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

ISSN:0003-2654    

DOI:10.1039/AN9467100223

出版商:RSC    

年代:1946

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9467100226

出版商:RSC    

年代:1946

数据来源: RSC

摘要:

NOTES 227 Notes NOTE ON THE PRESENCE OF HEAT-LABILE SULPHUR IN MILK POWDER MADE FROM MILK PRE-HEATED AT A HIGH TEMPERATURE (190” TO 200” F.) IN recent publications,V the efficacy of high temperature pre-heating of the liquid milk as a means of stabilising full cream milk powders against development of tallowy “off” flavours and of retarding loss of vitamins A and C during storage has been pointed out and the improvement in keeping properties has been attributed mainly to production of anti-oxidant active sulphydryl compounds by the action of heat on the protein. Details of a method based on the work of Almya and of Townley and Gould,* which has been found useful as a qualitative and as a rcugh quantitative test for labile sulphur in milk powders made from milk pre-heated at a high temperature may therefore be of interest.A quantity of milk powder containing 50 g. of milk solids is reconstituted to the solids content of fresh milk (1205%) and placed in a specially shaped vessel (see Fig. 1) made from a “330” ml. Pyrex beaker by This process is now in commercial use. A Fig. 1. A = Cylinder of “oxygen-free” nitrogen. B = Wash bottle containing alkaline triacctoxybenzene (1 :2 :4-triacetoxybcnzene 20 g., C -= Wash bottle containing water. D = Flow meter. E = Specially shaped flask. F = Thermostatically controlled water bath. G = Condenser. H = Trap. I = Absorptioii tubes containing alkaline zinc acetate solution. potassium hydroxide 27 g. water 200 ml.). rounding the bottom and fusing to the mouth a 500-ml. round-bottomed flask from which the bottom has been renioved and of which the neck has been shortened.The milk roughly fills the lower straight sided portion of the vessel and the upper bulb and a loose plug of glass wool in the neck of the flask serve as a foam trap. Oxygen-free nitrogen is passed through the milk and thence uia a reflux condenser and trap to a sintered glass bubbler immersed in a few ml. of alkaline zinc acetate solution contained in a boiling tube of which the bottom is flattened. h second absorption tube placed in series with the first has never been found to contain any sulphur. The flow of gas is controlled at 60 litres per hour by means of a simple glass U tube flowmeter. In experiments to date commercial “oxygen-free” nitrogen has been further purified by passage through alkaline 1 2 4-triacetoxybenzene but this grade of gas has already been purified over copper and it is very doubtful whether the additional precaution is necessary.Various multiple aperture jets were tried and found unsatisfactory owing to gradual choking which tended to cause non-uniform gassing during the run; a single jet made from 2 mm. tubing was finally adopted. The temperature of the milk is controlled at 60” C. by immersion of the vessel in a thermostat at about 60.5” C. Air is swept out of the apparatus before heating is commenced and the flow of gas cut down to a trickle during the 20 minutes necessary to bring the milk to the required temperature. Colorimetric estimation-Place 6 ml. of 1 yo zinc acetate solution and 6 ml. of O.SyO sodium hydroxide solution in the absorption tube.After absorption wash the bubbler with 4 or 5 ml. of 1% hydrochloric acid dilute the liquid to a 17.5 ml. mark on the tube and insert a glass rod for mixing. Add 2 ml. of a freshly prepared 0.05% solution of paminodimethylaniline hydrochloride in diluted hydrochloric acid (1 + l) followed by 0.5 ml. of 0.02 M ferric chloride and allow to stand in darkness for 20-24 hours. Dilute the ferric chloride from a stock solution prepared by dissolving 6-75 g. of the hexahydrate in 125 ml. of concentrated hydrochloric acid and making up to 250 ml. Measure the blue colour developed by mean 228 NOTES of a photometer and filter a t about 650 mp. The Zeiss Pulfrich instrument with filter No. 7 and +3 cm. cell was quite suitable. A zero blank was easily obtained without any precautions other than limitation of the area of exposed rubber to a minimum.Calibration uguimt sodium sulphide-Standardise an approximately 0.01 N sodium sulphide solution by addition of 25 ml. to 50 ml. of 0.01 N iodine and titration of the excess iodine with 0.01 N thiosulphate. Prepare a series of dilutions in oxygen-free water (de-oxygenated by passing nitrogen) and immediately add 1 ml. portions to tubes containing the alkaline zinc acetate reagent and develop and measure the colour as described above. A suitable range of concentrations is @-3 mg. of sulphur per litre of coloured solution. Production of volatile sulphur from fresh milk-388 ml. of milk corresponding to 50 g. of milk solids, was used for each determination three-hour runs being made a t 50 60 65 70 and 75" C.The milk was obtained from consecutive morning milkings of the same cow and all runs duplicated on a different day, the mean of the two sets of data being recorded. The result (Table I) shows that no volatile sulphur could be detected a t 50" C. even after heating for 3 hours. At 60" C. a very faint reaction was obtained and the response increased rapidly as the temperature of heating was raised. Production of volalile sulphur froin milk powder-Several samples of high tern-perature (190 or 200" F. for 20 seconds) pre-heated spray-dried full cream powder were examined for the effect of time and tem-perature on the liberation of volatile sulphur. Owing to the season freshly made pow-der was not available and the materials used had been held for 2 months in 21 lb.gas-packed cans. The results showed that practically no volatile sulphur was obtained a t 20" C. in contradistinction to liquid milk which after heating at 190" F. gives a strong positive reaction when nitrogen is passed through it a t 22" C.4 At 40 50 60 and 70" C. increasing quantities of volatile sulphur were obtained (Table I). Milk reconstituted from powder therefore contains little or no free H,S that formed during pre-heating of the liquid milk presumably having been lost during the drying process. The proteins however have been so altered by the pre-heating treatment that they literate volatile sulphur a t a much lower temperature than does fresh milk. TABLE I PRODUCTION OF VOLATILE SULPHUR FROM FRESH MILK AND FROM MILK RECONSTITUTED FROM A HIGH TEMPERATURE PRE-HEATED FULL CREAM POWDER Duration Mg.of sulphur produced per kg. of milk solids' a t I\ of heating 7 (hours) 20°C. 40°C. 50°C. 60°C. 65°C. 70°C. 75°C. I - 0.00 0.01 0.04 0.08 0.43 - I 0.00 0.03 0.08 0.18 0.73 1 2 - - 0.00 0.05 0.15 0.48 1.12 3 - - 0.00 0.07 0.23 0.76 1.50 Fresh milk . . * 0.01 0.05 0.09 0.20 - 0.35 -0.01 0.09 0.16 0.32 - 0.56 -0.01 0.14 0.24 0.51 - 0.89 - 2 3 0.01 0.18 0.30 0.65 - 1.22 -! Reconstituted milk . . * 1 kg of milk solids = approx. 7.77 litres of milk. For the routine examination of milk powders 60" C. is probably the most suitable temperature and 1 hour an adequate period of heating. Under these conditions fresh milk gives a barely detectable reaction. Low temperature (lSO" 165" or 170" F.for 20 seconds) pre-heated powders tested to date have all given a completely negative reaction when examined some little time after manufacture possibly owing to destruction by oxidising fat or by traces of contaminating copper of any minute quantities of volatile sulphur which might have been produced by the pre-heating treatment or during the determination. High temperature pre-heated powders give a strong positive reaction. Investigation Board of the Department of Scientific and Industrial Research. This work formed part of a joint programme of the Agricultural Research Council and the Food REFERENCES 1. 2. 3. 4. Low Mattick Hiscox Crossley Lea Findlay Smith Thompson Kon and Egdell J . Dairy Res. 1945, 14 116. Findlay Higginbottom Smith and Lea Id.in the press. Almy L. H. J . Amer. Chem. SOC. 1925 47 1381. Townley R. C. and Gould I. A. J . Dairy Sci. 1943 26 689. TEMPERATURE RESEARCH STATION CAMBRIDGE C. H. LEA November 1945 NOTE ON TECHNIQUE FOR MICROBIOLOGICAL ASSAY OF JITAMINS BY METHODS INVOLVING MOULD GROWTH THE difficulties of manipulation for methods of microbiological assay involving the harvesting drying and weighing of mycelia of numerous replicates may well prevent the general adoption of these methods on account of the time and space involved. The following technique has been found to save a considerable amount of time labour and space in incubators etc. and renders the assay of large numbers of samples easy. The moulds (Neuvospora sitophila for pyridoxine or Phycomyces BZakesZeeanus for aneurine) are grown in the usual way on 10 ml.of medium containing the appropriate standard or sample under assay in 50-ml NOTES 229 Erlenmeyer Pyrex flasks. X number of these racks made of sheet copper are convenient for routine work. They and their contents can be steamed or autoclaved according to the method used and the flasks are replaced on them after inoculation. Since the racks are interchangeable they can be placed one on top of the other for incubation in the constant temperature room and so a considerable economy of shelf space is effected. When the mycelial growth is ready for harvesting we steam the racks and contents for 10 minutes to kill and touglicn the mould. The contents of each flask are then filtered on a small Buchner funnel (diameter 5 cm.) fitted with a hard filter paper such as Whatman No.54. I t is convenient to remove the mycelium from the flask by twisting it round a thin glass rod flattened a t one end. The flask and mould are washed with two 5-ml. quantities of distilled water from a tilting pipette fitted to a wash bottle. The mould mycelium is then carefully detached from the filter paper and rolled into a ball which is pressed between two filter papers (Whatman No. 54) to remove excess moisture. Care should be taken that the thin edges of the growth are well rolled in because they become brittle when dry. The balls of mycelium are then dried in batches of ten. This is effected by placing limiting rings of “Alda” (British Oxygen Co. aluminium-silicon alloy welding rod gauge Ath inch) of about 1.3 cm.internal diameter in the bottom of a flat aluminium dish of diameter 7.5 cm. (Fig. 2 ) . The mycelia can be coded by a pencil mark on These flasks are placed in order in racks holding 50 (Fig. 1 ) . The rings are easily made. le ,I Drainage Holes ; Each Tray has 1 inch Rim to prevent slspping of Flasks. Fig. 1. Rack for Flasks. Fig. 3. Drying Dish with Loose Rings. the Petri dish inside each limiting ring. The Petri dishes and contents are dried to constant weight for which we find that 3 hours in a vacuum oven a t 100’ C. is suitable. The dishes and mycelia are then weighed in equilibrium with air and each mycelium is removed with forceps in turn. This gives the weight of each mycelium by difterence from the preceding total weight and saves much time.I t is convenient to use a good air-damped balance. A series of ten replicates on three levels of aneurine using Phycomyces Blakesleeanus gave the following error calculated as maximum deviation from the mean. Level of Average weight Maximum deviation Error assay of ten replicates from mean 0.1 pg. 29.7 mg. & 1.3 mg. 4.3% 0.2 3 49-6 , rt3-1 , 6.2 ,, 0.4 , 79.5 , &5*6 , 7.0 ,, As with all these microbiological assay methods the higher levels give more erratic results since the relation between standard dose and response is only linear over a given range. There was no progressive variation between individuals in a series so there appears to be no absorption of moisture during weighing. The technique seems reasonably accurate (considering the small quantities assayed) over levels normally encountered in the assay of foods and would save much time and labour where large numbers of samples have to be handled e g .in nutritional surveys. I acknowledge with gratitude the generosity of Messrs. J. Lyons & Co. in permitting the publication of this note on a technique which was developed in their laboratories. REFERENCES 1. 2. Stokes J. L. Larsen A. Woodward C. R. and Foster J. W. J . Biol. Chew. 1943 150 17-24 Barton-Wright E. C. ANALYST 1945 70 290. J. LYONS & Co. LTD. THE LABORATORIES ENID A. M. BRADFORD HAMMERSMITH ROAD LONDON S.W. 230 XOTES SEPARATION OF THE COBALT COMPLEX OF 8-NITROSO a-NAPHTHOL FROM OTHER COLOlrIIED METALLIC COMPLEXES (Read at the Meeiitzg of the Socicty on Wedtzesdny A p i l 3 1946) SEVERAL a-nitrosophenols form coloured co-ordination compounds with cobalt and can be used for thc colorimetric determination of the metal.Coloured complexes are also formed with tin copper silver bismuth nickel chromium and iron. It has been found possible to separate cobalt from these metal even when they are present in great excess and the reactions now described should be of service in deter mining cobalt in their presence. The main elements likely to interfere with the colorimetric determinatioi of cobalt in biological materials are iron and copper and since 1 pg. of cobalt can be quantitatively separate( from 5000pg. of iron it should be possible to apply the technique after destruction of organic matter Preliminary attempts to determine cobalt in biological materials by direct application of the suggestec method after wet ashing have given low results but it may prove possible to overcome this difficulty.In order to increase intensity and specificity it is an advantage to be able to extract the colourec complex in a small amount of organic solvent. Of the o-nitrosophenol derivatives available 8-nitrosc a-naphthol appearecl to be the most promising as the cobalt complex formed with it is intensely coloured and only slightly soluble in waterZ (1 part in 6 x lo6). The red complex formed by cobalt and /?-nitrosc a-naphthol is produced rapidly in the cold over the $H range 4-9; it is readily extracted by organic solvent such as amyl alcohol benzene chloroform or carbon tetrachloride and is not destroyed by strong acid o alkali.Under similar conditions copper iorms an orange-coloured complex and iron gives both green an( red complexes. The two iron compounds can be separated from each other and from the cobalt comple: by chromatographic adsorption from a carbon tetrachloride solution on a magnesium oxide or alurnin; column. The red derivative is converted into the green ferrous form on treatment with alcoholic sodiun hydroxide (0.5 N) or reducing agents such as sodium hydrosulphite. The green form is only slightl: soluble in carbon tetrachloride but is soluble in 0.5 N sodium hydroxide in 50% aqueous alcohol. Thc copper complex is destroyed by aqueous or alcoholic alkali. The chromium complex is red and stable t c alkali but destroyed by acid.When solutions of the /?-nitroso or-naphthol complexes of the metals in carbon tetrachloride are shaker with concentrated hydrochloric acid the cobalt derivative is unchanged but the coloured complexes o other metals are immediately destroyed. This reaction permits estimation of cobalt in presence of largi excess of iron copper or other metals. The specific destruction of complexes other than that of cobal also occurs with 90% sulphuric acid or 90% acetic acid. The complexes of cobalt copper and iron can also be separated by chromatographic adsorption of thc carbon tetrachloride solution on a column of alumina or magnesium oxide and development with alcohol The cobalt complex passes through first but if a large excess of iron (e.g. 10 times as much iron as cobalt is present this separation is difficult.The separation is made more difficult by the presence of the twc different iron complexes one of which has a similar colour to that of the cobalt derivative. The red irox complex has a rather bluer shade than the cobalt complex. Quantitative separation of the coniplexei formed from 2-5 pg. of each metal is possible with a column 1 cm. in diameter and 5 cm. in length. The /3-nitroso or-naphthol cobalt complex in carbon tetrachloride solution can then be separated frorr complexes of other metals in three ways. 1. By chromatographic analysis when only two or three metals are present and none in great excess 2. By destruction of the complexes formed by other metals on shaking with concentrated hydrochloric acid. 3. By treatment with 0-5 N sodium hydroxide in 50% alcohol the iron complex is extracted and onlj cobalt and chromium complexes remain.A method of estimation of cobalt depending on methods 2 and 3 has been worked out. The amoun' of 8-nitroso a-naphthol used must be sufficient to combine with all metals present in the solution anc capable of reacting. biETHOD-The solution containing between 0-5 and 10 pg. of cobalt is neutralised with sodiun hydroxide and acetic acid and methyl red as indicator so that the pH lies between 5.0 and 7.0. The volumc of this neutralised solution should be under 20 ml. and 5 ml. of a lo/ solution of P-nitroso a-naphthol* ir a mixture of 407; carbon tetrachloride and 6OyG of absolute alcohol by volume are added and shaken foi 10 minutes to allow the cobalt complex to form and to be dissolved in the carbon tetrachloride.The carbor tetrachloride layer is then allowed to settle and the supernatant aqueous layer removed by suction. Thc carbon tetrachloride solution is transferred t o a 10- or 15-ml. stoppered measuring cylinder or graduatec tube being washed in with conc. hydrochloric acid of AnalaR grade. It is twice extracted with 10 ml. o conc. hydrochloric acid by shaking settling and removal of the upper layer by suction. This treatmen. decomposes the complexes of other metals and removes some of the excess reagent. The remaining acic is removed by two washings with water and the remaining excess reagent dissolved out by shaking witk 10 ml. of N sodium hydroxide the excess of which is in turn removed by washing with 10 ml.of water If the carbon tetrachloride solution at this stage is not a clear pink or red it should be washed with 1 volumc of 0.5 N sodium hydroxide in 50% alcohol to remove any remaining iron complex which will impart i green colour to the aqueous alcohol layer. Excess alkali is then removed by twice washing with water As much water as possible is removed by suction. If the colour is to be read in a microcolorimeter absolutt alcohol is added to make the total volume equal to twice that of the remaining carbon tetrachloride solutior (c.g. 1-5 ml. of carbon tetrachloride solution with 0.2-0.3 ml. of remaining water are made up to 3 ml.). I readings are taken in a photometer requiring 1 ml. or less of solution the water can be removed by filtratior through dry filter paper.The absorption of green light which is proportional to the amount of coball present is determined and the amount of cobalt is then ascertained by reference to a standard curve obtainec by determination of the absorption produced by known amounts of cobalt ranging from 0 to l O p g . A * The /3-nitroso a-naphthol is twice recrystalled from glass-distilled water. Filtration of the hol solution is necessary to remove dark coloured impurities NOTES 231 blank determination is carried out using water in place of cobalt solution and the final extract is then placed in one cell of the photometer or above the neutral density screen of the colorimeter. If a colorimeter is used the depth of the blank extract is adjusted so as to be equal to that of the unknown solution.SUMMARY-The p-nitroso a-naphthol complexes of several metals can be dissolved in carbon tetra-chloride. If this carbon tetrachloride extract is washed with concentrated hydrochloric acid the complexes formed by metals other than cobalt are destroyed. The excess reagent can be removed by washing with sodium hydroxide solution. Iron forms two complexes with /I-nitroso a-naphthol; a red iron complex is converted into a green derivative by reduction. The green compound can be extracted from carbon tetrachloride solution by a solution of sodium hydroxide in 50% aqueous alcohol. These reactions are used in a method for the colorimetric determination of cobalt. I should like to thank Dr. H. H. Green for his interest in this work. REFERENCES 1. 2, Yeo J. H.and Barton C. J. Ind. Eng. Chem. Anal. Ed. 1940 12 405, Cacciapuoti B. N. and Ferla F. A?m. China. applicata 1939 29 166. VETERINARY LABORATORY MINISTRY OF AGRICULTURE AND FISHERIES NEW HAW WEYBRIDGE E. BOYLAND Decem bey 1945 DISCUSSION Mr. L. A. HADDOCK said he used a similar method several years ago for the determination of traces of cobalt. He found it necessary however to buffer the solution a t pH 3 to 4 and to boil and cool before extracting the cobalt complex. Without boiling low results were obtained. Amy1 alcohol was found to be a better solvent than the chlorinated hydrocarbons. Interference from chromium and tin could be circumvented to some extent by working in a tartrate solution. Mr. K. F. MILTON asked why the author used 8-nitroso-a-naphthol in preference to a-nitroso- /%naphthol.In his experience loss of cobalt on ashing was due to entrainment in the silicaceous residue and could be overcome by ashing in a platinum basin a t a low temperature and then removing silica by treatment with hydrogen fluoride and volatilisation as silicon fluoride. In reply Dr. BOYLAND said that if excess of the reagent was present the colour development by cobalt did not appear to be increased by heating the reaction mixture. The advantages of carbon tetrachloride over amyl alcohol as a solvent for extraction were (u) its lower solubility in water so that with repeated washing very little solvent was lost and ( b ) being heavier than water it enabled washings with aqueous reagents to be carried out rapidly by shaking in tubes allowing to settle and removing the aqueous layer by suction through a capillary tube.The advantages of /3-nitroso-a-naphthol over a-nitroso-&naphthol are (a) the greater ease of purification of the reagent (b) the higher partition coefficient of the cobalt com-plex between organic solvents and water and fc) the greater intensity of the colour of the complex and suitability for colorimetric estimation. THE USE OF CUPFERRON FOR THE ESTIMATION OF LARGE QUANTITIES OF IRON IN FAECES IT has been fashionable for a number of years to administer large quantities of iron usually in the form of iron ammonium citrate (of the order of 90 grains per day) to the human subject in certain cases of anaemia. The necessity arose to carry out balance experiments in such cases i.e.to compare the excretion of iron in the faeces and urine with the intake in the diet and the administration of iron ammonium citrate. Since the absorption of iron even with such large doses is small a number of problems arose. URINE-It has been shown that the iron content of the urine is negligible except in all but a few con-ditions and even in these the amounts excreted are minute cf. T0mpsett.l The following are typical results: Normal . . . . <0.01 mg. of Fe per litre Haemochromatosis . . 0.16 , ,* ,, Pernicious anaemia . . . . 0.19 1.28 mg. of Fe per litre Nephritis with gross albuminuria . . 1.72 2.33 , 1 I DIETS-A normal diet contains approximately 10-15mg. of iron per day. FAECES-~ornlal faeces contains approximately 10-15 mg. of iron per day.The estimation of such amounts is achieved by colorimetric meth0ds.l The estimation of such amounts is achieved by colorimetric methods.' When however large amounts of iron have been ingested and since the greater part of this appears in the faeces it is obvious that such colorimetric methods are inapplicable if accurate results are required. A gravimetric method in which the iron is pre-cipitated as a complex with cupferron and is subsequently converted into and estimated as Fe,O has proved to be satisfactory. Faeces is a heterogeneous mixture and contains a considerable amount of calcium phosphate. In respect of this cupferron has an advantage since it can precipitate iron from acid solution. Finally the ash is moistened with nitric acid and re-ignited.The ash is dissolved in 20% hydrochloric acid and the solution made up to a definite volume. A portion of the solution containing 0.1 to 0.3 g. of iron is taken for analysis and diluted to 150ml. with 20% hydrochloric acid. A fresh 6% aqueous solution of cupferron is then added with constant stirring until the formation of a white precipitate of nitroso-phenylhydroxylamine indicates that excess has been added. The precipitate is filtered through a No. 42 Whatman filter-paper washed first with 20% hydrochloric acid and finally with 20% ammonia. The filter paper and precipitate are then dried and ignited in a platinum dish. The ash content Method-A weighed amount of dried faeces is ashed in a silica dish. The resultant ignited precipitate is weighed as Fe,O, 232 NOTES of the filter paper is allowed for.dried faeces and completing the determination. The method was checked by adding known amounts of an iron salt to The following are typical results : Iron (Fe,O,) added g. . . 0.0500 0.1000 0.1500 0.2000 0.2500 0.3000 0-4000 )) (Fe,O,) recovered g. . . 0.0505 0-1003 0.1502 0.2001 0.2503 0.3003 0.4005 Although certain other metals e.g. titanium are precipitated by cupferron accuracy in determining the amount of iron absorbed is not impaired. Titanium occurs in diets and faeces in traces and since in balance experiments patients are placed on a constant daily diet the daily intake of titanium is unchanged. REFERENCE 1. Tonipsett S. L. Biochem. J. 1934 28 1536. BIOCHEMICAL DEPARTMENT ROYAL INFIRMARY GLASGOW S. L. TOMPSETT February 1946 DETECTION OF MANGANESE WITH AURINTRICARBOXYLIC ACID THE ammonium salt of aurintricarboxylic acid gives bright red lakes with various metals e.g.with aluminium, beryllium yttrium lanthanum cerium neodymium erbium zirconium and thorium. All these except the lakes of beryllium and aluminum are dissolved or decolorized by addition of a moderate excess of am-monium carbonate. The substance is considered a very sensitive reagent for aluminium when applied to precipitated aluminum hydroxide. The latter forms with it in acetate solution a bright red precipitate which persists after a mixture of ammonia and ammonium carbonate has been added. In pursuing some investigations with this reagent we found that it forms with manganese a compound of a deep violet colour very easily produced and much more characteristic than that with aluminium.The manganese salt is treated with ammonia which produces a slight precipitate. The latter is dissolved in a slight excess of acetic acid and an aqueous solution of the ammonium salt of aurintricarboxylic acid is added. I t separates even when manganese ions are present a t considerable dilution; 0.25 mg. of manganese could be detected in 1 ml. of solution. The violet pre-cipitate is stable in presence of small quantities of ammonium carbonate. A greater excess of this reagent does not dissolve it but turns it red and microcrystalline. Ammonia and sodium hydroxide produce the same change. The violet precipitate dissolves in dilute hydrochloric acid and tartaric acid but is stable in presence of acetic acid alcohol or ether.For the purpose of investigating whether other metal ions give a similar reaction with aurintricarboxylic acid or interfere with the reaction of the manganese ion we treated the acetates of different ions with the reagent and state the result in the following table: Immediately the violet compound separates. P b Cr , , 9 s , , , Fe , ,. I , 9 I Sn 9 I 1 I $ 9 9 1 Cu forms red colour; , , 1 ,I Zn no reaction; 11 J I I , Hg , I J S t ,* co , f , I 9 . ,, Mg 8 I ? P I ? ,. ,, Ni , , I I I ,? Bi , , 9 * I I , Ag , 3 t I . I 5 1 , no reaction; does not interfere with manganese reaction Au Sr MOO oxide insoluble in actic acid wo3 P I I I * I 1 1 Pd no reaction Ru , ,, UO, A1 , , insoluble in ammonium carbonate oxide insoluble in acetic acid no reaction; does not interfere with manganese reaction Rh 8 J S red precipitate which dissolves in ammonium carbonate For the detection of manganese in minerals that have been fused with alkali carbonates a portion of the acid filtrate from the silica is neutralised with ammonia and then acidified with acetic acid and the reagent is added.The presence of aluminum does not interfere; it is however optional to follow the routine practice of separation of Al Zn Cr ions from Fe Co Ni and Mn. The violet compound when dried was found to contain 24.5% of manganese. METHOD OF TEST-TO a few ml. of the test solution ammonia is carefully added until a slight precipitate appears. This is dissolved in a small excess of acetic acid until the solution appears clear again.There-upon a O-lyo solution of the ammonium salt of aurintricarboxylic acid is added. In a short time when manganese is present the violet precipitate appears or if the quantity of manganese present is very small the solution acquires a violet colour easily to be distinguished from the colour given by aluminium or the rare elements mentioned. REFERENCE Treadwell and Hall “Qualitative Analysis,” New York 1937 page 191. DEPARTMENT O F CHEMISTRY INTER-AMERICAN UNIVERSITY PANAMA L. S. MALOWAN March 194 NOTES 233 A NOTE ON THE DETERMINATION OF NITROGEN IN FOODSTUFFS BY THE K JELDAHL METHOD DIGESTION CONDITIONS THE Kjeldahl method for the deterniination of nitrogen has been the subject of a voluminous literature, and there have been many improvements on the original formula of Kjeldahll using potassium permanganate and sulphuric acid.Gunning’s modification3 has been generally adopted in some form or other being essentially the raising of the boiling point of the sulphuric acid by sodium or potassium sulphate. Potassium permanganate was omitted. Arnold‘ introduced the heavy metal catalysts (mercury copper) and raised the sodium sulphate concentration to a value (15-30 g. Na,SO to 3 6 5 0 ml. H,SO,) which had it been generally accepted would have enhanced the accuracy of the method. Phelps and Daudt? using mercuric oxide as catalyst laid down a digestion time of 24 hours with log. of sodium sulphate to 25ml. of sulphuric acid for the complete recovery as ammonia of the nitrogen of pyridine zinc chloride.The Official British Method in the Fertilisers and Feeding Stuffs Act of 1926 copied in numerous textbooks requires 10 g. of sodium sulphate to 25 ml. of sulphuric acid to be heated for 1 hour after clearing. The A.O.A.C. offers various fcrmulae in which the sodium sulphate concentration may be zero log. to 15-25 ml. of sulphuric acid or 15-18 g. to 25 ml. of sulphuric acid. The time is rarely laid down but is usually given as “some time after clearing,” or “1 hour after clearing.” Normal laboratory practice assumes that complete digestion will have taken place within 2$ hours though much shorter times are not infrequent. Recent work (Chibnall Rees and Williams,6 Shirley and Becker,‘ Miller and Houghton8) has thrown doubt on the accuracy of the method as thus standardised.There is evidence to show that the heterocyclic compounds present in the proteins and possibly those produced by condensation in the early stages of digestion require much longer times for complete breakdown. The experiments here described were undertaken to establish the relationship between sodium sulphate concentration (conditioning temperature) and digestion time on the one hand and nitrogen recovery from typical foodstuffs on the other. ExPERIMENTAL-Tests showed that over a wide range results were independent of catalyst concea-tration though as there was some evidence of nitrogen loss in very protracted (12 hr.) digestions with mercury copper sulphate was used throughout. Sufficient of the test material to yield some 25 mg. of nitrogen 12.5 ml.of sulphuric acid and 0-2 g. of copper sulphate were digested in 300 ml. Kjeldahl flasks with different quantities of sodium sulphate and for different times. In general the solution was “clear,” Z.C. pale blue after 5 6 6 0 minutes. The length of time for complete nitrogen recovery was not affected by variations in the clearing time. It is therefore important that a total digestion time should be specified rather than a time after clearing. Ammonia was liberated by addition of 40ml. of 40y0 sodium hydroxide solution and distilled into 25 ml. of N/10 sulphuric acid the excess of which was titrated with C0,-free sodium hydroxide solution, using as indicator methyl red masked by methylene blue (de Wesselow’s). The vertical axis gives nitrogen found, expressed as a percentage of the maximum (asymptotic) value.The four curves indicate the effect of four different concentrations of sodium sulphate (expressed as grams per 100 ml. of sulphuric acid). Bosshard added fuming sulphuric acid or phosphoric acid. The graph shows a series of determinations made on flour. The horizontal axis is time in hours. Similar results were obtained on soya flour milk powder and desiccated yeast. The conditions laid clown in the standard methods represented as they are by the area between the vertical lines A and B on the graph may give recoveries ranging between 96% and 100%. Moreover as it is not uncommon for directions to allow latitude in the amount of sodium sulphate used and in the digestion time determinations following such directions may be subject to a varying error.The high concentrations of sodium sulphate which reduce digestion time to 3 hours cause depositio 234 NOTES of sooty materials in the neck of the flask and in the fume extractors. by the findings are therefore: The optimum conditions suggested Sodium sulphate 40g. per 100ml. of sulphuric acid Copper , 1-6 g. , 1 I 9 , Total digestion time 6 hours. REFERENCES 1. 2. Bosshard E. Id. 1885 24 199. 3. 4. 6. 6. 7. 8. Kjeldahl J. 2. Anal. Chem. 1853 22 375. Gunning J. W. Nedevl. Tydschv. v. Phavm. Feb. 1889. Arnold C. 2. anal. Chem. 1892 31 525. Phelps I. K. and Daudt H. W. J. Assoc. Off. Agv. Chenz. 1919 3 218. Chibnall A. C. Rees M. W. and William E. I. Biochem. J. 1943 37 354. Shirley R. L. and Becker W.W. Ind. Eng. Chem. Anal. Ed. 1945 17 437. Miller L. and Houghton J. A. J. Biol. Chem. 1945 159 373. WAR DEPARTMENT LABORATORY No. 2 SUPPLY RESERVE DEPOT BARRY DOCKS GLAMORGAN R. S . ALCOCK January 1946 A CARBONATE ESTIMATION APPARATUS ALTHOUGH many forms of apparatus are available for the estimation of carbonates by the indirect method, the majority including the familiar Rohrbeck Geissler and Schrodter types are top-heavy owing to the disposition of the acid container and the drying unit above the reaction chamber. They have moreover, an extensive external surface which has to be dried very carefully before weighing. The apparatus described below has been designed to minimise these disadvantages and to satisfy as far as is practicable the following requirements (1) the centre of gravity of the system to be low ; (2) the apparatus to have a small superficial area; (3) the shape of the vessel to allow of quick drying of the external surfaces.The decomposition vessel A (Fig. 1) is a conical flask (capacity about 150c.c.) with a ground neck (2-5.cm. diameter) into which fits the combined drying unit and acid container B. The lower part of the drying unit is provided with an inner tube C which is sufficiently wide to take care of any accidental suck-back of the drying liquid. The acid container D is in the form of a pipette with its lower end tapering to a fine jet E and its upper end carrying a small stopcock F. The upper parts of the drying unit and acid container are provided with ground caps G and H respectively.I Fig. 1. L---J Fig. 2. The drying unit is charged by introducing a suitable quantity of concentrated sulphuric acid through a small funnel inserted into G and the acid container is filled by immersing the jet in diluted hydrochloric acid (1 + 1) and applying suction at H. A known weight of the carbonate is introduced into the flask and the material is covered with water. After inserting the unit B the apparatus is carefully wiped dry and weighed. The carbonate is decomposed by running in the acid a t a rate which may be controlled by manipulating the stopcock F. When the reaction is complete dissolved carbon dioxide is removed fro NOTES 235 the solution by warming and shaking the flask while a stream of air is led through the apparatus. After cooling the flask to ordinary temperature the caps G and H are replaccd and the apparatus is dried and weighed in accordance with the usual procedure.A simple form of the apparatus in which the drying unit and acid container are separately sealed to the stopper of the reaction flask is shown in Fig. 2. Both forms of apparatus are robust and more easily cleaned than the ordinary types. UNIVERSITY COLLEGE CARDIFF S. T. BOWDEN February 1946 THE DETERMINATION OF LIME IN REFRACTORY DEAD-BURNED MAGNESIA THE oxalate - permanganate procedure commonly used ior separating calcium from magnesium involves treating a hot hydrochloric acid solution with ammonium oxalate and making just alkaline to methyl red with ammonia. When the ratio of calcium to magnesium is very small the separation is unsatisfactory unless a very large excess of ammonium oxalate is used to keep magnesium in solution and ensure quanti-tative precipitation of calcium oxalate.' It is apparently generally accepted that the solution from which precipitation takes place should not contain cations other than those of calcium magnesium and the alkali metals and that iron and aluminium if present should be removed by preliminary double precipitations with ammonia.Alternative procedures are available however which avoid removal of iron and aluminium by precipitating calcium oxalate in slightly acid solution2 a t pH 3-4 ; but under these conditions precipitation of small amounts of calcium may be incomplete. Hillebrand and Lundell state3 that although iron is quantitatively precipitated by oxalate in ammoniacal solution more or less of the precipitate is dissolved if washed with cold ammonium oxalate solution They also state that aluminium when alone is not precipitated by oxalate in ammoniacal solution.According to McAlpine and Soule,* ferric iron is not precipitated by oxalates except as reduction to ferrous iron takes place and oxalates do not precipitate aluminium. It would appear then that in the usual separation of calciuni from magnesium prior removal of ferric iron and aluminium is unnecessary unless they are present in relatively large proportion. Moreover since the removal of iron and aluminium involves increasing the ammonium chloride content and since a large amount of this has the effect of retarding the precipitation of calcium oxalate the procedure as well as being time-consuming may be actually harmful, Precipitation of calcium oxalate without removal of iron and aluminium has been successfully applied by us to the analysis of dead-burned sea-water magnesia a material of the following average composition : MgO 90-93% CaO 2-5% Fe,O 1.57/, A1,0 1-5% SiO 2% Mn 0.1%.The method adopted which utilises precipitation in the normal way a t a pH of about 6 but using a large excess of ammonium oxalate, was developed and tested on synthetic solutions corresponding to magnesias of different lime contents (1-4%). These solutions contained NaCl 11 g. Fe,O 0.0297 g. A1,0 0.0318 g. MgO 0.9627 g. CaO 0-01-0.04 g. The iron aluminium magnesium and calcium here expressed as oxides were added in the form of soluble salts of analytical reagent quality.The sodium chioride added also of analytical reagent quality corresponded in amount to that arising from fusion of refractory magnesia material with sodium carbonate followed by solution in dilute hydrochloric acid. Fusion with sodium carbonate is a necessary preliminary to any analytical separations on this type of magnesia owing to the presence of acid-insoluble silicates. It was found that precipitation of calcium oxalate in presence of iron and aluminium yielded results as correct as those obtained with solutions from which iron and aluminium had been removed. When less than 0.03 g. of lime was present the amounts found were low but with this and greater quantities the average recovery was over 98%. Experimental details of the method follow.Procedure-Grind the sample to pass B.S. Mesh No. 200 sieve and fuse 1 g. with 10 g. of sodium carbonate. Dissolve the cooled melt in dilute hydrochloric acid containing 35 ml. of the concentrated acid and boil with a few drops of concentrated nitric acid to oxidise any ferrous iron. Add 20-25 g. of ammonium oxalate and dissolve with stirring. Precipitate calcium oxalate by dropwise addition of concentrated amnonia solution until the colour changes to yellow and allow to stand in a warm place for 30 to 60 minutes. Then filter through a No. 30 Whatman paper and wash thoroughly with cold 0.1% ammonium oxalate solution. Dissolve the precipitate with hot dilute hydrochloric acid containing 10 ml. of the concentrated acid and wash the paper thoroughly with hot diluted hydrochloric acid (1 in 100).Add 25 ml. of saturated ammonium oxalate solution dilute to 250 ml. heat to boiling and precipitate calcium oxalate as above. Allow to stand in a warm place for 60-120 minutes. Then filter wash thoroughly with cold water and finally titrate with N/10 permanganate according to the recognised procedure. Results are compared below with those obtained here by the usual method which involves double pre-cipitations of ferric oxide and alumina by ammonia before twice precipitating calcium oxalate as described. The same figures within the limits of experimental error are given by both procedures. Add methyl red solution dilute to 350 ml. and heat to about 90" C. % CaO % CaO Sample Fe,03 and A1,03 removed Proposed method 1 4.14 4.18 4.09 4.14 2 5.14 5.21 5.12 5.20 3 5.06 5.11 5.05 5.14 4 4-90 4.97 4.93 4-98 6 4.67 4-73 4.62 4.69 6 4-99 5.04 4.96 4.98 7 4.51 4-54 4-51 4.62 8 4.63 4.67 4.53 4.5 236 NOTES As previously mentioned when the magnesia contains less than 3% of lime the figures obtained are low.In such cases it is useful for routine work to increase the lime content artificially by adding known amounts of standard calcium chloride solution although this procedure is analytically unsound. We thank the Directors of the British Periclase Co. for permission to publish this note. RRFERENCES 1. 2. 3. 4. Bobtelsky &I. and Malkowa-Janowski 2. utgew. Chem. 1927,40 1436. Hoffmann J. I. and Lundell G. E. F. J . Res. Natl. Bur. Stundards,l938 20 607; Lingane J.I., Hillebrand and Lundell “Applied inorganic Analysis,” 1929 p. 494. McAlpine and Soule “Quantitatave Chemical Analysis,” 1933 p. 318. Ind. Eng. Chesn. Ana2. Ed. 1945 17 39. PALLISER WORKS HARTLEPOOL Co. DURHAM F. C . GILBERT W. C. GILPIN January 1946 THE EFFICIENCY OF DESICCANTS SEVERAL investigators1 have published figures for the comparative efficiencies of various desiccants the latest and most complete being due to Bower.z His method of establishing these relationships was to pass moist air through U-tubes containing the various desiccants arranged in progressive order of efficiency. The efficiency of any particular desiccant is expressed as the number of mg. of water vapour remaining in 1 litre of air after passing through that desiccant. The purpose of this note is to demonstrate that conclusions can be drawn from Bower’s table which if put in practice can give rise to serious errors in gravimetric analysis..4t least one modern text-book which has achieved some popularity in this country quotes a portion of Bower’s table and then proceeds to point out that alnmina and lime when used as weighing forms, should never be cooled over calcium chloride-which has a lower efficiency according to Bower-but always over a desiccant of higher efficiency such as magnesium perchlorate or barium oxide. These instructions might be accepiablc if it had been added that the crucible contailling the residue should be covered even whilst in the desiccator. This important injunction is stressed in text-books written by such authorities as Lundell Hoffman and Bright,s and Kolthoff and Sandell,’ who also recommend re-ignition and re-weighing with the weights from the earlier weighing still set on the balance-pan.Since the impression is given in the instructions referred to above that hygroscopic residues will remain dry whilst being cooled providing a desiccant of greater efficiency is used in the desiccator it is necessary to emphasise that Bower’s figures can only be a very rough guide as regards desiccants used in a desiccator. Their main value lies in assessing the relative merits of desiccants used in drying-trains where the con-ditions are similar to those under which the figures were obtained. G. F. Smith5 was unable to dehydrate magnesium perchlorate dihydrate by exposing it to either barium oxide or phosphorus pentoxide in a desiccator, although the relative efficiencies are as follows : The conditions in desiccators are very different.Mg. Gf water remaining in 1 litre of air L4nhydrous magnesium perchlorate 0.002, Phosphorus pentoxide . . 0*00025, Barium oxide . . 0.00065, Some further results quoted by Morton7 are also of interest in this connection. Hydrated copper sulphate was placed in desiccators over alumina phosphorus pentoside or calcium chloride. The amounts of water removed by these three desiccants respectively were 42.8%. 41.5% and 40.0% of the total. In a second series of tests which included barium and magnesiiim perchlorates activated alumina proved to be the most efficient desiccant ; the perchlorates were the poorest.Similar tests were carried out using coffee and flour. Morton also quotes results obtained by another method of comparing efficiencies. Catalysts for the conversion of carbon monoxide to carbon dioxide are affected by water. Hence the amount of conversion to the dioxide after passing through a particular desiccant gives a measure of the water vapour present. The first four in order of efficiency were activated alumina magnesium perchlorate calcium chloride and barium oxide. Calcium chloride and activated alumina have efficiencies of 0.36 and 0-006* respectively according to Bower; the efficiencies of the others are recorded above. Although the method of drying in these tests was similar to that of Bower insofar as the moist air was passed through the desiccant, the rate of flow was 200 litres per hr.whereas Bower used a rate of flow of 1-5 litres per hr. It will be seen that there is little similarity between the orders of efficiency. From these results it is evident that when choosing a desiccant for a particular purpose any table of desiccant efficiencies is only of real use if the experimental conditions under which the results were obtained w e sinzilar to those for which the desiccant i s required. Some convincing figures which demonstrate the inefficiency of desiccators have been supplied by Booth and McIntyre.8 They measured the fall in vapour pressure after admitting air saturated with water-vapour into a desiccator. Several desiccants were tested and the fall in vapour pressure was plotted against time. Their results showed that even after 60 min.there was still an appreciable amount of unabsorbed water-vapour present. These investigators point out that if on removing the lid from the desiccator half of the volume of contained air were replaced by atmospheric air the partial pressure of the water-vapour would only fall by 2 mm. in 10 min. Since a crucible would not be left to cool for much longer than this a hygroscopic residue could absorb an appreciable amount of water. It might also be pointed - * This figure has recently been revised by Bower and is now reported as 0.001 NOTES 237 out that this could not be remedied by leaving the residue in the desiccator for such time as is necessary for the desiccator atmosphere to become dry. Once the residue has absorbed water i t may not relinquish it to a more efficient desiccant even after long exposure to it in a desiccator.This phenomenon is ex-emplified by G. F. Smith’s results (supra) when he attempted to dehydrate magnesium perchlorate dihydrate by means of phosphorus pentoxide. The procedure recommended by Lundell Hoffman and Bright and by Kolthoff and Sandell (Zoc. cit.), namely to provide the crucible with a well-fitting cover to weigh as soon as cool to re-ignite re-cool and rc-weigh with the weights set on the pan should reduce these errors to negligible proportions. Axio-matically it might be added that if the residue has to be left for some time before it can be weighed it should be re-ignited before weighing. These rules are more important than the choosing of a desiccant of high efficiency or even using a desiccator at all.REFERENCES 1. 2. 3. 4. 6. 6. 7. 8. Mellor J. W. “A Treatise ole Quantitative InovgaTaic AnaZysks,” Charles Griffin & Co. Ltd. 1913, Bower J. H. Bur. of Stands. J . Res. 1934 12 241; 1944 33 199. Lundell Hoffman and Bright “The Chemical Analysis of Iron and SteeZ,” John Wiley & Sons Inc., Kolthoff and Sandell “Text Book of Quantitative Inorganic Analysis,” Macmillan & Co. New Smith G. F. “Dehydration Studies,” G. Frederick Smith Chemical Co. Monograph. Morley E. W. J . Amer. Chem. SOC. 1904 26 1171. Morton A. A. “Labomtovy Technique in Organic Chemistry,” McGraw-Hill Book Co. Inc. 1938, Booth H. S. and McIntyre L. Ind. Eng. C h e w Anal. Ed. 1930 8 148. p. 118. 1937 pp. 91-92. York 1943.Chapter I. DEFT. OF FUEL TECHNOLOGY THE UNIVERSITY SHEFFIELD RONALD BELCHER Januavy 1946 THE CONTINUOUS PRODUCTION OF DOUBLY DISTILLED WATER THE apparatus shown in Fig. l(a) affords a continuous supply of high-quality doubly distilled water. Apart from the reservoir and float system standard parts with interchangeable ground glass joints are (a) Fig. 1. employed. water nor the final distillate suffers contamination. Surfaces exposed to water are of Pyrex glass and platinum so that neither the excess of fee& Clock-glass G prevents entry of dust and fumes 238 NOTES A rapid stream of distilled water from a steam oven still or other source maintains a constant head in reservoir A the excess overflowing and being suitably collected. Immersed in the liquid is a light float B, 35 mm.in diameter. into the bottom cjf which is sealed a small loop of platinum wire. Valve rod C is 3 mm. in diameter and carries at its upper end a small hook of platinum wire which engages with the loop on the float. Valve D a sphere 7 mm. in diameter formed upon the valve ro3 is ground into the extremity of the reservoir stem. Control float E. 24 mm. Details of the float assembly are shown in Fig. 1 (b). _-a .-Fig. 2. in diametkr is sealed to the lower end of C. The-depth of water maintained in flask F is determined by the position of float E with respect to the bottom of the flask when the valve is closed. To adjust the buoyancy clamp the reservoir vertically and assemble the float system. Lift the latter to close the valve and fill the reservoir with water.The valve should now remain closed without leak. Introduce mercury or lead shot into float B until the valve first commences to leak and then opens to about 4 mm. Raise a beaker containing water until the surface of the latter touches float E. On raising the beaker a further 5 mm. the valve should close completely. Kemove float B and close the tip of the tube surmounting it. Introduce distilled water into the flask to a little below the working level. Assemble the apparatus and pour a rapid stream of distilled water into the reservoir until over-flow occurs. The level in the flask should now rise to its working position and the valve should close. Having started the steam still redistillation is commenced by suitably heat-ing the flask.If the valve is satisfactorily ground in its leakage is very slight. However if the apparatus is out of use for several days the reservoir may empty itself into the flask. In such an event distilled water is poured rapidly into the reservoir until the float system rises. As distillation is proceeded with, the level in the flask rapidly corrects itself. A simple modification shown in Fig. 2 is useful for the production of distilled water when the usual source is out of action. The reservoir is an inverted boiling tube in which a small hole is blown near the closed end. An overflow device fed from the condenser jacket maintains a constant head of warm water in the reservoir. The float assembly resembles that of Fig. 1 but the upper float is a cylinder of sound cork which slides stiffly upon the float rod.Dimensions niay be adjusted to suit any type or capacity of flask. For rapid distillation a l-litre Pyrex conical flask is particularly suitable. This is heated directly with a large burner the asbestos ring preventing the flame from rising above the water level and hence cracking the flask. The float system should be set to maintain the level a t about 2 cm. Under these condition< vigorous boiling with the minimum of spurting is achieved. FULLER'S LTD. HAMMERSMITH LONDON W.6 J. T. STOCK M. A. FILL February 26th 1946 A THERMOSTATICALLY-CONTROLLED LOW TEMPERATURE BATH THE bath described below was developed for the routine examination of alcoholic liquors such as alcoholic flavouring essences wines spirits etc.on which determinations of specific gravity a t 15.5" C. are required. Any predetermined temperature down to about 10' C. below room temperature may be maintained auto-matically so that the device is of general use. As in the well-established apparatus for the cryoscopic examination of milk,l cooling is effected by the evaporation of ether in a current of air. The rate of evapora-tion and hence the cooling effect is however regulated by controlling the air stream. It is lagged with a 2-cm. layer of cotton wool a tinplate canister serving as an outer jacket. The cooler A is a 160 mm. x 28 mm. boiling tube which is fed from ether reservoir B by way of valve C so that the volume of ether in A is maintained a t approximately 35 ml. This is operated by the unit originally devised for micro-stirring the power available being ample.Air is drawn into the cooler through tube E and leaves through F after bubbling through the ether. The toluene - mercury regulator G is of the gas-controlling type but has an additional side tube H which is connected to a water jet pump. Alternatively the pump may be connected to the branch of a T-piece inserted into tube F. Operation is as follows. At room temperature the drawn-out extremity of tube J dips beneath the surface of the mercury in the regulator stem. The speed of the pump is then adjusted so that air is drawn The bath shown in Fig. 1 is a beaker containing 2 litres of water. Surrounding the cooler is corrugated ring stirrer D. No alteration to the regulator is then required NOTES 239 through the ether in A a t about 150 bubbles per min.fine adjustment being made by a screw clip upon tube F. A path of low resistance thus being opened air is now drawn in preferentially through J so that bubbling in A becomes slow or ceases altogether. As the temperature of the bath rises J is closed by the rising of the mercury column causing the air stream to be drawn through the ether again. The temperature a t which the bath operates thus depends upon the setting of the thermoregulator. As the bath cools the level in the regulator stem falls until the tip of J is uncovered, J * . .'.;.'*. . . a ' . . . . . . - . . . . * * . . * t d 2 * < . a b . .* e . 8 ' b l . . Fig. 1. Fig. 2. In early experiments with the apparatus attempts were made to control valve C by means of a single float K.The addition of a second smaller float L provides a steady upthrust which almost compensates for the weight of the valve system. Details of the valve assembly are shown at (a) in Fig. 1. Valve C is a 7-mm. sphere formed on the 3-mm. glass stem and is lightly ground into guide M the ends of which are constricted to 4 mm. bore. The rate of bubbling should be reasonably steady. A simple constant-head device applied to the pump as shown in Fig. 2 enables good results to be obtained with widely-fluctuating mains pressures. On adjusting the regulator to maintain bath temperatures of 1 5 O and 10" C. respectively the maximum variations during daily runs were found to be f 0.06" and f 0.09" C.respectively. During the observations the laboratory temperature varied from 16" to 23°C. Owing to agitation caused by bubbling very poor results were obtained. This allows float K to maintain satisfactory control of the ether level in A. Both floats are of sound cork and slide stiffly upon the stem 240 ABSTRACTS OF CHEMICAL PAPERS The rates of consumption of ether are shown in Fig. 3 which also indicates the time required to attain a desired bath temperature (initially 2OOC.) with the gentle suction rrivinrr the most sensitive control. 2 4 6 XME hr. Fig. 3. REFERENCES Obviougly i r i s desirable to pre-cool the bath to within a degree or so of the desired temperature e.g. by adding ice. Alter-natively the rate of cooling may be greatly increased by temporarily using greater suction. As is clear from Fig. 3, only a small amount of ether (80 to 250 ml. per normal working day) is required to maintain the desired temperature. It is preferable to use dry ether but the device works quite satisfactorily both with mix-tures of ether and light petroleum recovered from fat extractions and with wet ether. Despite the small size of the cooling unit, it can be used to control a much larger bath than that described provided that the operating temperature is not more than a few degrees below that of the laboratory. Thus a well-stirred bath con-taining 3gal. of water was maintained without difficulty at 15" f 0.05"C. In such cases it is of course necessary to pre-cool the bath to its working temper-ature; otherwise wastage of time and of ether is excessive. 1. 2. Monier-Williams G. W. ANALYST 1933 58 254 and references cited. Fill M. A. and Stock J. T. I d . 1944 69 212. FULLER'S LTD. HAMMERSMITH m7.6 J. T. STOCK M. A. FILL January 12th 194

ISSN:0003-2654    

DOI:10.1039/AN9467100227

出版商:RSC    

年代:1946

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9467100240

出版商:RSC    

年代:1946

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9467100241

出版商:RSC    

年代:1946

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9467100247

出版商:RSC    

年代:1946

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9467100248

出版商:RSC    

年代:1946

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9467100249

出版商:RSC    

年代:1946

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9467100250

出版商:RSC    

年代:1946

数据来源: RSC