摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9406500539

出版商:RSC    

年代:1940

数据来源: RSC

摘要:

540 HINTON AND MACARA THE COMPOSITION OF SOME JAM FRUITS The Composition of some Jam Fruits and the Determination of the Fruit Content of Jams BY C. L. HINTON F.I.C. AND T. MACARA F.I.C. (Read at the Meeting May 1 1940) IN an earlier paper1 analytical data for the proximate composition of samples of a number of jam fruits were summarised. It was pointed out that there could be no finality in the figures since the districts of supply the varieties in cultivation and the effects of seasonal conditions would all be liable to change over a period and thereby affect the average figures or the range of extremes. With a view to keeping in touch with any such trends and to extending the data in some directions further samples of fruits have been examined in the laboratories of the Research Association as opportunity permitted and the results are given in the present paper.Many of the samples were purchased locally some were obtained direct from Covent Garden Market and others were samples from deliveries of jam fruit used by members of the Research Association. Included are a number of samples of fruit grown on the Continent. The present data include figures for certain analytical characteristics not investigated in the earlier work viz. combined acid (and hence also total acid), lead numbers and @H. These additional figures are the result of the working out of the lead precipitation method and the fact that experience over a number of years has shown this method to have considerable value in the examination of jams. Some of these figures were summarised in the paper mentioned,2 but they are now given in detail.ANALYTICAL METHODS A description is given of the methods used where these have not already been described,lS2 or where alterations in the procedure have been made. Preliminary Preparation of Sam$le.-Portions of the well-mixed minced material were quickly weighed out in duplicate for (a) Determination of insoluble solids, seeds and pectin; (b) Preparation of an aqueous extract on which the determinations of soluble solids acidity etc. could be made. In preparing stone fruits the stones from a weighed quantity of fruit were scraped free from any adherent tissue allowed to dry in the air and weighed. Only the fleshy part of the fruit was analysed and the analytical data for these fruits refer to the flesh only.Iizsoluble SoZids.-The residue of fibre etc. after the first boiling and filtration, was boiled with two further quantities of water for periods of 15 minutes each and finally washed thoroughly on the filter. Filter and contents were dried overnight at about 105" C. All the filtrates and washings were reserved for the determination of pectin (see later). Seeds.-The dried insoluble matter was detached from the filter and boiled for a short time in weak sodium hydroxide solution (about N/50) to open the material and clean the seeds. These were allowed to subside the alkaline liquor was poured off and the seeds and fibre were boiled with water and then transferred to a filter and washed with hot water. The residue was turned out on to a white tile and the seeds were teased out with a spatula placed in a weighed box dried at 105" C., cooled and weighed.Pectin.-Experimental work in these laboratories has shown that pectin-containing fruit tissues tend to give up their pectin in varying degree according to the nature of the liquid by which they are extracted. It has of course been know AND THE DETERMINATION OF THE FRUIT CONTENT OF JAMS 541 for some time that the pH of the extracting liquid is important. It now appears that the nature and concentration of salts in fruit juices can also have a marked effect. When a fruit is boiled with water the pectin is being extracted not by water only but by a diluted solution of the juice of the fruit. The composition of this solution will vary according to the composition and dilution of the juice.I t is thus clear that the conditions of extraction of the pectin when the fruit is simply “ boiled with water ” may vary considerably. In particular it may be noted that in the preparation of an aqueous extract of the fruit the pectin is being extracted by a fairly concentrated solution of the juice. When however the fruit is boiled with a fair amount of water and the fibre etc., is then washed copiously with boiling water the pectin is virtually being extracted by an excess of distilled water only. It appears that the amount of pectin extracted by the latter procedure may be appreciably greater than by the former. Table I shows some results obtained by the two methods of procedure. Smaller differences of the same kind have been observed repeatedly also in the analysis of jams.It appears that they may partly but cannot entirely be accounted for by adsorption affects. TABLE I-AMOUNTS OF PECTIN EXTRACTED FROM FRur-rs BY DIFFERENT METHODS Pectin extracted from 7 - 7-Rlackcurrants Raspberries Raspberries Per Cent. Per Cent. Per Cent. Mode of extraction etc. (canned) (Pulp) (Pulp) filtered but not washed through. Pectin deter- (2) o.35 0.13 0.08 and{(1) 0.39 Boiled with an equal weight of water for 1 hour, mined in an aliquot part of filtrate . . Boiled with successive portions of water and washed (1) 0.57 (1) 0.33 (1) 0-22 through well . . . . { ( 2 ) 0.57 (2) 0.27 (2) 0.18 In view of this it was thought desirable to modify the method for determining pectin in fruits by applying it to the filtrate and washings from the insoluble matter.In some of the determinations the whole of the filtrate and washings was used, in others an aliquot portion. The subsequent procedure was that of the Card-Haynes determination without preliminary separation of the pectin with acetone ; thus the results must be regarded as “crude calcium pectate.” Figures for pectin in fruits given in the earlier paper1 are probably somewhat low in comparison with the present results the pectin having been determined on aliquot parts of a 20 per cent. extract. SoZubZe SoZids.-For this and other determinations of soluble constituents, 250 g. of the minced sample were gently boiled with 250 ml. of distilled water for an hour with frequent stirring. After cooling the mixture was made up to 500 g., well mixed and filtered through paper or a fine sieve.The soluble solids content of the extract was then determined usually by means of the specific g r a ~ i t y ~ but in some instances by both specific gravity and dipping refractometer the results being aver aged. The figures so obtained were in g. of soluble solids per 100 ml. of the extract. In preparing the extract 100 g. of fruit yield only 200-1 g. of total liquid (where I = percentage of insoluble solids in the fruit). Moreover this (200-1) g. of liquid occupy only ~ ml. in volume (D being the density or sufficiently closely, the sp.gr. of the extract). Hence to convert the results to the percentage by (200-1 j . weight in the original fruit they were multiplied by _____ 100 D carried out on the aqueous extract i.e.acid and lead numbers. (200-1) D The same factor was applied of course to the results of other determination 542 HIXTON AND MACAR.4 THE COMPOSITION OF SOME JAM FRUITS Free and Combined A cid.-Previously to 1932 these determinations were made directly on the aqueous extract. Afterwards they were usually made on the pectin-free filtrate by the procedure described earlier.2 A few determinations were made on both the aqueous extract and the pectin-free filtrate; the differences if any were negligible. All acidities even those of malic acid fruits are expressed for convenience as citric acid. Lead N.umbers.-These were determined as described in the earlier paper2. In the analyses of the last few years use has been made of an improved method for finding the end-point of the lead titrations especially for the aqueous lead number.This is as follows: A first rough titration is made with the molybdate solution added in 0.5 ml. portions. A fresh portion of lead filtrate is then diluted and molybdate solution is added to within about 0.5 ml. of the expected end-point (as shown by the rough titration). The mixture is boiled the precipitate is allowed to settle and the partly clear liquid is decanted through a fluted filter. The precipitate is then transferred to the filter and washed thoroughly two or three times with a jet of almost boiling water. Finally the filtrate and washings are heated to boiling and the titration is completed the molybdate now being added 0.1 or 0.2 ml.at a time and the mixture spotted out with indicator after each addition. It will be noticed that the figures shown for “lead number per 1 per cent. of total acid” correspond numerically to what was before expressed as “lead number per 0.1 g. of total acid.”2 This is so of course because the first expression refers to a unit total acid content in the sample of 1 per cent. and the second refers to a unit of total acid of 0-1 g. in 10 g. of sample on which the lead number is based, i.e. again 1 per cent. of the sample. The former mode of expression is rather more convenient and in the present paper replaces the earlier one. @H VaZ.ue.-This was determined on the aqueous extract by means of the quinhydrone electrode in conjunction with a saturated calomel electrode.The formula for calculation of the pH from the reading in millivolts was $H = (454-mv.)/ 0.0001984T where mv. is the reading in millivolts and T the absolute temperature as O C. As a control for the accuracy of the system a standard buffer solution (0-4 per cent. solution of cream of tartar) was used having a @H of 3.57. TABLE II-pH VALUES OF GOOSEBERRY EXTRACTS DETERMINED WITH THE HYDROGEN -4ND QUINHYDRONE ELECTRODES pH with NO. hydrogen electrode 3.00 3.32 3.04 2-95 2.90 3.22 3.21 pH with quinhvdrone electrode ---A 7 Initial Subsequent reading* readings 3-04 3.13 (18 mins.) 3.33 3.38 (7 , ) 3.09 3.13 (9 , ) 2.90 2.93 (5 ) * ) 2.89 3.91 (5 ) ) 3.24 (6 , ) 3-21 3.19 3 - 2 4 (10 , ) 3 - 40 (15 hours) * About 1 minute after mixing in the quinhydrone except for No.3 (3 minutes). With some extracts especially of gooseberries and currants a marked drift of the apparent $H occurred. This drift sometimes amounted to as much as 0.1 unit in a few minutes but varied considerably from one sample to another. Some comparative determinations on gooseberry extracts showed that the initial value obtained with quinhydrone was usually quite close to that obtained with the hydrogen electrode. (Table 11 AND THE DETERMINATION OF THE FRUIT CONTENT OF JAMS 543 In determining the pH of the fruit extracts therefore the initial reading was taken to give as nearly as possible the correct value. It seems possible that the drift is due to some action of reducing substances in the fruit juice on the equimolecular mixture of hydroquinone and quinone which is formed when quinhydrone dissolves.The principal substance likely to have a sufficiently powerful reducing action is ascorbic acid; but without further work it would not be safe to ascribe the effect definitely to this substance. DETAILED ANALYTICAL DATA FOR THE FRUITS I t has been thought desirable to give the detailed analyses of each individual sample (Tables I11 to XV). This is the most satisfactory way of making them available for use in the interpretation of the analysis of jams etc.; extreme and average figures have only limited value since a sample which is extreme in one respect is usually more normal in other ways. ,4n asterisk is placed against figures which are more extreme than any of the corresponding figures of the earlier paper.1 Gaps in the tables occur because many of the samples were obtained primarily for other work and time permitted the determination only of the analytical figures required €or that work.NoTEs.-Gooseberrzes.-The averages where comparison is possible are not very different from those reported earlier,l but rather low minima have been found for soluble solids and free acid. The aqueous lead number (per 1 per cent. of acid) is a measure of the approximate proportions of citric and malic acids in the fruit. If the fruit acids were entirely citric acid the figure would be 13.55; if they were entirely malic acid it would be approximately 5 ~ 8 . ~ The average value of 10-36 found corresponds to a mixture of 41 per cent. of malic and 59 per cent.of citric acid. The extremes however (11.7 and 9.0) correspond to 24 per cent. and 59 per cent. of malic acid respectively. Stra~Jberries.-\hen the " plugs " had not been removed in picking they were taken out as far as possible prior to analysis. The averages were close to the earlier ones,l and none of the extremes lay outside the ranges previously established. The weight of seeds is a fairly constant proportion of the total insoluble matter, averaging 54 per cent. the extremes being 44 per cent. and 61 per cent. The lead number (aqueous) per 1 per cent. of acid indicates an average pro-portion of about 11 per cent. of malic acid in the acids of this fruit. A range of variation from 0 to 40 per cent. was shown by individual samples. Only one sample approached the latter figure however and this was in the period before the intro-duction of the improvement in the titration mentioned above.No subsequent sample has shown a larger proportion of malic acid than 18 per cent. There is a fairly definite relation between the $H and the proportion of combined to total acid. This can be seen from Fig. 1. The dotted line is the neutralisation curve for citric acid in Xi10 concentration and the points for the strawberry samples lie fairly near this line. The deviations from the citric acid curve are doubtless due to various causes e.g. the fact that the neutralising bases are not entirely alkalies, but to some extent alkaline earths; the presence of small amounts of malic acid; variations in concentration from the decinormal ; lack of accuracy in the various determinations involved.On the whole in spite of these sources of deviation, the correspondence is quite good. It is obvious that the pH of a fruit extract is not an independent property but is governed by the proportions present of the organic acids and their salts. Ras$berries.-For the purpose of arriving at the average and extreme figures of Table V the data for 24 samples mostly of Scottish fruits specially examined in 1934 and recorded previously (T. M a ~ a r a ) ~ have been brought in. In comparison with earlier figures,l the averages for soluble solids and free acid are about the same but the average for insoluble solids is 1 per cent. lower. This must probably be attributed to the large proportion of samples of the Lloyd Georg 544 HINTON AND MACARA THE COMPOSITION OF SOME JAM FRUITS variety; this has come into considerable favour for jam-making and it tends to have a smaller proportion of insoluble matter than other varieties.Its content of soluble solids and acid would appear to be more normal. The weight of seeds averages 77 per cent. of the total insoluble solids with a range from 70 to 82 per cent. From the lead number per 1 per cent. of acid the average proportion of malic acid in the total acids is not more than about 3 per cent. In an extreme instance it was 19 per cent. but this sample was analysed in the early period of the leadprecipitation method and the result may be open to some doubt. Later figures though few, indicate practically no malic acid in this fruit.a38 0.36 ul P 0.34 2 A I 0.32 e s! fi 0.30 z 8 0.28 p 0.26 0.2 4 s 2 k x x x x x dh + x %' x K/ x 'x 0 % I 3.1 2 .3 .4 .5 6 -7 .i3 P " FIG. I. RELATION BETNEEPI p H OF STRAWBERRY EXTRACTS A N D THE RATIO OF COMBINED TO TOTAL ACIDS. [The broken line shown IS rhc neutra1lza:ton curve for L I C ~ I C acid 1 The relation between the pH and the proportion of combined acid in the total acid as for strawberries corresponds approximately to a partly neutralised solution of citric acid. Figures for pectin are not given as it rapidlydisappears from this fruit. Redcwrants.-The averages on the whole are very close to the earlier ones. The lead numbers both aqueous and acetone tend to be higher than can be accounted for by assuming the total acid present to be citric acid.(This would require values of 13.55 and 15.0 respectively for the lead numbers per 1 per cent. of total acid.) This seems to be due to precipitation of a certain amount of lead by the colouring matter of the fruit which however does not contribute to the acidity as determined by titration. The extracts from two samples were submitted to a decolorising treatment with vegetable carbon and the lead numbers and total acid were determined on the decolorised solutions. It was found that the lead numbers per 1 per cent. of acid had fallen slightly the acetone lead numbers now being close to the figure of 15.0 which would be expected from citric acid or a mixture of citric and malic acids. (Table XVI TABLE 111-GOOSEBERRIES Date 99 July 3 99 3 ) 3 93 13 17 1931 June 15 17 July 1 1932 June 1 11 7 9 21 1934 June 13 1936 '1 8 7) July 11 71 13 17 Desuiption Small green .. . . . . Green hard . . . . Some partly ripe not fresh . . . . Very small partly ripe not fresh . Green . . . . Green fairly fresh . . ,. Firm some beginning to ripen . . Large green beginning to soften . . Large green firm . . . . . . Large green some beginning to ripen not very fresh . . . . . . Green but beginning to ripen not very fresh Green and firm . . . I Green but softening . . . . a . Medium to small firm moderately ripe . Medium to small green firm . . Mostly very small green firm . . Rather small a few turning red . . . . Green and hard .. . . . . Rather small green vcry firm . . . . Large green . . . . . . . . Mixed sizes . . . . . . Highest . . . . Lowest . . . . Average . . No. of samples . . . . Insol. solids Per Cent. -2.48 3.49 2.26 2-34 2.84 -3.49 2.24 2-66 5 Acid as citric (cryst.) s%s w7 Leadnumbers Cent. Cent. Cent. Cent. Aqueous Per Per Per Per (----*-, - 1.50 0.33 1.83 17.3 - 1.99 0.32 2.31 23.8 7.5 1-91 0.36 2.27 24.3 6.2 1.70 0.39 2.09 24.5 7.5 2.06 0.37 2.43 23.4 7.7 1.99 0.40 2.39 25.9 7.5 2.14 0.33 2.47 26.1 10.2 2.49 0.33 2-82 29.9 9.5 2.16 0.39 2.55 24.6 7.7 2.26 0.35 7.7 2.04 0.34 8.2 2.19 0-32 - 1-94 0.32 7.8 2-24 0.36 7.4 2.30 0.36 6.5 1-27 0.38 8.2 2-26 0.39 7.6 2-22 0.36 - 1.72 0.44 - 2.08 0.48 I 1-54 0.26 10.2 2.49 0.45 6*2* 1.27" 0.26 7-81 2.00 0-37 15 21 21 2.61 27.3 2.38 24.1 2-51 25.8 2.26 22.2 2.60 28.6 2.66 28.7 1.65 -2.65 28.1 2.58 28.6 2.53 25.8 1.80 16.2 2.16 -2.82 29.9 1.65 16.8 2-37 25.0 21 1 TABLE IV-STRAWBERRIES Acid as citric (cryst.) Insol.Sol. A 1 solids Seeds solids Free Combined Total Lead Per Per Per Per Per Per ~---=-Cwt. Cent. Cent. ( h i t . Cent. Cent. Aqueous Date ” July 3 1932 June 28 ’ 9 July 8 9 ) $ 7 5 1933 June 15 1l y7 27 37 77 30 ID36 7 ) 30 ” July 2 7 - 1 7 77 9 ) 20 1937 June 21 i 25 7’ J u l y 2 77 33 22 Description Large fully ripc . . ,. - _- 8.2 0*9!1 0.41 1.40 17.9 I 7.7 1-04 0.38 1-42! 18.1 hlostly fully ripe but firm . . I . - - 9.3 1-08 0.35 1.43 17.9 Ripe not fresh slight mould .. - 7.6 2.05 0.33 1.38 18.3 Full ripe ex Kent . . . . - - 9.2 0.75 0.28 1.03 13.0 - - - 0.95 0.37 1-32 15.5 - - - 0.74 0.37 1.11 12.5 - - I 0.48 0.29 0.77 9.8 - - - 0.93 0.38 1.31 16.7 Partly ripe . . . * -Large full ripe . . . . Small full ripe not fresh . . season pickings) . . . . Medium size just ripe . . . . Poor specimens just ripe (end of G~~dsize,notfullyripe exKent . . 2.05 0.91 9.3 1.24 0.35 1.59 16.7 Rather small ripe and dry but some Medium to small some mould . . 2.14 1.22 8.0 1-05 0.38 1.43 17.5 Rather small fairly ripe some crushed 2.63 1.40 9-0 1.30 0.42 1-76 22.7 Moderate size mainly soft and ripe. . 1.64 0.76 7-6 0.71 0.30 1-01 13-mould . . . I . . 2.09 1.02 8.0 0.95 0.36 1.31 17.0 Mixed sizes good condition.. . . 1.89 1-18 8.2 1.02 0.37 1.39 18.4 Medium size mostly ripe . . . . 2.27 1.27 - I - - -- I - Small uniform ripe . . . . 1.96 - 10.1 -Mixed sizes mainly ripe fresh . . 1.92 - 9.4 -Medium t o small dry . . . 1.94 1-11 -- - _-0.89 0.41 1-30 16.1 Medium to small dry . . . . 2.02 1.1‘3 -. 1.00 0.42 1.42 18.0 I - - I 1.17 0.39 1.56 19.7 Dutch Jucunda rather under-ripe . . 1-57 - 6.0 0.70 0.21 0.91 1204 crushed and mouldy . . . . 2.60 - 10.0 1.00 0.34 1.34 17.2 rather sandy . . . . . . 3-45 - 9.7 1-08 0.44 1.52 20.2 . 2.11 - 8.8 ().!):< 0.3% 1.31 18.2 crushed fairly fresh . . . . ]*!I4 - 98.3 0.98 0.4.7 1.43 19.6 8.1 0.90 0.38 1.28 16.8 many mouldv plugs taken out . . 2.59 - 7.8 0.88 0.38 1.26 16.8 Highcst . .. . . . 2.63 1-40 10.1 1-30 0.45 1.72 22.7 1 .owest . . . . . . 1-57 0.76 6.0 0.48 0.31 0.77 9.8 -1vcrage . . . . . . . . 2-11 1.1 I 8-56 0.95 0.36 1.31 16--_ 0.78 0-32 1.10 14.4 Medium to small some under-ripe 2-32 -Dutch Everns rather over-ripe, Dutch Jucunda ripe slight mould, Dutch Jiicunda meclium size ripe, Dutch Everns small ripe some Dutch small ripe bruised sligllt Dutch small very much crushed, ratlicr wet and not fresh . . mould plngs taken out . . . . 2.01 -No. of samples . . . . . 19 9 20 26 26 26 85 A These reqlllts 3rcL doiibtful dnd are riot included in extrriiiec arid average TABLE V-RASPBERRIES Acid as citric (cryst.) Insol. Sol. c A solids Seeds solids Free Combined Total Per Per Per Per Per Per Cent. Cent. Cent. Cent. Cent.Cent. Date 1930 July 10 Y 9 YY 10 YI YY 15 37 15 Y Y Y Y 22 IY 3 3 23 1931 99 17 YY 16 YY Y Y 20 1933 9s 26 1935 Aug. 9 1936 July 28 Date 1930 July 16 39 99 20 YY YY 23 97 YY 29 91 Aug. 5 1931 June26 1932 99 7 91 July 15 1934 17 17 79 79 18 1938 97 29 * Aug. 9 Description Large ripe ex Kent - - - 1.45 0-38 1.83 Moderate size ripe ex Hants . . - - - 1.96 0.37 2.33 Fairly large ripe ex Kent . . - - - 1.37 0.37 1.74 Fairly large ripe 6% Kent . . - - - 1-57 0.40 1.97 Medium size ripe fairly fresh . . . . - 4.37 - 1.39 0.38 1.77 Medium size some under-ripe . . - 4.09 - 1-24 0.31 1.55 Mixed sizes mostly soft and rather mouldy, poor quality . . . 9.04 7-23 6.4 1.02 0.42 1.44 Large some bruised generally good .. 5.00 3.71 8.2 2.02 0-34 2.36 Large crushed in lower layers rather over-ripe . . . . . . . . . 5.33 - 7.8 1.94 0.45 2.39 - 5.25 4.19 7.5 2.01 0-47 2.48 - 6.12 4.60 6.0 1.80 0.48 2.28 . . 4.90 - 10.0 2.04 - I Scottish . . - - - - 1-69 0.43 2.12 Medium size rather over-ripe . . . . 6.24 - - 2.14 0.45 2.59 Highest . . . . . . 9.04 7.23 12*2* 2-50 0.48 2.59 Lowest . . . . 3.29* 2.38 6-0 1.02* 0.31 1.44 Average . . 5.19 4-00 8.37 1.71 0.41 2.07 No. of samples . . 31 30 28 36 13 13 I J v Embracing also analyses of 1934 season already published (T. Macarad). TABLE VI-REDCURRANTS Description Acid as citric (cryst.) Insol. Sol. ( L I solids Seeds solids Free Combined Total Lead Per Per Per Per Per Per - Cent. Cent. Cent. Cent. Cent. Cent.Aqueous 2-12 0.35 2-47 35.4 Medium to large ripe good condition - - -Medium to large ripe rather moist but otherwise good . . - - - 2.70 90.39 3.09 43.1 Slightly dirty - 5.84 - 2.54 0.42 2.96 35.4 Large fully ripe wet with juice . . - 3.10 - 2.40 0.45 2.85 37.7 Ripe but not fresh wet condition . . - 3.83 - 2.40 0.42 2.82 34.9 Fairly large ripe rather crushed . . 6-42 4-69 10.8 2-06 0.41 2.47 34.8 Moderate size rather under-ripe dry 6.23 4.74 10.9 2.48 0.49 2.97 41.7 Kentish . . . . 8-41 4.80 9.0 2.67 0.43 3.10 -Large ripe good condition Large fresh condition very few damaged . . Norfolk medium size ripe good con-dition . . - - _- - - 2.73 -- - - - -_ I -- - - - 2.60 0.50 3-10 41-- - - - - - -Highest . . . . 6.42 5-84 20.9 2.73 0.50 3.10 43.1 Lowest .. 5-41 3.10 9.0' 2.06' 0.35 2.47 34.8 Average . . . . 6-02 4-50 10.23 2.46 0.43 2.87 38.5 No. of samples . . 3 6 3 10 9 9 7 * These results are doubtful and are not included in extremes and average TABLE VII-BLACKCURRANTS Datc 1930 July 17 99 99 21 $9 Y) 24 97 Aug. 2 931 June 16 > Y 9) 18 ~9 n 25 39 July 14 932 99 13 7) 99 20 1933 9) 5 9) > Y 20 1934 Aug. 2 1936 July 27 39 28 9) Aug. 8 99 >> 11 1937 July 16 99 93 23 1938 June 21 $7 July 22 bescription Medium size ripe . . Mixed sizes rather dirty . . Fairly large ripe not fresh Mixed sizes slightly moist with juice Belgian very mixed size poor condi-tion . . . . Very small to medium size fairly ripe not fresh .. Medium to small fairly ripe and fresh Medium size very soft some crushed Size varied fair proportion under-ripe --Large fresh condition dry . . Large ripe . . . . Large ripe . . . . Medium size over-ripe . . -Dutch many very large firm but ripe Dutch very large not over-ripe but rather soft and moist with juice . . French rather small some unripe, not very fresh heavily sprayed (lime-sulphur) . . French moderate size fairly ripe, some mouldy and crushed Dutch medium size ripe good con-dition . . ,. Latvian canned . . Esthonian canned . . Canadian canned . . Highest . . Lowest Average . . Insol. solids Per Cent. - ---6.34 5-98 7.87 6.79 5.98 5.77 5.53 6-33 4.1 1 4.74 4.94 5.44 5.24 4.26 -5.13 5.68 5.46 ---7.87 4*11* 5.57 Seeds Per Ccnt.2.89 4-35 3.94 3-01 2.33 4-00 3.12 3-54 ------ - ---I ----- -4.35 2.33 3.40 NO. ofvsamples . . *. 17 8 %I. solids Per Cent. ----10.6 10.9 11-3 12-8 8-9 9.2 13.6 13.6 -----13.6 11.5 13.3 11.3 15.4 --I 15.4 8.9' 11.99 Acid as citric (cryst.) A > Lead Free Per Cent. 3.66 2-67 3-38 2.73 3.11 3.18 2-85 3.57 3.69 3.80 3.40 3.85 3.40 2.93 2.99 2-66 3-71 3-03 2-42 3.98 3.86 2.67 - --3.98 2*42* 3-25 Combined Per Cent. 0-67 0.58 0.52 0.45 0.70 0.67 0.67 0.72 0.80 0-74 - -0-61 0.65 0.53 0.52 0.72 0.66 0-58 0.7 1 0.69 0.66 - - -0.80 0.45 0.64 13 22 20 Total Per Cent.4-33 3.25 3.90 3-18 3-81 3-85 3-52 4.29 4.49 4.54 --4-01 3-58 3-52 3.18 4.43 3.69 3.00 4.69 4-55 3-33 ---4.69 3-00 3.86 20 Aqueous 58.9 39.5 51.3 42.6 50-50.8 46.0 57.8 64-64.8 ---46-46.1 39.7 58.3 48.7 40.9 63-60.7 48.9 ---64.8 39.5 51.6 1 TABLE VIII-PLUMS Acid as citric (cryst.) Insol. t Sol. r c solids Stones solids Free Combined Total Per Per Per Per Per Per DRtC 1930 July 28 19 Aug. 5 91 9 1 6 9 7 7 18 11 9) 25 91 11 10 1931 Aug. 5 9) 11 31 93 Sept. 2 99 ?1 4 Date 1930 July 25 99 Aug. 7 79 Sept. 4 1931 July 27 13 Aug.7 1932 Sept. 5 99 19 13 Description Cent. Cent. Cent. cent. Cent. Cent. Italian blue medium size moderately ripe 1.16 4-5 - 2-11 0.40 2.51 Fully ripe some slightly crushed . . . . 1.19 4.5 - 1.82 0.37 2.19 Blue type small fully ripe . . . . 1.57 4.3 - 1-72 0.52 2.24 Blue-green small ripe . . . . 2.62 4.3 .- 1.21 0.36 1.57 Victoria mixed sizes unequally ripe rather crushed . . . . 1.32 4.2 - 1-32 0.30 1.62 Medium size fully ripe . . . . 0.98 2.9 - 1.32 0.29 1.61 Red large ripe but condition poor. . . 1.23 4.0 - 1.78 0.32 2.10 bruised . . . . 0.85 4.0 - 1-53 0.35 1.88 Red over-ripe bruised and wet with juice . 1.29 5.4 - 1.16 0.34 1.50 Blue medium size fully ripe . . . . 1.36 5.5 12-1 1.94 0.47 2.41 Victoria fairly large mixed ripe over-ripe and green .. . . 1-31 2.8 11.2 1.61 0.35 1.96 Victoria mixed sizes ripe bruised . . . 1-31 4-6 10.4 1.65 0.36 2.00 Golden very uneven in size and ripeness, fair condition . . . . 1.25 3.9 12.1 1.68 0.37 2.05 Red small to medium size ripe . . . . 1-75 3.3 16.6 2-62 0.43 3.05 Blue type hard and greenish . . . . 1.76 3.8 12.0 1.37 0.38 1.75 Victoria Kentish fairly large ripe and sound 1.15 3.7 11.7 1.31 0.23 1.54 Blue type mainly ripe . . . . 1.39 4.0 15.6 1.84 0.51 2.35 Highest . . . . 2.62* 5.5 36.6 2.62 0.52 3.05 Lowest . . 0.85 2.8 10.4 1.16 0.23 1.50 Average . . 1.38 4.11 12.72 1-65 0.37 2.02 No. of samples . . 17 17 Golden large ripe to over-ripe some slightly 8 17 17 17 * These results are doubtful and are not included in extremes and average.TABLE IX-GREENGAGES Acid as citric (cryst.) Insol. t Sol. ,-Per Per Per Per Per Per Cent. Cent. Cent. Cent. Cent. Cent. A Description solids Stones solids Free Combined Total 1-49 0.54 2.03 Small hard unripe . . ,. . . 2.93 5.0 -Rather small ripe . . . . 1.96 5.2 - 1.12 0.50 1.62 Mixed in size ripe bruised . . . . 2.33 5.1 - 1.25 0.44 1.69 English small firm ripe not fresh . . . . 1.41 7.1 - 1.17 0.41 1.58 Italian mostly sound and ripe . . . . 1.14 6.5 9.8 1.41 0.41 1.82 Medium size full ripe . . . . 1.98 5.3 17.2 1-16 0.64 1.80 English ripe soft a little bruised and some mould ,. . . 1.38 2.9 15.5 1-73 0.44 2-17 English large ripe and soft . . 1.14 3.5 13.2 1.01 0.36 1.37 - - - - 0.96 0.49 1.45 English medium size rather unripe .. - - - 1.97 0.43 2.40 - - - - 2.20 0.56 2.76 Highest . . . . 2.93* 7.1 17.2 2*20* 0.64 2.76 Lowest . . 1.14 2-9* 9.8" 0*96* 0.36 1.37 Average . . . . 1.79 5.1 13.91 1.41 0.48 1.89 No. of satnplcs . 8 8 4 11 11 11 t On entire fruit; other data on stone-free portion only Date 1930 Sept. 1 Y Y n 5 99 n 8 Y l 93 12 $l 33 23 Date 1930 July 25 30 17 Aug. 6 Y l 21 7 15 ly 27 $9 Sept. 3 I1 13 8 Y I Y Y 19 yY 29 97 Oct. 3 1932 Aug. 30 1- Sept. 9 37 l7 29 11 9 16 TABLE X-DAMSONS Acid as citric (cryst.) L Insol. t Sol. r Per Per Per Per Per Per Cent Cent. Cent. Cent. Cent. Cent, Description solids Stones solids Free Combined Total Rather small ripe and sound . . . . 1-92 8.4 - 2.53 0.58 3.11 Small ripe .. . . . . . 1.74 8.9 - 2.39 0.05 3.04 Mostly small ripe not fresh . . . . 2.26 9.9 - 2.21 0.63 2.84 Medium size ripe not quite fresh . . . . 2.15 10.8 - 2.05 0.60 2.65 Large fully ripe or over-ripe and wet with juice . . 2.18 7.3 - 2.01 0.63 2.64 Medium to small firm and fresh sour flavour 2.50 6.8 13.6 2.26 0.53 2-79 Mostly small ripe not fresh . . . . 2.39 7.7 13.0 2.49 0.64 3.13 Rather over-ripe . . . 2.43 5.8 15-6 2.14 0.64 2-78 ripe . . . . 1.44 4.6 14.8 2-01 0.38 2-39 Highest . . . . . . 2.50 10.8 15.6 2.53 0.65 3-13 Lowest 1-44 4.6 13.0 2.01 0.38 2.39 Average . . . . . . 2.11 7.8 14-25 2.23 0.59 2-82 Californian rather large some soft and over-No. of samples . . 9 9 4 9 9 9 t On entire fruit- other data on stone-free portion only.* These results a;e doubtful and are not included in extremes and average. TABLE XI-APPLES Acid as citric (cryst.) A Insol. Sol. r Per Per Per Per Per A-\ Cent. Cent. Cent. Cent. Cent, Hard green . . . a . - - 1.61 0.24 1-85 Hard green sour . . L . - - 1.37 0.19 1.56 Small green . . - - 1.27 0.28 1.55 Large green sour . . - - 1.61 0.22 1.83 Large green bruised . . - - 1.34 0.24 1.58 Small green bruised I - 1.24 0.20 1.44 Medium size beginning to ripen bruised . . - - 0.96 0.25 1.21 Medium size dark green hard bruised sweet taste - - 0.82 0.22 1.04 Very large beginning to redden and ripen slightly bruised . . I - 0.94 0.22 1.16 Medium size fairly ripe slightly bruised . . - - 0.82 0.30 1.12 Kentish . . . . . .. . 2.21 9.8 1.21 0-24 1.45 Hard yellow-green . . . . . . 8-09 11.2 1.15 0.28 1.43 Bramleys rather large green some rather sweet . . 2.61 11.1 1.08 0-24 1.32 Rather large green fairly sweet . . . . 3-20 11.7 0.82 0.28 1-Highest . . . . . . 3.20 11.7 1.61 0.30 1-85 Lowest a . . . 2-09 9.8 0-61 0.19 0.89 Average * . . ,. . . 2-53 11.0 1.12 0.25 1.37 No. of samples . . * . 4 4 15 15 15 Description solids solids Free Combined Total Medium size green but fairly ripe - - 0.61 0.28 0.8 Ilatc! 1029 Sept. 29 2930 Aug. 26 Date 1930 Aug. 25 3 7 Sept. 5 37 99 11 1931 Sept. 22 77 Oct. 1 1932 Sept. 24 3 ) 79 28 1934 -Description TABLE XII-BILBERRIES Acid as citric Insol. Sol. c solids Seeds solids Free Combmed Per Per Per Per Wr Cent.Cent. Cent. Cent. Cent. Cumberland (a small loss of juice occurred in transit) 3.87 - 9-4 1-10 Norwegian fully ripe good condition . . . . 3-96 2-31 - 1.21 TABLE XIII-BLACKBERRIES Acid as citric (cryst.) Insol. Description solids Per Cent. Large firm and black but not fully Large hedgerow fruit uneven ripe-ness . . . . . . 7.44 Hedgerow (Middlesex) medium size, firm uneven ripeness . . 9.72 Small fairly ripe wet with rain . . 9.55 Medium size fully ripe . . . . 9-15 Small not very ripe rather wet . . 9-47 Large uneven ripeness wet with rain 8.44 Medium size full ripe slightly wet Rather small fairly ripe and fresh . . 9-21 Medium size barely ripe some mould 9.64 Large fair condition but some mouldy . . . . 5-05 Rather large slightly under-ripe fresh condition .. . . 7.86 Highest . . . . 10-74 Lowest . . 505* Average . . . . 8.75 ripe * . -with juice . . . . 10.74 No. of samples . . 11 CANNED BLACKBERRIES. Solid Pack U.S.A. . . . 8.56 Seeds Per Cent . 4.34 5.56 7.30 8.01 7.65 7.63 -8.88 6.93 7-26 3.79 -8-88 3-79 6.73 10 I Sol. solids Per Cent. --- -----8.1 7.9 7.7 8.2 8.2 7.7* 8.0 4 Free Per Cent. 2.26 1.20 1.75 0.48 0.72 0.79 1.09 0.60 0.36 0.64 1.82 1-03 2-26* 0*36* 1.06 12 Combined P a Cent. 0.34 0.37 0.47 0.45 0-45 0.62 0.56 0-47 0.47 0.49 0.40 0.43 0.56 0.34 0.45 12 10.35 0-69 0.31 Total ' Per Cent.2.60 1.57 2.22 0.93 1.17 1.31 1.65 1.07 0.83 1-13 2.22 1.46 2.60 0-83 1-51 12 1.00 -0.24 Lead &-Aqueous 22-14.5 21.6 9.5 11.9 11.6 13-10.0 7.2 10.1 19-14.6 22.5 7.2 13.9 12 10. TABLE XIV-APRICOTS Datc 1932 July 1 1938 19 2 ¶% 99 2 1939 Jan. 6 Date 1932 Nov. 8 1937 Oct. 2 99 9% 2 99 77 2 99 %7 2 1938 Feb. 22 9’ Aug. 23 99 99 23 99 l 9 23 > > 97 23 Description Acid as citric (cryst.) Insol. t solids Stones s%s Fw Lead Per Per Per Per Per Per Cent. Cent. Cent. Cent. Cent. Cent. Aqueous - 1-16 5.5 9.9 0.92 0.62 1.64 14.7 Italian ripe . . . . 1.58 - 14.0 2-02; 0.67 2.69 27.0 Italian unripe . . . . 1.57 - 12.4 2.15 0.63 2.78 - . . 1.78 6.5 15.7 1.19 0.59 1.78 - South African .. Highest . . . . 1.78 6.5 15.7 2.15 0.67 2-78 27.0 Lowest . 1.16 5.5 9.9 0.92 0.59 1.54 14.7 Average . . . . 1.52 6.0 13.0 1-67 0.63 2.20 20.8 No. of samples . . 4 2 4 4 4 4 2 t On entire fruit; other data on stone-free portion only. Insol. Description solids Per Cent. - 1.24 Average pasty consistency . . . . 1.00 Average pasty consistency . . . . 1-20 Very thick and fruity . . . . 1.66 Average pasty consistency . . . . 1-15 South African . . 1.41 Spanish (casks) . . . . 0.92 Spanish (cash) . . . . 0.89 Highest . . . . 1.73 No. of snlnples . . * . 10 Syrian (casks) ,. . . 1-73 Syrian (casks) . . 1.54 Tdowest * . . . 0.89 Average . . . . . . . . 1.27 TABLE XV-APRICOT PULPS Acid as citric (cryst.) stotnes s 2 i s pw Per Per Per Per Per Cent.Cent. Cent. Cent. Cent. - 10.7 1.36 0.54 1.90 - 14.6 1.80 0.38 2.18 - 13.0 2.05 0.63 3-68 - 11.8 2.64 0.55 3-19 - 16-2 1-33 0.63 1.96 - 16.4 1-70 0.56 2-26 - 12.0 2.17 0.30 2.47 - 12.5 2-17 0.33 2.50 - 13.0 1.83 0.68 2.51 - 13.0 1-69 0.73 2-42 - 16.4 2-64 0.73 3.19 - 10.7 1-33 0.30 1-90 -._ 13-32 1.87 0.53 2.40 . __ 10 10 10 10 Lead &-Aqueous 20.8 24.0 27.0 33.0 22.4 20.3 28.2 28.3 27.2 27.4 33.0 20.3 25.86 10 Not determined when present; other data on stone-free portion only AND THE DETERMINATION OF THE FRUIT CONTENT OF JAMS 553 ‘ABLE XVI-EFFECT OF REMOVAL OF COLOUR ON THE LEAD NUMBERS OF REDCURRANT EXTRACTS No. Lead No. per 1 per cent. of total acid -- Aqueous Acetone 1 Before decolorising .13.6 16.0 After J J 13-2 15.2 2 Before , 13.5 16.3 After J J 13-3 14.8 The aqueous lead numbers (per 1 per cent. of acid) indicate that the average proportion of malic acid in this fruit is practically nil. In one sample it appeared to be as high as 20 per cent. but this again was one of the early analyses by the lead method and is open to some doubt. BZackcurrants.-The minimum figures for insoluble and soluble solids and free acid are lower than befor& and the averages for soluble solids and free acid are also appreciably lower. The proportion of seeds in the insoluble matter varies from 39 per cent. to 61 per cent. the average being 49 per cent. As with red currants the lead numbers per 1 per cent.of acid exceed the figures to be expected from citric acid. This again appears to be due to lead-precipitating effects of the colouring matter. The lead numbers and acidities were determined on the extracts of the last three samples after treatment with decolorising carbon. Appreciably lower figures for the lead numbers per 1 per cent. of acid were found and the acetone lead numbers were now much nearer the figure for citric acid or citric and malic acids. (Table XVII) TABLE XVII-EFFECT OF REMOVAL OF COLOUR ON THE LEAD NUMBERS OF BLACKCURRANT EXTRACTS Lead No. per 1 per cent. of total acid NO. - Aqueous Acetone 1 Before decolorising . . 13.9 16.5 After J J 12.4 15.0 2 Before , 13.8 16.5 After ,) 13.0 15.3 3 Before J 14-4 17.1 After , 12.6 15.4 Allowing for the average effect of the colouring matter as thus indicated the average lead number per 1 per cent.of acid shows that about 19 per cent. of the total acid is malic acid. The extreme figure found might indicate up to 35 per cent. but this was obtained in the early days of the lead method. In only one later sample does the proportion seem to be at all high-about 32 per cent. The pH values are on the whole rather higher (about 0.1) than would correspond to the proportion of combined to total acid assuming the latter to be citric acid or a mixture of citric and malic acids. Possibly somewhat high results may have been due to the upward drift during the determination mentioned earlier. This was often rather marked with blackcurrants.PZzcms.-The average figure for insoluble solids is higher than previously recorded,l but there is little difference in the averages for soluble solids and free acid. An appreciably higher maximum value for the insoluble solids is to be noted 554 HINTON AND MACARA THE COMPOSITION OF SOME JAM FRUITS Few samples were examined by the lead process as until the use of the pectin-free solution was introduced in 1932 the titrations with stone fruits were difficult and very probably in error. This may account for the very low figures (per 1 per cent. of acid) obtained for the two samples examined in 1931. The pH values when compared with the proportion of combined to total acid, were on the whole rather lower (about 0.1) than would correspond to the neutral-isation curves of either malic or citric acid.Greengages.-The average and maximum soluble solids are much higher than beforel; the same applies to a less extent to the free acid. Damsons.-A rather lower average than previously was found for the free acid? Extreme figures for insoluble and soluble solids and free acid all lie within the previous limits. The aqueous lead numbers indicate very little citric acid. The two results of this determination for 1931 samples are open to some doubt for the reason mentioned in discussing the results for plums. A$pZes.-No new extreme limits were established for insoluble and soluble solids and free acid and the averages for these are close to the previous ones1 There is some evidence on comparing the $H values with the notes on flavour and appearance that the $H followed the degree of ripeness the riper fruit having higher $H.A correspondence of this kind was not observed with the other fruits. BiZberries.-The Cumberland sample had lost a little juice in transit and the figure for insoluble solids may therefore be slightly high. The percentage of the soluble constituents would not have been appreciably altered however. Blackberries.-Lower minimum figures than before have been found for the insoluble solids and free acid; also a much higher maximum. The very wide range of free acid content shown by this fruit may be noted. Since the combined acid does not vary correspondingly the $H tends to follow the free acid and therefore also shows a wide range. Ajwicots and Apricot P.uZ$s.-No figures for apricots were included in the earlier paper.1 Although there is no absolute certainty a general consideration of the figures for each of the samples of pulp in comparison with the averages and with the data for the fresh fruit makes it reasonably likely that but little water had been used in their preparation.It may be mentioned that several other samples were met with in which the analysis pointed fairly definitely to the addition of an appreciable proportion of water. These of course have not been included. The lead numbers per I per cent. of acid would of course not be affected by any added water. They indicate about 40 to 50 per cent. of the acids to be malic. The $H values when compared with the proportion of combined to total acid, lie fairly close to the neutralisation curve of a mixture of equal parts of citric and malic acids.USE OF THE DATA IN DETERMINING THE FRUIT CONTENT OF JAMS Of the analytical characteristics included in the Tables the insoluble solids con-tent has perhaps been the most frequently used in assessing the fruit content of jams, but suffers from the disadvantage of the possible uneven distribution of the fruit from jar to jar. This difficulty does not apply to the soluble constituents of the fruit since these as a result of the boiling are fairly evenly distributed throughout the liquid or jelly portion of the jam including that part which permeates the fruit itself and the effect of the uneven distribution of the fibrous portions of the fruit is negligible. Unfortunately the total soluble constituents derived from the fruit cannot be determined in a jam because of the merging of these constituents part of which are sugars in the added sugar in the jam.Hence the data for soluble solids content AND THE DETERMINATION OF THE FRUIT CONTENT OF JAMS 555 although affording a useful and independent figure in the examination of fruit pulps, are useless for jams. The acid and salt constituents (free and combined acid) are however available, but here again certain difficulties arise. In the first place when a jam is made from sulphited fruit pulp any oxidised SO in the pulp remains as sulphate in the finished jam an equivalent amount of free fruit acid being liberated from the salt constituents. Hence the free acid will be higher and the combined acid lower than in the original fruit.The sum of the two however will be unaltered. Under such conditions, therefore only the total fruit acid in the jam can be accepted as being directly related to that in the original fruit. A second difficulty arises from the possible presence in the jam of added liquid pectin containing a certain amount of acid derived from the apple material used as a source or added for the purpose of extracting the pectin. The lead precipitation method2 was introduced to overcome this difficulty and gives useful results with the citric acid fruits. Another source of uncertainty is the possible addition during the boiling of the jam of some acid or salt such as citric acid or a citrate. The magnitude of this difficulty however should not be exaggerated.It is very unlikely that any such additions would amount to more than the equivalent of a few per cent. of fruit in the jam; otherwise the effects on flavour colour or setting properties would be likely to be objectionable. INTERPRETING REsuLTs-The discussion of these points indicates that the determination of the fruit content of a jam is beset with difficulties and in general the results are only approximations unless the composition of the fruit used in making the jam is known. It should be noted however that the lower the fruit content the closer the results will be to the truth (in terms of percentage of fruit in the jam). As stated in a previous communication,l it is unwise to rely on the insoluble solids figure alone especially when this is obtained from only one sample.With the best will in the world it is not possible for the manufacturer to ensure that the fibre of the fruit is uniformly distributed throughout all the jars from a single batch. Public Analysts meet with a serious difficulty in this respect for should it be found desirable to initiate a prosecution under the Sale of Food and Drugs Act they must confine their report to the official sample. On the other hand it has been a growing practice of many authorities of late years to take informal samples and while the results of these cannot be referred to in a prosecution the knowledge obtained from their analyses should strengthen the analyst’s conclusions. If the analyses of two or more samples of the same make of jam are compared it will generally be found that while the insoluble solids may vary considerably the total acidity and other constituents are reasonably uniform.When this happens it would obviously be unfair to base an opinion on the insoluble solids figure obtained in the analysis of the official sample if this happened to be lower than the results obtained from the informal samples. If all the determinations suggested below are carried out a much sounder conclusion can be arrived at from a consideration of all the figures for fruits containing mainly citric acid. It is true that the lead numbers are much less helpful with fruits containing mainly malic acid e.g. plums apples etc. but generally these fruits are so cheap that there is little inducement to lower the quality of the jam seriously.In calculating the fruit content of a jam from all the analytical data both the minimum and average figures for the particular fruit should be used. Should the results calculated from the lead numbers and acid figures on the minimal basis indicate a deficiency in fruit the analyst would be justified in initiating proceedings. It would not however be safe to accept the results based on a similar calculation from the insoluble solids figure unless they were confirmed by results obtained fro 556 HINTON AND MACARA THE COMPOSITION OF SOME JAM FRUITS other samples or by those calculated from the acid figures and lead numbers on the basis of average data. When a low fruit content is indicated by the calculation of all constituents on the basis of the average data for these constituents it is suggested that no prosecu-tions should be initiated but that the manufacturers should be given an opportunity of proving that the full quantity of fruit was used.These instances occur as the result of more than the normal amount of condensed steam entering the pulp. Steam pulps must always contain condensate. It should be noted in this connection that fruit preserved with sulphur dioxide sometimes contains excess of water and the manufacturer may be unaware of this fact. This occurs not infrequently with blackcurrant pulp which is steamed before preservation and arises from an excessive condensation of steam. Without a full analysis of the contents of each cask it is difficult to detect occasional casks of such pulp. Manufacturers have been warned to buy pulp made by the hot process on the basis of weight of fresh fruit per cask, and to check this by determinations of the acidity and specific gravity of the juice.It should be noted that so far no single sample of fruit has been found to contain the minimum percentages of both the insoluble solids and acids. With the rasp-berries containing the lowest percentage of insoluble solids the acids were up to the average. Blackcurrants having a low insoluble solids have been found to contain less acid than the average but always more than the minimum. Therefore when considering the results it should not be necessary to base a decision on the results calculated from all constituents on the minimum basis. A microscopical examination of the jam should always be made particularly of jams containing seeds e.g.raspberry jam. Cases have been known in which seeds had been added in substantial amount to a raspberry and gooseberry jam but the very low proportion of raspberry fibre other than seed revealed the sophistica-tion which was afterwards admitted. The proportion of seeds to fibre is also a valuable indication of this form of adulteration. Some results are given in the tables indicating the proportions generally occurring in the original fruit. IMPROVEMENTS IN THE LEAD PRECIPITATION METHOD AS APPLIED TO JAMS In applying the lead method to jams as described in the original paper,2 ex-perience has revealed some minor difficulties and sources of uncertainty. These and the means of dealing with them are described below.FILTRATION OF JAM SOLUTION.-Fi~tration of the 50 per cent. extract of the jam through paper is often slow. This can be avoided by using coarse muslin or a 30-mesh sieve. POSSIBLE ERROR IN DETERMINATION OF COMBINED AcID.-Errors in the deter-mination of the combined acid have been found to arise owing to traces of sulphates or chlorides in the jam. These substances when ignited at even a moderate tem-perature in presence of an excess of sugar decompose and form carbonates thus increasing the alkalinity of the ash and causing the combined acid to appear high. If sugar is absent or is present only in relatively small proportion as in the fruits themselves this decomposition does not occur at least with small amounts of these salts. It was found that the effect could be prevented by adding a sufficient amount of alkaline material such as potassium or calcium carbonate to the solution before ashing.For 50 ml. of pectin-free filtrate 30 ml. of N/10 potassium carbonate solution is a suitable addition. In dissolving the ash subsequently of course more acid is required and in calculating the alkalinity of the ash that of the added carbonate must be deducted. shown in the original paper2 that the proportion of lead malate which is precipitated varies somewhat with the amount present and with the amount of citrate also present. AVOIDANCE OF ERRORS I N THE PRECIPITATION OF THE LEAD MALATE.-It Wa AND THE DETERMINATION OF THE FRUIT CONTENT OF JAMS 557 The proportions of the two acids must be kept within certain rough limits in order to secure precipitation of a constant proportion of the malate.This was provided for in analysing different fruits by arranging for the amount of fruit extract taken for the analysis to be varied and for suitable amounts of either malic acid or citric acid to be added according to the kind of fruit. These arrangements may sometimes be interfered with in determining the aqueous lead number of jams containing much added pectin. The presence of the latter entails that a larger proportion of malic acid is present than in the fruit from which the jam is named. This means that the jam from a fruit which is naturally a “citric acid fruit” (Group ii) comes to resemble in its acid content a “mixed acid fruit” (Group i); and a jam from a “mixed acid fruit” (Group i) approaches a “malic acid fruit” (Group iii).There will be a tendency for the lead malate to be precipitated to a smaller extent than under the standard conditions. This is most likely to occur with gooseberry apricot or blackberry jams containing much liquid pectin. The difficulty can be overcome by treating the jam in question according to the group it tends to resemble. Thus for the aqueous lead number of an apricot jam of this type the amount of pectin-free filtrate to be taken will be that containing about 0.65 g. of total acid; and instead of 3 ml. of 10 per cent. malic acid solution, 3 ml. of 5 per cent. citric acid solution will be added. Usually it is known before-hand that the sample is one likely to require this modification. If this is only dis-covered after the analysis has been carried out in the usual way the determination of the aqueous lead number should be repeated as modified.The acetone lead number does not appear to be liable to this source of error. INSUFFICIENCY OF SOLUTION FOR TITRATI0NS.-It sometimes happens in analysing jams very low in acid content that the amount of pectin-free filtrate available is insufficient to permit of using the proper amount for the aqueous lead number. In that event the deficiency may be made up with a definite amount of citric or malic acid as required. An allowance for this can be made though the accuracy of the final lead number is reduced to some extent. An alternative method is to take two-fifths quantities for the lead number determinations the amounts of reagents of course being reduced in the same proportion and to make up the mixture to 100 ml.before filtration. For the first rough titration 25 ml. of the filtrate should be taken the full 50 ml. being used for the final titration. ADDITION OF MALIC OR CITRIC ACID TO CONTROL THE PRECIPITATION OF LEAD MALATE.-It has been pointed out that there is a lack of clarity in the requirement that the strength of the solutions of these acids should be correct to within 1 per cent. of the total.2 This statement means that the strength of the solutions should be within the range 9.9 to 10.1 per cent. or 4.95 to 5.05 per cent. respectively and does not refer to the total acid in the solution taken for the test. described in connection with the analysis of the fruits (see p.542). be present in jams as a natural constituent of the fruit or as a result of oxidation of sulphur dioxide either in pulp used in making the jam or to a negligible extent, in the jam itself. Lead sulphate is partly insoluble under the conditions of the aqueous lead precipitation and completely so under those of the acetone lead precipi-tation. In the former neither the amount precipitated nor the amount retained in solution is constant; both vary with the amount of sulphate present in the mixture. This effect is seen in the following experiment in which different amounts of sulphate were added to solutions prepared to represent jam solutions under examination by the aqueous lead test. Mixtures as shown (Table XVIII) were dissolved in water and each was treated with 20 ml.of 10 per cent. lead acetate solution made up to 250 ml., Some of the acid is also perhaps lactic acid. IMPROVEMENT IN END-POINT OF THE LEAD TITRATIoN.-This has already been CORRECTION OF LEAD NUMBERS FOR SULPHATE PRESENT I N JAMs.-sulphate ma 558 HINTON AND MACARA THE COMPOSITION OF SOME JAM FRUITS mixed and filtered. The titrations with molybdate were carried out as usual, on 50 ml. of filtrate two individual workers each making two titrations. The averages of the four titrations of each filtrate are shown in the Table. From these figures it is possible to derive corrections to be applied to the titration of the aqueous lead number. These are shown in Table XIX. The determination of the sulphate can be made on the ash if the precaution is taken of adding excess of alkali prior to ashing as already described (p.556). TABLE XVIII-LEAD PRECIPITATED IN THE AQUEOUS LEAD TEST BY VARYING AMOUNTS OF SULPHATE (7.5 ml. of 5 per cent. citric acid 10 ml. of N/10 NaOH and 50 g. of sugar in each mixture) Potassium sulphate added with molybdate precipitated by sulphate g. ml. ml. 0 . 0 9.81 -0.0125 9.66 0.15 0.025 9-60 0.31 0 - 050 9.41 0.40 0 * 075 9.30 0.51 Back titration Difference due to extra lead The acetone lead number is also raised by any sulphate present. Here the lead sulphate is completely precipitated and the correction is therefore equal to the lead equivalent of the sulphate present. Each 0.01 g. of K,SO in the amount (P) of pectin-free filtrate used for the test requires a deduction of 0.25 ml.from the titration difference before the acetone lead number is calculated. TABLE XIX-CORRECTION FOR SULPHATE (AQUEOUS LEAD NUMBER) Sulphate as K,SO, in the amount (P) of pectin-free filtrate taken R. 0.01 0.03 0.03 0.05 0.07 0.10 Deduction from titration difference ml. 0.1 0.3 0 . 3 0.4 0 . 5 0 . 6 It may be mentioned that the amounts of sulphate in jam only become significant in this respect when fruit pulp containing much oxidised sulphur dioxide or sulphite has been used in manufacture. MODIFIED CALCULATION OF THE FRUIT CONTENT FROM THE LEAD NUMBERS.-In the earlier paper2 the acetone lead number (per 1 per cent. of total acid) in a jam containing no lactic acid was taken to be 15 the value for citric or malic acid.On this figure was based the calculation of and the allowance for any lactic acid which might be present. The data now reported show that the value is usually slightly higher than 15, and appreciably higher with black- and redcurrants. For these fruits it was shown that the high figures appear to be due to the colouring matters. These colouring matters are not removed in the ordinary way and as in any event they are natural constituents of the fruit it seems more correct in calculating the fruit content of jams to use the average value for the acetone lead number of the particular fruit in question. For blackcurrants which with redcurrants differ most widely from the figure for the pure acids a calculation shows that the fruit content indicated will be about 2 per cent.too low if the figure 15 is used in place of the average figure 16-25 found for that fruit. The percentage of lactic acid calculated from the acetone lead number is likely to be more nearly correct if a value appropriate to the kind of fruit present is used AND THE DETERMINATION OF THE FRUIT CONTENT O F JAMS 559 For convenience in reference the average values for the lead numbers (per 1 per cent. of acid) of the fruits are collected in Table XX and the average total acid contents are also shown. The values of L and A are those to be substituted in formula VI of the earlier paper2; and the values of L,’ are those now to be used in TABLE XX-AVERAGE VALUES FOR THE TOTAL (PER 1 PER CENT. OF ACID) Total acid Per Cent. (A,) Gooseberries 2.37 Strawberries 1-31 Raspberries .. 2.07 Redcurrants 2.87 Blackcurrants . . 3.86 Blackberries 1.51 Apricots . . 2.20 ACID CONTENT AND LEAD NUMBERS OF JAM FRUITS Aqueous lead Acetone lead number per 1 per number per 1 per cent. of total acid cent. of total acid (Ll) (h’) 10.36 15.4 12-68 15.31 13.36 15-34 13.46 16 - 25 13-47 16-25 9.22 15.4 10-6 14.9 place of the citric or malic acid value of 15 in forming an opinion as to the presence of lactic acid and in calculating and correcting for it. It should be noted that if I t the acetone lead number per 1 per cent. of acid corrected for sulphate as described above lies above the value of L for the fruit in question there can be no allowance for lactic acid to be made in evaluating I (aqueous lead number per 1 per cent.of acid) since obviously there cannot be a negative amount of lactic acid. The fact that I’ lies above the average value for the fruit simply means that the fruit used is slightly divergent from the normal. There may actually be a small amount of lactic acid present but in such a case it is clearly impossible to allow for it. The error is not likely however to be significant. For routine tests the titration of the ash to arrive at the combined acid (and hence the total acid) may sometimes be omitted reliance being placed simply on the acetone lead number for finding the total fruit acid (i.e. less lactic acid). The corrected value of a for substitution in formula V12 is then given directly by In such a shortened procedure in order to find the amount of pectin-free filtrate to be used for the lead number determinations it is necessary to make a guess at the approximate total acid content from the free acid titration alone. In conclusion we wish to thank Messrs. Chivers & Sons Ltd. for help in obtaining samples of fresh fruits from Holland and the Council of the Research Association for permission to publish this work with a view to assisting in the maintenance of the Jam Standards. REFERENCES 1. 2. 3. 4. T. Macara ANALYST 1931 56 35. C. L. Hinton id. 1934 59 248. T. Macara id. 1931 56 391. - id. 1935 60 592. BRITISH ASSOCIATION OF RESEARCH FOR THE COCOA, CHOCOLATE SUGAR CONFECTIONERY AND JAM TRADES HOLLOWAY LONDON N.7 Muy 15th 194

ISSN:0003-2654    

DOI:10.1039/AN9406500540

出版商:RSC    

年代:1940

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/AN9406500560

出版商:RSC    

年代:1940

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/AN9406500562

出版商:RSC    

年代:1940

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9406500563

出版商:RSC    

年代:1940

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/AN940650565b

出版商:RSC    

年代:1940

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/AN9406500566

出版商:RSC    

年代:1940

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN940650568b

出版商:RSC    

年代:1940

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/AN9406500569

出版商:RSC    

年代:1940

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9406500570

出版商:RSC    

年代:1940

数据来源: RSC