fisher, R. A., “Statistical Methods for Research Workers,” Oliver and Boyd, 6th Edn., 1936, 10th - and Yates, F., “Statistical Tables for Biological, Agricultural and Medical Research,” Oliver & Gaddum, J. H., “n4ethods of Biological Assay depending on a Quanta1 Response,” M.R.C. Special Gridgeman, N. T., ANALYST, 1946, 71, 376. Irwin, J . O., Supp. J . Roy. Slat. SOC., 1937, 4, 1. -- J. Hygiene, 1943, 43, 121. Jones, J . I. &I., Biochem. J., 1945, 39, 334. - and Elliot, J. F., Ibid., 1943, 37, 209. Knudsen, L. S., and Randall, W. A., J . Bacteriol., 1945, 50, 187. Nixon, W. C. W., Wright, M. D., and Fieller, E. C., Brit. N e d . J., 1942, i, 605. Olsson, N., Archiv. f u r GefEugelktmde, 1936, 10, 11. - Kungl. Fysiografiska Sallskapets i Lund Forhandlingar, 1939, 9. 1. Smith, K. L., Marks, 11. P., Fieller, E. C., and Broom, W. A., Quart. J. Pharm., 1944, 17, 108. Welch, B. L., Biomelrika, 1937, 29, 21. Specification No. 9 1 1, 1940. Edn., 1946. Boyd, 3rd Edn., 1946. Report Series No. 183, H.M. Stationery Ofice, 1933. NATIONAL PHYSICAL LABORATORY TEDDINGTON, MIDDLESEX

ISSN:0003-2654    

DOI:10.1039/AN9477200037

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 MILTON, LIDDELL AND CHIVERS : ESTIMATION OF FLUORINE 43 A New Titrimetric Method h r the Estimation of Fluorine BY R.F. MILTON, H. I;. LIDDELL AND J. E. CHIVERS INTRODCCTION- Despite the importance attached to the distribution of fluorides in micro quantities in foods, water, etc., and the consequent effect upon teeth, it is only comparatively recently that it has been possible to estimate such traces with any degree of accuracy. The colori- metric method of De Boer,' based upon the fading of a zirconium alizarin lake, was used for many years as the standard micro procedure, and modifications of this are still favoured in waterworks practice. The work of Willard and Winter2 showed the limitations of this procedure, particularly with regard to rate of fading of the lake when fluorides were added. They suggested instead a method based on titration of the fluoride solution with thorium nitrate and use of zirconium alizarin sulphonate to indicate the point when an excess of thorium over and above that required to combine with fluorine was present in the solution. This technique was improved by Arm~trong,~ who suggested a dilute alizarin sulphonate solu- tion as the indicator, by Hoskins and Ferris: by Rowley and Churchills and finally by Eberz, Lamb and Lachele.6 The technique advocated by the last-named authors is capable of giving reproducible results after some experience, but the end-point is rather vague and there is some lag in the completion of the reaction.This factor has bcen reduced to some extent by the back-titration technique of Dahle et aZ.,' and Elsworth,* and has been further clarified in the Society's official publication on the ~ u b j e c t .~ The possibility of using other dyestuffs instead of alizarin in the formation of the thorium lake has been investigated, and we have shown that Solochrome Brilliant Blue B.S. (Colour Index 723), which is the sodium salt of sulpho-dichlorohydroxy dimethylfuchsin dicarboxylic acid, is suitable for this purpose. It possesses the following advantages over alizarin : (1) The colour change is sharp from pink to blue, and is more sensitive than that usually given by alizarin methods. (2) The reaction is immediate, no lag being observed.44 MILTON, LIDDELL AND CHIVERS: A NEW TITRIMETRIC METHOD OUTLINE OF METHOD- Samples containing fluorides, after suitable treatment, are buffered to $H 3.0 and titrated with thorium nitrate in presence of Solochrome Brilliant Blue B.S.until the colour obtained matches a blank consisting of a trace of thorium nitrate added to a buffered solution of the dyestuff. The method is standardised against known amounts of fluoride and a calibration curve is prepared relating titre of thorium solution to fluorine content. The method is suitable for amounts of fluorine from 2pg. to 1OOpg. With larger quantities, thorium fluoride comes out of solution and affects the colour matching. Suitable aliquots are there- fore titrated to keep within these limits. Alternatively a protective colloid may be used whereby thorium fluoride is maintained in solution and the titratable range increased accordingly. INVESTIGATION INTO OPTIMUM CONDITIONS- (a) VoZume of titrating solutiofzs- Varying the amount of the final titrating solutions has been investigated to ascertain the effect of dilution upon the end-point. I t is established that up to 100ml.can be titrated as readily as 25ml. without increasing the concentration of the indicator. Thus although the depth of colour is weaker, it is still quite readily matched. The method should, however, be standardised on a volume equal to that to be titrated in the particular determination. TABLE I 25 100 Fluorine present, pg. . . .. .. 20 20 20 40 40 40 0.004 N Thorium nitrate required, ml. . . 0.71 0.72 0.71 1-40 1.39 1.44 Volume of sample solution titrated, ml.. . 10 25 100 10 (b) Use of bufer- The use of a buffer prepared from half-neutralised chloroacetic acid (0.24 M ) assures that the titration is carried out at pH 3.0 or thereabout.At this point very reproducible results are obtained. Titration in neutral solution is indefinite, and the sharpness of end-point is increased with increasing acidity until pH 3.0 is reached. Solutions more acid than this do not give good reproducibility on titration. The use of the acid buffer also allows of greater sensitivity-thus twice as much thorium solution is required at pH 3-0 (3.12 ml. per 100 pg. of F) as at pH 7.0 (1.25 ml. per 100 pg. of F). (c) Concentvation of dye- The amount of dye used does not seem to affect the titration figure of a solution, but ease of matching is greatly influenced. Thus 0.5 ml. of 0.01 per cent. solution in 50 ml. of liquid gives a very pale colour the change of which is not easy to judge, and 3.0 ml.of 0-01 per cent. solution has so much basic residual red colour that the blue colour of the thorium lake is masked. In practice the aim is to obtain the sharpest colour change with the largest amount of dye, and this occurs with 2-0 ml. of a 0.01 per cent. solution, in 50 ml. volume. ( d ) Excess of thorium solution added- The end-point of the titration is assessed by comparing the tube with a similar tube to which all the reagents and a small quantity of thorium solution are added. The amount of the excess of thorium added greatly affects the titration and it is essential that the calibration curves relate to the conditions of experiment. It is not clear why the titration figure should vary with the excess of thorium added, and it would appear that the thorium fluoride itself enters into the formation of the lake. Precautions must be taken that the amount of thorium nitrate added to the comparison tube is always the same as that used when the calibration curve is prepared. Table I1 shows the volumes of 0.004N thorium solution required for 60pg. of fluorine corresponding to different volumes added to the blank.Thorium solution added to blank ml. 0.05 0.08 0.10 0.15 0.20 0.30 TABLE I1 Thorium solution required by 50 pg. F. ml. 1.55 1-62 1.84 2-09 2.36 2.78 Thorium solution required by 50 pg. F. corrected for blank ml. 2.50 1-54 1.74 1 -94 2.18 2-48FOR THE ESTIMATION OF FLUORINE 45 Although higher titration figures are obtained with increased additions to the blank, if the quantity added is above 0.10 ml.the end-point tends to become difficult to recognise. The method is not specific for fluorine, as many substances that form complex ions with The effects of some interfering substances are recorded in Table 111. EFFECT OF SUBSTANCES OTHER THAN FLUORINE ON THE TITRATION- thorium will behave in a similar manner. TABLE I11 EFFECT OF INTERFERING SUBSTANCES ON TITRATION OF 40pg. OF FLUORINE Alcohol : ml. present .. Titration figure, ml. . . Sodium chloride : mg. present Titration figure, ml. , . Sodium carbonate: mg. present Titration figure, ml. . . Sodium sulphate : mg. present Titration figure, ml. . . Sodium perchlorate : mg. present Titration figure, ml. . . Sodium borate: mg. present Titration figure, ml.. . Sodium acetate: mg. present Titration figure, ml. . . Sodium citrate : mg. present Titration figure, ml. . . Potassium chloride : mg. present Titration figure, ml. . . Sodium silicate : mg. present Titration figure, ml. .. Sodium phosphate : mg. present Titration figure, ml. . . Sodium tartrate : mg. present Titration figure, ml. . . .. .. .. .. .. . . .. .. .. . . .. . . .. .. .. .. . . .. . . .. . . . . 0 1.41 0 1.41 0 1.41 0 1-41 0 1-41 0 1-41 0 1.41 0 1.41 0 1.41 0 1-41 0 1.41 0 1.41 1 d 1.41 0*92* 1.53 1.54 1.58* 1 3 2-38 --t 1 10 1.46 1.70" 10 100 1-43 1-43 1 10 1.40 -t 1 10 1-39 1.08 3 (Basic colour only) 10 100 1.43 1-47 10 100 1-41 1-04 c) 100 --t -1 1 5 -t + 10 100 500 ') - * Poor end-point. t Decolorised. It is concluded from these experiments that the method is applicable only to relatively pure solutions of fluorides and that with few exceptions most other ions modify the titration value.This is also the experience of workers on the de Boer technique and the alizarin - thorium titration method of Willard and Winter. I t is usually necessary, therefore, to separate the fluorine from such interfering substances and this is most conveniently done by distillation as silicon tetrafluoride by heating with silica and an acid of high boiling-point. The experimental work on the effect of interfering substances indicates that distillation of the fluorine should best be carried out with perchloric acid, since traces of any acid used are certain to distil over and the salts of this acid have least effect on the subsequent titration.Other workers6 have shown that distillation is effective with this acid, and with glass wool as a source of silica. Ellsworths investigated the temperature of distillation and showed that satisfactory results are obtained- if the range is kept between 135" and 145" C. An all-glass distillation apparatus is preferred. The sample, together with about 10 ml. of perchloric acid, is placed in the distillation flask. A thermometer in an elongated ground jointed mercury pocket which is of such length that, it dips below the surface of the liquid. Wqter is added from a funnel at such a rate and the bunsen so adjusted that distillation proceeds at between 135" and 145" C. To ensure complete distillation of all the fluorine, about 200 ml. of distillate must be collected, although about 80 per cent.of the fluorine comes over with the first 50 ml. If the temperature of distillation falls below 135" C., the removal of fluoride becomes incomplete even with 200 ml. of distillate. A distillation temperature above 145" C. results in the distillation of excessive amounts of perchloric acid, which may modify the subsequent titration. Blank distillations show that a titration figure is always obtained, equivalent to about 4pg. of fluorine. Higher blanks than this are usually due to impurity in the perchloric acid, which should be heated to 140" C. and then redistilled before use. DETAILS OF DISTILLATION OF FLCORINE- This is said to be derived from the glass distillation apparatus.46 MILTON, LIDDELL AND CHIVERS: A NEW TITRIMETRIC METHOD The type of silica used in the distillation is important.Some authors suggest powdered glass, but glass wool seems to be most satisfactory. Precipitated silica gel is definitely unsatisfactory. Some experiments in which silica gel, obtained during heating of the sample in glass vessels with caustic soda, was present, gave results corresponding to only about 40 per cent. recoverv. When silica gel was added to standard fluoride solution before distillation not more than 80 per cent. recovery was obtained. Complete recovery could be obtained by using glass wool in the distillation flask. CALIBRATION CURVE- Although the method as outlined is capable of giving reproducible results without difficulty, it is suggested that a calibration curve correlating titration figure and fluorine content be made each time a change in the conditions is encountered.The lake formed with thorium salts and the dye is of variable composition and in consequence slight modifica- tions in the conditions may influence the end-point. Taking the concentrations of reagents found to be optimum and titrating with 0.004 N thorium nitrate solutions, a typical calibration series is as follows. TABLE I11 Fluorine yresent, pg. . . .. 5 10 20 40 GO 80 100 0.004 N Thorium nitrate sdiution required, ml. . . .. . . 0.25 0.40 0.72 1-39 3.00 2-69 3.28 METHOD FINALLY ADOPTED REAcENTs-percht!oric acid: GO per cent. (pure) ; redistilled. GJass wool: fluorine-free. Standard thorizmz nitrate solution: 0.004 N ; dissolve 552 m g of Th(NO3),.4H,O in 1 litre of water. Solochrome Brilliant BZue B.S.: 0.02 per cent. solution in water. Clzloroacctic bzq$er: dissolve 22.7 g. of chloroacetic acid to 100 ml. in water; titrate 50 ml. of this solution with 6 N sodium hydroxide to neutralise; combine the two portions and dilute with water to 1 litre. PROCEDURE-Ash the sample containing the fluoride after heating to dryness with calcium oxide according to the procedure recommended in the Society's publication.9 Transfer the ash with the aid of a minimum quantity of water to a distilling apparatus (described above), add a small quantity of silver perchlorate to precipitate any chloride present, and allow the distillation to proceed. Place about 0.1 g. of glass wool and 15 ml. of perchloric acid in the distillation flask with the sample and add water via a dropping funnel continuously at such a rate that, with the heating suitably adjusted, the distillation tem- perature is maintained between 135" and 145" C.Dilute the distillate to a known volume, and measure an aliquot containing less than 100 pg. of fluorine for titration. Transfer the aliquot to a Nessler glass standing on a white tilc, and neutralise it to phenolphthalein end-point with dilute alkali. Then just discharge the pink colour by adding a dilute solution of perchloric acid. Add 1 ml. of dye solution and then dilute perchloric acid solution until the yellow colour of the dye just changes to pink. Into a similar Nessler tube introduce a volume of distilled water equal to that of the sample, one ml. of dye solution and 0-5 ml.of chloroacetic buffer. To this tube add also 0.1 ml. of 0.004 N thorium nitrate solution accurately from a micro-burette. The colour changes from pink to bluish purple. Then titrate the unknown sample titrated with 0-004 N thorium nitrate until it exactly matches the blank in colour. From the titration figure subtract 0.1 ml. and refer the result to the calibration curve to obtain the concentration of fluorine in the sample. Table IV shows results of some determinations carried out in triplicate on known amounts of fluorides, submitted to the distillation technique and titrated by the method described. Distil about 200 ml. of liquid, Then add 0-5 ml. of chloroacetic buffer solution. TABLE IV Fluorine in fluoride taken t%. 1.9 3-8 7-6 38 76 95 Fluorine found 1.5; 1.7; 2.1 3.7; 3.5; 4.0 7.6; 7.4; 7.4 37-6; 37-6; 38.2 75-2; 76.1; 75.8 95.0; 94.6; 94.4FOR THE ESTIMATION OF FLUORINE 47 -ADAPTATION OF THE METHOD TO COLORIMETRIC TECHNIQUE- The principle of the method described above may be applied to a colorimetric technique. In this case there is formed a blue lake with thorium nitrate and the dye.The fluorine solution is then added and the colour of the solution is diminished proportionately to the formation of the thorium fluoride complex. This reduction of colour intensity may be measured-most conveniently on the Spekker absorptiorneter. The method is standardised by means of a number of standard fluoride solutions treated in the same manner. As in the titrimetric technique, rigid adherence to the conditions of calibration is necessary since the colour intensity is dependent upon the concentration of all substances in solution. It requires more careful control and is not capable of the same degree of accuracy. SLJMMARY- 1. A new method is given for the estimation of small amounts of fluorine. It is based upon titration of tlic fluoride solution with thorium nitrate solution until excess is shown by the formation of a lake with Solochrome Brilliant Blue B.S. Optimum conditions for the estimation are described. The use of the colorimetric technique is not recommended. 2. The method has the following advantages over the existing alizarin technique. (a) The end-point is more definite and easily judged and therefore allows oi greater sensitivity ; (b) The end-point is immediate; (c) The colour does not fade. 3. The method allows the estimation of from 2 pg. to 100 pg. of fluorine within the accuracy of titration from a micro-burette, i.e., 0.02 nil., or equivalent t o about 0.5 pg. of fluorine. F1.e are indebted to the Director-General of Scientific Research (Defence) Ministry of Supply, for permission to publish this work. REFERENCES 1. 2. 3. 4. 6. 6. 7. 8. 9. De Boer, J. H., Chem. Weekblad, 1924, 21, 404. Willard, H. H., and Winter, 0. B., Ind. Eng. Chem., Anal. Ed., 1933, 5 , 7. Armstrong, W. D., J. Amer. Chenz. Soc., 1933, 55, 1741; Ind. Eng. Chem., Anal. Ed., 1936,8, 384. Hoskins, W. &I., and Ferris, C. A., Ibid., 1936, 8, 6. Rouley, R. J., and Churchill. H. V., Ibzd., 1937, 9, 551. Eberz, W. E., Lamb, F. C., and Lachele, C. E., Ibid., 1938, 5, 259. Dahle, D., Bonnar, R. V., and Wichmann, H. J., J . Assoc. 08. Agric. Chem., 1938, 21, 459. Elsworth, F. F., and Barritt, J., ANALYST, 1943, 68, 298. Society of Public Analysts and Other Analytical Chemists, Sub-committee Report on Determina- tion of Fluorine in Foods, ANALYST, 1944, 69, 243; 1945, 70, 442. 23-24, WELBECK WAY October, 1946 LONDON, W.l

ISSN:0003-2654    

DOI:10.1039/AN9477200043

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 FOR THE ESTIMATION OF FLUORINE 47 The Estimation of the Volatile Matter Content of Propellant Explosives Part 2.* The Estimation of Ethyl Alcohol and Ether BY T. G. BONNER IN the manufacture of nitrocellulose powders a mixed solvent of ethyl alcohol and ether is invariably used to facilitate the rrixing of constituents and to ensure homogeneity of the product.The removal of these solvents in the final stage of manufacture is never complete, and a small residuum is always tenaciously retained in the propellant. A knowledge of the exact amount of this volatile matter is of considerable importance in the chemistry of pro- pellants, particularly in relation to the effect on ballistic stability of changes in the volatile matter content arising from variations in the temperatures and humidities under which the propellant is stored and used. Several attempts have been made to estimate this residual volatile matter in simple nitrocellulose powders containing only cellulose nitrate and diphenylamine, but most of the * For Part 1, see ANALYST, 1946, 71, 483-490.48 BONNER: THE ESTIMATION OF THE VOLATILE MATTER methods described are liable to considerabk error.Desmarouxl obtained an aqueous solution of the organic solvents by heating under reflux and distilling with aqueous sodium hydroxide solution, and then estimated them by physical methods. The same author2 later estimated the ethyl alcohol and ether in the aqucous distillate by oxidation with potassium dichromate in acid solution; the ethyl alcohol was separately estimated by the method of Fischer and Schmidt: involving conversion into ethyl nitrite, which was removed by a stream of carbon dioxide and passed into acid potassium iodide solution, the iodine liberated being titrated with thiosulphate. Dalbert4 also estimated the ethyl alcohol and ether together by di- chromate oxidation but replaced the method of Fischer and Schmidt for ethyl alcohol by one depending on surface tension effects.Lalande5 estimated ether alone by drawing a stream of air through the aqueous distillate, removing the ethyl alcohol in a strongly alkaline solution of potassium permanganate and then absorbing and oxidising the ether to acetic acid with dichromate in diluted sulphuric acid (1 +1), the unchanged dichromate being esti- mated iodimetrically. A preliminary investigation of these methods indicated that the estimation cf mixtures of ethyl alcohol and ether at concentrations of about 0.1 per cent. in aqueous solution was possible with an accuracy to within 1 or 2 per cent. The ethyl alcohol is readily oxidised quantitatively to acetic acid by the method of Szeberenyi6 by boiling with potassium dichro- mate in a 1 : 10 by volume mixture of concentrated sulphuric acid and the aqueous alcohol- ether solution.The ether is not attacked under these conditions and can be estimated by difference after oxidation of another portion of the aqueous solution in a 1 :I by volume mixture of sulphuric acid and solution, which converts both the ethyl alcohol and ether quantitatively to acetic acid; this oxidation is carried out by allowing the mixture to stand at room temperature for 14 to 2 hours. In applying this method to the estimation of an aqueous distillate obtained by heating under reflux and distilling a sample of propellant with aqueous sodium hydroxide two major difficulties were encountered. First, a small but appreciable amount of volatile oxidisable matter, from the disintegration of the propellant, distilled with the ethyl alcohol and ether and secondly, in modern nitro-cellulose powders dibutyl phthalate is often present arid from it butyl alcohol is formed by the hydrolysing action of the sodium hydroxide; the butyl alcohol distils and interferes in the subsequent dichromate oxidation of the ethyl alcohol and ether.The first difficulty was met by distilling with sodium hydroxide solution a synthetic mixture of cellulose nitrate, diphenylamine and any other constituents in the amocnts present in a 25-g. sample of the propellant and determining the amouut of oxidisable matter in the distillate obtained; a correction was then applied for this amount.The presence of butyl alcohol in the distillate, however, required the development of a method of estimating ethyl alcohol, ether and butyl alcohol together in dilute aqueous solution. THE ESTIMATION OF ETHYL ALCOHOL, BUTYL ALCOHOL AND ETHER IN DILUTE AQUEOUS SOLUTION Attempts to effect complete hydrolysis of the dihutyl phthalate and subsequent dis- tillation of the whole of the butyl alcohol were unsuccessful; prolonged hydrolysis and dis- tillation did not achieve more than about 80 per cent. recovery of butyl alcohol from known quantities of dibutyl phthalate. Methods of estimating similar simple aliphatic compounds in dilute aqueous solution have been described by Christiansen and Fulmer' for mixtures of ethyl alcohol, butyl alcohol and acetone, by Bayly,s who in\-estigated the oxidation of aliphatic alcohols in about 0.5 per cent.aqueous solution with I)otassiurn dichromate in 45 per cent. sulphuric acid solution ; by Skrabal,g who claims that with minor modifications the Fischer and Schmidt method (Zoc. it.)^ could be applied to an aqueous solution of any simple aliphatic alcohol with an accuracy to within about 1 per cent.; and by Fresenius,lo who estimated aqueous butyl alcohol solutions by oxidation with dichromate followed by distillation and titration of the acid products in the distillate with sodium hydroxide solution. AppZication of Lalande's method-As a first step, the direct estimation of ether in dilute aqueous solutions containing ethyl and butyl alcohols by Lalande's method (loc.it.)^ was investigated. It was found that an alkaline potassium permanganate solution absorbed both alcohols, whilst the ether, unaffected by passage through this solution, could be ab- sorbed and oxidised quantitatively to acetic acid by potassium dichromate in a 1 : l by volume mixture of sulphuric acid and water. By drawing a slow stream of air through the aqueous solution of the three constituents at 30" to 40OC. for 5 to 6 hours, then throughCONTENT OF PROPELLANT EXPLOSIVES 49 alkaline potassium permanganate solution and finally through the acid potassium dichromate solution, it was established that a quantity of ether of the order of 50 mg. could be estimated with an error of about 1 to 2 per cent. Oxidation of butyZ aZcohoZ-The oxidation of butyl alcohol was next studied and it was found that, under the conditions that convert ethyl alcohol quantitatively into acetic acid in Szeberenyi’s method (Zoc.it.),^ 1 molecule of butyl alcohol consumes 3 atoms of oxygen; this oxidation procedure is subsequently referred to as the “mild” oxidation method. Attempts to discover other oxidation conditions giving a simple stoichiometric relation between butyl alcohol and oxygen but not affecting ether were unsuccessful, and it was evident that the only immediate possibilities were the complete combustion of the three constituents t o carbon dioxide and water, or the quantitative conversion of all three into acetic acid. The former possibility was rejected when the wet combustion method of Williams,lf employing potassium dichromate or potassium iodate in concentrated sulphuric acid solution, gave erratic results with aqueous solutions of these constituents Since the oxidation of ether to acetic acid in diluted sulphuric acid (1 + 1) appeared to be sensitive to any change in the ratio of acid to water, the investigation of the oxidation of butyl alcohol to acetic acid had to be confined to this acid concentration.Employing a dilute aqueous solution of butyl alcohol of known concentration and this concentration of acid, the oxidation was carried out a t different temperatures for varying periods of time, and it was finally established that if the temperature was maintained at 0” C. for 24 hours and then raised to and maintained a t room temperature for a further 1Q hours, the oxidation proceeded quantitatively to acetic acid; no further change then took place in the potassium dichromate content of the oxidising solution and the amount of potassium dichromate consumed corresponded to 8 atoms of oxygen per molecule of butyl alcohol.Under these conditions of oxidation ethyl alcohol and ether were both quantitatively oxidised to acetic acid. This oxidation procedure was designated the “total” oxidation methcd. Results of the direct estimation of synthetic aqueous butyl alcohol solutions by the mild and total oxidation procedures are given in Table I. An accuracy of to within 1 or 2 per cent. is evident. TABLE I ESTIMATION OF BUTYL ALCOHOL IN AQUEOUS SOLUTION Butyl alcohol per 100 ml. of aqueous solution taken g. 0.1084 0.1200 0.1 170 0.1170 0.1200 0.1200 o.oaio Type of 2xidation Potassium dichromate consumed $5 0.3 19 0.426 0.482 1.224 1-232 1.260 1-25s Butyl alcohol found 0.0802 0.1074 0.1212 0.1 154 0-1162 0.1188 0.1187 gmt< Error per cent.- 1.0 - 1.0 + 1.0 -- 1.3 + 0.6 - 1.0 - 1.0 APPZica,fioiz of methods above-These oxidation methods were applied to synthetic aqueous solutions of ethyl alcohol, butyl alcohol and ether. Three aliquot portions of the solution were separately treated (1) by the “mild” oxidation method, (2) by the “total” oxidation method and (3) by Lalande’s method for ether; the quantity of dichromate consumed in each was determined iodimetrically and calculated to 100 ml. of the original solution. The ether was thus obtained directly while the alcohols were obtained indirectly by the following method of calculation.For 100 ml. of the aqueous solution, let the amounts of potassium dichromate in grams required in the various oxidations be M. for the preferential oxidation of the two alcohols by the mild oxidation method. T. for the total oxidation of the three constituents to acetic acid by the total oxida- A. for the oxidation of ethyl alcohol to acetic acid. B. €or the oxidation of butyl alcohol to acetic acid. C. for the oxidation of ether to acetic acid. tion method. The amounts of dichromate represented by M, T and C are experimentally determined values; the amount of dichromate consumed by the butyl alcohol in 100 ml. of the aqueous50 BONNER: THE ESTIMATION OF THE VOLATILE MATTER solution in the mild oxidation is 3B/8, since one molecule of butyl alcohol requires 3 atoms of oxygen for the mild oxidation and 8 atoms for the total oxidation.Then for the mild oxidation of 100 mi. of the solution M = A + (3B/8) T = A + B + C. 5A = 3C + 8M - 3T and 5B = 8(T - M - C) the amount of dichromate equivalent to both alcohols is therefore obtained. The relationship between potassium dichromate and each of the three constituents is given by and for the total oxidation of 100 ml. of the solution From these two equations, 1 g. of potassium dichromate EZ 0.1886 g. of ether E 0.02344 g. of ethyl alcohol = 0.0944g of butyl alcohol, from which the amount of each constituent preser.t can be calculated. Results of the esti- mation of synthetic aqueous solutions of ethyl alcohol, butyl alcohol and ether are given in Table 11, and indicate an accuracy to within 1 per cent.for the ether estimation and to within about 2 to 3 per cent. for the alcohols. TABLE I1 ESTIMATION OF MIXTURES OF ETHYL ALCOHOL, BUTYL ALCOHOL AKD ETHER IN AQUEOUS SOLUTION Potassium dichromate I A \ Found, per 100ml. - Ethyl Butyl Aqueous solution Type of Calculated Amount Ether alcohol alcohol taken contained : oxidation equivalent consumed (direct) (indirect) (indirect) g./100 ml. 8. €5 g- g- g. Mild 0.624 0.626 TGt a1 1.576 1 *588 Mild 0.650 0.646 Ethyl alcohol 0.0499 Butyl ,, 0.1037 Ether O*Ot co Total 1.644 1.648 Mild 0.597 0.595 Ethyl alcohol 0.OE02 Butyl ,, 0.1095 Ether 0-05 10 Ether 0.0620 } Total 1-597 1.610 Ethyl alcohol 0.0453 Butyl ,, 0.1015 0-0504 0-04CO 0.1051 0-0517 0.0491 0.1100 } 1 0.0625 0,0435 0.1033 In appl>*ing this method to estimations on aqueous distillates from propellants containing dibutyl phthalate it was necessary to apply corrections for oxidisable impurities in the dis- tillate, in both the mild and the total oxidation, and these increased the error of the method to the order of about 5 per cent.In the absence of any other suitable method, however, this procedure was regarded as satisfactory for pro\-iding a preliminary estimate of the true ethyl alcohol and ether contents of nitrocellulose powders. In the wide variety of powders investigated the ether content was invariably higher than the alcohol content, the former usually ranging from about 0.2 to 2 per cent. and the latter from about 0.1 to 1 per cent.; some old types of powders contained over 5 per cent. of residual solvent. When the necessity arose for an accurate routine method for the estimation of these volatile constituents certain unsatisfactory features of the method described became apyarent. These included the large amount of sample required (25 to 50 g.), which is not always available, and the length of time required for an estimation (2 to 3 days); further, certain special in- vestigations required greater accuracy than was possible with this procedure. As an alter- native, the possibility was considered of vaporising the ethyl alcohol and ether in a current of air without decomposition of the propellant and subsequently absorbing and differentially oxidising them in acid dichromate solutions of different concentrations.THE SEMIMICRO-ESTIMATION OF ETHYL ALCOHOL AND ETHER VAPOURS ENTRAINED IN AIR Somogyi12 describes a method for estimating mixtures of ethyl alcohol and ether vapours in air by passing the air first through 9 h’ sulphuric acid, which preferentially absorbs the alcohol, and then through a solution of potassium dichromate in diluted sulphuric acid (1 + l), in which the ether is absorbed and oxidised to acetic acid; the ethyl alcohol is estimated byCONTENT OF PROPELLANT EXPLOSIVES 51 subsequently oxidising its solution in sulphuric acid with potassium dichromate. Quantities of the order of 0.25 to 0.025 g. of each constituent were estimated by this method with an accuracy to within about 3 per cent. Komar, Sergunin and Fainberg13 criticise certain features of this method and apply a slightly modified form of it to the estimation of much smaller quantities of ethyl alcohol and ether in air; their results show that when the amount of ether present is less than 5 mg.the recovery of it is less than 90 per cent., but with larger quantities the method is accurate to within about 3 to 4 per cent. I t was evident that this method might be further modified to include the simultaneous absorption and oxidation of the ethyl alcohol; to this end the conditions necessary for the quantitative oxidation of small amounts of ethyl alcohol (5 to 30mg.) to acetic acid at room temperatures were investigated. I t was found that this could be achieved quite readily with potassium dichromate in diluted sulphuric acid (1 + 10) in about 14 hrs.at ordinary room temperatures. To test the modified method, weighed quantities of ethyl alcohol and ether contained in thin sealed glass tubes were introduced into a 500 ml. flask fitted with an inlet and an outlet tube each carrying a stop cock, the inlet tube reaching to the bottom of the flask. After the stop cocks were closed the tubes were fractured by shaking the flask The flask was placed in an absorption train similar to that shown in the diagram, in the position occupied in the diagram by the three-necked flask. The first absorption spiral tube contained the acid dichromate solution for the oxidation of the ethyl alcohol, the second absorption spiral tube alkaline potassium permanganate solution (prepared as described later) and the third the usual acid dichromate solution for oxidation of the ether.The alkaline potassium permanganate solution was used because in determinations on propellants its presence was effective in absorbing any oxidisable volatile constituents that would not be affected by the weak oxidising solution in the first absorption tube but that might be oxidised bythe stronger solution in the third tube. At the head of the absorption train were twoconical flasks, the first containing a concentrated chromic acid solution to remove any oxidisable impurities in the air drawn through the train and the second serving as a trap for any acid spray from the first. The last absorption tube in the train was connected to a bottle in which a partial vacuum was maintained by means of a water pump.After all the stopcocks had been opened a slow stream of air was drawn through the apparatus, carrying the ethyl alcohol and ether vapours into the absorption tubes. After 3 to 4 hours the air flow was stopped, the acid dichromate solutions were washed out and the unchanged potassium dichromate was estimated iodimetrically. Results for several such determinations are given in Table 111, and these show that the method is accurate to within about 2 per cent. for quantities of ethyl alcohol and ether not less than about 5 mg. TABLE I11 ESTIMATION OF MIXTURES OF ETHYL ALCOHOL AND ETHER VAPOURS ENTRAINED I N AIR Taken in mixture r 1 Ethyl alcohol Ether g. g. 0-0365 0.0795 0.0343 0.0475 0-0227 0.0152 0.01 87 0.0 155 0.0097 0~0110 Ethyl alcohol found g .0.0361 0.0340 0.02 16 0.0 185 0*0096 Ether Error found Error per cent. g. per cent. - 1.1 0.0803 + 1.0 - 0.9 0.049 1 + 3.4 - 4.8 0.0155 + 2.0 - 1-1 0.0 1 60 + 3.2 - 1.0 0.0 109 - 0.9 APPLICATION TO THE ESTIMATION OF ETHYL ALCOHOL AND ETHER IN PROPELLANTS- T'arious methods were considered for removing the ethyl alcohol and ether from nitro- cellulose powders free from volatile impurities oxidisable by the acid dichromat e solution used in the first absorption spiral tube. I t became evident that their complete removal could only be effected by dissolution of the sample of powder in a suitable solvent. Kraus14 gives a comparison of the solubilities of cellulose nitrates, of nitrogen contents ranging from 10.20 to 12-29 per cent., in 70 different solvents; from this list a selection of the most likely solvents was made and of these, mononitrobenzene proved by far the most suitable.Dissolution of a 2 to 3-g. sample of a nitrocellulose powder was achieved in about 2 hours a t 100" C. Blank determinations on the solvent alone, and also on solutions of the usual constituents of nitrocellulose powders in it, indicated complete absence of interference by62 BONNER: THE ESTIMATION OF THE VOLATILE MATTER volatile oxidisable products. The method adopted therefore was to agitate the sample of powder (2-3 g.) with 25 ml. of nitrobenzene by means of a gas-tight stirrer arrangement in the three-necked flask shown in the diagram. The flask was immersed in a boiling water bath and a stream of air was bubbled through the solution to remove the ethyl alcohol and ether.Other constituents of nitrocellulose powders volatile to some extent at 100" C., e g . , diphenylamine, were almost completely retained by passing the vapours through a condenser before drawing them into the first absorption tube. Acetone and camphor, which are present in some types of powders, were removed by the alkaline ptassium permanganate solution (both of these volatile constituents are unaffected by the oxidising solution in the first ab- sorption tube but would be oxidised in the stronger medium in the third absorption tube). To test the method, weighed amounts of ethyl alcohol and ether were dissolved in nitrobenzene and an aliquot portion of the solution was transferred to the three-necked flask; the other constituents of a typical nitro-cellulose powder were added in the amounts present in a 2-g.quantity of sample and the estimation was carried out a3 indicated above. The time neces- sary to effect complete removal, absorption and oxidation was about 4 hours. Results given in Table IV indicate errors of 2 to 3 per cent. for both ethyl alcohol and ether. Duplicate results obtained with different types of nitrocellulose powders are given in Table V; excellent TABLE IV ESTIMATION OF MIXTURES OF ETHYL ALCOHOL AND ETHER IN NITROBENZENE SOLUTION Taken in mixture 7 Ethyl alcohol g. 0.0188 0.0105 0.0105 0.0097 0.0094 0.00323 Ether g- 0.0455 0.0 142 0-0142 0.0262 0.0 164 0.0074 Ethyl alcohol found g* 0.0186 0.0 105 0-0104 0.0097 0.0093 0.003 1 Ether Error found per cent.€5 - 1.4. 0.0465 0 0.0144 - 1.0 0.0143 0 0-0266 - 1.1 0.0170 - 3.7 0-0072 Error per cent. + 2.2 + 1-4 $- 0.7 + 1.6 + 3-7 - 2.7 TABLE V THE ESTIMATION OF ETHYL ALCOHOL Sample of propellant Modern nitrocellulose powders : (1) MA.668 . . .. . . . . (5) MA.621 . . . . . . . . (3) Dupont 4825 .. . . . . Neonite (small flake) . . .. . . Celluloid (camphor present) . . .. German igniter (acetone present)" . . AND ETHER IN PROPELLANT EXPLOSIVES Ethyl alcohol Ether per cent. per cent. 0.08; 0.09 0.57; 0.58 0.13; 0.12 0.99; 0.97 0.40; 0.40 0.99; 1.01 0.75; 0.77 0.10; 0.11 0.38; 0.39 0.00; 0.00 0.21; 0.20 0.00; 0.00 * Acetone found 1.08 and 1.12 per cent. Estimation to be described later. reproducibility is evident. The table also includes the result of analysis of one sample con- taining camphor and one containing acetone in place of ether; the acetone content was 1-10 per cent., but this was completely removed by the alkaline potassium permanganate solution, for no oxidation was found to have occurred in the third absorption tube.The method used for estimating this acetone will be given in Part 3 of this paper. The fact that nitroglycerine does not interfere in the method was dem-onstrated by carrying out an estimation on a sample of solventless cordite that contained a high percentage of nitroglycerine but no solvent; no oxidation took place in either of the acid dichromate solutions. The method has been found completely satisfactory for all types of propellants. Full details of the solutions and pro- cedure employed are given below.DETAILS OF METHOD- Afiparatzzs-This is shown in the diagram. The absorption spiral tubes have an over-all length of about 18 inches and the diameter of the spiral is about 2 inches; the total internal volume is about 60 ml. SoZ.~tions-To prepare the acid dichromate solution for €he oxidation of the ethyl alcohol, transfer 25ml. of an aqueous solution containing exactly 8 g . of potassium dichromate per litre to a clean dry 100 ml. graduated flask and add 2.5 ml. of concentrated sulphuric acid.CONTENT OF PROPELLANT EXPLOSIVES 53 Introduce the bulk of this solution into the first absorption spiral tube shown in the diagram. Retain the flask, as the solution is eventually returned to it. To prepare the acid dichromate solution for the oxidation of the ether, transfer 25ml.of an aqueous solution containing exactly 16 g. of potassium dichromate per litre to a clean dry 200 ml. flask and add, while cooling, 25 ml. of concentrated sulphuric acid. Introduce this solution into the third absorption spiral tube shown in the diagram and retain the flask. To prepare the alkaline potassium permanganate solution boil gently under reflux for 10 hours 104 g. of potassium permanganate and 261 g. of potassium hydroxide with 1 litre of water. After cooling, pour off the supernatant solution and introduce about 30 ml of it into the second absorption spiral tube. Procedwz-Crush the propellant sample into small pieces (about 3 mm. across) with a steel pestle and mortar, weigh accurately 2 to 3g. and add it to 25ml. of nitrobenzene (AnalaR quality) in the 250ml.three-necked flask shown in the diagram. (The relative effects of crushing and grinding samples will be described in Part 4 of this paper.) Stir the nitrobenzene solution vigorously and, with the flask immersed in a boiling water bath, draw a stream of air through the solution at the rate of 1 to 2 bubbles per second for 5 hours. Then stop the flow of air, wash the dichromate solutions back into their respective flasks and make up the volumes to the marks with water. Of the 100 ml. of oxidised ethyl alcohol solution add 25 ml. to a solution of 2 to 3 g. of potassium iodide in about 30 ml. of water and, aEter 2 minutes, dilute the solution to about 100 ml. with water and titrate the liberated iodine with 0.05 N sodium thiosulphate solution, using starch solution as indicator. Treat the oxidised ether solution similarly except that, as the acid concentration is much higher, add the 25-ml. aliquot portion to a solution of the potassium iodide in 100 ml. of water and, after 2 minutes, dilute to about 200ml. with water and titrate. Calculate the amounts of ethyl alcohol and ether present from the relation to the potassium dichromate given yre- viously (p. 50). SUMMARY An account is given of the methods of determining the residual contents of ethyl alcohol and ether in nitrocellulose propellants. A new method is described which employs dissolution of a small sample of the propellant in nitrobenzene at 100" C.; the ethyl alcohol and ether vaponrs are removed in a current of air and are differentially absorbed and oxidised in acid potassium dichromate solutions of different concentrations. The method is suitable for all normal types of nitrocellulose and nitroglycerine powders and is applicable in presence of the usual constituents of propellants including acetone, camphor, dibutyl phthalate, diethyl diphenylurea and diphenylamine. Arising out of the preliminary investigation of the problem a method is described for the estimation of mixtures of ethyl alcohol, butyl alcohol.and ether at concentrations of 0.05 to 0.10 per cent. in aqueous solution.64 STRAFFORD AND WYATT: THE DETERMINATION OF SMALL AMOUNTS Acknowledgment is made to Imperial Chemical Industries (Explosives Division) for making available a valuable report in which the earlier attempts at estimating ethyl alcohol and ether in simple nitrocellulose powders were reviewed and critically assessed. In conclusion, the author wishes to thank Mr. G. L. Hutchinson of the Armaments Research Departnien t for his helpful discussion of the problem and the Director-General of Scientific Research (Defence), Ministry of Supply, for permission to publish this material. REFERENCES 1. 2. 3. 4. 6. 6. 7. 8. 9. 10. 11. 12. 13. 14. Desmaroux, J., Mem. des Poudres, 1924, 21, 211. Fischer, W. M., and Schmidt, A., Ber., 1926, 59, 679. Dalbert. K., Menz. des Poudres, 1934-5, 26, 312. Lalande, A., Itid., 1932-3, 25, 104. Szeberenyi, P., Z . anal. Chem., 1915, 54, 409. Christiansen, L. M., and Fulmer, E. I., I n d . Eng. Chem., Anal. Ed., 1935, 7, 180. Bayly, W. A., J . SOC. Chenz. I n d . Vict.: 1940, 40, 267. Skrabal, R.. 2. anal. Chem., 1940, 119, 222. Fresenius, R., Zeit. Anal. Chem., 1941, 122, 459. \;C'illiams, R. J., J . Amer. Chem. SOL, 1937, 59, 288. Somogyi, E. V., Z. angew. Claena., 1926, 39, 280. Komar, N. P., Sergunin, N. A., and Fainberg, P. B., J . AppZ. Chem., U.S.S.R., 1934, 7, 424. Kraus, A., Nitrocell., 1941, 12, No. 4, 63-4. - Ibid., 1928, 23, 285. November, 1946

ISSN:0003-2654    

DOI:10.1039/AN9477200047

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 64 STRAFFORD AND WYATT: THE DETERMINATION OF SMALL AMOUNTS The Determination of Small Amounts of Aluminium the Aurintricarboxylate Method BY N. STRAFFORD AND P. F. WYATT IN a previous paper1 we describe a procedure for the separation of very small amounts of aluminium and iron in water, with subsequent determination of the aluminium by means of ammonium aurintricarboxylate. This method gives sufficiently accurate results for waters, but we had occasion to attempt to apply it to the precise determination of small amounts of aluminium in organic compounds, after wet decomposition of 2g.of the organic material by means of sulphuric, nitric and perchloric acids2 The resulting acid solution contained up to 10 mg. of iron and 0 to 300 pg. of aluminium, and two difficulties were met with in the analysis of this solution, viz. (1) the amount of iron present was too great, and the conditions were otherwise unsuitable, for complete separation by extraction as ferric thiocyanate, (2) measurements of optical density by means of the Spekker photoelectric absorptiometer showed that the fading of the aluminium aurintricarboxylate colour, rapid a t first, then gradually becoming slower, which occurs in slightly basic medium, cannot be controlled sufficiently well to give accurately reproducible results, even when the conditions are carefully standardised.The first of these difficulties was overcome by converting the iron into its “cupferron” complex, and separating it by extraction with chloroform from a solution containing sulphuric acid at 4N to 5h7 concentration. The excess of cupferron reagent can then be extracted suffici- ently well to avoid interference with the subsequent aurintricarboxylate reaction. With regard to the second difficulty it was found that after development of the aluminium complex colour as usual in acetate buffered solution, removal of the colour due to excess of reagent could be effected by buffering with ammonium borate to pH = 6.0 f 0.5, and that it was un- necessary to raise the pH to 7-5.With buffering just on the acid side of neutrality in this way, no fading of the aluminium lake occurs, so that results are highly reproducible, and the sensitivity of the method is increased. Under the modified conditions, no interference has been found with up to 10 mg. of calcium, magnesium or phosphate (P,O,), or up to 1 mg. of common heavy metals, and it is possible that even larger amounts may be tolerated. Beryllium interfFres, giving a colour of intensity similar to that produced by the same weight of aluminiuni.Iron and copper are removed in the cupferron extraction; it is necessary t o ensure thoroughly complete removal of iron, as this element gives a colour about half a s in- tense as that given by aluminium, but small amounts of copper can be tolerated. The procedure recommended for organic compounds is as follows.OF ALUMINIUM BY THE AURINTRICARBOXYLATE METHOD 55 REAGENTS-The reagents used are as described in the previous papers.f*2 The cup- ferron reagent is a freshly prepared and filtered 6 per cent. solution in water. It must be prepared from material of analytical quality; B.D.H. reagent is suitable. An aqueous solution should be only slightly straw coloured, and a chloroform solution should show no brown discoloration due to decomposition products.PROCEDURE-Decompose 2 g. of the organic material in a 100-ml. Kjeldahl flask with sulphuric, nitric and perchloric acids,2 and remove nitric acid by repeated evaporation with water, in the usual manner. Dilute the acid solution until it is 5 N to 6 N in sulphuric acid, and transfer it to a graduated 50-ml. separating funnel, using the minimum amount of wash water to effect the transference. To this solution, which usually has a volume of 20 to 25 ml., and which should contain not more than 10mg. of iron, add 2.5mLof 6 per cent. cupferron solution, mix well and add. 10ml. of chloroform, B.P. Shake vigorously for 40 seconds, allow to separate, and run off and reject the chloroform layer. Wash with a few ml. of chloroform, without mixing, to displace the drops of strong iron “cupferrate” solution remain- ing on the surface of the aqueous layer and in the stem of the funnel.Then shake for 30 seconds with 5ml. of chloroform, allow to separate, and reject the chloroform layer. Add 0.5 ml. of cupferron solution; the turbidity produced should be white and show no colour due to iron. Extract successively with 10 ml. followed by two 5-ml. portions of chloroform, shaking for 30 seconds each time, to remove all but a trace of the free cupferron from the aqueous layer. After each extraction the stopper of the funnel should be rinsed with a little water and the washings added to the contents of the funnel, but the final acidity of the solution should not be allowed to fall below 4 N, or traces of aluminium may tend to be extracted.Transfer the aqueous layer to a 100-ml. conical flask and wash the funnel with small amounts of water. Heat the solution to boiling, and boil for a few seconds to expel any chloroform present; then cool to room temperature. Add one drop of methyl red indicator, and ammonium hydroxide solution, 10 A’, until the solution is just alkaline. Add dilute hydrochloric acid, 5 N , drop by drop, until the solution is just acid, and then 5.0 ml. in excess, followed by 2 drops of saturated bromine water, which should immediately bleach the in- dicator. Failure of the indicator colour to disappear indicates that the excess of cupferron has not been extracted properly. Finally, add 0-5 ml. of 10 per cent. hydroxylamine hydro- chloride solution, to reduce the excess of bromine, and dilute the solution to 100ml.in a measuring flask (Solution A). Pipette 20-0 ml. of Solution A into a 100-ml. conical flask and dilute to 30 ml. with dis- tilled water. Add 1.0 ml. of gum arabic solution (5 per cent. in water), 5.0 ml. of ammonium acetate buffer solution, and 2.0 ml. of 0.2 per cent. ammonium aurintricarboxylate solution. Mix well, heat to boiling, and boil gently on a hot plate for 5 minutes. Cool to room tem- perature, add 4.0 ml. of 0.8 N ammonium borate solution, mix, dilute to 50.0 ml. and allow to stand for not less than 5 minutes. Determine the optical density of the test solution and of a reagent blank solution (similarly obtained) on the Spekker photoelectric absorptiometer, using a 4 cm.cell for the range 0 to 10 pg. of aluminium and a 1 cm. cell for the range 10 to 70 pg. of aluminium, with either Chance blue-green glass filters No. 6 (OB2) or Ilford green No. 604 filters. If the amount of aluminium present exceeds 70pg, take a smaller aliquot portion of Solution A and adjust the acidity so that 1.0 ml. of 5 N hydrochloric acid is present, before addirg the acetate buffer solution. Preparation of standard curve-Establish the standard curve required by measuring known amounts of standard aluminium solution (1 ml. = 10 pg. of Al) into 100-ml. conical flasks, adding 1.0 ml. of 5 N hydrochloric acid and diluting to 30 ml. Then develop the colour in these solutions as described for the test solution, and determine the optical density of each solution in turn against the first solution (containing no added aluminium) as reference solution.A typical series of results, using a 1 cm. cell, is as follows: Aluminium present, pg. . . .. .. 10 20 30 40 60 60 70 Optical density: 1. With Ilford green No. 604 filters . . 0.14 0.285 0.43 0.57 0-72 0.86 1.00 2. With Chance blue-green No. 6 filters 0-10 0.20 0.305 0.405 0.51 0.62 0-71 It is advisable to test Solution A for absence of iron. Take a 50-ml. aliquot portion, add 2 ml. of 1 n/r sodium citrate solution, 1 ml. of 10 per cent. thioglycollic acid solution, and finally 5 ml. of 10 N ammonium hydroxide, and mix. The solution should show no trace of pink colour due to iron.56 Afiplication to water samples-For waters, we recommend that the procedure pre- viously describedl be modified as follows. After extraction of the iron as thiocyanate, boil the solution to remove ether, cool and dilute to 50 ml. in a measuring flask. Take a 20-ml. aliquot portion and determine its acidity by titrating with N sodium hydroxide to methyl red indicator. Reject this test, take a second 20-nil. aliquot portion and add the same amount of N sodium hydroxide as was required by the first test. Treat the reagent blank similarly. Add to blank and test 1.0 nil. of 5 N hydrochloric acid and then develop the colour of the aluminium complex exactly as described above. The optical density of the solution may be measured by the Spekker absorptiometer, or the colour may be matched with the iron thio- glycollate colour disc in the B.D.H. Lovibond Nessleriser. With the above modified pro- cedure, the disc reading( yg. of Fe) divided by 20 represents yg. of aluminium, and if a 20/50 d. aliquot portion is taken, 8.Opg. of iron (disc reading) = 1 pg. of aluminium in the total solution which corresponds to 0.10 parts of aluminium per million on a 10-ml. sample or 0.04 parts per million on a 25-ml. sample, as bef0re.l REFERENCES ALEXANDER: A COLOUR REACTION OF CERTAIN CLASSES OF AZO DYES WITH COPPER 1. 2. Strafford, N., and Wyatt, P. F., ANALYST, 1943, 68, 319. Strafford, N., Wyatt, P. F., and Kershaw, F. G., Ibid., 1945, 70, 232. IMPERIAL CHEMICAL INDUSTRIES LIMITED ANALYTICAL LABORATORIES BLACKLEY, MANCHESTER, 9 October, 1946

ISSN:0003-2654    

DOI:10.1039/AN9477200054

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 56 ALEXANDER: A COLOUR REACTION OF CERTAIN CLASSES OF A20 DYES WITH COPPER A Colour Reaction of Certain Classes of Azo Dyes with Copper BY W.A. ALEXANDER A CHANCE observation of the behaviour of the dyestuff Bordeaux B with dilute copper solutions led to an investigation from which it appears that a certain class of dyes can be dis- tinguished by means of the characteristic reaction described below. The reaction also serves, under certain conditions, as a sensitive test for copper. TEST-Add a few drops of a dilute (about 0.05 per cent.) aqueous solution of the dye t o be tested to 10 ml. of a weakly acid solution of a copper salt (0.0001 M to 0.001 M ) , and then add sufficient sodium acetate to bring the pH to about 8-5. Carry out a control test-without copper. If the dye belongs to the reaeting class, a distinct colour change will be noticed Most of the reacting dyes are pink or red-and with these the colour becomes yellow-brown; in two instances the colour change in presence of copper is from blue-violet to blue-grey.Some of the reacting dyes, e.g., Bordeaux B, are more sensitive than others; these scnsitive dyes may be used as reagents for copper. When so used, the reaction provides a delicate test for that metal, and is capable of detecting as little as I pg. of copper in 10 ml., i.e., a concentration of 1 in 10,000,000. In testing for copper, the solution must be dilute; if suffi- ciently concentrated for cupric hydroxide to be precipitated the colour change is not observed. In testing for copper, too, the amount of dye solution taken should be the minimum necessary to give a distinct colour to the control; if too much be taken, the excess tends to mask the colour change.The test is particularly suitable for detecting copper in water for domestic use, where there is little interfering material. INTERFERENCE-The remarks under this heading, of course, apply either when the copper ion is used to distinguish certain dyes or when a sensitive dye is used for a qualitative test for copper. High concentrations of all salts (over 1.0 M ) lower the sensitivity of the reaction some- what. Borates, fluorides, chromates, nitrites and nitrates, at concentrations below 0.1 M , do not interfere. Phosphates and silicates mask the test somewhat, but not at concentrations below 0.001 M . Cyanide, even in traces, masks the test completely. Of the metals tested, only nickel reacts similarly to copper-but only when the pH is greater than 8.5 and the concentration of the nickel greater than 1 in 200,000.Manganese, cobalt, lead, silver, barium, strontium, calcium, magnesium, cadmium and arsenic do not interfere at low concentrations. Antimony, tin and bismuth do not interfere when the This applies to substances such as sodium chloride and potassium sulphate.ALEXANDER: A COLOUR REACTION OF CERTAIN CLASSES OF A20 DYES WITH COPPER 57 reagent is added after the solution has been filtered at pH 8.5 (test for copper). Chromium, aluminium and ferric iron adsorb the dye when their hydroxides are precipitated in its presence -there is no colour change, however, and traces do not interfere. Ammonium ion lowers the sensitivity and causes the formation of a dark brown in place of a yellow-brown tint with sensitive dyes of a red colour.REACTIVE DYEs-Of the dyes examined-representative of several classes-only certain azo dyes are reactive. and the conclusions drawn may be summarised as follows. (1) Copper-sensitive dyes contain an azo group linked in the 2 or 1 position to sulphonated a- or jS-napht hol respectively. (2) Reactive dyes derived from a-naphthol are substituted in the 4 and/or 5 positions with SO,' groups, while those derived from IS-naphthol are substituted thus in the 3 and 6 positions. (3) In both classes, the 8 position may be occupied by SO,' or OH. (4) Dyes that are insensitive include those closely related azo dyes derived from K- or /3-naphthol, in which the above order of substitution is reversed or substituents are not present.(5) The remaining part of the dye structure appears to have little influence on the reaction with copper. Tables I to IV illustrate these conclusions, together with the structure of the dyes. Of the insensitive dyes, only those closely related to the sensitive class are shown. Table I shows the reactive dyes derived from a-naphthol and Table I1 the inactive dyes from the same source. Table I11 gives the reactive dyes derived from 13-naphthol-these are rather more sensitive as a class than those in Table I and include the very sensitive Bordeaux B, No. 88. The numbers in all four tables refer to the Colour Index. Only one exception to the substitution order mentioned above was noted, No.54 (Table I), which has sulphonic groups in the 3 and 6 positions, whereas one would expect it to be a 4 5 or 4:8 disulphonate for a reacting a-naphthol dye. This may, however, be due to the presence of an excessive proportion of these reactive isomers. With all the reactive dyes except two the colour change is similar-from red to yellow- brown; the two exceptions are Azo Acid Violet AL (Table I) and Azo Acid Blue (Table I , No. 59), with both of which the change is from violet to blue-grey. MECHANISM OF REAcnoN-several workers have studied the lakes formed by the inter- action of certain metals with azo and other dyes. Many of the former have been shown by Drew and Landquist,l Beech and Drew,2 and Boyle, Cumming and S t e ~ e n , ~ to be inner co- ordination complexes.When copper is the metal, these are frequently soluble in water and amorphous in structure. Such compounds are usually formed under alkaline conditions ; for example, the authors named have shown that if sulphonic groups be present a sulphonate may be first formed, and no inner co-ordination results until the sulphonic groups are neutra- lised. Again, a great many of the compounds which have been recorded are brown, or reddish- brown in the solid phase. Lake formation, too, generally requires the presence of a hydroxvl group in the ortho position with respect to the azo group. These facts indicate that the delicate colour change noted at extreme dilution may be due to the formation of a copper lake. There are, however, one or two facts that are not so readily reconciled with this view.Lake formation, it appears, can also occur with compounds having an ortho carboxyl or amino substituent in place of the hydroxyl group, and such compounds do not react with copper at extreme dilution in the manner described. Again, the authors cited make no deductions with respect to substitution rules and lake formation similar to those given above; copper lakes are obtained from a number of ortho hydroxy azo dyes whether derivatives of naphthalene or not, but only certain sulphonated naphthol dyes give the characteristic reaction with copper. For example, Boyle, Cumming and Steven show that dye No. 151 (Table IV) forms a reddish-brown copper lake, but it does not react characteristically at extreme dilution. A comparison, at great dilution and equivalent concentrations, between the colours obtained on dissolving the solid Bordeaux B - copper lake and that resulting from addition of the dye to the copper ion at great dilution showed that the former was considerably darker (browner) in shade.Table IV shows the non-reacting /3-naphthol dyes.58 ALEXANDER: A COLOUR REACTION OF CERTAIN CLASSES OF A20 DYES WITH COPPER Name of dye or Colour Index No. Fast Red Azo Acid Violet AL No. 51 No. 59 No. 74 VR No. 179 No. 194 No. 32 No. 67 No. 77 No. 86 No. 91 No. 201 No. 246 No. 387 No. a20 1 -OH -OH -OH -OH -OH -OH -OH -OH -OK -OH -OH -OH -OH -OH -OH -OH TABLE 1: REACTIVE DYES DERIVED FROM a-NAPHTHOL 2 0 -N,-C?-SO,' Positions or substituents - 4 - - -SO,' - -so; -so; -so: -so; - 5 TABLE 11 : NON-REACTIVE DYES DERIVED FROM a-NAPHTHOL -N,-<>SO,' I OH -N:# OH OCHs OCH, S O ; -so: SOl' -so,' -so; - -so; -so; -SOa' -so; -so; -so; -so. ' -so; - -so; -so,' -50; OH I -NH.SO*+H. -SH.CO.CHa -NH. -so/ -NHZ SO;ALEXANDER: A COLOUR REACTION OF CERTAIN CLASSES OF A20 DYES WITH COPPER 59 Colour Index KO. of dye No. 59 No. 88 No. 89 No. 359 No. 151 So. 196 No. 196 No. 201 No. 201 No. 202 No. 28'1 No. 286 NlvoH TABLE 111: REACTIVE DYES DERIVED FROM /%NAPHTHOL lw Positions of substituents 1 2 -OH -OH -OH -OH 4 5 6 -so; -so; -so: -SO,' TABLE Iv: NON-REACTIVE DYES DERIVED FROM /%NAPHTHOL (3 - N a G O H OH - N * - q ) v / OH \ so; -OH -OH -OH -OH -OH -OH -OH -OH 8 - - -so; 40s'60 NOTES The formation of the co-ordination compounds studied by the authors cited requires heating in concentrated solutions, and it is difficult to see how the rapid reaction at extreme dilution described above can be due entirely to lake formation of this type. It seems more reasonable to suppose that certain dyes are adsorbed by colloidal cupric hydroxide. REFERENCES 1. 2. 3. Drew, H. D. K., and Landquist, J. K., .J. Chem. SOC., 1938, 292. Beech, W. F., and Drew, H. D. K., Ibid., 1940, 608. Boyle, J. L., Cumming, W. AT., and Steven, A. B., J . Roy. Tech. Coll., Glnsgow, 1940,617. THE ROYAL TECHNICAL COLLEGE July, 1946 GLASGOW

ISSN:0003-2654    

DOI:10.1039/AN9477200056

出版商:RSC    

年代:1947

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE.By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time.The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years.The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion.The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on.Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp.15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction 60 NOTES Notes THE DETERMINATION OF COPPER IN FOOD IN a study of methods for the determination of copper in food, it was found that certair? difficulties associated with the preparation of samples by dry-ashing could be overcome anti that the procedure for photometric absorption measurement, when using sodium diethyl- dithiocarbamate as the colouring agent, could be simplified. AsHING-Whilst a dry-ashing procedure is more convenient and less liable to contamina- tion from reagents than a wet-ashing one,it is generally ac~eptedl,~?~that it gives !ow recoveries of copper if the ashing temperature exceeds 600" C.This comparatively low temperature not only needs control but may cause a difficulty in obtaining reasonably complete ashing of some products. The generally accepted explanation of the loss of copper is that it is due to formation of an acid-insoluble compound and not to vo1atilisation.l Piper4 has suggested that the compound is a complex silicate of copper, and support for this is given by Bailey and McHargue,6 who obtained lower results when using silica dishes for dry ashing than when they ashed by the wet method; by Comrie,6 who obtained greater losses when using old silica dishes than when new ones were used, and by Van Niekerk,' who observed slagging of copper salts during dry ashing when they came into contact with the sides of the silica dishes he used.It is the general practice to extract the ash with hydrochloric acid and to determine the amount of copper present in the extract, and an alternative explanation of the loss of copper is that it is due to the reduction of the copper compounds present to metallic copper by the carbon which is necessarily formed during dry ashing. This reduction occurs at relatively low temperatures8 and, as copper is only feebly attacked by hydrochloric acidYs losses are to be expected when this acid alone is used for extraction. If this view is correct it is to be expected that the use of a more suitable extracting acid will result in a full recovery of copper. The results of some recovery experiments with a farinaceous product ashed at 650" to 800" C.are given in Table I. These clearly show that the presence of nitric acid in the extracting acid results in a much more complete recovery of added copper. TABLE I RECOVERY OF COPPER FKOM ASH WITH DIFFERENT EXTRACTING ACIDS Copper added Pi5 50 50 60 50 50 60 - Hydrochloric acid Copper found Recovery A -I PLg. 70 8.0 - 13.2 10.4 12.6 9.2 9.2. 2.4 9-2 2.4 11.2 6.4 11.2 6.4 Mixture of hydrochloric and nitric acid P 7 Copper Copper added found Recovery PLg. PS. % - 2 1.6 - 50 70.2 97.2 50 '70.6 98.0 50 67-0 90.8 50 71.2 99.3 50 6'7.0 90.8 50 68.8 94.4 It is possible to obtain consistently satisfactory recoveries of added copper when hydro- chloric acid alone is used to extract the ash, provided the ashing temperature is kept at 450" to 490" C.This does not, however, show that the copper already present in the product is completely recovered, nor are the satisfactory recoveries obtained when nitric acid is used a proof of the accuracy of the nitric acid method. A series of analyses by the two dry-ashing methods were, accordingly, run in parallel with a standard wet-ashing method.1 The results,NOTES 61 given in Table 11, whilst showing excellent agreement between the nitric acid and the wet ashing methods, show also that the hydrochloric acid method is not reliable. TABLE I1 DETERMINATION OF COPPER IN DIFFEREKT PRODUCTS Dry-ashing - ----A HC1 HC1 -k HXO, Product extraction extraction Wet-ashing p.p.m. p.p.m. p. p. Ill. Peas . . . . . . 6.3 7.4 7-4 6.3 7.3 7-4 6-4 7.3 7.3 6.3 7.4 7.4 2.0 6.0 6.0 2.1 6-0 6-1 6.1 5.9 Mixed pickles .. 3.4 8.9 8.8 5.2 9.1 9.0 5.7 9.1 8.8 6.6 9-0 9.0 Treacle pudding . . 2.1 6.0 5.9 When nitric acid has been used in the treatment of a ~ h , ~ ~ l ~ J l it has either been used as a part of what is virtually a wet-ashing procedure carried out in open dishes rather than in a flask9 or because a subsequent electrolytic separation of copper makes the presence of hydro- chloric acid undesirable.l0P1l Innone of these instances is the nitric acid used to ensure a more complete extraction of the ash than would be obtained if hydrochloric acid alone is used. Measurement of Photometric absorfitio??---The use of nitric acid often results in a yellow- coloured extract. The colour varies from sample to sample and it is, therefore, necessary to measure or allow for the blank of each extract.With food products containing low amounts of copper, a solution of the extract as concentrated in respect of copper as is practicable should be used and the dilution necessary if separate aliquots of the extract are taken for blank and colour measurement should be avoided if possible. TABLE 111 PHOTOMETRIC ABSORPTIOX OF A COPPER SOLUTION* AFTER ADDITION OF VARIOUS AMOUKTS OF SODIUM DIETHYLDITHIOCARBAMATE Weight of sodium diethyldithiocarbamate Photometer added, mg. readingt 2 50.8 6 57.0 10 69.0 20 82.8 50 82.8 75 83.2 100 82.6 250 83.0 500 85.4; * Containing 94 pg. of copper in 50 ml. t Water setting 47.8. $ Slight cloudiness in the solution. As can be seen from Table 111, the absorption of a copper solution is independent of the amount of sodium diethyldithiocarbamate present once the maximum absorption has been reached. It is, therefore, practicable, by using the solid reagent for colour development, to measure the blank and the copper absorptions on the undiluted extract. There is apt to be waste when the pure solid reagent is used, as, at most, only 20- 30mg.are required for full colour development. Further, if too much is used, the test solution tends to be cloudy owing to incomplete solution of the diethyldithiocarbamate. It is therefore suggested that the reagent be diluted with a salt which is readily soluble and is without influence on the copper colour. X i : 25 mixture with sodium chloride will be found to be a convenient one to use.METHOD-Dry-ash a suitable sample of the product in a silica basin in the normal manner, igniting at 600" to 850" C . Extract the ash by warming it with 5 to 10 ml. of a62 NOTES mixture of 2 volumes of diluted hydrochloric acid (1 + 1) to 1 volume of diluted nitric acid ( l + l ) , both of analytical reagent purity. Transfer the extract to a 100-ml. beaker, add about 2 g. of A.R. citric acid or ammonium citrate and 2 ml. of 1 per cent. gum arabic solution, neutralise with A.R. ammonium hydroxide (sp.gr. O*SSO), and add 1 to 2 ml. in excess. Allow the solution to cool and transfer, with filtration if necessary, to a 50- or 100-ml. volumetric flask and make it up to the mark with water. Set the photometer to a predetermined setting with a part of the contents of the flask, using Ilford 601 spectrum violet filters.Transfer another part to a beaker or, using the solution already in the photometer cell, add about 0.5 g. of a 1 : 25 mixture of sodium diethyl- dithiocarbaniate and A.R. sodium chloride. Stir to dissolve the mixture and measure the absorption of the solution. The increase is that due to the copper colour. Calibrate the photometer by means of a standard solution prepared from A.R. cupric sulphate or pure copper foil, with the same size of measuring cell as that used in the test, and measuring the absorption as directed above. Thanks are due to the Metal Box Co., Ltd., for permission to publish, and to Dr. €3. Liebmann for invaluable advice and constructive criticism. 1. 2. 3. 4. 6.6. 7. 8. 9. 10. 11. REFERESCES Sandell, E. B., “Colorimetric Determination of Traces of Metals.” Snell, F. D., and Snell, C. T., “Colorimetric Methods ofdnalysis.” Greenleaf, C. A., J. Assoc. Off. Agric. Chew., 1942, 25. 385. Piper, C. S., “Soil and Plant Analysis,” University of Adelaide, 1942. Dailey, L. F., and McHargue, J. S., Plant Physzol., 1945, 20, 74. Comrie, A. A. D., ANALYST, 1035, 60, 532. \.’an Niekerk, P. le Roux, Onderstepoort J . Vet. Sci. Anirn. Indust., 1937, 9, 623. Partington, J. R., “ A Textbook of lnorganic Chemistry,” Macmillan & Co., London, 1939, pp. 791 Hanak, A., 2. Uniersuch. Lebensm., 1930, 59, 511. Grandel, Pharnz. Weekblad., 1930, 69, 913 and 1345. Haddock, L. A., and Evers, N., AXALYST, 1931, 57, 495. Interscience Publishers Inc., Chapman & Hall, London, 1936. Kew York.1944, Chap. XVII. Chap. XVI. and 796. RESEARCH DEPARTMENT THE METAL BOX CO., LTD. ACTON, LONDON, W.3 JOHN H. HIGH October, 1946 NOTE ON THE ASSAY OF SOLUTIONS OF d-TUBOCURARINE CHLORIDE FOR INJECTION THE renewed interest in d-tubocurarine chloride, resulting from its extensive use for muscular relaxation during surgical operations,’ has made it desirable that analysts should be familiar with clieniical and physical methods which, apart from the fundamental biological assay, may be used for the standardisation of injections. In our laboratories it has been found that the colorimetric and polarimetric methods, described below, may be used for the routine examination of solutions, which usually contain 1 per cent. w/v of crystalline d-tubocurarine chloride.POLARIMETRIC ASSAY-Crystalline d-tubocurarine chloride, C,,H,,O,N &12 5H20, possesses a specific rotation of +190” (C 1.0 in water) equivalent to [~]2,+215” for the an- hydrous salt. The specific rotation in water, however, is practically independent of the concentration and consequently the optical rotation of a solution is a linear function of its d-tubocurarine content. This property forms a useful method for the assay of solutions, the optical rotation of an aqueous 1 per cent. w/v solution of crystalline d-tubocurarine chloride being + 1.90”. COLORIMETRIC ASSAY-d-Tubocurarine chloride yields with the Folin-Ciocalteu phenol reagent2 a brilliant blue colour, which will detect as little as 0.01 mg. of the alkaloid. The reaction may be made quantitative when carried out under the following conditions.Standard sohtion-Dissolve 10 mg. of crystalline d-tubocurarine chloride, C,,H,,O,N 2C12. 5H,O, in water and make up to 100 ml. 3’ est solzitiorz-Dilute the solution under examination to approximately the same con- centration as the standard solution. Reap+-Folin-Ciocalteu phenol reagent.2 For use, dilute 1 volume of strong stock solution with 2 volumes of water.NOTES 63 CoZour reaction-Measure 2 ml. of the standard or test solution into a 25-ml. glass-stoppered measuring cylinder, add 3 ml. of reagent and adjust the volume to 25 ml. with water. Add 2 ml. of 20 per cent. w/v sodium carbonate solution, mix, and heat a suitable volume (5 ml.) in a test tube placed in a boiling water bath for 3 minutes Prepare under identical conditions reattion mixtures from the standard and test solutions and compare them in a suitable colorimeter.From the readings obtained calculate the d-tubocurarine chloride content of the test solution. A phenol, which may be present as an antiseptic in a solution for injection, will interfere with the colorimetric assay, and either a correction must be applied to the colorimeter reading or the phenol must be removed before addition of the reagent. When dealing with prepara- tions of uncertain composition the analyst must proceed on the assumption that a phenolic antiseptic is present. For example, if a single 1-ml. ampoule, containing 10mg. of d-tubo- curarine chloride, is available, the following procedure should be adopted.The ampoule is opened, a portion of the solution (about 0.5 ml. required) is transferred to a 50-mm. micro- polarimeter tube and the optical rotation is determined. This polarimetric assay consumes no material and the solution is returned to the ampoule, from which 0-5 ml., ac- curately measured with a pipette or a micrometer syringe, is transferred to a separating funnel containing 25 ml. of water, and the resulting diluted solution, rendered faintly acid if neces- sary, is extracted with three portions (2.5 ml.) of chloroform. The chloroform extracts are discarded and the aqueous layer run into a 50-ml. standard volumetric flask to which the aqueous washings from the separating funnel are added to adjust the volume to 50 ml. The solution is well shaken and used for the colorimetric assay.After the polarimetric and colori- metric work has been completed sufficient of the original solution will remain in the ampoule for a biological examination, if this is required. The methods described in this communication have yielded results correct to within &5 per Lent. I t might be feared that the polarimetric assay would be unreliable on account of possible racemisation of the d-tubocurarine but , in our experience, solutions of the chloride undergo little change when subjected to the usual process of heat sterilisation. I am indebted to the Directors of The Wellcome Foundation for permission to publish this information. Cool the reaction mixture. REFEREKES 1. 2. Gray, T. C., and Halton, J . , Proc. Roy. SOC. Ned., 1946, 39, 400; Prescott, F., Organe, G., and “Official and Tentative Methods of Analysis of the Association of Ojicial Agricultural Chemists,” Rowbotham, S., Lancet, 1946, 11, 80.5th Edn., 281. THE CONTROL LABORATORIES G. E. FOSTER W’ELLCOME CHEMICAL U‘ORKS December, 1940 DARTFORD, KENT OXALIC ACID EXTRACTANT IN VITAMIN C ASSAY SOLUTIOXS of oxalic acid have advantages over metaphosphoric or trichloroacetic acid as extractants for vitamin C in being cheaper and more stable, and avoiding precipitation of protein, whilst effectively inhibiting the action of ascorbic acid oxidase. In a collaborative investigation on vitamin C in tomatoes, involving the pxeparation of large volumes of extracts, the opportuiiity was taken to compare the results obtained on a given fruit with oxalic and metaphosphoric acids respectively, using sufficiently large numbers of fruit to obtain averages in which the sampling error was reduced to a low level. With 1 per cent. and 2 per cent. solutions of osalic acid the average results were respectively 98 and 99 per cent. of those obtained when 5 per cent. metaphosphoric acid solution was used. The pH of 10 to 40 per cent. extracts in 1 per cent. oxalic acid solution was 1.8 to 2.0 and that in 2 per cent. solutions 1.1 to 1.2. Control experiments showed the presence of much ascorbic acid oxidase. The extracts in meta- phosphoric acid showed no appreciable loss after a week’s storage in the refrigerator in brown bottles filled with nitrogen-the routine procedure applied to metaphosphoric acid extracts. With these precautions, oxalic acid can safely be used as an extractant in vitamin C assays on tomatoes and similar large fruit. It is, however, less suitable for extracting unripe walnuts containing much “apparent vitamin C” of which the dye titration value depends on the pH (cf. Nature, 1946, 158, 133). OVALTINE RESEARCH LABORATORIES FRANK WOKES The pH of the tomato flesh was 4.5 to 5-5 and that of the skin 7 to S. KING’S LANGLEY, HERTS November, 1946

ISSN:0003-2654    

DOI:10.1039/AN9477200060

出版商:RSC    

年代:1947

数据来源: RSC