ISSN:0003-2654    

DOI:10.1039/AN94772FX037

出版商:RSC    

年代:1947

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94772BX039

出版商:RSC    

年代:1947

数据来源: RSC

摘要:

viiiITHE ANALYSTHIS MAJESTY’S COLONIAL SERVICE.HERE are vacancies for Chemists in the Joint Departmentof Chemistry Malayan Union and Singapore. Appoint-ments are perm’anent and pensionable after 3 years onprobation. Salary scale: $400 a month rising by annualincrements of $25 a month to $800 a month (for exchangepurposes $I equals 2s. 4d.). On continnation in permanentappointment would be required to contribute 4 per cent. ofsalary to Widows and Orphans Pensions Scheme. Warservice and experience will be taken into account in determin-ing the initial salary to be offered. Cost of living allowanceat present $10 a month plus 20 per cent. of salary (30 per cent.for married officers) subject to a maximum of $110 a month($160 for married officers).Allowances also paid in respectof officers’ children under 18. Government quarters (ifavailable) provided at a nominal rent. If unavailable anallowance is paid in lieu. Income tax at local rates only(Malayan rates not yet announced). Free medical attend-ance. Free passages for officers and their wives and children(under 10 years of age) up to four persons in all once each waym each tour of service. Tour on first appointment 3-4 yearsearning approximately 5* months home leave.Qualifications: Only candidates who hold a good honoursdegree in chemistry and/or the Fellowship or Associateshipof the Royal Institute of Chemistry can be considered.Preference will be given to unmarried candidates under 35years of age who hold the Institute‘s Certificate in Branch E.(Food, Drugs, and Water) and who have gained experiencem a Government or Public Analyst’s Laboratory.Applica-tion forms obtainble from the Director of Recruitment,Colonial Service, 15, Victoria Street, London, S.W.I.A QUALIFIED CHEMIST with a Chemical and/or Pharma-ceutical qualification required as an Assistant to theManager of the Manufacturing Department of a West Londonfirm of Manufacturing Chemists. Commencing salary &,o.Write, giving full details of age, experience and qualificationsto Box No. 3669, THE ANALYST, 47, Gresham Street, London,E.C.2.UALIFIED CHEMIST, BSc. or A.R.I.C., required for 0 Research Laboratory of a firm of Manufacturing Chemistsin West London. A pharmaceutical qualification would be anadvantage although not essential.The position is apermanent one. Commencing salary L450. Write giving fulldetails to: Box No. 3668, THE ANALYST, 47, Gresham Street,London, E.C.2.UALIFIED CHEMIST with Chemical or Pharmaceutical Q qualifications required for the Analytical Control Labora-tory of a toilet and perfumery factory in North-West London.The position is a permanent one. Cornmencing salary L450.Write giving full details to Box No. 3661, THE ANALYST, 47,Gresham Street, London, E.C.2.ANALYST (age 30 to 35 years) required for a position ofauthority in the Analytical and Control Laboratory of anorganisation manufacturing foods and pharmaceut’cals inN.W. London. Applicant should hold the F.R.I.C. (branchE) qualification, as well as a degree in chemistry (includingphysical chemistry).A pharmaceutical qualification wouldbe an advantage, and only candidates having several years’industrial experience in a similar position will be considered;they should have an up-to-date knowledge of analyticalmethods (particularly of organic materials) and be familiarwith the routine estimation of vitamins (including spectro-scopic methods). A superannuation scheme is in operation.Write stating salary required to Box No. 3666, THE ANALYST,47, Gresham Street, London, E.C.2.ANALYTICAL CHEMIST (either sex) required to takepart in the work of routine control of foods and pharma-ceutical products, and in the general work of the analyticalaboratory. Candidates should hold a degree in Chemistryor its equivalent, and have had some analytical experiencepreferably including physical methods of analysis) eitherwith a public analyst or in an industrial laboratory. Theposition is pensionable, and the salary wiU be between L400and L500 per annum according to experience.Apply toPersonnel Department, Glaxo Laboratories, Greenford,Middlesex.HE DISTILLERS COMPANY LIMITED require aqualified chemist with experience of analytical work forresearch on analytical methods. Applicants should possessa first or second class honours degree or equivalent, and anF.R.I.C. in analytical chemistry and/or knowledge of thenewer physical techniques employable in analysis would be anadvantage. Applications should be made to the Controller ofResearch and Development, The Distillers Company Limited,Research Department, Great Burgh, Epsom, Surrey, statingage, qualifications, experience and salary required.IMPERIAL CHEMICAL ISDUSTKIES LIMITED,Plastics Division, WelwyIi Garden City, require for theirAnalytical Department two Analvtical Chemists.Candidates,who may be male or fema1e;should be either HonoursGraduates in Chemistry or Associates of the Royal Instituteof Chemistry and should preferably have specialised . inMetallurgical Analysis or Spectrographic Analysis, 1.e.Emission and U.V. Adsorption. Age preferably under 35.Apply for Application Form to the Staf€ Manager, PlasticsDivision, Imperial Chemical Industries Ltd., Black FanRoad, Welwyri Garden City, Herb., quoting a/%HE Goodwill Library and Laboratory of ;I Consultingand Analytical Chemical Practice in New Zealand,together with an adjacent dwelling house, is offered at about,$OOO.The practice includes the analysis of foods, drugs,wdters, oils, fertilisers, feeding stuffs, brewing materials, etc.Full particulars available in London. Write Box 3667, THEANALYST, 47, Gresham Street, London, E.C.2.LOKDON Manufacturer of Quality Soft Drink requiresLaboratory Assistant for Quality Control, Compounding,etc. Minimum of Inter. BSc. standard essential. Salaryaccording to qualifications. Write giving experience, age,etc., to Box 3668, THE ASALYST, 47, Gresham StreetLondon, E.C.2.SAVORY & MOORE LTD.MAY FAIR A BRANDALUMINIUM OXIDEof British ManufactureS tandardised forCHROMATOGRAPHICADSORPTIONANALYSISSEPARATIONandFurther information f r o m :SAVORY & MOORE LTD.LAWRENCE RD., TOTTENHAM, v.15ANTED Back volumes runs and sets of THE ANALYST-w J . C . S . ; ‘J.S.C.X.; Brit.‘ C h m . Abs. A . and B.; BWIchzmical J . ; Trans. Faraday S? ; Nature; Annud Reports;and any chemical and Scientific Journals. Write BoxNo. 3669, THE ANALYST, 47, Gresham Street, London, E.C.

ISSN:0003-2654    

DOI:10.1039/AN94772FP045

出版商:RSC    

年代:1947

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94772BP051

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 OCTOBER, 1947 VOL. 72, No. 859 Polarographic Determination of Lead in Foodstuffs BY F.R. JONES AND (MISS) D. M. BRASHER -1 POLAROGRAPHIC method has been developed for the determination of lead in foodstuffs. It is simple and convenient and does not require preliminary separation of the lead; the conditions of electrolysis are made such that trace metals (Fe, Sn, Zn, As, Cu) do not interfere with the lead wave. The method could be used as an alternative to chemical analysis in routine work. Few references in the literature relate to the polarographic estimation of lead in organic materials. Yosidal devised a method based on the preliminary separation of lead electro- lytically as PbO, ; Teisinger, estimated lead in blood by adding hydrochloric acid and recording the current - voltage curve directly; Forche3 improved the accuracy of this method by first decomposing the organic matter with sulphuric, nitric and perchloric acids, evaporating the resulting solution to dryness and submitting a solution of the residue in alkaline tartrate to polarographic analysis. These methods suffer from disadvantages, the first because of the necessity for preliminary separation of lead, the second through interference of tin, and the third through interference of both tin and iron.A further difficulty is that a satisfactory lead wave is not normally obtained from the electrolysis, in the polarographic cell, of the sulphuric acid solution resulting from the wet destruction of foodstuff; this is because of interference. by residual organic matter. As an outcome of the work herein reported, the difficulties can be overcome as follows:- (a) Interference of residual organic matter-Complete destruction of organic matter has been found essential to the production of a horizontal current - voltage curve in the absence of trace metals.(b) Interference of ferric iron-This produces a wave at a potential more positive than that of lead, and in samples containing a relatively large quantity of iron the pronounced 423 This is accomplished by the use of perchloric acid.424 JONES AND BRASHER POLAROGRAPHIC DETERMINATION [Vol. 72 oscillations that follow the iron wave, and the accompanying maxima, make it difficult or impossible to measure the lead wave. Iron, therefore, is first reduced with hydroxylamine hydrochloride.* Investigation has shown that reduction is incomplete in solutions of acid normality greater than 2.5, but is effective, up to 2000 p.p.m. of iron in the sample taken, if the normality is suitably adjusted.The resulting ferrous ion is reduced at the dropping mercury electrode at about -1.2 volt, and therefore does not interfere with the lead wave, which occurs at -0.5 volt. (c) Interference of ti.n-In the stannous state (after treatment with hydroxylamine hydrochloride) in sulphuric acid solution of concentration approaching 2-5 N , tin produces a wave at - 0.45 volt, that is, at a potential almost identical with that of lead. Investigation has shown, however, that, even with a concentration of 300 p.p.m. of tin in the sample taken, the tin wave can be eliminated without effect on the lead wave, by adjustment of the pH to a value between 2-5 and 3-0 by addition of sodium hydroxide.At values much above 3-0, for example at fiH 5.5, the height of the lead wave is considerably reduced. The control of pH is very simply effected with the aid of two indicators which also act as maximum suppressors. Other trace elements likely to be present in foodstuffs do not interfere with the lead wave. Zinc and arsenic are reduced at -0.7 and -1.1 volt respectively, and copper is reduced at zero potential in presence of hydroxylamine hydrochloride, which provides sufficient chloride ions to stabilise the potential of the anode (a pool of mercury in the reaction cell) at that of a calomel half-cell. With these precautions, a satisfactory lead wave can be obtained from the sulphuric acid solution resulting from the wet destruction of the material, but the value of the diffusion current is affected by the viscosity of the electrolyte.It has been shown5 that, in solutions of sulphuric acid and of sodium sulphate, the diffusion current of lead, and of other ions, is inversely proportional to the square root of the viscosity of the electrolyte. The electrolyte, prepared as indicated above, consists mainly of a solution of sodium sulphate, of which the concentration-and hence also the viscosity-may vary largely depending upon the quantity of sulphuric acid remaining after destruction of the sample and upon its subsequent dilution. The diffusion current is very simply corrected for viscosity with the aid of the curve given in Fig. 2, and the corrected value is referred to a calibration curve, Fig.3, to obtain the concentration of lead in the solution electrolysed. The amount of lead that can be determined by this procedure is limited by its solubility in sulphuric acid, but with a 5-g. sample containing up to 40 p.p.m. no loss of lead has been experienced. METHOD APPARATUS- The Heyrovsky cell used for electrolysis is shown, in position under the dropping mercury electrode, in Fig. 1. The water-bath in which it stands is capable of being lowered from this position and the bung carrying the electrode is fitted with a short glass tube which, by dipping into the water when the bath is raised, isolates the contents of the cell from the atmosphere. A second glass inlet (2) is fitted through the bung. In the analyses reported below, hydrogen, used for removing air from the cell and its contents, was generated electrolytically.Polarograms were recorded with a HeyrovskJi Micro-Polarograph (Nej edly, Prague) modified by incorporation of a circuit for compensa- tion of residual current. The photographic paper used in the recording drum had a grid printed photographically upon it so that the current - voltage curve and the grid both appeared on development. PROCEDURE- Prefiaration of the solution for eZectroZ?rsis-Destroy 5 g. of the sample in a Kjeldahl flask in the usual way with sulphuric and nitric acids. Note the volume of sulphuric acid used; it should not exceed 2ml.* When destruction is apparently complete, add about 50 ml. of water and boil until fumes are evolved.Add 3 drops of perchloric acid, heat and add more perchloric acid if a bright yellow colour is not developed in about 1 minute; add Readings of current and potential were made directly. (1) * The concentration of lead in the solution electrolysed may be too small for the accurate measurement of the lead wave if more than 2 ml. of sulphuric acid are used with a sample of low lead content. Destruction of some foods can be accomplished with less than this quantity of acid if the sample is first allowed to stand overnight in contact with nitric acid.October, 19471 OF LEAD IN FOODSTUFFS 425 about 60ml. of water and boil until fumes are evolved. The residual acid should now be clear and colourless. Transfer to a measuring cylinder with the aid of two or three small quantities of water, each boiled in the flask, and bring the diluted acid to a volume, V ml., which must be near to, but not greater than, 15 times the volume of sulphuric acid used for the destruction of the sample.Determine its normality, S, by titration of a small portion with 0.5 N sodium hydroxide; it should be less than 2.5 (= 1.25 M ) . Transfer 10 ml. of the acid solution to the polarographic cell, add about 0.1 g. of hydro- xylamine hydrochloride, connect the side-tube (Fig. 1 (1) ) to the hydrogen supply, place the cell over a bunsen and boil the solution, very gently to minimise loss by evaporation. After 5 minutes, bubble hydrogen through the solution and place the cell in the water bath in the lowered position under the dropping mercury electrode.Add 3 drops each of bromophenol blue and thymol blue indicators, B.D.H., followed by 5 N sodium hydroxide from a 10-ml. graduated pipette until the colour of the solution is just violet; add 2.5 N sulphuric acid from a 1-ml. graduated pipette until the colour is just yellow. Note the combined volume ANODE .WATER LEVEL R SEALED THROUGH GLASS Fig. 3 . Electrolytic Cell for Determination of Lead of alkali and acid added (v mi.). Normality of Sodium Sulphate [lOS/(lO + v)] Fig. 2: Viscosity Factor. The volume of indicators added can be neglected as it approximates to that of the'water lost by evaporation. The volume of the solutionelectrolysed is thus (10 + v) ml. Raise the water-bath and cell to the position shown in Fig. 1, transfer the hydrogen supply to tube (2) and introduce sufficient mercury through tube (1) to cover the tip of'this tube and the platinum anode.Adjust the level of water in the bath so that the end of the glass tube is immersed. Continue the passage of hydrogen for a further 10 minutes, and meanwhile adjust the temperature of the bath. Record the polarogram under standardised conditions of rate of flow of mercury and rate of change of applied potential. It is only necessary to record between -0.2 and -0.7 volt. (2) Correctiovt fur viscosity-The graph of the viscosity factor, Fig. 2, was constructed from experimentally determined viscosities (relative to water) of solutions of sodium sulphate; rl2 is the viscosity of the 1-67 N solution which results from the neutralisation to PH 3-0 of 2.5 N sulphuric acid with 5 N sodium hydroxide and which was used for the con- struction of the calibration curve, Fig.3; ql is the viscosity of a solution of sodium sulphate of given normality. The values of (ql/qz)) lie on a smooth curve which is not quite linear. To correct the diffusion current as obtained from the polarogram for the variation of the viscosity of the electrolyte from the standard value, y2, calculate the normality of sodium sulphate in the solution electrolysed : Normality = 10 S/(10 + v)426 JONES AND BRASHER : POLAKOGRAPHIC' DETERMINATION LVol. 72 where S = normality of the dilute acid solution as found by titration, and v = volume of reagents added to 10 ml. of this acid solution, and refer the value found to Fig. 2. Multiply the diffusion current measured at the half-wave potential of lead, viz., - 0.5 volt, by the value of (vl/y2)* corresponding to the normality of the sodium sulphate.In determining the diffusion current from the polarogram no correction for variation of drop time is necessary; the drop time is sufficiently con- stant under standardised conditions. (3) Calculation of lead content-The calibration curve, Fig. 3, was constructed from polarograms of solutions of known lead .9 content; for each determination 10 ml. of a 3 treated with hydroxylamine hydrochloride and neutralised exactly as described above. The normality of the solution of sodium sulphate electrolysed was 1.67 (= molarity 0.835); its molar concentration of lead was 0 calculated from the known amount of lead 10 20 30 40 50 in the acid solution. The points on the curve Molarity of Pb in solution in Fig.3 should lie on a straight line passing Calibration Curve of Pb in Na,SO, through the origin. solution (16.7 N ) at pH 3. To calculate the lead content of the sample analysed , refer the diffusion current, corrected for viscosity, to the calibration curve to obtain the molarity of lead in the solution electrolysed. If M be this molarity, the weight of lead in grams is : 0.30 - 4 a 0.20 - c, ri 5 d 1 w 0.10 - solution of lead in 2.5 N sulphuric acid was Fig. 3. 0.207 RI (10 + v) in the solution electrolysed, and 0.0207 MV (10 + v) in the sample, where V = the volume in ml. to which the sulphuric acid resulting from the destruction of the sample was diluted. If 5 g. of material was destroyed the lead content is: 4140 MV (10 + v) p.p.m.RESULTS The accompanying table shows results obtained by this method on samples of canned meat and fish, the lead contents of which were first determined by chemical analysis with an accuracy of f0.5 p.p.m. Known quantities of tin and lead were added and the table shows the quantity of tin added to, and the total lead present in the sample taken for analysis. The last column shows the molarity of lead in the solution electrolysed. The standardised conditions of electrolysis were : Temperature of water in bath . . .. . . 25°C. Height of mercury column above tip of capillary . . Rate of flow of mercury . . .. .. . . 1.56 mg. set.-' Rate of change of applied potential .. . . 0.2 volt min.-l Counter residual current . ... .. . . set as required The results, which show that the method is not affected by the presence of tin up to 115 p.p.m., are considered to be sufficiently accurate for all normal requirements. Kolthoff and Lingane6 state that the accuracy of polarographic analysis under ordinary conditions is of the order of &2 per cent. in the concentration range to lo4 molar (16,000 to 160 p.p.m. lead) and f 5 per cent. in the range lo4 to lo6 molar (160 to 16 p.p.m. lead). these low values being due to the high atomic weight of lead; larger relative errors are t o be expected with molarities 60.0 cm. Sensitivity . . .. .. . . .. .. 1/1 Potential applied to drum . . . . .. . . 2.0 volt The table shows that the molarities are in the range 10" toOctober, 19471 OF LEAD IN FOODSTUFFS 427 of the order of for the wave heights are very small, e.g., about 3 mm. in the first result quoted. TABLE Tin added p.p.m. 0 35 35 80 35 35 0 35 3 5 36 80 115 Lead content (total) p.p.m. 5 5 8 13 18 20 23 29 32 32 32 41 Lead determined by polarograph p.p.m. 3 7 10 13 18.5 21-5 23 28.5 32 35 27.5 41.5 r p.p.m. 0 + 2.0 + 2.0 + 1.0 + 0.6 + 1.5 0 - 2.5 0 + 3.0 - 4.5 $- 0.5 Error m per cent. 0 + 40.0 + 25.0 + 8-3 + 2.8 -+ 7.5 0 - 8.6 0 + 9.4 - 14.1 + 1.2 Molarity of lead in solution electrol ysed 4.0 x 4-7 x 10-6 6.2 x 10-6 9-5 x 10-6 1-1 x 104 1.1 x 10-6 3.5 x 106 1.7 x lo6 1.8 j< 104 1-9 x 10-6 1.7 ;< lo6 2.9 j< 10-6 The authors wish to thank Messrs. J. Lyons & Co., Ltd., in whose laboratories the work was conducted, for permission to publish this paper. REFERENCES 1. 2. 3. 4. 5. 6. Yosida, S., Oriental J. Dis. Infants, 1938, 23, 15. Teisinger, J., 2. ges. exp. Aged., 1936, 98, 620. Forche, E., “Polarographische Studieoc,” Univ. Leipzig, 1938; Biochem. Z . , 1935, 277, 178. Strubl, R., Collection Czeckoslov. Chem. Commun., 1938, 10, 466. Brasher, D. M., and Jones, I?. R., Trans. Faraduy SOL, 1946, 42, 775. Kolthoff, I. M., and Lingane, J. J., “Polarogruphy,” p. 10, Interscience Publishers Inc., New York, 1941. THE LABORATORIES J. LYONS & Co., LTD. LONDON, W.14 June, 1947

ISSN:0003-2654    

DOI:10.1039/AN947720423b

出版商:RSC    

年代:1947

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE.By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time.The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years.The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion.The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on.Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp.15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C.Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner.He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction October, 19471 OF LEAD IN FOODSTUFFS 427 The Determination of Small Amounts of Hexachlorocyclohexane (Benzene Hexachloride) BY BERNARD H. HOWARD (Rend at the Meeting of the Society on Wednesday, October Ist, 1947) INTRODUCTION HEXACH~OROCYCLOHEXANE, benzene hexachloride , is a mixture of isomers of which the y-isomer (" Gammexane ") is strongly insecticidal. The normal commercial product contains about 13 per cent.of this isomer, to which almost the whole of the insecticidal activity is due. The toxicity towards mammals is also mainly associated with the gamma is0rner.l Although biological, i.e. , insecticidal, methods of assay are known,2 chemical methods were required. Such a method should, as far as possible, (1) be readily applicable to grain and other foodstuffs and to dust and spray deposits on surfaces or fabrics, (2) be applicable to the routine testing of numerous samples in a chemical laboratory of modest equipment, (3) be sensitive to a few micrograms of benzene hexachloride, (4) be specific for benzene hexachloride, especially to distinguish it from other insecticides such as DDT, and (5) distinguish between the gamma and other isomers present.The method here described complies with conditions (l), (2) and (3). Point (4), which requires a closer examination of the properties of the substances concerned, has not been fully covered at this stage and is undergoing further investigation. With regard to (5), there appears to be no chemical method available for distinguishing the isomers. A knowledge of the proportion of gamma isomer in the original preparation is necessary to estimate the insecticidal activity of the amount of benzene hexachloride revealed by chemical methods.428 HOWARD: THE DETERMINATIOK OF SMALL AMOUNTS OF [Vol. 72 PRELIMINARY EXPERIMENTS A. A method involving the separation of trichlorobenzenes with alkali, followed by their intensive nitration, has been described.2 The nitro-chloro compound decomposes, when boiled with alkali, to give a brightly yellow-coloured nitro-phenol.In the absence of a photo-electric absorptiometer, which was employed by the authors of the above-mentioned method, the possibility of using simple comparisons with Nessler glasses was tested. However, the colour did not appear strong enough to show less than about 0.1 mg. The method was not proceeded with as it was not considered to satisfy the above general conditions (2) and (3). B. Although a method of determining total chlorine, such as that of Carius, might seem potentially more sensitive than the method removing only half the total chlorine, later to be described, this advantage was considered to be outweighed by the difficulties and hazgrds of the Carius technique.Furthermore, in presence of much foreign matter a large amount of nitric acid would be required: this is to be avoided because A.R. nitric acid contains up to 1 mg. of chloride per litre. Rough experiments suggested that benzene hexachloride is inert to ammonia, silver nitrite and potassium cyanide, the chlorine atoms appearing not to undergo readily any replacement reactions. D. Previous reports that benzene hexachloride reacts readily with alkalis to yield trichlorobenzenes and alkali chlorides were confirmed and, since this reaction readily lends itself to compliance with requirements (1) and (2) above, it was examined further. C. Van den Linden3 reported that with alcoholic potash the reaction C6H6Cl6 + 30H’ = C,jH,Cl, + 3Cl’ $. 3HzO is quantitative.This was confirmed, but in practice alcoholic alkali was found to have two serious disadvantages-@) Caustic potash, even of A.R. quality, contains up to 0.01 per cent. of chloride. Two ml. of 10 per cent. solution, the amount of alkali used in the preliminary experiments, would therefore contain chloride equivalent to approximately 50 pg. of benzene hexachloride. Even this high blank figure tended to increase when the solution was stored in the laboratory atmosphere. (b) In the determination of benzene hexachloride in foods, the final extract for reacting with alkali consisted of a solution of the insecticide in vegetable fat. Enough alkali had to be added to decompose all this fat: sometimes 5 ml. or even more of the 10 per cent. solution. In some instances the chloride in the reagents was much greater than that derived from the benzene hexachlorid.: The use of alkali was therefore abandoned.E. Organic bases, that might be freed from chloride by distillation, were next tried as dehydrochlorinating agents. Pyridine appeared to be without effect, but monoethanolamine was satisfactory. After distillation from alkali, the chloride content of this reagent was less than 5pg. per ml., corresponding to about 15pg. of benzene hexachloride per ml. It was also found that, under the conditions used, this reagent is without effect on fats. The presence of fats, therefore, does not necessitate the use of a large amount of reagent. Enough must be added, of course, to neautralise any free acid in the fat. To test the reaction, various amounts of benzene hexachloride were decomposed by various amounts of monoet hanolaminc in stoppered tubes immersed in a boiling water bath and the liberated chloride was titratecl by Volhard’s method.To investigate the applicability of the method to all forms in which benzene hexachloride might be met in practice, decomposition tests were performed on (a) the substance alone, as would be found in dusts or smoke deposits, (b) solutions in mineral oils, as would be found in spray deposits, (c) solutions in vegetable oils, as would be obtained when foodstuffs are extracted to isolate the benzene hexachloride. Shell oil P.31, a non-volatile paraffin oil, was the mineral oil used. Three samples of arachis oil were available and it was assumed that the reaction in other vegetable oils would be similar.The benzene hexachloride used was recrytstallised material containing 95 per cent. of the gamma isomer. The mixture of isomers met in practice behaves very similarly with dehydrochlorinating reagents. The larger quantities were weighed direct into the reaction tubes; the smaller quantities were obtained by evaporating the appropriate volumes of a 0.100 per cent. solution of the substance in ether. Each result shown in the table is the mean of at least three tests. In tests 7 and 8 the monoethanolamine was added as a 1 per cent. aqueous solution; in tests 10, 11, 12, 20, 27 and 28 as a 10 per cent. solution in chloride-free glycerol. The DECOMPOSITION OF BENZENE HEXACHLORIDE BY MONOETHANOLAMINEOctober, 19475 HEXACHLOROCYCLOHEXANE (BENZENE HEXACHLORIDE) 429 glycerol was used merely as a solvent, as experiments suggested that when several milligrams of solid benzene hexachloride were used the reaction with the small volume of mono- ethanolamine did not always proceed to completion, because of insufficient mixing.Of the vegetable oils, (1) and (3) had low acid values, about 0.3, whilst (2) had a very high acid value, about 40. Test No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 20 27 28 29 Benzene hexachloride taken mg. 100 100 100 100 100 1.0 5.0 5-0 100 100 5.0 1.0 100 100 100 100 5.0 5-0 5.0 1.0 100 100 5.0 6-0 1.0 1.0 1.0 1.0 300 mg. DDT. Monoethanolamine used ml. 2 2 2 2 0.1 0.1 0.1 in 10 ml. water 0.05 in 5 ml. water + 3 ml. 0.1 in 2 ml.alcohol 0.1 in 1 ml. glycerol + 2 ml. alcohol 0.1 in 1 ml. glycerol + 2 ml. alcohol 0.1 in 1 ml. glycerol 1 1 0.5 0.1 0.1 0.1 0.1 0.1 in 1 mi. glycerol 0-5 0.1 0.1 0.2 0.1 0.2 0.1 in 1 ml. glycerol 0.2 in 2 ml. glycerol 2 alcohol Added matter Time in water bath min. 15 30 60 180 60 60 60 60 30 60 60 60 30 60 60 60 30 60 60 60 30 60 60 60 60 60 60 30 30 Decom- position per cent. 98 98 102 103 80 99 74 62 87 90 100 100 87 101 92 43 74 94 104 102 100 20 76 104 102 101 41 17 97 These results show-(i) That amounts of benzene hexachloride from 1 to 100 mg. can be determined accurately either alone or dissolved in mineral or vegetable oils, by decomposing with small amounts of monoethanolamine. In tests 5, 9 and 10, 80 to 90 per cent. decom- position was produced by 1.6 times the amounts of monoethanolamine required by calculation.Where small quantities are being determined, it is obviously advantageous to use very small amounts of the reagents. (ii) The presence of oils necessitates the use of more reagent (cf. tests 5, 16; 18, 23). The aqueous solution of monoethanolamine gives low results, and the glycerol solution does not seem to be necessary for complete reaction of the smaller amounts of benzene hexachloride (test 6). (iv) The low results obtained from arachis oil solutions with the glycerol solution of the reagent are surprising (tests 27, 28). The addition of glycerol renders the mixture of oil and monoethanolamine homogeneous, and a quicker reaction was expected on this account. (v) Under similar conditions the benzene hexa- chloride is more rapidly decomposed when dissolved in arachis oil than in mineral oil.(vi) The highly acid arachis oil No. 2 prevented the decomposition of the benzene hexachloride dis- solved in it (test 22). That decomposition occurred at all is remarkable, as enough acid was present in the oil to neutralise all the monoethanolamine added. (vii) It is known that DDT is dehydrochlorinated by means of alkali under the same conditions as is benzene hexachloride. The test with DDT, No. 29, indicates that its behaviour with monoethanol- amine also is similar to. that of benzene hexachloride. The decomposition of DDT by organic bases has already been noted.' For smaller amounts of benzene hexachloride, 20 to 200 pg., both alone and dissolved in the oils (except the very acid arachis oil), and with quantities of monoethanolamine similar to those shown in the above table, the decomposition was still sufficiently close to the theoretical for practical use.The chloride was determined turbidimetrically in these experiments. (iii)430 HOWARD: THE DETERMINATION OF SMALL AMOUNTS OF Tol. 72 F. In practice it is essential to be able to determine benzene hexachloride when inorganic chlorides may be present, e.g., in foodstuffs. Extraction with ether gives a material free from inorganic chloride, as the following tests prove. (i) Two g. of sodium chloride and ammonium chloride were each shaken with 50 ml. of ether. After filtering and evaporating, no turbidity was detectable on addition of silver nitrate. (ii) 100-g.samples of several foodstuffs not contaminated with benzene hexachloride were treated with ether, and the extracts tested in the manner described below. In no case did the final solution show an appreciable turbidity with silver nitrate solution. The materials thus shown to give negligible blanks were maize, barley, wheat, ground nuts, flour, dried yeast, fish meals, meat and bone meal, bitter almonds, dried apricots and milk. The method finally adopted is as follows. METHOD REAGENTS- (1) Distilled water: chloride-free. (2) Ether. (3) Monoethanolamine: re-distilled from caustic soda. (4) Nitric acid: 10 per cent. of A.R. concentrated acid in water. (5) Sodiuns chloride solutions: a 0.06 per cent. solution is diluted tenfold before use, to give a standard solution for turbidimetric determination of chloride; 1 ml.of the diluted solution contains as much chloride as is liberated from 0.1 mg. of benzene hexachloride by dehydrochlorination. (6) Silver Nitrate solution: about 0.1 N , in a dropping bottle. (7) Silver nitrate solution, standard: 0.01 N . (8) Ammonium thiocyanate, and ferric alum solutions, for determination of chloride by Volhard’s method ; or solution of dichlorofluorescein for determination of chloride by Fajans’ method. PROCEDURE- (i) For foodstuffs. Extract 50 to 1OOg. of the sample with ether. The tenacity with which the benzene hexachloride is held varies with the conditions of application. From grain, for example, benzene hexachloride added as a dust may be removed almost completely by two simple washes with ether, but when it has been added as an oil spray more thorough extraction is necessary.For all foodstuffs, therefore, Soxhlet extraction, until all fat is removed, is recommended. (ii) For deposits. Wash the object well with a jet of ether. If there is any doubt as to absorption of benzene hexachloride by the object, the Soxhlet method should be adopted if possible. Filter the ethereal solution resulting from these procedures into a boiling tube fitted with a ground-glass stopper. Evaporate the ether in a stream of air while the tube is gently warmed. Add 0.1 ml. of monoethanolamine, or, if oil is present, 0.1 ml. for every ml. of oil. (This is because the figures given in the table demonstrate that about one-tenth as much reagent as oil will react satisfactorily.) Stopper the tube and immerse in boiling water to a depth of about 2 in.for 1 hour, with frequent shaking. A wire basket to hold about ten tubes was found convenient for holding the tubes in a can of boiling water. Remove from the water bath after an hour and add 5 ml. of the 10 per cent. nitric acid, or, if more than 06ml. of monoethanolamine has been used, add 10ml. of acid for every 1 ml. of reagent, Add next from 15 to 20 ml. of water and, when cool, 20 ml. of ether, and shake. After settling, blow off the ethereal layer through a Werner - Schmid tube. If the aqueous layer is still cloudy repeat the ether extraction. The oils, trichlorobenzenes, etc. having been removed by this ether extraction, the aqueous solution is in a suitable state for estimation of chloride.With 0.01 N reagents it was found possible to determine down to 0.2 mg. of benzene hexachloride by Volhard’s method. For smaller quantities, down to 20 pg., the chloride can be determined turbidimetrically. Any faint cloudiness in the solution can be removed by filtration. Bring the volume up to the 50-ml. mark of the Nessler glass. In other glasses prepare standards containing different amounts of the diluted salt solution, and the same volumes of monoethanolamine and nitric acid as were used on the sample under test, in a volume of 50 ml. Add three drops of the silver nitrate solution to the sample and standards, stir, and compare against a dark ground after about 2 minutes. Sensitivity-In 50ml. of solution in a Nessler glass the eye can detect a turbidity due to 5 pg.of chloride ion, equivalent to 14 pg. of benzene hexachloride. In field experiments involving dust and spray deposits the density of the deposit has been found by collectingOctober, 1947) HEXACHLOROCYCLOHEXANE (BENZENE HEXACHLORIDE) 431 samples on 3 in. x 1 in. microscope slides, having an area of 19.4 sq. cm. By this method the minimum surface density detectable is 0.7 pg. per sq. cm. In tests on foodstuffs, where a sample of 100 g. might be used, this is equivalent to a concentration of 0.14 p.p.m. The method is sufficiently sensitive to measure very slight contamination of foodstuffs. Selectivity-Many organic chlorine compounds lose chlorine in treatment with alkali, but none of these occurs naturally. Production of a positive result in the test described above, when applied to foodstuffs, is therefore evidence of contamination by organic chlorine compounds.The most likely such substance with which benzene hexachloride might be confused is DDT, and a test to distinguish the two is necessary where doubt is possible. Of the numerous colour reactions of DDT the pyridine - xanthydrol reaction* is simple. It is very sensitive to DDT and its analogues but gives no colour with benzene hexachloride. This could be used on a small portion of a sample to distinguish the two insecticides. Test 29 suggests that the treatment with monoethanolamine as described in this paper would be applicable to the determination of DDT, but this has not been investigated in further detail. However, a much smaller amount of chloride is removed from DDT than from benzene hexachloride, 1 g.of the former giving 100 mg. of chloride ion and 1 g. of the latter 366mg. The method would therefore be only about one-third as sensitive if it were applied to DDT. SOME APPLICATIONS OF THE METHOD (1) To grain-Wheat, contained in a beaker, had been exposed to a smoke of benzene hexachloride produced from a Gammexane Smoke Generator. It remained toxic to adult Calandra granaria, even after two sievings. The extract from 100 g. of the wheat was found to contain 0.5 mg. of benzene hexachloride, corresponding to 5 p.p.m. in the wheat. (2) To dust deposits-(a) In an experimental chamber of 260 cu. ft. capacity 3 in. x 1 in. microscope slides were placed on the floor and on shelves, and other slides were fixed to the walls by pellets of modelling clay.A 0.5-02. portion of a Gammexane Smoke Generator was ignited, and after 3 hours the slides were picked up by forceps and placed in the stoppered boiling tubes for removal to the laboratory. The densities of the deposit on the floor and shelves at different heights were very similar, average 20 pg. per sq. cm. The deposit on walls or ceiling was less, about 4pg. per sq. cm. (b) A ship’s hold was treated with smoke generators, and samples were collected on microscope slides. The deposit on horizontal surfaces was heavy, from 20 to 220pg. of benzene hexachloride per sq. cm. (3) Recent investigations into the behaviour of these insecticides in the animal body, e.g., the determination of DDT in the milk of cows whose diet contains the ~ubstance,~>G suggest further applications of the method here described, which is likely to obviate certain” difficulties, due to the presence of milk fat, previously encountered in this field.The method might also be adapted to the determination of the insecticides in the blood. SUMMARY A method for the analysis of insecticidal deposits, or of residues in foods, without the use of elaborate equipment was required. After examination of alternatives, a method depending upon extraction with ether followed by dehydrochlorination with monoethanol- amine, and subsequent determination of the separated chloride, was developed. The scope and limitations of the method are discussed. The author wishes to thank Imperial Chemical Industries for the gift of the “Gammexane” used in these experiments, Dr.E. E. Turtle for help in preparing this paper and W. McAuley Gracie, Esq., Director of Infestation Control, for permission to publish. REFERENCES 1. Slade, R. E., Chemistry and Industry, 1945, 314. 2. 3. Van den Linden, Ber., 1912, 45, 236. 4, 5. 6. Carter, R. H., Ibid.. 54. 7. Imperial Chemical Industries Ltd., Private communication. Stiff, H. A., and Castillo, J. C., I n d . Eng. Chem., Anal. Ed., 1946, 18, 316. Schechter, M. S., Pogorelskin, M. A., and Haller, H. L., Analytical Chemistry, 1947, 19, 51. Forrest, J., Stephenson, 0.. and Waters, W. A., J. Chern. Soc., 1946, 333. MINISTRY OF FOOD, INFESTATION DIVISION 58, HIGH HOLBORN, LONDON, W.C.l July. 1947432 WILSON AND HUTCHINSON : THE DETERMINATION OF [Vol. 72 DISCUSSION The PRESIDENT said the author had remarked that commercial Gammexane usually contained about 13 per cent. of the gamma isomer. Was this proportion sufficiently constant to enable a reasonably reliable estimate of insecticidal potency to be based on determinations of total benzene hexachlorides ? Rlr. J. H. HIGH asked if it was possible to take advantage of physical properties of the isomers to effect, not necessarily a complete, but a t least a partial, separation, and to estimate the relative amounts of the isomers from differences in the physical properties before and after the separation. He also asked if the reproducibility of the results obtained with alkali was good; if it was, the presence of a constant propor- tion of chloride might not be a fatal disadvantage. Mr. F. C. HYhlAs asked if any control experiments had been made to determine “blanks” on prepared foods, It was to be expected that blank determinations on grains and on inorganic chlorides would yield negative results, but there was some reason to think that blanks on prepared foods containing added halides might be appreciable. Mr. HOWARD, in reply to the President, said that although the proportion of active isomers in commer- cial benzene hexachloride varied with the conditions of manufacture, it was likely to be fairly constant under the same conditions. But he understood that the material was now being marketed with higher proportions of the active constituents. In reply to Mr. High, he said that the different isomers did not differ much in physical properties. He had heard that work had been done in America on discrimination between the isomers by means of chromatography and infra-red spectrography. The blank figure resulting from the use of alkali had been found to be somewhat variable, and this had led to uncertainty in the true figure. The author said that he had not made determinations of the kind mentioned by Mr. Hymas, on prepared foods.

ISSN:0003-2654    

DOI:10.1039/AN9477200427

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 432 The WILSON AND HUTCHINSON : THE DETERMINATION OF Determination of Nitromethane in [Vol.72 Air BY H. N. WILSON AND W. HUTCHINSON IN the manufacture of nitromethane it is necessary to ensure that the atmosphere contains only minute quantities of the nitro-body, which has toxic properties. A method was therefore required to determine nitromethane concentrations of the order of 1 or 2 mg. per litre in the atmosphere where work on nitroparaffins was in progress. Preliminary work showed that nitromethane could be determined in 0-ZN sulphuric acid by the polarograph, giving a well defined step with a half-wave potential of -0.7 to -0.8 volt against the saturated calomel electrode.Suitable solutions were made up and polarographed with a Cambridge instrument at a sensitivity of 1/700. Fig. 1 shows the step height against concentration at this sensitivity. It was found that one division of step height = 16.8 mg. of nitromethane per litre of 0.2 N sulphuric acid. Recovery of nitromethane in air by passage through gas absorption bottles containing 0.2 N sulphuric acid was unsatisfactory and was abandoned in favour of a technique using an Experiment 1 2 3 4 6 6 7 8 9 10 Nitromethane added mg- 36.2 24-8 18.5 11.0 6.20 4-762 3.824 3.018 1.268 0.621 Concentration in atmosphere at 20" C. and 760 mm. mg./litre 13.7 9.4 7.0 4.2 2.3 1.8 1.45 1-13 0.478 0.224 % by volume 0.475 0.320 0.238 0.143 0.079 0.061 0.050 0-038 0.016 0.008 Nitromethane found mg.34.4 23.6 17.6 10.5 5.9 4.514 3.606 2.852 1.192 0-578 Percentage recovery at 20" C. 95.0 95.2 95.1 95.5 95.2 94.8 94.3 94.5 94-0 93.0 evacuated winchester. This employs a winchester fitted with a two-holed rubber bung carrying a 50-ml. tap funnel and a right-angled glass tube with tap for connection to a good water pump. To test this method, known amounts of nitromethane contained in sealed glass bulbs were introduced into the winchester, the volume of which was known. The air was removed by the water pump, the pressure being measured by a mercury manometer. The glass tap to the pump was then closed, the pump disconnected and the bulb inside the winchester broken. The winchester was allowed to stand under reduced pressure for 24 hours to ensure complete vaporisation of the nitromethane.Air was then admitted until atmos- pheric pressure was reached, the tap closed and the winchester allowed to stand a furtherOctober, 19471 SITROMETHAKE I N AXE 433 2 hours to ensure thorough mixing of the air with the nitromethane. Fifty ml. of 0 - 2 N sulphuric acid were introduced by cooling the winchester slightly and allowing the acid to be drawn in via the tap funnel. The Winchester was well shaken and allowed to stand 20 minutes and the 0.2 N sulphuric acid containing the nitromethane polarographed without de-oxygenating . The data on p. 432 indicate the recovery of nitromethane from air, in concentrations varying from about 0.5 to 0.01 per cent. by volume. It thus appears that under these conditions the dilute sulphuric acid in equilibrium with the atmosphere at 1 atmosphere pressure absorbs 95 per cent.of the nitromethane present and this figure must be taken into account in the analysis of samples of air, PROCEDURE-Evacuate a Winchester of known volume to about 30mm. of mercury pressure, measuring the pressure with a manometer. Then open it in the atmosphere to be tested, taking the temperature at the same time. Introduce 50 ml. of 0.2 N sulphuric acid by cooling the Winchester slightly and allowing the acid to be drawn in. Shake well and allow to stand for 30 minutes. Polarograph the sulphuric acid solution, without de- oxygenating, at a suitable sensitivity, e.g., 1 / 7 0 or 1/70, over the voltage range -0.3 to - 1-3 volt against the saturated calomel electrode. 0-2 0.4 0-6 0.8 1.0 Nitromethane, grams per litre of 0.2N H,SO, Prepare a graph similar to Fig. 1 by dissolving known weights of pure nitromethane in a known volume of 0.2 N sulphuric acid and polarographing the solutions under the same conditions. Plot grams or milligrams of nitromethane per litre of 0.2 N sulphuric acid against the step height. From the graph, the volume of 0-2 N H,SO, used and the volume of the air sample taken, calculate the proportion of nitromethane in the atmosphere, allowing also for the 95 per cent. recovery. If some other nitro-body is expected to predominate, a new graph must be prepared. Fig. 1 Note-Other nitroparaffins present will react similarly to nitromethane. SUMMARY A method for the determination of small quantities of nitromethane in air has been The nitromethane is absorbed in 0.2 N sulphuric acid and the concentration described. in this detemined with a polarograph. REFERENCE Kolthoff, I. M., and Lingane, J. J . , “Polavography,” 1941 Edition, p. 384. IMPERIAL CHEMICAL INDUSTRIES LTD. RESEARCH DEPARTMENT BILLINGHAM-ON-TEES December, 1946

ISSN:0003-2654    

DOI:10.1039/AN9477200432

出版商:RSC    

年代:1947

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE.By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time.The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years.The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion.The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on.Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp.15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C.Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner.He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction 434 BONNER : THE ESTIMATION OF THIS VOLATILE MATTER [I’ol. 7 2 . The Estimation of the Volatile Matter Content of Propellant Explosives Part 3.* The Estimation of Acetone BY T. G. BONNER ACETONE is widely employed in the manufacture of various types of cordite (z.e., propellants, containing both nitrocellulose - and nitroglycerine). The acetone is used in optimum admixture with water to facilitate the formation of a homogeneous solution of the con- stituents of the cordite, which is necessary to ensure uniformity of product.The presence of the solvent in the final product is, of course, undesirable, and the last stage of manufacture is designed to remove as much of it as possible by “stoving” at an elevated temperature. This removal is never complete and in order to assess the effect of the residual acetone on ballistic properties, particularly in relation to variations in the acetone content with changing temperature and humidity, an accurate method of estimation is of paramount importance. Various w ~ r k e r s l ~ ~ ~ ~ have reported attempts to determine the residual acetone content, but no evidence is advanced that the methods give absolute figures and in general the results are quite arbitrary.Friedmann4 recommended reducing the sample to shavings, introducing 2 to 5 g. into a U-tube immersed in a bath at 75” C., drawing a stream of carbon dioxide or nitrogen through the U-tube into either 23 per cent. potassium hydroxide solution or water, and determining the absorbed acetone by Messinger’s method5 by conversion to iodoform with excess of iodine in presence of sodium hydroxide and back-titration with sodium thiosulphate. Although this method has useful features, no evidence is adduced to prove that heating at 75” C. removes the whole of the acetone from the sample, a point which is emphasised by Kostevitchs in a criticism of the method used by Benesch,’ and later by Graulich,8 of heating samples of propellants to release the volatile matter for estimations.I t is well known that solvent matter is tenaciously held by nitrocellulose and its quantitative removal by heat done is only conceivable with grou’nd material or very small grain or flake samples, and the reduction of larger sizes of cordite to such a state of subdivision introduces the difficulty of avoiding loss of solvent during the process. These methods were not considered reliable either for routine analysis or for special investigations, and an improved technique was sought. Two possibilities were considered for the quantitative removal of the acetone from a propellant; first, dissolution of the cordite in a suitable medium followed by volatilisation and absorption, and secondly, extraction of the acetone from the cordite by an organic solvent.Since the amount of acetone present in cordites rarely exceeds 0-6 per cent. and also a method suitable for 2- to 3-g. samples was considered necessary, the quantity of acetone to be estimated was of the order of a few mg. Methods applicable to the estimation of small quantities of acetone include Messinger’s r n e t h ~ d , ~ which has been investigated in detail by Goodwing; the hydroxylamine hydro- chloride method,1° in which the hydrochloric acid liberated by the formation of acetone oxime is titrated with standard alkali solution; the formation of double salts of acetone with mercuric salts first employed by DknigWl; colorimetric determination based on the condensa- tion of ace tone with such compounds as o-nitr~benzaldehydel~?~~; and a micro-diffusion method based on the bisulphite reaction described by Winnick.l* A very useful critical review of methods of estimating small quantities of acetone in air has been given by Komar,15 who preferred a modification of Messinger’s method. An examination of all the above methods indicated that the first two were the most satisfactory.Further, for a given amount of acetone, the equivalent volume of standard iodine solution required in Messinger’s method is nearly four times the volume of standard alkali solution of the same normality required in the hydroxylamine hydrochloride method, and this fact was considered to justify a preference for the former method, which later became a necessity on grounds of com- patibility of reagents with other constituents of the propellant present during the estimation.With this method of estimating the recovered acetone, the two procedures outlined above for the quantitative removal of the acetone from cordite were investigated. * For Parts 1 and 2, see ANALYST, 1946, 71, 483; 1947, 72, 47.October, 19473 CONTENT OF PROPELLANT EXPLOSIVES 435 THE QUANTITATIVE REMOVAL OF ACETONE FROM CORDITE BY ENTRAINMENT WITH AIR AND The removal of the residual organic solvent matter in a propellant by passing a stream of air through a solution of the sample in nitrobenzene at 100" C. has already been described in the method of estimating ethyl alcohol and ether in nitrocellulose powders, in Part 2 of this series.I6 Cordites dissolve even more readily than nitrocellulose powders in nitrobenzene and this method was therefore adopted for cordites.To absorb the acetone carried over by the air stream, various solvents were investigated; it was found that absorption was in- complete in saturated sodium bisulphite solution, water and dilute sulphuric acid, and concentrated sodium hydroxide solution was not wholly satisfactory. Complete absorption was effected, however, in a 1 : 1 by volume mixture of concentrated sulphuric acid and water. An apparatus was used identical with that described in the method for nitrocellulose powders (see Part 2) except that only one absorption tube was employed in place of the three required in that method. The procedure used in carrying out the separation of the acetone in this way and its subsequent titration was as follows.ABSORPTION ABSORPTION METHOD About 10 ml. of the sulphuric acid was introduced into the absorption tube, while 2 g. of the cordite sample, cut up into &-in. lengths, were added to about 25 ml. of pure nitrobenzene in the 250-ml. three-necked flask. The flask was heated in a boiling water bath and a stream of air bubbled through the nitrobenzene solution to carry the acetone vapour into the sulphuric acid in the absorption tube. After 5 hours, the flow of air was stopped and the sulphuric acid run out and carefully neutralised with 30 per cent. sodium hydroxide solution; 1 drop of phenolphthalein was used as indicator and the solution was cooled during neutralisation. Forty ml. of N sodium hydroxide solution were added and, after cooling in ice for 10 minutes, 10 ml.of 0.1 N iodine were slowly run in, the flask being shaken during the addition. After the flask had been replaced in ice for 10 minutes, the iodine that had not reacted was liberated by addition of a slight excess of 2 N sulphuric acid and titrated with 0-05 N sodium thio- sulphate, with starch solution as indicator. A blank determination was carried out on 10 ml. of the original diluted sulphuric acid (1 + 1) and the amount of acetone present in the sample calculated. The accuracy of the method was tested by introducing a solution of acetone in nitro- benzene of known concentration into the flask, adding the other ordinary constituents of cordite, viz., nitrocellulose, nitroglycerine, nitroguanidine and diethyldiphenylurea, and carrying out an estimation as described above.No interference by these constituents was observed and the results obtained for various solutions of acetone in nitrobenzene given in Table I indicate an accuracy of 3 to 4 per cent. with a maximum error of 5 per cent. for One ml. of 0.1 N iodine = 0.0009675 g. of acetone. TABLE I ABSORPTION METHOD-WEIGHED AMOUNTS OF ACETONE IN NITROBENZENE SOLUTION REMOVED AT 100°C. AND ABSORBED IN SULPHURIC ACID Weight of acetone taken mg. 5.3 1 8-85 2-62 1-88 1-45 Weight of acetone found Error mg. per cent. 5.08 - 4.3 2.95 + 3.5 2-49 - 5.0 1-89 + 0-5 1.50 + 3.0 quantities of acetone of the order of 1-5 to 5 mg. No difficulties were encountered in applying the method to the analysis of cordites. Confirmation of the reliability of the method was obtained by applying it to a sample of solventless cordite; no acetone or other organic solvent is used in the manufacture of this type of cordite and an analysis for its acetone content gave a figure of 0.00 per cent. The only unsatisfactory feature of this method is that it is impracticable for dealing with the large numbers of samples encountered in routine analysis.For this reason the possibility of quantitative extraction of the acetone with an organic s olven t was investigated.436 BONKER: THE ESTIMATIOK OF THE VOLATILE BIATTEX [Vol. 72 THE QUANTITATIVE EXTRACTION OF ACETONE FROM CORDITE WITH AN ORGANIC SOLVENT The quantitative extraction of moisture from cordite by means of dioxan has already been described in Part 1 of this series1' Of possible solvents for the present purpose, dioxan was unsuitable in that it consumed appreciable traces of iodine, and methyl alcohol had to be rejected owing to its dissolving some nitroglycerine, which by its interaction with sodium hydroxide gave rise to decomposition products interfering in the iodine titration. In point of fact, no single organic solvent was found to be suitable for the quantitative extraction of acetone from cordite; eventually, it was found that a mixed solvent consisting of 3 volumes of nitrobenzene and 2 volumes of chloroform satisfied requirements.Trials were made with TABLE I1 Weight of acetone taken mg. 6.36 6.36 6.36 3.34 5-30 4-16 6.36 6-81 4.24 7.42 6-30 5-40 8-40 5.40 5.40 5.40 5-40 4.32 7-66 6-40 5.40 5.40 4.32 7.56 7-56 ESTIMATION OF ACETONE IN NITROBENZENE - CHLOROFORM SOLUTION Volume of organic solvent ml.20 20 20 15 15 15 15 15 15 15 15 10 10 10 10 10 10 10 10 10 10 10 10 10 10 Volume of water ml. 25 25 25 25 25 25 25 25 25 25 35 50 50 50 50 50 50 50 50 50 50 50 50 60 60 Volume of N NaQH ml. 15 15 16 16 15 15 15 15 15 15 16 15 15 15 16 LO 10 10 10 10 10 10 10 10 10 Time of reaction min . 20 40 40 20 10 20 25 25 26 30 35 15 20 27 30 15 20 20 20 25 25 25 25 30 40 Weight of acetone found mf-5 6-05 6.19 6-19 3.23 5.10 4-26 6.31 6-63 4-11 7.15 5.30 5-20 5.22 5-26 5-24 5-01 5.26 4.28 7-35 5.27. 5-27 5.28 4-23. 7.41 7.49 Error per cent. - 20 - 3.0 - 3.0 - 3.3 - 3.9 + 2-4 - 0.9 - 2.9 -3.1 -3.6 0 - 3.7 - 3.3 - 2.6 - 3.0 -6.1 - 2.6 - 0-9 - 2.8 - 2.4 - 2.4 - 2.2 - 2.5 - 2.0 - 0.9 solutions of acetone of known strength in this mixed solvent, the estimations being carried out directly by Messinger's method; the acetone solution was vigorously stirred with the aqueous sodium hydroxide and standard iodine solution during the time allowed for the acetone and iodine to react.All solutions except the iodine solution were maintained at 0" C. before being mixed in the reaction vessel, which was kept during the estimation in a Dewar flask containing ice. The measured volume of iodine was added slowly from a burette over a period of 5 minutes. In a series of determinations the factors that were varied were the relative volumes of the mixed organic solvent and the aqueous solution, the strength of the sodium hydroxide solution and the length of time allowed for reaction between the iodine and acetone.From the results given in Table I1 it can be concluded that (a) an increase in the volume of organic solvent relative to the volume of aqueous solution necessitates a longer period of time for completion of the reaction, (b) a decrease in the strength of sodium hydroxide solution must be compensated by an increase in the time allowed for reaction, (c) quantities of acetone of the order of 5 mg. dissolved in this mixed solvent can be estimated with an accuracy of 2 to 3 per cent. under the optimum conditions. It was ascertained that neither nitrocellulose nor diethyldiphenylurea interfered in the estimation and nitro- guanidine is practically insoluble in nitrobenzene and chloroform. A further series of determinations were carried out with nitroglycerine added to the synthetic solutions of acetone.The variation of factors influencing the estimation was modified in relation to the knowledge gained from the first series of determinations and from the results given in Table I11 it is evident that the extent of interference by nitroglycerine increases with an increase in either the amount of nitroglycerine present or the strength of the sodium hydroxide solution orOctober, 19471 CONTENT OF PROPELLANT EXPLOSIVES 437 the length of time allowed for the estimation. As the conditions are approached under which no interference at the end-point occurs, the interval of time between the stage at which the end-point is reached and the return of the blue colour of the starch-iodine complex increases until it is of the same order as that occurring when no nitroglycerine is present, i.e., when the gradual reappearance of the blue colour can be attributed solely to the effect of atmospheric oxygen.The last two results in Table I11 indicate the optimum conditions; TABLE I11 EFFECT OF NITROGLYCERINE ON METHOD OF TABLE 11 Volume of nitro- glycerine added ml. 0.30 0.10 0.10 0.10 0.15 Weight of acetone taken mg. 5-84 5-84 5.84 5.84 3.34 Volume of organic solvent ml. 15 15 15 10 10 Volume of water ml. 50 25 50 50 50 Volume of N NaOH ml. 10 15 10 10 10 Time of reaction min. 20 20 40 25 20 Weight of acetone found Error mg. per cent. 5-22 - 11.0 5-36 - 9.0 5.56 - 6.0 5*70* - 2 4 3-26* - 2.7 * No interference at end-point of titration.full experimental details based on these conditions are given below. Using this procedure, a sample of aolventless cordite which contained no acetone was analysed. This type of cordite has a higher nitroglycerine content than normal cordites, and the amount of nitro- glycerine extracted from it by the nitrobenzene - chloroform solvent was obviously much higher than that extracted from ordinary cordites. On two separate samples of this cordite, analyses showed apparent acetone contents of 0.005 and 0.004 per cent. which are negligible. No difficulty was experienced with the end-point and it is clear therefore that the method is quite satisfactory in presence of nitroglycerine. In Table IV is given a comparison of TABLE IV DETERMINATION OF ACETONE IN CORDITE-COMPARISON OF EXTRACTION AND ABSORPTION METHODS Acetone per cent.A f \ Sample Absorption method Extraction method Cordite W 124, lot BS 87 . . . . 0.09; 0.09 0.10; 0.10 Cordite W M 130, lot WAC 1724 . . 0.33; 0.31 0.34; 0.33 Cordite MD St., lot WA 791 . . 0.32; 0-30 0.30; 0.29 5 results obtained on some cordites by this method and by the method of entrainment by air from solution in nitrobenzene at 100" C. described above; excellent agreement is evident. Final confirmation of the accuracy and reliability of the method was provided by the following experiment. Three g. of a sample of a W.M. cordite containing mineral jelly and diethyldiphenylurea was allowed to stand in contact with 20 ml. of the nitrobenzene - chloroform solvent overnight. Exactly 5 ml. of the supernatant solvent was then removed and replaced by 6ml.of a synthetic solution of acetone in the same solvent, and this was again allowed to stand overnight. The acetone contents of both this final solution and of the 6 ml. aliquot portion originally removed were estimated. The estimation of the acetone content of the 5ml. aliquot portion enabled the acetone content of the residual 15ml. to be calculated; to this figure was added the known amount of acetone present in the added 5 ml. of synthetic solution, and this was compared with the result of the direct analysis of the final solution. As the results of the duplicate determination given in Table V +ow, these figures differ by about 2 per cent. This experiment establishes that complete extraction of the acetone occurs on standing overnight, for no increase in the acetone content of the supernatant solvent is detected after allowing to stand for a second time overnight.For most purposes this procedure of allowing the sample of propellant to stand in contact with the solvent overnight was convenient, but if results are required more quickly, the time of standing can be reduced to a few hours by increasing the amount of nitrobenzene relative438 BONNER: THE ESTIMATION OF THE VOLATILE MATTER [Vol. 72 to the chloroform in the mixed solvent. When this modification was used, however, it was found that for each particular type of cordite the altered conditions of the estimation varied slightly. Therefore, before this more rapid method is employed, it is necessary to investigate the optimum ratio of nitrobenzene and chloroform and the time to be allowed for extraction for the type of cordite under analysis.TABLE V 3 g. of sample in 20 ml. of nitrobenzene - chloroform solvent RECOVERY OF ACETONE ADDED TO AN EXTRACTED CORDITE SAMPLE (1) Weight of acetone found in 5 ml. of supernatant solvent .. .. .. .. .. .. (2) Weight of acetone in residual 15 ml. of solvent from (1) . . .. .. .. .. .. (3) Weight of acetone added to residual 15 ml. of solvent .. .. .. .. .. .. (4) Total weight of acetone present in final solution, i.e., (2) + (3) . . .. .. .. .. .. (5) Total weight of acetone found in final solution . . Error .. .. .. .. .. .. .. (a) and (b) are duplicate estimations. 6.93 5.40 12-33 12.6 +2*1% 2.48 7.44 5.40 12.84 12-6 - 1.9% The method is applicable in the presence of ethyl alcohol and has been used without modification for the estimation of acetone in cordites manufactured with a mixed ethyl alcohol - acetone solvent.Details of the method are given below. EXTRACTION METHOD Make up the solvent as required by mixing 3 volumes of AnalaR nitrobenzene and 2 volumes of B.P. chloroform. Cut up the sample of cordite into $-in. lengths, and add a weighed 3-g. portion to 20 ml. of the solvent in a 25-ml. cylinder fitted with a ground-glass stopper. Stopper the cylinder and allow to stand overnight. After shaking and allowing to settle, transfer 5ml. of the supernatant solution to a 200-ml. peawhaped flask and add 6 ml. of the nitrobenzene - chloroform solvent and 50 ml. of water. After stoppering, place the flask in an ice bath, in which is also maintained a N-solution of sodium hydroxide.After 15 minutes in the ice bath remove the flask to a Dewar flask containing ice and clamp it vertically with the lower portion immersed in the ice. Remove the stopper and add 10ml. of the N sodium hydroxide. Introduce a motor driven stirrer into the flask and add 10 ml. of 0.1 N iodine dropwise over a period of 5 minutes from a 10-ml. burette, keeping the solution efficiently stirred during the addition. Continue the stirring for a further 20 minutes and then remove the flask and add a slight excess of N sulphuric acid immediate$. Titrate the liberated iodine without delay, with 0.05 N sodium thiosulphate. Near the end-point vigorous shaking is necessary to remove the last traces of iodine dissolved in the nitrobenzene - chloroform layer to the aqueous layer.Carry out a blank determination on 10ml. of the nitrobenzene - chloroform solvent and, after correcting for the very slight consumption of iodine in this “blank” (usually equivalent to 0.05 or 0.10 mg. of acetone per 10 ml. of solvent), calculate the amount of acetone present from the relationship between the iodine solution and acetone given above (p. 435). SUMMARY Existing methods of estimating the residual acetone content of cordite are critically reviewed, particularly from the viewpoint of ensuring quantitative removal of the acetone from the cordite prior to its estimation. A new method is described in which the acetone is extracted with a mixed nitrobenzene - chloroform solvent and estimated by Messinger’s method with an accuracy of 2 to 3 per cent. Interference by nitroglycerine has been studied in detail and the conditions established for its complete elimination. In conclusion, I should like to thank Mr. G. L. Hutchison, of the Armament Research Department for his helpful advice, and the Director-General of Scientific Research (Defence), Ministry of Supply, for permission to publish this material.October, 19471 CONTENT OF PROPELLANT EXPLOSIVES 439 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. REFERENCES Pieroni, A., Atti. r. accad. Lincei, 1918, 27, 11, 52; Chem. Abstr., 1919, 13, 789. Duin, C. F. van, at al., Rec. Trav. Chim., 1919, 38, 163; Chem. Abstv., 1919, 13, 2596. Margueyrol, M., and Loriette, P., Mem. des poudres, 1922, 19, 362; Chem. Abstr., 1923, 17, 1715. Friedmann, F., Zeit. ges Schiess. und Sprengstoffw., 1921, 16, 121; Chem. Abstr., 1922, 16, 343. Messinger, A., Ber., 1888, 21. 3366. Kostevitch, M., Zeit. ges Schiess. und Sprengstoflw., 1931, 26, 416. Benesch, E., Chem.-Zeit., 1927, 51, 578. Graulich, W., Nitrocellulose, 1931, 2, 13. Goodwin, L. F., J. Amer. Chem. SOC., 1920, 42, 39. Mitchell, C. A., “Recent Advances in Analytical Chemistry,” Churchill, London, 1931, Vol. I. D6nig&s, G., J. Pharm. Chim., 1899, 9, 7; Abst., ANALYST, 1899, 24, 92. Adams, C. A., and Nicholls, J. R., ANALYST, 1929,54, 5. Noyes, L. F., J. Lab. Clin. Med., 1941, 26, 1216; Chem. Abstr., 1941, 35, 3667. Winnick, T., J. Bid. Chem., 1941, 141, 115. Komar, N. P., Ukrain. Khem. Zhur., 1929, 4, Sci. Pt. 349; Chem. Absfr., 1930, 24, 3460. Bonner, T. G., ANALYST, 1947, 72, 47-54. - Ibid., 1946, 71, 483-490. CHEMISTRY DEPARTMENT ROYAL HOLLOWAY COLLEGE ENGLEFIELD GREEN, SURREY March, 1947

ISSN:0003-2654    

DOI:10.1039/AN9477200434

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 October, 19471 CONTENT OF PROPELLANT EXPLOSIVES 439 Spot-tests for the Detection of Alloying Elements in Tin-Base Alloys* BY B.S. EVANS AND D. G. HIGGS TIN is extensively used as the basis material for the manufacture of bearing metals and solders. The composition of bearing metals varies considerably according to the particular work required of them. The alloying elements are usually some or all of the following: lead, antimony, zinc, copper and aluminium in varying proportions. Tests have been worked out for lead, copper, arsenic, antimony, zinc and aluminium. Apparatus-In addition to the droppers, stirrers and capillary tubes already described in former papers4 the following are needed: (a) white porcelain spot-plate, and (b) apparatus used for the detection of arsenic (vide (111) Arsenic, and this Vol., p. 108). Cleaning the specimen-The surface of the sample is thoroughly cleaned by rubbing it with emery paper-Grade “F” (Buff), or similar-prior to addition of the attacking reagent.The tests-Of the tests described, those for lead, copper and arsenic are completed on the surface of the sample; the tests for antimony, zinc and aluminium require for completion the removal of the reaction drops from the specimen at some intermediate stage. The test described for lead is the only one of this series that is new to spot-testing. The tests for the remaining elements are either identical with or modifications of tests published earlier, e.g., antimony and arsenic: “Lead-base Alloys”l; aluminium : “SteelsyJ2 and “Zinc-base alloy^"^; copper and zinc: “Aluminium- and Magnesium-base alloy^."^ Iron is seldom added to tin-base alloys, but is usually found as an impurity varying in amounts from 0.02 to 0.05 per cent.The only specification6 in which iron is a constituent gives a figure of 0.10 per cent. Fe, and since no spot-test could be expected to differentiate between an alloying content of 0.1 per cent. and an impurity of 0.02 to 0.05 per cent., a test for it has not been included. (I) LEAD Reagents-(a) Nitric acid (sp.gr. 1.42). (b) Distilled water. (c) Urea (solid). (d) Potassium iodide solution (4 per cent.). Method-Place 2 drops of (a) on the thoroughly cleaned surface and leave them to react until a solid crust has formed or, for less reactive alloys, until the reaction appears to be com- plete. Add 2 drops of (b) and stir; then add a small quantity of (c), sufficient to form a small heap on the end of a pen-knife blade and again stir until the crystals are well mixed with the drop.Add 2 or 3 drops of (d) and stir thoroughly. In presence of much lead, say above 10 * Communication from the Armament Research Department (formerly the Research Department, Woolwich) .440 EVANS AND HIGGS: SPOT-TESTS FOR THE DETECTION OF per cent., a very heavy bright yellow precipitate, and down to about 1 per cent. a heavy yellow precipitate, is formed; with about 0.5 per cent. of lead a slight yellow precipitate only is pro- duced. The precipi- tate of lead iodide may be transferred to a filter-paper, dried and retained for future reference. present and all gave positive results. (11) COPPER [Vol. 72 In absence of lead the composite drop on the specimen is water-white.Tried on: Samples Nos. 10, 7, 12, 11, 22, 15, 8, 6, 4, 3, 14, 5, 9, 13, 1, 23, 21-Lead Nos. 2, 16, 24, 25, 26-Lead absent and all results negative. Reagents-(a) Nitric acid (spgr. 1-42). (b) Diluted ammonia (1 + 1). (c) Mixture of a-benzoin-monoxime (saturated solution in alcohol), 10 vols. ; diluted ammonia (1 + l ) , 20 vols.; citric acid solution (50 per cent.), 5 vols. Method-Place 2 drops of (a) on the thoroughly cleaned surface and leave to react until the attack is complete, add 2 drops of (b), stir well (the drop should now be alkaline), then add 4 to 6 drops of (c), again stir well and leave for 5 to 10 minutes. In presence of copper a dirty green complex separates out slowly, whilst in absence of copper the drop remains water-white. The deep blue coloration produced on addition of the 2 drops of (b) when copper is present is quite unmistakable and could be used as a quick test for copper.Tried on: Samples Nos. 6, 21, 22, 1, 16, 5, 13-Copper present and all results positive. Nos. 14, 15, 2, 3, 4, 7, 8, 9, 10, 11, 12, 24, 25--Copper below 0.05 per cent. and all results negative. (111) ARSENIC (b) Hydrochloric acid (concentrated). (c) Arsenic-free zinc. (d) Mercuric chloride test paper. (e) Ferrous sulphate (small crystals). Reagents-@) Diluted hydrochloric acid (1 + 1) saturated with bromine. A+j!watus-(g) A glass tube 1 in. by Q in., ground flat at both ends, (It) a glass tube 22 in. by 8 in. fitted at one end with a half-inch length of rubber tubing so arranged that a little of the tubing overlaps the end of the glass tube, forming a slightly tapered end which serves as a stopper; this tube with its rubber end should fit snugly into tube (g), (j) rubberised vaseline such as is used for stop-cock lubricants, and (K) cotton-wool.To prepare the tube (h) for the test, insert a tightly packed plug of cotton-wool into the tube so that its lower end is about +in. from the bottom of the tube, the plug being about +in. deep. To the rubber-tubing end of the cotton-wool plug add fine crystals of (e) until a layer about &in. thick has been formed, insert a second plug of cotton-wool to prevent the ferrous sulphate from falling out when the tube is in position for the test. Cut a strip of paper (d) about & in. by 12 in., insert it in the glass tube and then plug the free end of the tube loosely with cotton-wool; the tube is now ready for the test.Method-Thoroughly clean the surface of the specimen with emery paper. Dip the end of the glass tube (g) into the hot sealing grease ( j ) , then withdraw it and, after making 'sure that there is no film of grease across the end, press it firmly on the specimen and allow the grease to set. Add 4 drops of (a) inside the wide tube and leave to react for 5 minutes. Add 15 drops of (b). Drop a small granule of (c) into the wide tube and allow the reaction to proceed for a few seconds; then, before the bromine has been destroyed, insert the rubber- stoppered end of the prepared tube (h) and leave for 15 minutes. Detach the top tube, (h), remove the top plug and shake out the test strip. A yellowish-brown stain on the strip indicates the presence of arsenic. Four samples gave a slight yellow coloration of the bottom Q in.of the strip, and subsequent chemical analysis has shown that these samples contained 0.014, 0.011, 0.020 and 0.027 per cent. of arsenic respectively. In absence of arsenic the paper remains quite white; this is in sharp contrast to the same test as applied to lead-base alloys, where heavy greyish-black stains were produced by high antimony contents. Tried on: Samples Nos. 13, 2, 3, 4, 14-Arsenic present and all results positive. absent and all results negative. Nos. 1, 5, 6, 7, 8, 9, 10, 11, 12, 15, 16, 21, 22, 23, 24, 25-ArsenicOctober , 19471 Reagents-( a) (b) ALLOYISG ELEMENTS IX TIN-BASE ALLOYS (117) ANTIMONY Nitric acid (sp.gr.1.42). Hydrochloric acid (concentrated). Potassium nitrite (solid). Rhodamine “B”6 (0.01 per cent. solution in water) 441 Method-Place 2 drops of (a) on the thoroughly cleaned surface and leave to react until a solid crust has formed, or, for the less reactive alloys, until the reaction appears to be complete. Add 3 drops of (b) and transfer quickly, by means of a capillary tube, to a well of a white porcelain spot plate. Add a further 2 drops of (b) and then a few small crystals of (c) and leave to react for about half a minute. In another well of the spot-plate place 4 drops of (d) and add to them 2 or 3 drops of the solution from the first well; stir, add 2 more drops of (b), stir again, then leave.In presence of much antimony an immediate heavy purple precipitate or coloration is produced; 0-12 per cent. of antimony gives a purplish coloration to the drop. A positive reaction was given by three samples to which antimony had not originally been added, but chemical analysis has shown that the samples contained 0.26, 0.22 and 0.15 per cent. respectively. While removing the reaction solutions to filter-paper for future reference it was noticed that samplesbthat gave a dirty reddish-pink colour on the spot-plate {regarded as having no antimony present) now gave slight purplish precipitates when washed once or twice with water. All samples not supposed to contain antimony were tested on filter-paper and it was found that down to about 0.06 per cent. of antimony could be detected in this way.AnalaR tin, spectrographic tin and the reagents alone did not give a purple precipitate. When dry, the purplish precipitates became mauvish in colour. It is recom- mended that removal of the drop to a filter-disc should not be used as part of the test. Tried on: Samples Nos. 15, 21, 1, 11, 6, 22, 10, 7, 12, 13, 4, 2, 5, 16-Antimony present Nos. 3, 9, 14, 24, 8, 26, 27-Antimony below 0.09 per cent. and a11 The antimony in samples Nos. 3, 9, 14, 24, and 8 was first detected by removal of the reaction drop to a filter-disc and subsequently confirmed by chemical analysis of another portion of each alloy. (V) ZINC In absence of antimony the reagent drop has a dirty reddish-pink colour. and all results positive. results negative. Reagents-(a) Nitric acid (sp.gr.1.42). (b) Urea (solid). (c) Diluted ammonia (1 + l), 1 vol.; ammonium acetate* solution, 2 vols.; potassium cobalticyanide solution (10 per cent.) , 2 vols. (d) Diphenylcarbazone (1.5 per cent. solution in alcohol). (e) Acetone. (f) Isopropyl alcohol. Method-Place 1 drop of (a) on the thoroughly cleaned surface and leave until the reaction appears to be complete; add a small heap of (b), sufficient to cover the point of a pen-knife blade, follow with 5 drops of mixture (c) and stir thoroughly. Add 5 drops of ( d ) , stir, and after a few seconds transfer, by means of a capillary tube, to the centre of a disc of close- grained filter-paper supported on the open mouth of a beaker; the transfer should be made 3 or 4 drops at a time in order to spread out the spot for subsequent acetone washing.Allow to spread completely, then wash three times with 3 drops of (e), and continue with three or four 3-drop washings of (c). Zinc, lead and copper all give precipitates under the conditions existing before treatment of the transferred drop ; copper slowly destroys the reagent colour, the decolorisation being greatly accelerated by acetone. The acetone wash also dissolves, ciecolorises and washes out the lead precipitate, whilst the deep blackish-purple precipitate due to zinc is dissolved and spread out over a limited area as a deep permanganate-coloured patch. Washing with isopropyl alcohol (f) removes any incidental reagent colours but leaves the zinc patch in its original position. In presence of zinc an intense blackish-purple spot at the centre of the paper, surrounded by a permanganate-coloured patch about 18 to * Preparation of ammonium acetate solution: add, to 1140 ml.of distilled water in a 3-litre porcelain beaker placed in a cooling bath, 500 ml. of 0.880 ammonia solution followed by 570 ml. of glacial acetic acid, the solution being stirred continuously. Allow to cool; the solution should be neutral.442 2 in. in diameter, is obtained. In absence of zinc the paper has a clear centre (sometimes ;I slight light brown or pink smudge due to traces of copper or lead precipitates not completely washed out) and a narrow ring about 2Q in. in diameter, which vanes in colour from light brown to maroon. Zinc down to 047 per cent. gives a fair reaction.Where the presence of zinc is doubtful it is best to wait 5 minutes after the last addition of (f) before deciding whether the centre contains a precipitate or a colour which does not fade. Tried on: Samples Nos. 5, 13, 14, 3, 16, 2, 4, 19, 20, 18, 17, 15-Zinc present and all Nos. 1, 6, 7, 8, 9, 10, 11, 12, 21, 22, 23, 24, 25-Zinc absent and all EVANS AND HIGGS: SPOT-TESTS FOR THE DETECTION OF [Vol. 72 results positive. results negative. (VI) ALUMINIUM Heageitts-(a) Concentrated hydrochloric acid saturated with bromine. (b) Mixture of sodium hydroxide solution (20 per cent.), 3 vols.; potassium cyanide solution (10 per cent.), 1 vol. (c) Ammonium aurintricarboxylate (0.01 per cent. solution in alcohol). (d) Mixture of ammonium chloride solution (20 per cent.), 1 vol.; ammonium phosphate solution (10 per cent.), 1 vol.(e) Ammonium chloride solution (20 per cent.). Method-Place 2 drops of (a) on the thoroughly cleaned surface and allow them to react until the bromine colour is all but dispelled, then add 4 or 5 drops of (b) stir well, and if thc NO. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 TABLE I SPECIMENS OF ALLOYS USED IN THE TESTS. Mark DOF .. E X 14 . . EX15 . . EX16 .. E X 7 .. EX46 .. EX47t .. EX48t . . EX40t . . EX50 .. EX51 .. EX52 .. EX53 .. EX54 .. EX55 .. EX56 .. EX78 . . EX79 .. ,EX80 .. EX81 . . BCN .. BCM .. USA .. “Pure” Tin .. . I .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. “Chempure” Tin “Spectro” Tin . . A/R Tin.. .. Pb 0.05 3.4 1 4.38 1.10 8.37 - 39 20 1.0 46-95 23-25 38-65 0.84 1.31 19-45 - 0.56 30-24 0.68 30.63 0.37 21-94 0-49 - - - 0.01 Sb 9-75 0.22* 0.09* 0*26* 0*15* 7.0 3 0.06* 0.09* 3-11 9.57 2.24 1-20 0-09* 11-12 0.12 - - - - 9.89 5-63 0*08* - - - 0.03 CONSTITUENTS PER CENT.Zn 7.60 11-41 6-10 40.9 - - - - - - - - 26.34 19.16 0.36 9.27 0.46 0-50 1-33 1.11 - - - - - - - * Found first by spot-test and later confirmed by chemical analysis. t Samples not analysed chemically. heavy white gelatinous precipitate has not dissolved add a further drop of (b). Treat a circle of close-grained filter-paper with 1 ml. of reagent (c), causing it to spread evenly and finally drying over a source of hot air. Place the paper on the open mouth of a beaker and add the reaction solution, which is removed from the sample by means of a capillary tube, to the centre of the paper, in a dropwise manner.When the last drop has been added and the liquidOctober, 19471 ALLOYIXG ELEMENTS IN TIN-BASE ALLOYS 443 has finished spreading, remove the filter paper from the beaker, place it flat on a clean porcelain tile and cover it with a 7-cm. filter-paper thoroughly wetted with mixture ( d ) ; press the latter paper on to the reaction filter-paper, to ensure good contact at all points and after a few seconds strip it off and reject it. Return the original paper to its beaker, leave it for 5 minutes, then wash it twice with 3 or 4 drops of (e) and finally dry it. In presence of aluminium the paper shows a sharp pinkish-crimson irregular ring about 1Q in. in diameter outside which is a broad band of colour, similar to that of the ring but less intense; the ground both inside and outside the ring should be white while wet. In absence of aluminium the paper should be completely white after 5 minutes standing. With 0.26 per cent. of aluminium, instead of the characteristic markings of the high aluminium contents there is a single light pinkish irregular band of the same diameter. Tried on: Samples Nos. 2, 1AAluminium present and both give positive results. Nos. 1, 3, 4, 5, 6, 7, 10, 11, 12, 13, 15, 16, 21, 22,23,24--Aluminium below 0.05 per cent. and all results negative. SUMMARY Tests are described for the detection of alloying elements in tin-base alloys. The alloying elements so detected are lead, copper, arsenic, antimony, zinc, and aluminium. With the alloys available the tests are specific and unambiguous. No test has been included for iron since the margin between impurity and alloying constituents is too small. Thanks are due to the Chief Scientist, Ministry of Supply, for permission to publish this paper. REFERENCES 1. Evans, B. S., and Higgs, D. G., ANALYST, 1947, 72, 105-109. 2. -,- , Ibid., 1945, 70, 75-82. 3. -,- , Ibid., 1947, 72, 101-105. 4. - - , Ibid., 1940, 71, 464-474. 5 . 6. S.T.A.7, “Services Schedule of Non-Ferrous ,Wetals and Alloys,” Dec., 1942, Group IV (T.B.3). Eegriwe, E., 2. anal. Chew., 1927, 70, 400. May, 1947

ISSN:0003-2654    

DOI:10.1039/AN9477200439

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 October, 19471 ALLOYIXG ELEMENTS IN TIN-BASE ALLOYS 443 A System of Qualitative Analysis for the Common Ammonium Benzoate Metals in Presence of Phosphates, using BY G. J. AUSTIN THE benzoate iron group separation1 has been p r o p o ~ e d ~ * ~ for group analysis, instead of the more common separation by ammonia. It gives much better separations than other methods and can be used in presence of phosphate. However, some of the phosphate passes into the filtrate and when ammonia is added phosphates of the bivalent metals may precipitate, thus interfering with the rest of the analysis.This is overcome in the system now proposed by using some of the principles employed in my phosphate method4,6 in which the solution remains acid until all the metals except magnesium and alkali metals have been separated. This system of analysis can be applied regardless of the presence of phosphate and, cxcept when 0-20 g. or more of phosphate (P,O,) is present, it will usually give much better separations than my phosphate or other methods. However, when phosphate is present the iron group precipitate is unsuitable for direct ignition and weighing, as a mixture of oxides and phosphates is obtained. An important advantage of the benzoate method of separating iron group metals, which is used in this system, is that it can be used when chromium is the only iron group metal present.Under these conditions chromium cannot be precipitated as basic acetate, formate or succinate. Uranium, beryllium, and tervalent cerium are only partially precipitated in the benzoate separation unless sufficient phosphate is present to precipitate these metals as phosphates, but these metals and also chromium can be precipitated in my phosphate method. When this system is used for ordinary qualitative analysis it is sufficient to wash the The phosphate method415 can be used in such instances.444 precipitates with water. to deposit benzoic acid on cooling, but this will redissolve on warming. AUSTIN: A SYSTEM OF QUALITATIVE ANALYSIS FOR THE [Vol. '72 Until the 5g.of ammonium acetate is added, the solution is apt A SYSTEM OF ANALYSIS SUITABLE FOR PHOSPHATES Remove Groups I and I1 as usual. (Chromates and Fe"' are best reduced with HI-see ref. 4.) To a solution of 0.5 g. in 20 ml. add dilute ammonia until a slight ppt. persists. Add 1 ml. of 5 N HCl. Heat to incipient boiling, add 2 ml. of 10% (NH4),S04 solution and if there is a ppt. add another 2 ml. of (NH&SO, solution and heat in boiling water for 15 to 30 min. Filter and wash with 0-05 N H,SO,. ppt. SrSO, BaSO, Solution. Add sat'd. bromine solution and boil off excess. To the cold solution add dilute ammonia until a slight ppt. persists. Add 1 ml. of glacial acetic acid and 2g. of NH,Cl, dilute to 100 to 150ml. Heat and add 20ml. of 10% ammonium benzoate solution.Boil. (PH is now 3.8 to 4.0.) Filter hot and wash with hot benzoate wash solution or with 2% ammonium nitrate solution. P p . Fe, Al, and Cr as phosphates and/or basic benzoates Solution. Add 5 g . of ammonium acetate. (pH is now 4.6 to 5.0.) Heat to boiling and pass H,S through the hot solution for 5 to 10 min. Boil for a few seconds and filter. Wash with 0.1 N acetic acid. Ppt. ZnS, CoS, NiS. w t-h Solution. Boil off H,S. To the gently boiling solution add 5-ml. portions of the periodate reagent until a positive spot test for periodate with the starch iodide solution is obtained. Filter and wash with a little water and then with hot 0-1 N HNO,. Ppt. MnO,.H,O. Solution. To the hot solution add 5 ml. of M citric acid and 25 ml. of sat'd. ammonium oxalate solution.Allow to stand at least 6 min., filter and wash. PPt- , CaC,O,.H,O. Solution. Concentrate to about 150 ml. Add 6 ml. of M ammonium phos- phate and to the hot solution add 20 ml. of conc. NH,. Stand over- night. Filter and wash with 2% NH,. The 20ml. of ammonium benzoate solution are sufficient for 0.10g. of aluminium or 0.20 g. of iron or chromium. For larger amounts of these metals, add the ammonium benzoate solution until the solution has $H 3-5 to 4 as indicated by a blue spot test with bromophenol blue indicator. At $H 3.0, after 5 minutes boiling, 0.2 mg. of iron or aluminium is left in solution, while at pH 3.5 to 4.0 less than 0.1 mg. remains dissolved. When present alone, chromium requires longer boiling than iron or aluminium; after 20 minutes boiling 3 mg.of chromium remained dissolved at $H 3.0 and 1 mg. at pH 3.5. However, when iron or aluminium was also present then usually not more than 0.1 mg. of chromium remained dissolved after 5 minutes boiling at $H 3-5 to 4-0. For ordinary qualitative analysis it is usually sufficient to boil for about one minute before filtering off the basic benzoates. Table I compares adsorption or co-precipitation of bivalent metals by precipitates of the iron group obtained by various methods. The tests by the ammonia method3 were with phosphate absent and at $H 6.7 to 7-3. The tests by my phosphate method were with 0.355 g. of P,O, present. I t may be noted that by ignoring any phosphate present and using the benzoate method as in this system of analysis, the adsorption of zinc, nickel, and cobalt is considerably less than if the phosphate is first removed and then the ammonia method used.Adsorption losses in the system now described, other than in the iron group, are very small ; some examples are given in Table 11. It is evident that as a general method the benzoate method is best.October, 19471 COMMON METALS IN PRESENCE OF PHOSPHATES TABLE I 445 ADSORPTION OF BIVALENT METALS IN THE IRON GROUP The figures represent the amounts of the various bivalent metals co-precipitated, expressed as percentages of the amounts taken Adsorption by benzoate method A I \ Weight of 0-072 g. 0.21 g. Adsorption Adsorption Adsorption metals taken phosphate P,O, P,O, by phosphate by ammonia by acetate (-Ap, absent present present methodP methods method' 4.9a 14 % 15 0.120 co 0.33 0.8 1.5 1.0 6.2 - 0.097Ca < 0.2 < 0.2 0-6 < 0.2 0.069Mg < 0.2 < 0.2 < 0.2 < 0.2 % 19 YO 8 % YO €5 g.% n 0.1 16 Mn 0.20 0.8 2.4 1.2 0.10 0.5 0.055 A1 0-127 Zn 1.4 n n 0.120 Ni 0.8 2-2 0.8 0-5 71 1.3 n n - - - - 0.093 Fe 0.127 Zn 0.2 3-0b 11 10 12 13.6 n 0.1 16 Mn 0.1 0-35 3.2 3.0 2.7 4. Pi n 0.120 co 0.1 0.8 2.6 0.7 6.0 4.0 n 0-120 Ni 0.1 0.5 1.7 0.3 6-8 6.0 n 99 - - 0-097Ca < 0.2 < 0.2 0.6 < 0.2 0.069Mg < 0.2 < 0.2 < 0.2 < 0.2 - - I9 0.171 Ba < 0-1* < O.l*c 30* 30* 0.2 14 0.088 Cr 0.127 Zn 4.5 15 29 26 90 0.1 16 Mn 0.4 3.8 10 8 3-2 0.120 co 0.8 4.5 4.5 5-5 75 0- 120 Ni 1.6 4.3d 4.5 3.5 90 - 0-097 Ca 0.2 0-7 7.0 5.0 0.8 - 0.069Mg < 0.2 0-5 1.5 1.5 1.6 - 0.171 Ba < 0.1* 6*0* 37* 52* 0.8 - 1-5 2.9 25 14 33 20 0.3 1.0 5.6 7 0.20 1.0 5.8 3.4 - n - 99 n 9 ) 99 99 - - - 0.022 A1 0.035 Cr 0.046 Fe 0.044 Cr } 0'116Mn 0.028 A1 0.044 Cr } 0*116Mn - - * The adsorption of barium and strontium is avoided by prior removal of these metals as sulphates a 52% of the P,06 taken was in the filtrate.b 8% n 93 n n 9 ) c 2.3% n 99 99 99 99 d 30% 99 9 ) 9) YY TABLE I1 TESTS ON ADSORPTION ELSEWHERE THAN IK THE IRON GROUP Taken Zn = 0.2000 of ZnS Mn = 0.2000 of MnS 1 0.142 of P205 g. The ZnS, weighed as sulphate, gave Zn = 0.2012 g. of ZnS and contained The MnO, was ignited at 1000°C. and weighed as MnsO,. Obtained Mn = 0.55% of the Mn taken. I 0.1992 g. of MnS. Mn E 0.200 of MnS Ni = 0.200 of NiS 0-142 of P,O, Mn = 0.200 of MnS c o = 0.200 of cos 0.142 of P20, Ca = 0-1500 of CaO Mg = 0.1500 of MgO 0.142 of P,O, Fe = 0.1000 of Fe,O, Iron ppt. ignited gave Mn = 0.1000 of MnO Ca = 0.1037 of CaO Mg = 0.0963 of MgO Less than O.lyo of the Mn taken was present in the nickel sulphide. Less than O-lyo of the Mn taken was present in the cobalt sulphide. 1.3% of the magnesium was carried down by the calcium oxalate. Obtained CaCO, = 0.1511 g. of CaO. 99 Mg,P,07 = 0-1483 g. of MgO. 0.1OOOg. of Fe,O, 0.1005g. of MnO = 0-0966g. of MgO Mn in MnO, estimated as Mn,P 0, Calcium was re-pptd. Ignition gave CaCO, = 0.1043 g. of CaO Mg ppt. ignited gave Mg,P20,446 ABSTRACTS OF CHEMICAL PAPERS [Vol. 72 REAGENTS USED- 190 ml. of water containing 1.5 ml. of glacial acetic acid. bicarbonate and 1 g. of potassium iodide. acetic acid per 100 ml. Sodium periodate solution-Dissolve 4-0 g. of the salt (Na,H,IO,) by warming in about Starch iodide-Prepare 1 per cent. starch solution and in 100 ml. dissolve 10 g. of sodium Benzoate wash solution-This contains 1 g. of ammonium benzoate and 2 ml. of glacial Dilute to 200 ml. and filter. REFERENCES 1. 2. 3. 4. - Ibid., 1940, 65, 335. 5. - Ibid., 1943, 68, 274. 18 STRATTON DRIVE, BARKING, ESSEX Kolthoff, J. M., Stenger, V. A., and Moscovitch, J . Amer. Chenz. SOC., 1934, 56, 812. Lehrmann, L., and Kramer, J., Ibid., 1934, 56, 2658. Austin, G. J., ANALYST, 1942, 67, 132. February, 1947

ISSN:0003-2654    

DOI:10.1039/AN9477200443

出版商:RSC    

年代:1947

数据来源: RSC