ISSN:0003-2654    

DOI:10.1039/AN94570FP013

出版商:RSC    

年代:1945

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94570BP015

出版商:RSC    

年代:1945

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94570FX025

出版商:RSC    

年代:1945

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94570BX027

出版商:RSC    

年代:1945

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/AN9457000231

出版商:RSC    

年代:1945

数据来源: RSC

摘要:

232 STRAFFOKD LVYATT AND KEKSHAW A SCHEME FOR THE PHOTOMETRIC A Scheme for the Photometric Determination of Minute Amounts of Arsenic Copper Lead Zinc and Iron (with Certain Other Metals) in Organic Compounds e.g. Medicinals BY N. STRAFFORD P. F. WYATT AND F. G. KERSHAW (Read at a meeting of the Microchemistry Group on January 23 1945) INTRODUCTION-Several good methods exist for the determination of minute amounts of metallic impurities more particularly arsenic,l lead2 and ~ o p p e r ~ with certain other metals, in organic compounds and much study has already been devoted to the application of such methods to rapid routine work. Under pressure of war-time demands however these methods proved still much too tedious for routine testing of certain classes of compounds, e.g.medicinals in a busy laboratory. Thus using the Metallic Impurities Committee’s methods,1$2B5 one senior assistant with hard working could test only about 12 samples per week tor arsenic lead and copper together with determinations of zinc and iron by other methods. The problem as it affected us had been partly met by the use of the emission spectrograph,4 but the method has several limitations (1) direct arcing of the organic substance is quite useless preliminary wet oxidation being found essential (2) concentration on cadmium sulphide as carrier is required in order to obtain the necessary sensitivity for arsenic (3) iron and zinc have to be determined by additional tests (colorimetric and turbidimetric respec-tively). The main application of the method was as a limit testhfor very small amounts of arsenic lead and copper (As,O3 up to 1 p.p.m.Pb and Cu up to 5 p.p.rn. each) and it could not be recommended for the accurate determination of greater amounts in experimental samples. Thus although by the use of the method it was found possible to increase the output to about 20 samples per week the attendant difficulties led to a search for a more versatile method of high sensitivity and precision which would enable all the required determinations to be made successively on a single portion of the sample with reasonable speed. The main scheme of analysis presented in this paper was therefore designed to enable photometric determinations of the five elements arsenic copper lead zinc and iron to be carried out successively on a single 2-g sample of the organic material.It has been devised specially for medicinal products with a very low metal specification limit but is readily adaptable to materials with a less rigid “heavy metals’’ specification. I t should also be applicable to other organic materials such as foodstuffs and biological samples DETERMINATION OF MINUTE AMOUNTS OF ARSENIC COPPER LEAD ZINC AND IRON 233 By carrying the tests through in batches of 8 (7 samples and a reagent blank) one assistant is able to analyse more than 20 samples per week for the 5 elements named or up to 30 samples if zinc is omitted. The necessary precise separation of the individual elements is achieved by solvent ex-traction of the metals in the form of metallo-organic complexes and the final determinations are carried out photometrically by means of the Spekker photoelectric absorptiometer.In particular a new solvent extraction procedure for arsenic which avoids the usual more tedious separation by distillation as arsenious chloride followed by evolution as arsine, has been devised. The standard Spekker equipment which employs a needle galvanometer in conjunction with a tungsten filament lamp and glass colour-filters has been preferred to that which incorporates a more sensitive mirror galvanometer and the more selective Ilford gelatin filters. The first-named more robust type of equipment is better adapted to hard routine use and for the purpose of the present (main) scheme is quite adequate. The main scheme of analysis for determination of the five elements copper arsenic, lead zinc and iron is shown diagrammatically below.Possible interferences with the types of organic compounds considered are very few and unimportant but an extension of the main scheme which overcomes these interferences and provides for determinations of bismuth, nickel and cadmium if present is also described later. I. MAIN SCHEME OF ANALYSIS I Wet decomposition-Decompose a 2-g sample in a modified 100-ml Kjeldahl flask with sulphuric, nitric and perchloric acids. Extraction of Copper and Arsenic Dilute the soln. and add hydrochloric acid to give minimum HCl concn. of 2 N (to prevent extraction Reduce arsenic to As111 with sodium iodide and sodium metabisulyhite and extract arsenic and of lead). copper with diethylammonium diethyldithiocarbamate in chloroform.I chloride and determine the op-tical density of the resulting “molybdenum-blue” soln 234 STRAFFORD WYATT AND KERSHAW A SCHEME FOR. THE PHOTOMETRIC as “carbamate” extraction reagent. Prepare the stock soln. once a week and the dilute soln. daily. Dissolve approx. 15 mg of diphenylthiocarbazone (dithizone) B.D.H. in 50 ml of redistilled toluene and shake vigorously in a 100-ml separating funnel with 50 ml of water containing 2 ml of ammonium hydroxide (reagent 2). Reject the toluene layer slightly acidify the aqueous layer with hydrochloric acid 5 N and extract with two 50-ml portions of redistilled toluene. Reject the aqueous layer combine the toluene extracts and wash with two 10-ml portions of water. Prepare this soln. freshly each day as required.Prepare as ( a ) but substitute chloroform B.P. redistilled for toluene throughout. (6) Sodium citrate s o h approx. 1 M-Dissolve 150 g of trisodium citrate (AnalaR) in water add 0.5 ml of conc. ammonium hydroxide dilute to 500 ml and shake thoroughly with 25-ml portions of dithizone soln. (0-0270 B.D.H. reagent in chloroform) until the last extract remains green and the aqueous layer becomes slightly yellow. Then add 5 ml of ZOyo AnalaR citric acid soln. and extract with 25-ml portions of chloroform until colourless. (7) Potassium cyanide soln., approx. 1.5 M-Dissolve 50 g of potassium cyanide AnalaR in the minimum amount of water dilute to 100 ml and repeatedly extract with 10-ml portions of dithizone soln. (0.02% B.D.H. reagent in chloroform) until the last extract remains green and the aqueous layer is tinged yellow.Extract the excess of dithizone with 10-ml portions of chloroform and dilute the extracted cyanide soln. to 500 ml with water. Provided that AnalaR cyanide is used the reagent is suitable for use for at least 6 months after preparation. (8) Iodide sol~z. 20~o-Dis-solve 20 g of pure sodium or potassium iodide in 100 ml of water add 0-2 ml of ammonium hydroxide soln. and extract with 10 ml of carbamate extraction reagent (reagent 4b) shaking for 30 sec. Reject the chloroform layer and wash with two 5 ml portions of chloroform. (9) Acid molybdate soh-Mix exactly 250 ml of dilute sulphuric acid 11 N (accurately standardised), (5) Dithizone so1ns.-(a) Approx. O-O08~o in toluene. (b) Approx.O-OOS% in chloroform. Fig. 1. Condenser-24 in. diam. Acid fume condenser and modified Kjeldahl flask. Orifices-1 in. diam. ; 44 in. betxveen centres. Flask-100 ml bulb capacity. Extension to neck 9 in. to 6 in. external diam. with 250 ml of ammonium molybdate soln. 70,k in water. Filter into a litre measuring flask, wash with water add exactly 250 ml of dil. perchloric acid 3 11; (accurately standardised), to the filtrate and dilute t o 1 litre at 20” C. with water. (Five ml of this solution should require 17.5 ml of 1%’ sodium hydroxide when titrated to methyl red indicator.) (10) Sodium metabisulphite soln.-5y0 in water filtered. (1 1) Pilute stannous chloride soln. 0-4%-Dilute 1-0 ml of stannous chloride soln. 20:4 w/v in conc. HC1 to 50 ml with water. Prepare the dilute soln.freshly as required and the SOYo soln. weekly. (12) Sodium sdphate-Anhydrous AnalaR. (13) Formaldehyde soln. 40% w/v. (14) Standard metal so1ns.-Prepare standard lead nitrate copper sulphate zinc sulphate and ferrous sulphate solns. (and if required the further metal solns. used in the extended scheme) such that 1 ml f O~oooO1 g (10 pg) of .metal in the usual manner. Prepare also a standard sodium arsenite soln. such that 1 ml f 0.00001 g (10 pg) of As,O,. B. APPARATUS-(^) 100-ml Kjcldahl flasks (Pyrex or Hysil) fitted with side funnel (carrying a protective cap) and extension to the neck (2 inch to 8 inch ext. diam.) as shown in Fig. l.* (3) 50-ml and Mix well. (2) Kjeldahl digestion rack and acid fume condenser (see Fig. 1). * The modified Kjeldahl flasks were made for us by Messrs.J. W. Towers & Co. Ltd. 44 Chapel Street Salford 3 -Lanes DETERMINATION OF MINUTE AMOUNTS OF ARSENIC COPPER LEAD ZINC AND IRON 235 100-ml conical flasks (Pyrex or Hysil). (4) Simple “cold finger” condensers consisting of test tubes 1.3 cm ext. diam. 7.0-7.5 cm long with flanged mouths to fit loosely 50-ml Hysil conical flasks. (5) 50-ml and 100-ml graduated cylindrical separating funnels with well-fitting glass stopcocks and stoppers and with the stems cut short to within & inch to 4 inch of the stopcock barrel. (6) Hilger Spekker photoelectric absorptiometer (standard type H.454) fitted with tungsten filament lamp and needle galvanometer (Cambridge Unipivot) with set of glass filters (H.455) and 1-cm and 4-cm standard glass cells (for liquids).(7) Set of Ilford filters Nos. 601-608 inclusive. (8) Suitable mirror galvanometer for use with the Ilford filters. Note-Items (7) and (8) are required only for the extended scheme. It is an advantage to connect the needle and mirror galvanometers to the Spekker instrument via a change-over switch so that either galvanometer can be put into the circuit as desired. C. PROCEDURE-1. Precautions-Owing to the minute amounts of metals involved, special care must be taken to reduce the reagent blanks to as low a limit as possible and to avoid contamination during the test. All apparatus must be thoroughly cleaned with hot diluted hydrochloric acid (1+ 1) followed by thorough washing with distilled water before use and the described methods of preparation and purification of the reagents must be adhered to.All extractions must be carried out with smooth rapid shaking (about 100 to 200 shakes per min.) and for the full time specified. 2. W e t decomposition-Introduce 2.00 g of the well-mixed sample through the side funnel, into the dry 100-ml Kjeldahl flask (Fig. l ) place the flask in position on the digestion rack, and add a mixture of 6 ml of conc. redistilled nitric acid and 4 ml of conc. sulphuric acid. Warm cautiously until reaction commences remove the flame until any initial vigorous reaction subsides and then boil down rapidly until the soln. begins to darken. Next add nitric acid in small portions heating after each addition until darkening again takes place until finally the soln.fails to darken and is only pale yellow in colour (ca. 20 to 25 ml of nitric acid are usually required in all). Run in 0.5 ml of perchloric acid and a little nitric acid and heat with fuming for about 15 min. Then add a further 0.5 ml of perchloric acid and heat for a few minutes longer. Allow to cool a little add 10 ml of water boil down to fuming cool and add 5 ml of water. The soln. should be quite colourless at this stage. Again boil down until white fumes appear and finally cool and dilute with 5 ml of water. During the whole of the above operations keep the funnel covered with its cap except when adding reagents to avoid risk of contamination. Basic substances e.g. methyl violet B.P. which are liable to deflagrate violently during the initial evaporation with acid should be treated first with 10ml of dil.(30%) nitric acid alone. After the initial vigorous reaction is over decant the acid into a clean beaker and wash the tarry residue with a little water (three or four 1-ml portions) adding the washings to the acid liquor. Add 4 ml of conc. sulphuric acid to the tarry residue agitate to disperse the cake and introduce nitric acid drop by drop with warming if necessary until vigorous reaction is over. Return the original acid liquor to the flask boil down until the soln. begins to darken and continue as described above. If no tarry cake forms add 4.0 ml of sulphuric acid slowly to the cooled liquor in the flask and then boil down and proceed as bef0re.l Prepare a reagent blank soln. by putting 4 ml of conc. sulphuric acid 20 ml of nitric acid, and 1.0 ml of perchloric acid in a 100-ml Kjeldahl flask and boiling down to fuming.Fume for about 20 min. boil down twice with 5-ml portions of water and finally dilute with 5 ml of water. 3. Extractiofz of copper and arsenic-Transfer the “test” and “reagent blank” solns. via the side funnel to 100-ml conical flasks rinsing out the Kjeldahl flasks with two 1-ml portions of water. Place 15.0 ml of dil. hydrochloric acid 5 N in each Kjeldahl flask, heat t? incipient boiling swirl vigorously to wash the sides of the flask and drain the acid into the corresponding conical flask rinsing with two 1-ml portions of water. If after the wet decomposition the test soln. contains insoluble deposit or suspended matter however small in amount filter through a 7-cm filter paper into the conical flask the subsequent washings, including the hot hydrochloric acid wash being also passed in turn through the filter.If much residue is present retain it as far as possible in the Kjeldahl flask and boil for about 1 min. with the hydrochloric acid before the acid is drained through the filter. Add to the contents of the conical flask 2-Om1 of iodide soln. (reagent 8) and warm to about 40” C. i.e. as warm as can be comfortably borne by the hand. Add 0-5 rnl of sodium metabisulphite soln. and transfer the soln. to a 50-ml graduated cylindrical separating funnel. Rinse out the flask with 1-ml portions of water until the volume of the soln. is 35 ml 236 STRAFFORD WYATT AND KERSHAW A SCHEME FOR THE PHOTOMETRIC Introduce 5.0 ml of carbamate extraction reagent (reagent 4b) and shake the warm soln.vigorously for 40 sec. holding the stopper firmly in place; then carefully loosen the stopper to release the pressure. Allow to separate and run the lower layer into a dry clean 25-ml separating funnel taking Fare not to allow any of the aqueous layer to enter the stem of the first funnel. Wash the aqueous layer with 0-5 ml of chloroform without mixing and run the chloroform wash into the second funnel. Extract the aqueous soln. with a further 2.0 ml of carbamate reagent for 30 sec. separate run the extract into the second funnel and wash the aqueous soln. with chloroform as before. Add 10ml of IV sulphuric acid to the combined chloroform extracts and washings and shake for 5 sec.* Allow to separate run the chloro-form layer into a clean dry 10-ml measuring cylinder wash the acid with 0.5 ml of chloroform and reject the acid.Add the chloroform washing to the main chloroform extract. Adjust the volume of the chloroform extract to 9.0 ml with chloroform and drain into a clean dry 50-ml conical flask. Wash the cylinder with 1-0 ml of chloroform add to the total extract, which now has a volume 10-0 ml (Extract A) 0.5 to 1.0 g of anhydrous sodium sulphate and swirl gently until the supernatant liquid clears. Return the acid layer to the original 100-ml flask rinsing the separating funnel with a little water and reserve it (Soln. B). Treat the “reagent blank” in an exactly similar way to the test soln. 4. Determiization of co@er-The colour of the diethyldithiocarbamate extract A is a measure of the copper present.Fill a 1-cm cell with the extract and determine the optical density on the Spekker absorptiometer with No. 7 blue filters against a. “solution blank” consisting of 7 ml of carbamate extraction reagent and 3 ml of chloroform mixed in a 50 ml flask and clalrified with anhyd. sodium sulphate. Determine the optical density of the “reagent blank” similarly deduct its value from the test value and read the copper content corresponding to the net value on a standard curve established as follows. Measure 10ml of water 4 ml of conc. sulphuric acid and 15-0 ml of hydrochloric acid 5 N into each of six 100-ml conical flasks. Add 0 1.0 2.0 3.0 4.0 5.0 ml of standard copper soln. (1 ml = 10 pg of Cu). Add 2.0 ml of iodide soln.to each followed by 0-5 ml of metabisulphite soln., dilute to 30-35ml and proceed exactly as described for the test. Determine the optical density of each of the extracts a t 10ml dilution a s before but against the first solution (containing no added copper) as “solution blank.’’ Plot a curve with pg of copper as abscissae and optical densities as ordinates. The curve is rectilinear a €ypical series of results being as follows: Copper CLg . . . . . . 10 20 30 40 50 Copper (on 2-g sample) p.p.m. 5 10 15 20 25 Optical density . . . . . . 0.130 0.262 0.400 0.522 0.650 After determining the optical density return the test and reagent blank solns. without loss to their respective flasks and rinse out the cell with the minimum amount of chloroform, adding the rinsings to the main soln.Determination of arsenic-Decant the extract A into a clean SO-ml conical flask and wash. the residue of sodium sulphate by decantation with three small portions of chloroform, taking care not to wash any particles of residue into the decanted soln. Reject the residue and add 2.0 (10.02) mlaof acid molybdate soln. (reagent 9) to the decanted soln. Insert a glass bulb into the mouth of the flask cautiously evaporate the chloroform and boil the soln. down on the hot plate until fuming accompanied by vigorous action begins. Imme-diately remove the flask allow to cool a little and remove the bulb (without washing since the acid must not be diluted). Insert a “cold finger” condenser filled with cold water place the flask on the hot plate and heat for 10min.a t such a temperature that a “blanket” of fumes fills the lower half of the flask and the condenser water finally attains a temperature of (30” C. (i.5”) at the end of the heating period when the flask is removed. Allow to cool a little and add 4.5 ml of water from a pipette in the following manner. Raise the condenser, and rinse it from the top downwards with about half of the water catching the rinsings in the flask. Then remove the condenser and rinse down the sides of the flask with the remainder of the water. Place a glass bulb in the mouth of the flask heat the soln. to b.p. and boil for 1 min. to remove most of the free chlorine present. Cool to 20” C. under the tap remove the bulb add 0.1 ml of sodium metabisulphite soln. and dilute to 5.0 rnl in a 10-ml measuring cylinder.Drain the soln. back into the flask add 0-5 ml of freshly prepared stannous chloride 5. * The washing with N sulphuric acid is introduced to prevent any possible interference by entrainment Even a trace of entrained phosphate would give by of phosphate if present in the material under test. reduction of the phosphomolybdate a blue colour and thus lead to fictitiously high results for arsenic DETERMINATION OF MIKUTE AMOUNTS OF ARSENIC COPPER LEAD ZINC AND IRON 237 soln. (reagent l l ) with swirling and leave for 10 min. Transfer the soln. (at 5.5 ml dilution) to a 1-cm cell and determine the optical density on the Spekker instrument using No. 1 red filters against a solution blank consisting of 2-0ml of acid molybdate soln. and 0.1 ml of sodium metabisulphite soln.diluted to 5.5 ml with water. Determine also the optical density of the reagent blank treated similarly to the test and allow for it. From the result find the arsenic content by means of a standard curve obtained as follows. Prepare a standard series and extract with carbamate extraction reagent as described for copper but in place of the standard copper soln. introduce 0 0.1 0.2 0.5 1-0 1.5 2.0 2.5 ml of standard arsenite soln. (1 ml = 10 pg of As,O,). Measure the optical densities after continuing as for the test soln., in a 1-cm cell with No. 1 red filters against the first s o h containing no added arsenic as solution blank and plot a curve as usual. The curve is a straight line a typical series of results being as follows: As@, pg .. . . 1 2 5 10 15 20 26 As,O (on 2 g sample) p.p.m. . . 0.5 1.0 2.5 5 7.5 10 12-5 Optical density . . . . . . 0.017 0.037 0.100 0.199 0.303 0.398 0-502 After observing the optical density check the acidity of each soln. as follows. Drain the soln. back into the flask and rinse the cell with a little water. Drain the cell on filter-paper before filling with the next soln. Dilute to about 20 ml add 0.1 ml of methyl red indicator and titrate with N sodium hydroxide. The colour change is from purple to green. The titre should be 6-75 (k0-1) ml corresponding to a normality (at 5.5 ml dilution) of 1.23 (&O-02) N . If the acidity is outside this range a correction may be applied (see later). 6. Separation of lead aizd zinc-Evaporate the acid soln. B reserved after extraction of copper and arsenic until no more iodine is evolved and fuming occurs.This is con-veniently done while the copper and arsenic are being determined. Allow to cool dilute with 10 ml of water add 2.0 ml of sodium citrate soln. 0.2 ml of sodium metabisulphite soln. and 0.2 ml of methyl red indicator. Almost neutralise with ammonium hydroxide (reagent 2), cool well and continue the dropwise addition of ammonia until the colour just changes to pure yellow; then just acidify with hydrochloric acid 5 N . Transfer the cold soln. to a 50-ml separating funnel and extract the indicator with two 5-ml portions of toluene. Run the aqueous layer back into the flask and wash the toluene layer with 1 or 2 ml of water, without mixing. Reject the toluene extracts return the aqueous soln.to the funnel add 0.5 ml of ammonium hydroxide and 2 ml of toluene and then (from a 10-ml burette) 1.0 ml of dithizone in toluene soln. (reagent 5a). Shake for lTisec. and if the dithizone extract does not change colour immediately to bright pink add ammonium hydroxide drop by drop, with shaking until the dithizone reacts. Continue adding dithizone soln. 1 ml or other convenient increment at a time until with the last addition the colour changes from bright pink to a slightly duller more purplish shade due to the presence of unchanged ditl uzone. ' Run the lower layer back into the flask wash the toluene layer with 1 or 2 ml of water and reserve the aqueous soln. for the determination of iron (soln. C). Add 10ml of N/10 hydrochloric acid to the toluene extract in the funnel shake for 30 sec.separate run the acid extract into a clean 50-ml conical flask and wash with 1 or 2 ml of water. Repeat the extraction-with a further 10ml of N/10 acid and add the acid wash to the first acid extract (soln. D). Then reject the toluene layer which should now be clear green in colour unless nickel or cobalt is present. Determination of Lead-Add to soln. D 0.5 ml of sodium citrate soln. and 0.5 ml of ammonium hydroxide (reagent 2) followed by 0.5 ml of potassium cyanide soh. (reagent 7). Transfer to a 50-ml separating funnel and rinse the flask with a little water. To the soln. add 2 ml of toluene and 0.5 ml of dithizone in toluene (reagent 5a) and shake well. If the toluene layer becomes bright pink continue the addition of dithizone soln.0.5 ml at a time, until the toluene layer develops a slightly duller tint and the lower aqueous layer a slight yellow tint due to a small excess of free dithizone. Then run the lower (aqueous) layer into a clean 100-ml flask wash the dithizonate layer with 1 or 2 ml of water and return the toluene layer to the original 50-ml flask. Return the aqueous layer to the funnel and shake with 2ml of toluene. If all the lead is extracted the toluene layer will be pale purplish-green, and the aqueous layer pale yellow. Return the aqueous layer to the 100-ml flask and add the toluene layer after washing with a little water to the main dithizone in toluene extract. Reserve the aqueous soln. for the determination of zinc (soln. E). The combined toluene extracts should have a volume of less than 10 ml since the amount of dithizone required to extract all the lead is usually less than 3ml.Return the toluene 7 238 STRAFFORD WYATT AND KERSHAW A SCHEME FOR THE PHOTOMETRIC soln. to the funnel add 10 ml of dilute ammonia-cyanide soln. (2 ml of ammonium hydroxide and 1 ml of potassium cyanide soln. per 100 ml of metal-free water) and shake until no change in colour occurs (about 10sec.). Allow to separate completely and run off and reject the ammonia wash which should be only very pale yellow in colour. If it is deeply coloured give the toluene soln. a second ammonia-cyanide wash. Finally wash with 2 ml of water. Separate any small amount of water retained in the funnel as completely as possible dry the stem of the funnel with filter-paper run the toluene extract into a dry 10-ml measuring cylinder and rinse the funnel with a little toluene.Dilute to the 10-ml mark with toluene mix and transfer to a dry 50-ml conical flask. Cork the flask to prevent evaporation swirl the solution and leave for a few min. to ensure that any small amount of water collects in a drop at the bottom. If the solution is then not perfectly clear filter it through a dry 9-cm paper into another dry flask. Measure the optical densities of the test solution and of the reagent blank solution (similarly obtained) on the Spekker instrument in a l-cm cell using blue-green filters No. OB2, against a solution blank of pure toluene. Find the lead content corresponding to the net optical density from a standard curve established as follows.Measure 0 0.5 1-0 2-0 3-0, 4.0 5-0 ml of standard lead soln. (1 ml = 10 pg of Pb) into 50-ml flasks add to each 20 ml of N/10 hydrochloric acid and continue as described for the determination of lead in the test soln. (beginning of Sec. 7). Having prepared the washed and clarified lead dithizonate in toluene extracts at 10-Om1 dilution determine the optical density of each soln. in turn against the first soln. containing no added lead as solution blank in a l-cm cell using blue-green filters No. OB2. This is virtually a straight line a typical series of results being as follows: Plot a curve as usual. Lead pg . . . . 5 10 20 30 40 60 Lead (011 2-g sample) p.p.m . 2.5 5 10 16 20 25 8. Optical density . . . . 0.077 0.153 0.305 0.450 0.597 0.745 Determiuation of zinc-Transfer soln.E to the separating funnel and shake for 10 to 15 sec. with 5ml of chloroform. Reject the chloroform layer and add to the aqueous layer 0-5 ml of formaldehyde soln. and 0.5 ml .of ammonium hydroxide soln. Then add dithizone in chloroform soln. (reagent 5b) 0-5 ml at a time with shaking until the colour of the extract changes from bright pink to a slightly duller shade. Run the lower layer into the original flask and wash the aqueous layer with a little chloroform. Add 2 ml of chloroform and 0-5 ml of dithizone soln. to the aqueous layer shake for 10 sec. and allow to separate. The chloroform layer should be purplish green in colour and the aqueous layer show a yellowish tint if extraction is complete. Add this extract to the main extract and reject the aqueous layer.Transfer the pink dithizonate in chloroform soln. to a separating funnel dilute to 15 ml with chloroform (used to rinse the flask) add 10 ml of dilute ammonia wash (2 ml of ammonium hydroxide in 100 ml of water) and shake until no further change in colour occurs (about 5 sec.). Separate reject the ammonia layer after washing with a little chloroform, and repeat the washing operation. Dry the stem of the funnel with filter-paper and run the chloroform layer into a dry 25-ml measuring cylinder. Wash the ammonia layer with a little chloroform and add the wash to the main extract. Adjust the volume of the soln. in the cylinder to 20.0 ml transfer it to a dry corked 50-ml flask swirl vigorously and leave for a few min. Determine the optical densities of this soln.and of the similarly obtained “reagent blank” soln. on the Spekkcr instrument using a l-cm cell and blue-green filters No. OB2. Read the pg of zinc present corresponding to the observed readings and obtain the net pg of zinc present by difference, using a calibration curvc prepared as follows. Take a suitable number of clean 50-ml conical flasks and add to each 20ml of N/10 hydrochloric acid 0.5 ml of sodium citrate soln. 0-5 ml of ammonium hydroxide 0.5 ml of. potassium cyanide soln. and finally 0.5 ml of formaldehyde soln. Transfer each soln. in turn to a separating funnel add 2 ml of Chloroform and then dithizone in chloroform soln., 0.5 ml at a time with shaking until a slight excess is present to remove any traces of zinc present in the reagents.Reject the extract and wash the aqueous layer with a little chloro-form. Return the extracted aqueous solns. to their respective flasks and add to each a suitable amount of standard zinc soln. (1 ml = 10 pg of Zn) to give a series increasing by at most 5 p g increments (see example below). Transfer the aqueous solns. in turn to the separating funnel and extract with dithizone in,chloroform soln. exactly as described for the test and finally dilute the washed extract to 20.0 ml with Chloroform. Determine the optical If the soln. does not clear filter through a. dry filter-paper DETERMINATION OF MINUTE AMOUNTS OF ARSENIC COPPER LEAD ZINC AND IRON 239 density of each soln. in turn against the first soln. containing no added zinc as solution blank using a l-cm cell and blue-green filters No.OB2. A typical series of results is the following: Construct the graph as usual. Zinc pg . . . . 2.5 5 10 15 20 25 30 35 40 50 Optical density . . 0-094 0.176 0.311 0.433 0.540 0.628 0.696 0-750 0.795 0.860 9. Deterntination of iron-Add to the aqueous soln. C reserved after extraction of lead and zinc 1.5 ml of hydrochloric acid 5 N transfer the soln. to a separating funnel and shake with 5 ml of toluene. Return the soln. to the 100-ml flask and reject.the toluene layer after washing with a little water boil for 5 min. cool to room temp. add 1.0 ml of thioglvcollic acid lo% followed by 2 6 m l of ammonium hydroxide soln. dilute to 50.0ml and mix. Determine the optical densities of the test soln. and of the reagent blank soln.(similarly obtained) on the Spekker instrument using a 4-cm cell and blue-green filters No. OB2. Establish the standard curve required as follows. Place in each of a series of 100-ml conical flasks 15 ml of water 4 ml of sulphuric acid 2.0 ml of sodium citrate soln. and known amounts of standard iron soln. (1 ml = 10 or 100 pg of Fe whichever is more convenient) as indicated below in the table of typical results. Add 0.2 ml of methyl red indicator nearly neutralise with ammonium hydroxide cool and make just alkalihe with ammonia. Add 1 6 m l of hydrochloric acid 5 AT extract the indicator completely with 5-ml portions of toluene boil the aqueous solns. for 5min. and cool. Add 1-0ml of thioglycollic acid lo% and 2 . 5 d of ammonium hydroxide dilute to 50-0m1 mix and determine the optical density of each soln.in turn against the first soln. (containing no added iron) as solution blank in a 4-cm cell using blue-green filters No. OB2. A typical series of results is as follows: Iron p g . . . . 20 40 60 80 100 200 Iron (on 2-g sample) p.p.m. 10 20 30 40 50 100 Optical density . . . . 0.089 0.180 0.271 0.360 0.446 0-885 DISCUSSION OF METHOD (a) Arsenic-Kahane and Pourtoy5 have shown that large losses of arsenic can occur during wet decomposition unless fully oxidising conditions are maintained throughout. We have found that even with the much smaller amounts of arsenic dealt with here a considerable proportion can also readily be lost. For this reason a 100-ml Kjeldahl flask fitted with a condenser dipping into 5ml of water contained in a boiling-tube surrounded with ice and water as used for arsenic distillations,] was first adopted.After decomposition the distillate was transferred to the flask and the whole was boiled down to fuming with the condenser removed before treating with perchloric acid. Although we still consider this the safest method of preventing loss of arsenic it proved too tedious and cumbersome for routine use. The alternative method described is reliable if care is taken not to let the residue char too much and a small but definite excess of nitric acid or finally perchloric acid is maintained in the soln. The apparatus shown in Fig. 1 is found to be very Convenient and effective for condensing the acid fumes and the modified design of Kjeldahl flask affords a fuller protection from contamination than the usual open type.For separation of the arsenic the sodium ethyl santhate reagent of Klein and Vorhess was first tried but proved unsatisfactory in the following respects (1) it was relatively troublesome to prepare (2) it tended to discolour rapidly and deposit insoluble matter, (3) extraction of arsenic was slow and not quite complete ( e g . with 1Opg of As20, about 8.5 pg were recovered). I t is suspected that the presence of alcohol in the reagent retards extraction. Sodium diethyldithiocarbamate also reacts with arsenious ions but was found similarly unsatisfactory and it was considered that the dithiocarbamate of an organic base should give better results. Finally diethylammonium diethyldithiocarbamate was found to meet all the requirements of easy preparation according to the reaction S.NH,(Et), 2NH(Et)2 + cs2 S=C<N(E't) , high stability and high solubility in chloroform alone while most important of all extraction of As111 is complete; under the proper conditions the amount left unextracted is certainly less than 0-2 pg of As20,.Quinquevalent arsenic however is left untouched so that complete reduction to the tervalent state is essential. A wide range of acidity is permissible; extraction was found to be complete over the range 1 N to 10 N in sulphuric acid. The arsenic extract was at first decomposed with bromine water6 and Milton and Duffield?s procedure' applied directly to the resulting soln. This generally gave good resiilts 240 STRAFFORD WYATT AND KERSHAW A SCHEME FOR THE PHOTOMETRIC but annoying discrepancies occurred which were traced to a slight turbidity in the soln.or to greasiness due to traces of organic matter separating on the side of the flask or to incomplete oxidation to the quinquevalent state. For this reason the more drastic method of treatment given was adopted. The presence of a little perchloric acid does not interfere with either the initial reduction and extraction of arsenic or the final reduction to “molybdenum blue.” In the latter reduction it appears to have a stabilising effect and results in a lower “reduction blank.” The use of a cold finger condenser is necessary to obtain adequate control of the acidity and to ensure that there is no loss of arsenic during decomposition. The intensity of blue colour obtained for a given amount of arsenic varies with the acidity’; thus the following results were obtained for solns.containing 25 pg of As,O, with varying acidity at 5.5 ml dilution. Soh. No. . . . . . . . . 1 2 3 4 5 6 7 8 Observed Spekker reading (1) test (25 pg of As,O,) . . . . 0.462 0.499 0.533 0.547 0.566 0.595 0.613 0.630 (2) blank . . . . . . 0.032 0.040 0.043 0-045 0.052 0.057 0.062 0-067 Net optical density . . . . . . 0.430 0.459 0.490 0.502 0.514 0.538 0-551 0-563 Mlof Nsodium hydroxide rewired . . 7.35 7.1 6-85 6.75 6.65 6.4 6.25 6.1 Normality (5.5 ml dilution) . . . . 1.34 1.29 1.25 1.23 1.21 1.16 1.14 1.11 In the method the strength of the acid molybdate soln. has been adjusted to give a final acidity in the test soln.of 1-23 (1t0.02) N (see Sec. 5). If the titration of the test soln. shows that the acidity falls outside this range a correction can be applied by means of the above table. The amount of carbamate extraction reagent specified (5 ml + 2 ml) will extract at least 25pg of As,?,. For iargcr amounts of arsenic increase the amounts of reagent used and of the final ddution accordingly. Thus ,for 25 to 1OOpg As,O, use 10ml + 5ml of carbamate extraction reagent dilute to 20 ml with chloroform for the copper determination, evaporate with 4 ml of acid molybdate reagent dilute the acid soln. to 10.0 ml reduce with 1-0 ml of 0.4% stannous chloride soln. and determine the optical density a t 11.0 ml dilution. Typical Spekker results for this range of arsenic content are as follows: A%Om clg * * .. . . blank 25 50 70 90 110 Optical density (net) . . (0.050) 0.250 0.509 0.707 0.892 1.090 In an effort to eliminate the reduction blank altogether addition of chlorate was tried,* but this caused such rapid fading that accurate Spekker observations were impossible. (b) Copper-Copper is rapidly and completely extracted as the characteristically coloured diethyldithiocarbamate complex. To accelerate reduction and extraction of arsenic the soln. is extracted warm and as the extract cools it becomes turbid owing to the separation of traces of water. Provided that sufficient care is taken in separating the chloroform and aqueous layers thk amount of anhyd. sodium sulphate specified is sufficient to absorb the water and clarify the extract. The addition of about 20% by vol.of absolute ethyl or methyl alcohol will also clarify the extract but this method was discarded because fading of the colour sometimes resulted and because subsequent evaporation of alcohol in presence of perchloric acid was considered a potential source of danger from explosion. (c) Lead-In presence of sulphuric acid alone lead may be partly or wholly extracted with arsenic and copper by the carbamate reagent but if hydrochloric acid is present in a concn. of a t least 2 N the lead remains wholly in the acid layer and the subsequent extraction from ammoniacal citrate-cyanide soln. provides a practically specific and highly sensitive method of determinati~n.~ A soln. of dithizone in toluene is found to have certain advantages over the usual soln.in chloroform or carbon tetrachloride; the excess of dithizone used in the extraction tends to enter the aqueous layer almost completely instead of contaminating the lead dithizonate layer while the optical density curve obtained is practically rectilinear, whereas that obtained with chloroform solns. showed marked convexity. (d) Zinc-Presence of cyanide completely inhibits the extraction of zinc by dithizone, but on adding formaldehyde the excess of cyanide is converted into formaldehyde cyano-hydrin and the zinc cyanide is decomposed. Under these conditions zinc is quantitatively extracted from the slightly ammoniacal soln. as the dithizonate. The photometric deter-mination as dithizonate is extremely sensitive and the amount of zinc present is frequently too great for its convenient application.In such event an extractive titration of the zinc with a standardised dithizone in chloroform soln. is preferable as follows. After addition of formaldehyde add 2 ml of hydrochloric acid 5 N to acidify the soln. and extract the residual dithizone with 5ml followed by two 2-ml portions of chloroform. The chloroform laye DETERMINATION OF MINUTE AMOUNTS O F ARSENIC COPPER LEAD ZINC AND IRON 241 should be green at first then colourless. Add 0.1 ml of bromothymol blue indicator and then ammonium hydroxide until the indicator becomes blue plus 0.3 to 0.4ml in excess. Add 2 ml of chloroform and titrate with dithizone in chloroform soln. approx. O-OOS~O added at first in any convenient increments of 1 to 5ml. Shake vigorously after each addition and discard the lower layer at convenient intervals until it is judged that most of the zinc has been extracted.Finally complete the titration in increments of 0.1 ml plus 1 to 2ml of chloroform until the last increment instead of changing the colour to bright pink leaves it green or purplish green. It is best to titrate the “reagent blank” soln. first then to stan-dardise the dithizone soln. against 5.0 or 10.0 ml of standard zinc soln. (1 ml = 10 pg Zn) added to the extracted “reagent blank” soln. and finally to titrate the test soln. (e) Iron-Iron is retained throughout in the aqueous soln. and since all interfering metals, except manganese which is also quantitatively retained are extracted in the previous opera-tions the thioglycollic acid method provides a specific method of determination.The inter-ference due to manganese in the small amounts likely to be present is quite negligible. (f) Iizterferences-Although the scheme has been found to provide in practice a virtually specific method of determination of the five metals considered. for the type of material examined one or two of the common metals interfere and while it has not been considered necessary to provide for their elimination in the main scheme a few ncjtes regarding the means of overcoming such interference and of including the determination of some of these metals in the scheme if desired may be acceptable. (i) Dithiocarbamate extraction stage-Under the conditions of the method bismuth and mercury are quantitatively extracted with arsenic111 and copper by the carbamate reagent.Mercury does not colour the extract but if present in sufficient amount may interfere with the determination of arsenic by giving a turbidity at the final reduction stage on addition of stannous chloride. Bismuth gives a yellow coloured compound and therefore interferes with the copper determination. The colour is not nearly so intense as that of the copper complex about 40 pg of bismuth being required to give an extract of the same optical density as that provided by 1 pg of copper under the same conditions. Hence if the amount of bismuth present does not exceed the copper content the error introduced in the copper determination cannot be more than about +2.5% which may be considered negligible for most purposes. The presence of an appreciable amount of bismuth is indicated by the appearance on addition of sodium iodide of a yellow colour which is not discharged by metabisulphite.Since quinquevalent arsenic is not extracted by the carbamate reagent bismuth mercury and copper can be separated from it by extraction as diethyldithiocarbamates before reduction the arsenic being reduced and extracted subsequently. In absence of a reducing agent part of the iron is extracted with the bismuth imparting to the extract an olive-brown colour and must be removed by repeating the extraction in presence of iodide and metabisulphite. The iron-free extract is decom-posed bismuth is separated from copper by extraction as dithizonate in presence of cyanide, and the copper is finally extracted from the residual solution after addition of formalde-hyde by means of carbamate reagent.The recovered iron is subsequently added to the main soln. after separation of arsenic. (ii) Dithizone extraction. stage-The only common metals that interfere with the determination of lead are bismuth and tinT1. Bismuth has already been removed while tin apparently remains throughout in the stannic condition and is not extracted by dithizone for no interference has been found from amounts of tin up to 500 p.p.m. The metals extracted a t this stage apart from lead and zinc are nickel cobalt and cadmium. Treatment of the dithizone extract with N/10 hydrochloric acid removes lead zinc and cadmium nickel and cobalt dithizonates being retained in the toluene layer. Although Sandelllo states that nickel dithizonate is partly decomposed by very dilute hydrochloric acid we find no appreciable trace of nickel in the acid layer under the given conditions.In the extended scheme (see later) the hydrochloric acid is buffered with a little sodium citrate to give a PH of about 1.5 as an added precaution against loss of nickel while permitting rapid extraction of zinc etc. To separate zinc from cadmium advantage is taken of the fact that whereas zinc dithizonate is readily decomposed by N sodium hydroxide cadmium dithizonate is reasonably stable. EXTENDED SCHEME OF ANALYsIs-Based on the observations outlined above the following extended scheme enables all interferences to be overcome and determinations of bismuth nickel and cadmium to be included 242 STRAFFORD WYATT AND KERSHAW A SCHEME FOR THE PHOTOMETRIC 11.EXTENDED SCHEME ARSENIC COPPER LEAD ZINC IRON BISMUTH NICKEL AND CADMIUM (All interferences of common metals-up to 500 p.p.m. of each-eliminated) Wet Decomposition Decompose 2 g of the sample in a modified Kjeldahl flask with sulphuric nitric and perchloric acids. I Extraction of Copper and Bismuth (Hg noble metals) Dilute the soln. and add hydrochloric acid to give the min. HCI conc. of 2 N as in Scheme I. Copper, Some iron is also removed but arsenic remains bismuth (Hg etc.) extracted cold with carbamate reagent. in the quinquevalent condition and is not extracted. I 1st Carbamate Extract Decompose the extract with H,SO + HClO, add iodide and metabisulphite and re-extract Bi Cu etc. with carbamate re-agent.Acid layer (Al) contains resid-ual iron. Add it to acid soln. B2. Carbamate extract-Decompose with H,SO,+HCIO, and dilute. Bismuth-Treat soln. (A2) with citrate and metabisulphite neu-tralise and add cyanide to pre-vent extraction of Cu Hg etc. Extract Bi with dithizone in tolu-ene soln. wash the extract with dil. KCN soln. and determine optical density. Alternatively for larger. a-mounts of Bi decompose the dithizone extract and determine Bi by extraction as iodobismuth-ous acid. Copper-Extract Bi with dithi-zone. Add formaldehyde to the aqueous layer and extract copper with carbamate reagent. Deter-mine the optical density of the ex-tract as in Schemc I. Acid ,&Y Reduce arsenic with iodide and metabisulphite and extract with 1 carbamate reagent as in Scheme I.I Acid Layer (B2) 2nd Carbamate Extract (Bl) A rsenic-Evaporate chloroform Evaporate acid layer (A1 added) add acid molybdate reagent and to fuming and treat as acid layer complete the determination of B in Scheme I. Extract lead, arsenic as in Scheme I. zinc nickel cadmium and cobalt with dithizone in toluene soln. as before. I I I 1 I Dithizone extract -4 queous layer Extract lead zinc and cadmium Determine iron as in Scheme I . with N/10 HC1-citrate soln. I I Dithizone layer (B3) h'i (Co) Sickel Decompose soln. with H,SO,, HNO and HClO,. Add citrate, bromine water and ammonium hy-droxide followed by dimethylglyo-xime soln. Determine the optical density a t 25 ml dilution in 4-cm cell using blue filters No.7. I HC1 extract (B4) (Pb Zn Cd) Lead Treat acid extract with citrate, ammonium hydroxide and cyan-ide extract and determine lead as dithizonate as in Scheme I. 1 Extraction of zinc and cadmium -After removal of lead treat the soln. with formaldehyde and ex-tract Zn and Cd with dithizone in chloroform soln. I Determination of Zinc and Cadmiunz Wash the extract with dil. ammonium hydroxide and determine the optical density of the soh. of mixed Zn and Cd dithizonates a i 20.0 ml dilution in l-cm cell using Ilford green filters S o . 604. Treat a 10-ml portion of the extract wtth N sodium hydroxide to decompose Zn dithizonate and measure the optical density of the residual Cd dithizonate using the same filters KO.G04. Cadmium is thus determined, and the zinc content is obtained by difference from the two optical density readings. M ETH o I) decomposition dilution and addition of hydrochloric acid extract the acid soln. directly in the cold with 10 ml followed by 5 ml of carbamate extraction reagent shaking for 30 sec. each time. (If sodium iodide has already been added add a few drops of nitric acid e\Faporate to fuming to remove iodine digest with 0.5ml of perchloric acid add 10ml of water and evaporate to fuming again then dilute with 10 ml of water add 15 ml of hydrochloric acid, 5 N cool and extract). Separate shake the acid layer with 5ml of chloroforni for 10 to 15sec. and add the chloroform wash to the main extract. Next reduce the arsenic in the acid layer by adding 2ml of sodium iodide soln.and warming. Add 0.5ml of sodium rnetabisulphite soln. extract with 5 ml followed by 2 ml of carbamate reagent and determine the arsenic in this second carbamate extract (€31) as before (Sec. 5 p. 236). Reserve the acid layer (B2). Transfer the 1st carbamate extract containing copper bismuth etc. and part of the iron to a 50-ml flask add 2 ml of diluted sulphuric acid (1+1) and 0-5 ml of perchloric acid, A. SEPARATION AND DETERMINATIOX OF ARSEXIC BISMI-TII A X D (.:OPPEK-A'ftel' We DETERMINATION OF MINUTE AMOUNTS OF ARSENIC COPPER LEAD ZINC AND IRON 243 evaporate the chloroform heat to fuming and then strongly for 10 min. Dilute with 15 ml of water boil for 1 min. cool add 1.0 ml of sodium iodide soln. and 0.2 ml of sodium meta-bisulphite soln.and re-extract with 10 ml followed by 5 ml of carbamate reagent. Add the residual acid layer (Al) to the main acid soln. (B2). Decompose the carbamate extract with 2 ml of diluted sulphuric acid (1+1) and 0-5 ml of perchloric acid as before and dilute with 10 ml of water (Soln. A2). Boil for 1 min. add 1.0 ml of sodium citrate soln. 0.2 ml of sodium metabisulphite soln. and 0.1 ml of bromothymol blue indicator and render just alkaline with ammonium hydroxide. Cool thoroughly just acidify with hydrochloric acid, 5 N and add 0.5 ml of potassium cyanide soln which should change the colour of the indicator to blue again. Extract the bismuth with dithizone in toluene soln. as described for lead (Sec. 7). Do not add ammonia as bismuth dithizonate is less stable than the lead compound in presence of free ammonium hydroxide ; thus Hubbard's procedurell gives slightly incom-plete separation.Not all the mercury will be present for some will have been lost by volatilisation during the initial wet decom-position; hence the determination of mercury is not considered. To determine copper, extract the aqueous layer 2 or 3 times with chloroform to remove all the excess dithizone, then add 1-Om1 of formaldehyde soln. with mixing followed by 1-Om1 of ammonium hydroxide (extraction is incomplete from acid soln. under the given conditions). Extract the copper with 5 ml followed by 2 ml of carbamate reagent dilute the extracts to 10.0 ml with chloroform clarify with anhydrous sodium sulphate and determine the optical density as described in Sections 3 and 4 pp.235 236). The same Spekker calibration curve applies. Wash the bismuth dithizonate in toluene extract with two 10-ml portions of dil. potassium cyanide soln. (1 ml of potassium cyanide reagent in 100 ml of water) shaking for 5 to 10 sec. each time. Wash the toluene layer twice with 5 ml of water without mixing dilute the washed extract, which is orange in colour to 10.0 ml with toluene and determine the optical density in a l-cm cell using blue No. 7 glass filters. Establish a standard curve by adding known amounts of standard bismuth soln. (1 ml = 10 pg of Bi) to 2 ml of diluted sulphuric acid (1+1) and 0 6 m l of perchloric acid evaporating to fuming diluting and continuing as for the test soln. (A2). Mercury and copper remain in the aqueous layer.If-the amount of bismuth is small it may be determined as dithizonate. ,4 typical series of results is as follows: Bismuth p g . . . . 5 10 20 30 40 50 Optical density . . 0.112 0.231 0.460 0.676 0.869 1.045 For larger amounts of bismuth (say 50 to 250 pg of Bi) we prefer a procedure based on Haddock's method,12 whereby the yellow compound fonned by bismuth with iodide in acid soln. is extracted with a mixture of amyl alcohol and ethyl acetate. To apply this method, transfer the dithizone extract to a conical flask and evaporate most of the toluene so that the vol. is reduced to about 10 ml. Add 2 ml of diluted sulphuric acid (1+1) boil off the toluene completely add 0 6 m l of nitric acid and 0-2ml of perchloric acid evaporate to fuming and fume strongly for 10 min.Add 10 ml of water evaporate to fuming cool add 10 ml of water boil for 1 min. add 0.1 ml of sodium metabisulphite soln. and boil for a further 1 min.* Cool thoroughly add (with swirling) 3-0 ml of a mixture of sodium iodide soln. and hypophosphorous acid (2 vol. of 20% sodium iodide soln. and 1 vol. of 30% hypo-phosphorous acid) and transfer to a 25-ml separating funnel adjusting the volume with wash water to 15 ml. Add 5 ml of amyl alcohol and ethyl acetate mixture (3+1 by vol.), shake for 10 to 15sec. separate run the lower layer back into the flask and transfer the solvent layer to a dry 10-ml measuring cylinder. Do not attempt to wash the extract or it will become turbid but separate the two layers as sharply as possible. Run 4 ml of mixed solvent through the funnel into the flask containing the acid layer and return the mixture to the funnel shake separate reject the lower acid layer and add the solvent layer to the first extract in the measuring cylinder.Adjust the vol. to 10-0 ml with mixed solvent and drain into a dry 50 ml conical flask. Swirl the soln. and allow any traces of aqueous soln. to collect in a drop at the bottom. Determine the optical density in a l-cm cell using blue filters No. 7. Establish a standard curve by extracting known amounts of bismuth with * In Haddock's procedure hypophosphorous acid is apt to reduce sulphur dioxide to hydrogen sulphide, with resulting formation of some Bi,S,. Subsequent addition of iodide usually slowly converts all the bismuth into iodobismuthous acid but a turbidity due to free sulphur then forms in the s o h For this reason we prefer to (1) remove all but a trace of sulphur dioxide by boiling (2) mix the hypophosphorous acid and iodide reagents before adding them to the test soh 244 STRAFFORD WYATT AND KERSHAW A SCHEME FOR THE PHOTOMETRIC dithizone in toluene as described for the dithizone method and then treat the dithizone extracts as described above finally determining the optical density of the iodobismuthous acid extracts in amyl alcohol-ethyl acetate mixture.A typical series of results is as follows: Bismuth pg 15 30 50 100 150 200 250 Net optical density . . 0.042 0.080 0.133 0.263 0.394 0.520 0.640 The optical density should be determined without undue delay. B. SEPARATION AND DETERMINATION OF DITHIZONE EXTRACTABLE hIETALS-After removal of copper bismuth etc.and separation of arsenic evaporate the combined acid layers (A1 and B2) to fuming treat as acid layer B in Scheme I and extract with dithizone in toluene soln. (see Sec. 6 p. 237) iron being determined as previously (Sec. 9 p. 239). After separating the dithizone in toluene extract add to it a further 20 to 25% excess of dithizone in toluene soln. and separate the lead zinc and cadmium by extracting with two 10-ml portions of hydrochloric acid and citrate soln. (2.5 ml of trisodium citrate soln., 1 M (reagent S) mixed with 100 ml of N/10 hydrochloric acid) shaking for 30 sec. each time. Reserve the combined acid extracts (soln. B4). The residual toluene layer contains all the nickel and cobalt.’ To determine nickel add 2.0 ml of diluted sulphuric acid (1+1) to the toluene extract contained in a 50-ml conical flask evaporate the toluene completely add O+ml of nitric acid and 0-2ml of perchloric acid evaporate to fuming and heat strongly for 10min.Allow to cool add 15ml of water boil for 2 min. cool add 0.5ml of sodium citrate soln. 1-Om1 of saturated bromine water and ammonium hydroxide soln. until the yellow colour is just completely discharged. Cool to about 20” C. add 2.0 ml of amm-onium hydroxide 2.0 ml of dimethylglyoxime soln. (0.2% in ammonium hydroxide 5 N ) and mix. Add a further 0-5 ml of saturated bromine water dilute to 25.0 ml mix and allow to stand fo? 15 min. Determine the optical density in a 4-cm cell using blue filters No. 7. To estab-lish a standard curve add known amounts of nickel to 2.0 ml of diluted sulphuric acid (1+1) and 0.2 ml of perchloric acid evaporate to fuming dilute and continue as above.A typical series of results is as follows: Nickel pg . . 5 10 15 20 30 40 50 Optical density . . . . 0.140 0.265 0.390 0-520 0.760 0.975 1.190 The curve is therefore not quite rectilinear. Determine lead in the reserved hydrochloric acid extract B4 as described in Scheme I (Sec. 7) and then determine zinc and cadmium in the residual citrate-cyanide layer as follows. Add 0.5 ml of formaldehyde soln. and 2.0 ml of hydrochloric acid 5 N and extract the residual dithizone with small portions of chloroform. Render. the soln. slightly alkaline with ammonium hydroxide extract zinc and cadmium with a slight excess of freshly prepared dithizone in chloroform soln.and wash the extract by shaking for 5 to 10sec. with two successive 10-ml portions of dil. ammonium hydroxide soln. 0-2 N . Dilute the washed soln. of zinc and cadmium dithizonates to 20.0 ml with chloroform and reserve 10 ml in ‘a clean dry 50-ml conical flask for the determination of cadmium. Determine the optical density of the remaining 10ml in a l-cm cell. For this determination use Ilford Spectrum green filters No. 604 since it is necessary to employ filters which give a rectilinear curve for both zinc and cadmium dithizonates. The same tungsten filament lamp is used but the more sensitive “spot” galvanometer is reqhired. After determining the optical density of the soln. of mixed zinc and cadmium dithizonates determine that due to cadmium dithizonate alone as follows.Transfer the reserve 10 ml of soln. to a 25-ml separating funnel and shake for 15 sec. each time with 10 ml of K sodium hydroxide soln. followed by two 5-ml portions of sodium hydroxide soln. diluted with 5 ml of water. Run the chloroform layer into a dry flask rejecting the sodium hydroxide layer each time then return the chloroform layer to the funnel and shake with 10ml of water. Determine the optical density of the washed pinkish-orange cadmium dithizonate in chloroform soln. in a l-cm cell using Ilford green frlters No. 604 as before. From the result determine the cadmium content by means of the standard curve remembering that the original dilution of the cadmium soln. was 20.0 ml. Determine the zinc content by difference thus From the standard zinc curve find the number of pg of zinc corresponding to the observed optical density of (a) the soln.of mixed zinc and cadmium dithizonates ( b ) the soln. of cadmium dithizonate alone. Then the difference between (a) and (b) gives the zinc content in pg of zinc. Observed optical density data for standard cadmium and zinc solutions are given in Table I which also includes similar data obtained by us for the other metals considered, using Ilford gelatin filters and a mirror galvanometer with the tungsten filament lamp DETERMINATION OF MINUTE AMOUNTS OF ARSENIC COPPER LEAD ZINC AND IRON 245 PLg 5 10 15 20 25 30 40 50 100 200 Dilution ml . . Cell cm . . Filter No. . . Filter colour .. TABLE I OPTICAL DENSITIES USING ILFORD COLOUR FILTERS 7 c u 0.100 0.202 0.303 0.404 0.504 -----10 1 602 blue As203 0.118 0-242 0.352 0.470 0.588 -1-18 --5.5 1 608 red Pb 0-302 0.610 0.915 1.218 1.523 -----10 1 604 green Metal Zn Fe 0.298 -0-596 0.055 0.90 -1.20 -1-50 -1-79 0.164 - 0.267 - 0.535 - 1.06 20 50 1 4 604 604 green green A - -Bi* 0.328 0.655 0.99 1.32 1-63 -----10 1 602 blue Ni 0.138 0.262 0.378 0.475 0.670 0.855 1-02 ---26 4 602 blue 7 Cd 0.145 0.295 0-435 0-58 0.73 0.88 1.44 ---20 1 604 green * Bismuth as dithizonate. Note on Spekker observations-Certain discrepancies obtained at first in optical density readings were traced to rapid loss of solvent by evaporation.Hence when the coloured solutions (particularly in volatile organic solvents) have been made up to their final volume for observation of the optical density on the Spekker absorptiometer they should be preserved in tightly-corked flasks or vials or in glass-stoppered cylinders and during the determination of optical density the cell should be kept covered with a glass plate. ACCURACY OF THE METHOD-Tests on the recovery of known amounts of metals added to certain medicinals gave the following results (Table 11). TABLE I1 RECOVERY OF ADDED METALS* Medicinal used Test No. As203 Pb Zn Ni co Cd Fe Mn Sn Sb P*Q Mepacrine hydrochloride - 1 2 - A B A B $-Aminobenzenesulphonamide 3 - A B 4 5 - A B A B 16 14.7 50 -30 32.4 10 10.0 5 5.2 2 2-2 20 20.0 10 10.9 5 5.1 25 23.9 10 8.6 - -- -- -6 A B 250 243 50 -50 49.6 8 8.1 30 28.9 15 14.6 50 49.1 5 0 - - - - - - - - - - -nil - - 15 15.1 5 5-6 - 37 200 205 - 23 25 24 50 49.8 10 10.3 - - - - -22 - 550 - - - - - - - - -7 - A B 100 104 200 -36 35-9 18 17.9 20 20.6 5 5.2 30 28.8 50 -25 24.5 150 154 110 -500 -- -500 -* A amount added in pg.B amount found in pg. Notes-(1) All values given are net values after deduction of the appropriate blanks, and where metals have been added (Tests 2 4 5 6 and 7) the amounts of metals found in the pure medicinals have been allowed for.(2) Tests 1 2 3 4 were carried out according to the main scheme; tests 5 6 7 by the extended scheme. (3) Bismuth in test 5 was determined as dithizonate; in tests 6 and 7 by the iodide method. The reproducibility of the results as shown by a large number of routine tests is of the order indicated in Table 111 246 STRAFFORD WYATT AND KERSHAW PHOTOMETRIC DETERMINATION OF ARSENIC ETC. The data given in Tables I1 and I11 indicate that the methods given provide an effective means of separation and specific determination of the metallic impurities considered in compounds such as medicinals which contain only small amounts of inorganic matter (other than the alkali metals). The degree of accuracy obtainable may be considered highly satis-factory for the purpose of routine control of quality.TABLE I11 REPRODUCIBILITY OF RESULTS Metal Range Reproducibility p.p.m. on 2-g sample p.p.m. on 2-g sample Copper Cu . . (a) 0-10 f 0.5 (b) 10-25 f l Arsenic as As,O . . 0 - 12.5 f 0.5 Lead Pb (a) 0 - 1 0 (b) 10- 26 f 0.5 f l Zinc Zn . . 0- 26 f l (titrimetric or photometric) Iron Fe . . . . . . (a) 0 - 5 0 (b) 60-250 f 2 * 5 Kickel Ni . . 0 - 25 f l Bismuth Bi (a) dithizone . . 0 - 2 5 (21) iodide . . 25- 125 f l f 5 Cadmium 0 - 2 5 & 1 SUMMARY-A scheme is presented for the successive determination of minute amounts of copper arsenic lead zinc and iron in a single 2-g sample of organic material. It has been devised principally for application to organic compounds such as medicinals with a very low metal specification limit but is sufficiently flexible to be adaptable to materials with a some-what higher metal content.The interferences of other common metals supposed present in amounts up to 500 p.p.m. have been investigated. Under the given conditions the method is found to be specific for arsenic lead and iron. Bismuth interferes with the determination of copper; cadmium is included with the zinc. Conditions are described for eliminating these interferences and for determining bismuth nickel and cadmium if desired. Data are given regarding the accuracy and reproducibility of the results obtained. 1. 9 I . 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. REFERENCES First Report of the Sub-committee on the Determination of Arsenic Lead and other Poisonous Metals in Food-colouring Materials to the Analytical Methods Committee of the Socety of Public Analysts. The Determination of Arsenic ANALYST 1930 55 102. Second Report of the above Sub-committee. The determination of Lead ANALYST 1935,60 641. Third Report of the above Sub-committee. The Determination of Copper ANALYST 1939,64 339. Harper D. A. and Strafford N. J . SOC. Chem. I n d . 1942 61 74. Kahane E. and Pourtoy M. J . Pharw. Chim. 1936 23 5. Klein A. K. and Vorhes 17. A. J . Assoc. Off. Agr. Chem. 1939 22 121. Milton R . and Duffield M‘. D. ANALYST 1942 67 279. McClelland J . A. C. and Hardwick P. J. ANALYST 1944 69 306. Clifford P. A. J . Assoc. Ofl. Agr. Chem. 1943 26 26. Sandell E. B. “Colorimetric Determination of Traces of Metals. I ’ Hubbard D. M. I n d . Eng. Chew. Anal. Ed. 1939 11 343. Haddock L. A. ANALYST 1934 59 163. Interscience Publishers Inc New York 1944 p. 450. IMPERIAL CHEMICAL INDUSTRIES LIMITED ANALYTICAL LABORATORIES BLACKLEY MANCHESTER 9 January 194

ISSN:0003-2654    

DOI:10.1039/AN9457000232

出版商:RSC    

年代:1945

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9457000247

出版商:RSC    

年代:1945

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9457000250

出版商:RSC    

年代:1945

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/AN9457000253

出版商:RSC    

年代:1945

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9457000255

出版商:RSC    

年代:1945

数据来源: RSC