ISSN:0003-2654    

DOI:10.1039/AN94873FX009

出版商:RSC    

年代:1948

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94873BX011

出版商:RSC    

年代:1948

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94873FP013

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN948730123b

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

128 KENT- JONES AMOS ELIAS BRADSHAW AND THACKRAY [Vol. 73 The Micro-Analytical Test for Purity in Food with Special Reference to Cereals BY D. W. KENT-JONES A . J. AMOS P. S. E L I A S R. C. A. BRADSHAW AND G . B. THACKRAY (Read at the Meeting of the Society on February 4th 1948) INTRODUCTION THE examination of food by what is known in the United States as a micro-analytical technique for the presence of extraneous matter has in recent years seriously occupied the attention of the Food and Drug Administration in that country. It is now common practice in the United States for such tests to be made daily in the laboratories of mills, bakeries confectioners and biscuit and cake manufacturers since if a high count for extraneous dirt is found in food prosecutions may follow.This test is commonly known as the “Filth Test,” and it is not applied only to the examination of cereal products. Indeed, even in baked goods there is evidence that many of the other ingredients are more impure than the cereal portion. At this stage our main experience however has been with cereals, so this paper deals essentially with the analytical procedure in determining extraneous matter (filth) in these products. Unfortunately such extraneous dirt may also be a significant factor in most other foods such as spices chocolate milk meat products and fruit. The micro-analytical test should therefore be capable of being universally applied to foods although the technique employed must vary according to the nature of the food. The technique of this micro-analytical procedure is admirably dealt with in the U.S.Food and Drug Administration Circular No. 1,l and considerable space is devoted to the matter in the last (sixth) edition of Official and Tentative Methods of Analysis of the Association of Official Agricultural Chemisk2 For tests on cereals attention is also drawn to the Report of the New York Section of the American Association of Cereal Chemists.3 There can be of course many types of extraneous matter such as grit floor sweepings, earthy matter excreta (especially rodent excreta) but in general the micro-analytical test as it is understood to-day is mainly directed to the determination of rodent hairs and of insect mould and other fragments. If rodent hairs are found this is prima facie evidence that there is also likely to be contamination with excreta even though direct evidence of this is often harder to find.Rodent faeces always contain a mass of rodent hair and wheat is occasionally contaminated with such rodent excreta which are not easily separated from the grain and which when ground up in the rolls cause the presence of rodent hairs in the flour. Two small pellets of dry rodent faeces (weighing together 20 mg.) contained nearly 100 rodent hairs. The rodent hair may be regarded in the same way as B. coli in potable water that is to say not so much harmful in itself but presumptive evidence of undesirable uncleanliness. If solid excreta are present in what may be regarded as an appreciable quantity they can usually be separated by shaking the powdered finely-crumbled product with a liquid of sp.gr.about 1.49 in a separating funnel which permits the ground cereal to float and the excreta to fall. No definite standards are set in the United States for such extraneous matter i.e., for the number of rodent hairs or insect fragments per 100 g. of material. Food should be essentially free from extraneous material; if it is not warnings are issued and in bad cases prosecutions undertaken. Cleanliness in manufacture and the taking of precautions, consequent upon the findings of those dealing with the examination of dirt in food have un-doubtedly resulted in cleaner food. While there is no direct evidence of harm to health from the presence of such matter in food yet all- will agree that if food can be made cleaner and under more hygienic conditions this should certainly be done.There is. of course a limit to the implications of the test and they should not be pushed to extremes particularly in view of the inherent difficulties of the method. First the dirt and extraneous matter have to be separated from the food and secondly they have to be recognised and counted and for this second step it is generally necessary to employ a microscopic technique. In this paper we give the results of our experiences in this field after many The so-called micro-analytical test comprises two distinct steps March 19481 THE MICRO-ANALYTICAL TEST FOR PURITY IN FOOD 129 months of work and we gratefully acknowledge the initial help we received from many friends in the United States who allowed some of us to see the test in operation in the first place.We have examined many of these and give what we consider to be improved procedures. The test as described, can be carried out in any ordinary food laboratory and although it is desirable to employ, purely for ease of operation certain attachments in using the microscope these are not essential. They only render recognition of extraneous matter easier make the work less laborious and assist in obtaining better agreement on counts. Different laboratories there have slightly different techniques. SEPARATION OF EXTRANEOUS MATTER AND FILTRATION The food must be partially digested in vitru so that the extraneous matter can be separated but the digestion procedure employed must be one that rodent hairs insect fragments such as portions of mites (tyroglyphids) weevil and meal worms and even mould fragments can withstand without losing their distinctive microscopic features.Strong alkali, which destroys hair must be avoided. Starch must be hydrolysed and protein broken down by enzymic digestion. The actual separation which follows the digestion is normally done by shaking up the digested food with a light mineral oil such as petrol. The oil preferentially wets the rodent hairs insect fragments etc. which then float up and congregate at the oil/water and oil/glass interfacial layers. The bulk of the lower layer containing the food (once all the extraneous matter has been removed from it and for this more than one extraction with the mineral oil is necessary) is discarded and the dirt collected by filtering the petrol and the residual interfacial layer through a ruled filter paper on a Buchner funnel.Other procedures and variations are discussed later. For convenience of working we have used in routine tests 25g. of the foodstuff and if this is a baked product it has to be remembered that in making this receives a good mixing in the dough stage. In the United States often 100 g. of material or more are used but obviously steps should be taken to ensure, as far as is possible that the sample represents a fair average of the food being tested In important “border line ” cases a larger quantity than 25 g. is necessary and the test should be made in duplicate or triplicate. Before beginning the food digestion some preliminary fat extraction is desirable except for such foods as flour where the fat content is low for example below 2 to 3 per cent.As the solvent will “wet ” the rodent hairs precautions must be taken to see that no extraneous matter is lost at this stage. A useful way to effect this is to tie the sample in a filter paper bag. When the defatted material is subsequently removed the filter paper should be washed down with solvent or alcohol and these washings evaporated in the beaker used for the digestion. The earlier recommendations using salt and not digesting the food are not satisfactory and result in inaccurate and low counts. In one digestion method the cereal is mixed with excess of water (say up to 250 or 350 ml. for 25 g.) boiled to gelatinise the starch and cooled to about 35” to 45” C.; 0.5 to 1.0 g. of pancreatin is sprinkled on and the digestion carried out a t this temperature for some 3 to 6 hours or even longer. In another digestion method 400 ml. of dilute hydrochloric acid are added to the cereal food and the mixture is boiled in presence of a light mineral oil. After 15 to 20 minutes boiling the mixture is cooled to room temperature and the extraneous matter removed from the interfacial layer. From the results of our experiments we prefer a third method which is based on that given by the A.0.A.C.2 and is essentially a combination of the two methods just described. I t is given in detail later. This method which involves both boiling with acid and digestion with pancreatin is preferred as the digested food is in a less viscous state so that the sub-sequent extraction with petrol is easier emulsions are less likely to be formed and the final counting operation is facilitated.We have carried out tests on the same flour (85 per cent. extraction) by the three methods. Low counts result from the first method (use of pancreatin only) and although there is reasonable agreement between the second method (acid boiling and no pancreatin) and the method we suggest we prefer the latter for the reasons stated. With respect to apparatus two types are in use for extracting the digested food with petrol or light oil. There is the apparatus known as the Wildman trap illustrated in Fig. 1. This consists of a conical flask (say about 1 litre capacity) containing on a brass rod of approximately 3/16inch diameter a rubber bung which when pulled up fits into the neck The question of sampling is an important one.Several procedures have been advocated for the digestion of cereal foods 130 KENT-JONES AMOS ELIAS BRADSHAW AND THACKRAY [Vol. 73 of the flask. The rod threaded at the end carries a nut and washer fastening the bung. The nut should be countersunk to prevent breakage of the flask during use. The amount of liquid used is such that when the bung is pulled up by the rod into the neck of the flask, it is possible to pour off for filtering the supernatant oil and the interfacial filth layer without interference from the bulk of the liquid containing the digested food. This apparatus is particularly applicable to coarse materials such as dried fruits whole wheat and the like.For the examination of ground cereal products we prefer the alternative method in which special separating funnels are used-a procedure which we believe is gaining ground in America. These separating funnels which are shown in Fig. 2 should have a capacity of about 600 ml. or larger if a quantity of more than 25 g. of material is taken. The usual stop-cock is removed and replaced by a rubber tube of diameter about 9 mm. which can be closed with a strong screw clip. The rubber exit tube should be renewed fairly frequently as other-wise minute cracks may develop on the inner surface and retain hairs. .- - . Fig. 1. Wildman Trap. __.* _,.-.__.- I Rubber Tubing Fig. 2. Special Separating Funnel. It is the usual practice in the United States to filter the interfacial layer etc.on a smooth filter paper and we have found that the smooth side of a No. 1 Whatman paper is suitable. The paper can be ruled horizontally with pencil lines. The distance between the ruled lines depends on the magnification being used and it is convenient to rule so that the distance between two consecutive lines can be covered by two fields of view. With the magnifications we use normally this width is about 6mm. If this is done it is also helpful to have some vertical lines so that the paper can be mapped out and suspected hairs or insect fragments easily re-found when necessary for further examination. The paper is examined wet and if the count is not carried out immediately it should be kept covered for example in a Petri dish so that no dirt is lost and no dirt falls on it March 19481 THE MICRO-ASALYTICAL TEST FOR PURITY IN FOOD 131 Details of the complete procedure that we finally adopted as the most convenient and the most satisfactory for the extraction and collection of extraneous matter are as follows :-METHOD-Weigh 25 g.of the material de-fat if necessary and put into a 400-ml. beaker. Boil 100 ml. of 0.5 N hydrochloric acid in a separate beaker add the boiling acid quickly to the material and stir into a paste thoroughly for 30 seconds before placing the 400-ml. beaker over a small flame. Avoid the presence of unwetted material on the bottom of the beaker; any suitable procedure to effect this will suffice. If the paste seems too thick dilute somewhat with hot water. Boil the mixture for 10 minutes cool and dilute with about 100 ml.of distilled water. Add about 9.5 ml. of 5 N sodium hydroxide, stirring to avoid local concentration ; add 2.5 ml. of saturated trisodium phosphate solution and adjust the $H to 7.0 using phenol red (0.2 per cent. aqueous solution) as external indicator by adding a few drops of acid or alkali as necessary. When the temperature falls below 40" C. add 1 g. of pancreatin which should be free from any contamination suspended in 20 ml. of water. Dilute to about 350 ml. mix thoroughly and incubate at about 37" C. overnight. Pour the digest into a special separating funnel of about 600-ml. capacity prepared by cutting off the tap and replacing it by a wide rubber tube with screw clip. Add 25 ml. of petrol. Allow to separate for 20 to 30 minutes.Run off the bulk of the digest into the original beaker, but leave sufficient to form a small layer under the interface. Keep the removed digest for a second separation. Add to the layers in the funnel about 400ml. of distilled water. Mix gently by swirling and allow to separate. Draw off and reject the washings and add a further quantity of distilled water. Mix allow to separate and draw off most of this second washing. Run the liquids remaining in the funnel through ruled filter paper on a Buchner funnel or collect by one of the alternative methods described later. In the filter paper technique the paper should rest upon a light layer of kieselguhr to avoid the debris congregating over the holes and the paper should be large enough t o extend some distance up the sides of the funnel.Replace the original digest in the funnel and extract again with petrol as before. Remove the bulk of the digest and then wash the petrol and the small volume of digest underlying the interfacial layer twice with distilled water as previously described. Reject the washings and collect as before. Wash down thoroughly the inner surface of the separating funnel and of the rubber outlet tube with alcohol from a wash bottle and finally with distilled water. In view of the firmness with which hairs tend to adhere to the glass the addition of a few drops of a wetting agent such as Teepol to this final water wash is advised. Collect any extraneous matter in these washes. Serious errors can arise through not properly washing out the glass apparatus and leaving hairs on the glass ware.Procedures for examining microscopically the extraneous matter collected on the ruled filter paper or by other means are described later. Report the results as the number of specified contaminants e.g. rodent hairs or insect fragments etc. per 100 g. of sample or as is now customary in the United States, per pound. Although filtering the collected extraneous matter through paper as described has advantages an important one of which is that it imposes no restriction on the volume of liquid employed to detach and wash the extraneous matter yet there are also advantages in running the petrol - water mixture direct on to a ruled glass surface from which it is evaporated. Methods using the latter procedure make easier the subsequent microscopic examination.Two such methods that we have employed are given below. (1) Allow the washed petrol extracts together with the interfacial layer and a small amount of the aqueous layer to fall drop by drop on an inclined ruled glass slide fixed at approximately 10" to the horizontal. For convenience this slide should be of the width of a microscope slide but twice to three times as long. At a point 4 inches from the lower end it is just cleared by a microscope slide held a t an angle of approximately 10" to 15" to it. The liquid dropping down the long glass slide is spread between the two glass surfaces into a wedge-shaped film approximately 1 cm. long. The long slide is supported clear of a suitable heater covered with Shake gently to distribute the petrol throughout the solution 132 KENT-JONES AMOS ELIAS BRADSHAW AND THACKRAY [Vol.73 asbestos so that when the liquid flows slowly down the glass evaporation takes place and it is fmally held as the wedge-shaped film until evaporation is complete. This is most successfully accomplished if a thermometer resting on the microscope slide registers 50" to 60" C. according to the liquid being evaporated. (2) Allow the washed petrol extracts together with the interfacial layer and a small amount of the aqueous layer to evaporate on a water-bath in a Petri dish suitably ruled. Ensure that at any one time there is not much liquid in the dish. This prevents hairs etc. climbing the sides. Rinse out the separating funnel and rubber exit first with 20 ml.of alcohol and secondly with 20 ml. of water containing a few drops of Teepol. Evaporate these under the usual conditions in the same Petri dish. Ensure by suitable manipulation that the debris is evenly distributed over the centre of the dish and away from the edges; this requires washing the edges in the final stage with light petroleum. Just cover the deposit with about 1 ml. of a 3 1 mixture of castor oil and alcohol. With some coarsely ground cereals such as oatmeal or wheatmeal difficulties are encountered because branny particles tend to collect in the interfacial layer and render n . . . Prism rdector -ins. Fig. 3. Suitable arrangement for projection method of making counts. difficult the subsequent microscopical examination. We have tried various procedures to minimise the interfering effects of bran particles by adjustment of the time of digestion and the use of 40 per cent.alcohol in the shaking out but have had little success. In such instances it is advisable to spread the debris over a larger surface when examining under the microscope. MICROSCOPIC EXAMINATION AND COUNT The collected extraneous matter can be examined microscopically in the following ways (1) Viewed by reflected light from the filter paper as is the normal practice in the United States. (2) Viewed by transmitted light either through the filter paper oiled with castor oil, for example to make it translucent or through a ruled glass surface direct. (3) As in (2) but throwing the magnified image on a suitable screen by means of such an arrangement as is described later.and the appearance of the dirt is influenced by the means employed March 19481 THE MICRO-ANALYTICAL TEST FOR PURITY IN FOOD 133 It is necessary to be conversant with the appearance of the most common types of extraneous matter likely to be encountered and on this matter considerable valuable information will be found in the Food and Drug Circular No. 1 already mentioned especially with reference to insect fragments. Another useful reference book is that issued by the Ministry of Food entitled “Insect Pests of Food.”* The question of hairs is dealt with later in this paper but it has not been possible to deal in similar detail with insect fragments. In the United States it is customary to rely entirely on viewing the ruled filter paper, on which the dirt is collected by means of reflected light.This procedure is sound but the counting is often tedious each filter paper often taking 2 or 3 hours. It is equally as simple to use transmitted light which we in fact prefer. The filter paper is allowed to dry naturally and then treated with just as much oil as it will absorb. Castor oil diluted with 25 per cent. of alcohol is a convenient medium but paraffin is also satisfactory. The paper is placed between two glass plates pressed and examined by transmitted light . The separated and collected extraneous matter is examined microscopically and counted, normally at a magnification of 35 to 70. Any ordinary microscope will suffice although the modem binocular type such as the Greenough, is very suitable as it involves less eye-strain.We have found it convenient to work at a magnification of about 50 (although 35 would suffice) and a field of view of about 3mm. With an ordinary microscope this is obtained with a 1-inch objective and a x 8 eyepiece. A convenient arrangement is shown in Fig. 3. This consists of a special projection lamp such as “Cosmos 55,” 6 volts 5 amps., together with a lens to focus the beam on the iris diaphragm of the microscope at a distance of about 9 inches. A projection lamp can be bought with transformer case and lens complete. With this arrangement it is possible to throw the image on a screen by means of a prism fixed to the eyepiece. We recommend placing the screen which should have a glossy smooth surface-we use art paper-about 15 inches from the microscope which with the 1-inch objective and x 15 eyepiece gives a picture about 10 inches in diameter.The magnification 1 I I I I I I I J b View A View 6 I I 1 --- - - ----1 0 t 2 ins. SCALE Fig. 4. Mechanical stage suitable for counting procedures using Petri dish or glass plate. on the screen is about 130 to 150 an& under these conditions the appearance of the hairs, etc. is rather different from that as seen direct in the microscope. The magnification is greater but the clarity is reduced. There is considerably less strain on the eye with this arrangement but it may be necessary to verify doubtful hairs and other objects by taking off the prism and looking (through a dark glass) direct in the microscope.If the filter paper procedure is not adopted but a method involving evaporation direct on a glass surface, the microscopic examination either direct or particularly via the screen is much easier. Counts can be made by moving the ruled paper or glass by hand. This however is tedious and difficulties arise in ensuring that a portion of the field is not overlooked or counted more than once. Hence some sort of mechanical stage is desirable. Such a device is shown in Fig. 4 and with this arrangement the dish should be ruled in concentric circles. The stage is essentially a brass plate 3& x 44 x & inches which rests on the table of the microscope. The plate has a rim 4 inch deep which slides against the side of the microscope table.In the rim is a groove through which passes a lock-nut. Cut in the brass plate is a circular trough in which the glass dish just fits. A portion of the brass plate is cut away to allo 134 KENT- JONES AMOS ELIAS BRADSHAW AND THACKRAY : the light to pass. The dish just protrudes sufficiently to be turned by the finger thus enabling the plate to be revolved and hence all of it to be viewed with a minimum of trouble. An alternative stage consists of a smooth aluminium platform 6 x 9 inches bolted to the microscope through the holes that normally hold the slide grips with another smooth aluminium plate 44 x 6 inches sliding on this. Two pieces of wood about Q inch thick are screwed down on each side of the sliding aluminium plate and the Petri dish or glass plate, just fits between them.The dish can thus be moved up and down each ruled line to permit convenient counting. The sliding plate has a piece of wood screwed across the top which fits underneath the aluminium platform thus acting as a guide and enabling linear traverse to be made. If a microscope with a stage having a good traverse in both directions is available, there is no necessity to make a special stage for counting the glass slide or the horizontally ruled filter paper. Each analyst will use whatever technique appeals to him but we recommend direct evaporation on glass and the examination of the deposit by transmitted light throwing the image on a screen. Under these conditions the count can be made in 40 to 60 minutes. [Vol. 73 It is important for the analyst who is new to this test to know on what to concentrate, and we have felt it desirable to simplify the matter in the following way even if the proposed classification is not perfect.Even then different operatives may get somewhat different results especially in differentiating rodent hairs from other hairs and in the insect fragment counts . (1) The count should be reported as:-(a) Number of rodent hairs. (b) Number of other hairs. (c) Number of insect fragments. (d) Number of mould fragments etc. Since the most important factor is the number of rodent hairs reported only absolutely typical rodent hairs should be reported as such. This may mean that a few less typical rodent hairs may be missed or reported under the heading of other hairs but except in bad cases the count of the other hairs is not regarded as serious.It is essentially the typical rodent hairs that indicate contamination with rodent faeces. The rodent hairs regarded as typical-containing striated medulla-are shown in Figs. 5 and 6 and they probably represent 90 per cent. or more of the total rodent hairs. We have come to this conclusion after examining ground-up rodent faeces (which always contain a mass of rodent hairs) and hair from different body-parts of numerous types of rats and mice. (3) Vegetable fibres such as the hair from cereal products shown in Fig. 11 are not reported. (4) Difficulty is encountered with insect fragments and only those reasonably easily recognisable should be reported. It is true that a very prolonged examination of certain doubtful cases may increase the insect fragment count but as previously stated there is less objection to insect fragments except when the count is excep tionally high.In normal working we select for further examination only those fragments that do not show the colour and structure distinctive of the material under test. These can then be examined for confirmatory evidence such as shape and outline internal structure (as in larvae) or a covering of minute hairs. If any evidence of this kind is present the fragment is counted (a procedure to intensify the colour of insect fragments has been set out in the journal of the Association of Official Agricultural Chemistsb). A high insect count is an indication that the mill requires a thorough cleaning out and probably fumigation.(5) A close watch should be kept for mould fragments as an indication of unsoundness of the food. Bearing these facts in mind we feel it necessary to be able to recognise not only typical rodent hairs (there being no obvious difference between rat and mouse hairs except perhaps in size) but also human hair of various colours cat and dog hairs vegetable fibres cereal hairs and the more obvious insect and mould fragments. The lower magnifications and this applies also to Figs. 5 and 6 are as seen down the microscope, These are shown in Figs. 7 to 13 a b C d e Fig. 5. Characteristic rodent hairs. Rat hairs a b, c d and mouse hair e at a magnification of 60 diameters. a b c d e Fig. 6. Rodent hairs as in Fig. 6 but at a magni-fication of 150 diameters Q b C Fig.7. Human hairs a t a magnification of 60 diameters (a blonde ; b red ; c brunette). a b c Fig. 8. Human hairs as in Fig. 7 a t a magnification of 150 diameters a b Fig. 9. Animal hairs a t a magnification of 60 diameters. a dog; b cat. U b Fig. 10. Animal hairs as in Fig. 9 a t a magnification of 150 diameters. Fig. 11. A typical field as obtained from flour showing wheat hairs and bran a t a magnification of 60 diameters Fig. 12. Insect fragments a t a magnification of 60 diameters. Fig. 13. Fibre a t a magnification of 60 diameters March 19481 THE MICRO-ANALYTICAL TEST FOR PURITY IN FOOD 135 and the higher magnifications are as seen on the screen. (All the photographs shown were made after evaporation on glass and not after using the filter paper technique.) There is no difficulty in differentiating between rodent hairs and human hairs.The photographs of animal hairs given in this paper however need a little qualification to avoid misinterpretation. Some cat hairs under high illumination do show striations in the medulla. The cortex or outside portions of the hair however contain so much pigment that the striations do not persist when the illumination is reduced by means of the iris diaphragm. When viewed by reflected light or projected on the screen the illumination is automatically lower; the cat hairs therefore appear completely black as shown in the photograph. Some dog hairs have a medulla similar to that shown in Fig. 6 ( d ) but all the dog hairs we have seen have a distinct band of black pigment along each edge which is absent in the rodent hair.For ultimate diagnosis the reader is referred to Food and Drug Circular No. 1,l but for most purposes the above rules suffice. RESULTS OBTAINED First an effort was made to obtain some idea of the recoveries that might be expected when a known number of rodent hairs were added to flour. These results are shown in Table I and indicate that considering all the difficulties involved the test is satisfactory for the information required. TABLE I RECOVERY RESULTS Petri dish procedure No. of ham Percentage recovered recovery v Original flour . . . . 0 No. of rodent hairs added per 100 g. Long hairs (30 mm.) . . 16 16 80 80 Short hairs (1 mm.) . . 16 20 80 78 100 100 126 97.6 Oiled filter paper procedure No.of hairs Percentage recovered recovery r - 0 20 126 72 90 16 100 a4 106 It has been suggested that it is difficult to recover in baked goods the exact number of hairs known to be present in the ingredients. Much depends on the digestion methochmployed but so far we have not been able to make enough experiments on this point to speak with confidence on this aspect of the problem. Table I1 gives some results of applying this test to cereal products. The table gives an idea not only of the results obtained but also of the agreement between different operators, and other factors. It must be remembered that the question of sampling has to be borne in mind and also that the figures given are the result of multiplication by four since only 26g.are used in the actual test. The results are summarised in Table 111. It was not found possible to use the method given in this paper for all these products. The currants for example left much skin at the interfacial layer even after repeated washing. This made counting difficult and therefore the figures given are on the low side. With the prunes on the other hand the method was quite satisfactory and needed no modification. With regard to chocolate and spices our work has confirmed the conclusion reached by the Committee of the New York Section on Procedures for the Examination of Food Products for Extraneous Materials (1947)6 that the general methods used for cereals are not satisfactory for this type of product. We have therefore used the method described in that report.This consists essentially of heating the material under reflux together with dilute hydrochloric acid acetone and light mineral oil followed by a separation similar to our own except that shaking to mix the two layers is unnecessary and should be avoided. We do not propose to deal in detail with the application of this test to non-cereal products our present impressions being that the divergence between the results of different operators may be greater than that now likely to be obtained with cereal products if the method used in this paper is followed. Further work however may well effect an improvement in this situation. A selection of non-cereal products was also examined 136 KENT-JONES AMOS ELIAS BRADSHAW AND THACKRAY [Vol.73 TABLE I1 EXTRANEOUS MATTER (DIRT) CONTAMINATION OF CEREAL PRODUCTS All results reported are per 100 grams of product examined Insect Sample Rodent hairs Other hairs fragments Imported Canadian flour (white) . . Duplicate-same operator . . Imported Australian flour (white) . Duplicate-same operator . . a . A series of imported American flours (all white) . . 0 0 0 4 32 4 8 4 12 0 4 8 Home-milled biscuit flour (white) . . * . Duplicate-same operator . Home-milled biscuit flour (85 per cent. extraction) Duplicate-another operator . . A series of home-milled flours (all 86 per cent, extraction) . . m> s> 0 28 16 4 12 0 0 0 40 72 16 0 4 0 36 16 0 44 8 24 32 8 (many) 8 4 (many) 4 Two home-milled flours (85 per cent.extraction) . . Note the other (First figure in each case our own. lab. used 50-g. samples.) 4 l:j 0 Two flours from New Crop (1947) wheat . . (First figure in each case our own. Note the other 4 0 lab. has reported only the rodent hair count.) Two flours from Old Crop (1946) wheat . . (First figure in each case our own. Note the other lab. has reported only the rodent hair count.) 12 Wholemeal . . 160 0 16 Oatmeal . . 120 0 0 Bread . . 4 32 0 Breakfast foods (flakes) . . 48 0 8 Biscuits (brown type including a meal ingredient) two samples . . # . 24 0 16 40 0 12 Biscuits (butter) . . . I 24 16 0 Christmas pudding (farinaceous portion) . . . . 16 (fruit portion) . . f . 12 0 8 0 March 19481 THE MICRO-ANALYTICAL TEST FOR PURITY IN FOOD TABLE I11 137 EXTRANEOUS MATTER (DIRT) CONTAMINATION OF NON-CEREAL PRODUCTS All results reported are per 100 grams of product examined Sample Insect Rodent hairs Other hairs fragments Currants 0 4 20 Prunes 0 0 16 '2} Ground mixed spices .. Duplicate-another operator . . Chocolate . . Duplicate-another operator . GENERAL OBSERVATIONS This paper is mainly concerned with indicating an analytical technique to deal with the determination of extraneous matter (filth) in cereal products. Procedures have been described which should enable the analyst to obtain reasonably reliable results. It may be desirable, however to indicate how improvements in the cleanliness of cereal products could be brought about.It has been admitted that in baked goods often the factor responsible for a high count is not the cereal but the other ingredients but it must be remembered that usually these other ingredients are used in smaller proportion than the flour. Yet sometimes even flour has a higher count than is desirable and possibly a higher contamination than is usual in the United States where recent improvements in purity have taken place since the micro-analytical tests have been instituted. It must not be assumed from these observations that flour milled in Great Britain is not normally of high purity. Compared with other foods it is good although milling to long extraction aggravates the position particularly as the extraction of 86 per cent.has to be obtained on dirty wheat and this means that millers are reluctant to remove as much screenings (including rodent dung) from wheat as was formerly usual. In fact if this test is to be applied and a new standard of purity insisted upon there is a clear case for a revision of the method of calculation of the extraction from a dirty wheat basis to a clean wheat basis. Naturally this would necessitate a limit to the amount of screenings that it would be permissible to extract. The British miller as well as those engaged in the manufacture of cereal products is a skilled and conscientious manufacturer but special care in rat and mice proofing is desirable, as well as constant attention to cleanliness generally including that of sacks. It is our view that most of the trouble comes from the presence of rodent faeces (and particularly mice faeces) in the wheat; these are not easily removed unless special steps are taken and it is not always easy to do this.The screen room of a mill is largely designed to remove impurities from the wheat prior to the grinding operation the methods being based on differences in size and shape between wheat and the impurities. The difficulty is that the faeces vary so much in size and shape. Special procedures for removing dry faeces may be proposed, but probably much can be done by efficient scouring of the wheat followed by strong aspiration. If such steps are not taken, the count of rodent hairs may vary considerably from time to time according to the contamina-tion of the grain with faeces.According to some determinations made on every fifth sack, results of which were kindly sent us by other workers in this field white flour from certain reasonably clean new crop wheat gave per lOOg. rodent hair counts of nil to 4 while the counts on the old crop more highly contaminated with faeces was 12 to 40 and averaged about 28. On the whole and in view of all the circumstances our results suggest that generally the standard of purity of flour is reasonable but capable of improvement. It has been suggested that the rodent hairs in the faeces become disintegrated in milling so that a simple record of the number of hair fragments may be misleading. Our experience is that there is. little substance in this view since the average length of hairs in faeces and in flour is similar.We have attempted to make certain grinding experiments on mixtures of faecal pellets and wheat measuring the length of hair fragments in both the carefully teased out originap pellets and in the contaminated flour after grinding. Satisfactory control in such experiments is difficult but the general results confirmed the view we have already expressed. Flotation in the washing process may also help 138 KENT-JONES AMOS ELIAS BRADSHAW AND THACKRAY [Vol. 73 There is however a case to be made for the proposal to report not merely the number of hair fragments but the total length of the hairs. This would not be difficult to do approximately as judging from the extent to which it stretches across the field of view the diameter of which is known the worker knows the length of each fragment and hence the total length.The hair fragments vary from below 1 mm. to occasionally as high as 10 mm., but a little under 2mm. would seem to be the average length of the majority of the hair fragments. SUMMARY Improved methods which include several differing techniques for the examination of cereal foodstuffs for the presence of extraneous matter are given and photographs of hairs, etc. are shown to assist in identification of such matter. A procedure is advised for separating the extraneous dirt from the food (evaporation on glass is preferred to filtration) and an arrangement is shown by which the image of this dirt is thrown on a screen. This last step relieves eye-strain and makes generally for greater accuracy. Some results of applying the method are presented.We gladly acknowledge the assistance we have had from many helpers and mention in particular Dr. J. B. M. Coppock Director of the British Baking Industries’ Research Association and Mr. C. H. Groves who was responsible for the photographs. REFERENCES 1. 2. 3. 4. 5. 6. Food and Drug Administration of the Federal Security Agency Circular No. 1. “ Oficial and Tentative Methods of Altalysis of the Association of Oficial Agricultural Chemists,” “Report of the 1945-46 Committee of the New York Section on Procedures for the Examination “Insect Pests of Food,” Ministry of Food 1943. “Report on the Determination of Extraneous Materials in Baked Products Cereals and Eggs,” “Report of the 1946-47 Committee of the New York Section on Procedures for the Examination of 6th edition 1945 p.78. of Flour for Extraneous Materials,” Ceveal Chem. 1947 24 39. Kenton L. Harris J. Assoc. Official Agr. Chem. 1946 29 62-65. Food Products for Extraneous Materials,” Cereal Chem. 1947 24 283. 88 MADELEY ROAD and BRITISH BAKING INDUSTRIES’ RESEARCH ASSOCIATION CHORLEYWOOD LODGE CHORLEYWOOD HERTS. EALING LONDON W.5 DISCUSSION Dr. E. B. HUGHES said that the Society was very much indebted to the authors for this valuable paper. Dr. Kent-Jones had presented the paper in an admirable way and had been very fair to the industries concerned with the problem. This added one further example to the many which had earned him his excellent reputation and members would be very grateful to him. Dr.J. B. M. COPPOCK expressed his pleasure that his colleague Mr. Bradshaw had been able to participate in this work and asked whether the authors could indicate what an average rodent hair count in flour would correspond to in terms of number of wheat grains per piece of rodent faeces. Mr. R. W. MORRIS asked whether the test would give misleading results if applied to products such as chocolate that were subjected to severe grinding. Would not rodent hairs and insect fragments get ground Mr. N. HERON described a modification of the American technique that was found to be satisfactory in a recent examination of biscuits for rodent hairs. The material a t the interface was transferred to a No. 640 Whatman filter paper ruled with lines 6 mm. apart and the paper and residue were washed once with alcohol.The paper was then transferred to a Petri dish containing a layer of chloral hydrate less than 1 mm. deep and allowed to stand for about ij hr. but not more than 2 hr. a t room temperature. It was then examined by transmitted light a t a magnification of 25 with a binocular microscope. The light beam was focussed by a concave mirror the source of light being a Pointolite lamp fitted with a condenser. The characteristic markings of rodent hairs were readily recognised but any doubtful hairs were removed with fine forceps and examined at 160 diameters. Although chloral hydrate causes some swelling of animal hairs there is not sufficient distortion under the conditions described above to prevent recognition of rodent hairs. Miss E. I.BEECHING asked to what extent the use of the Entoleter would destroy traces of animal or insect faeces or debris and interfere with the correctness of counts. Mr. T. H. FAIRBROTHER said he thought the Entoleter would cause some breaking up of the faeces, and it is necessary to have a complete sieving system put in immediately before the Entoleter. up March 19481 THE MICRO-ANALYTICAL TEST FOR PURITY IN FOOD 139 Dr. N. L. KENT said that the use of the Entoleter on washed English wheat containing rodent excreta pellets caused slight breakage of the wheat with practically no break up of the rodent pellets. Mr. F. C. HYMAS asked if it would not be possible a t least with flour to concentrate the fragments on a smaller surface than that of a Petri dish and so reduce the tedium of counting.Dr. J. H. HAMENCE asked whether in view of the serious implication that might arise from the finding of “rat excreta in flour,” it was possible to distinguish between rodent hairs that were excretory and those that might be introduced into flour otherwise e.g. owing to rats having rubbed themselves against flour bags. Furthermore he asked if it was possible to detect the presence of mites’ eggs in cereal products by the method described. Mr. J. KING remarked that Dr. Kent-Jones in his textbook had dealt adequately with the widely-differing bacterial counts in flours. Did any correlation exist between bacterial counts and rodent hair counts? Mr. C. L. CLAREMONT asked if comparisons had been made of counts for cereal products from large and small producers and if any attempt had been made to identify insect fragments e.g.whether due to Tribolium or Ephestia. Mr. J . G. HAY asked if it was known whether loss of hair by rats was subject to any seasonal variation. Dr. E. C. WOOD asked if Dr. Kent-Jones had any evidence as to the homogeneity of flour such as would be obtained from counts on a dozen or more separate 25-g. samples of the same flour. In other words was it not possible that occasional faecal aggregates or clumps of insect fragments might survive the process of milling and give rise to high counts not truly representative of the batch in odd single samples ? Dr. E. E. TURTLE drew attention to the importance of attempting to correlate with counts of fragments the general hygienic conditions in premises in which flour is produced.It was also most desirable to carry out bacteriological tests in conjunction with counts. He pointed out that in a technique involving digestion with pancreatin there was a possibility that insect fragments other than those containing chitin would be destroyed. Under certain conditions this would be important because some insects a t stages in their life cycles e.g. some larval stages have only very small proportions of chitin. They might therefore be completely digested during the preparation for microscopic examination. Mr. D. W. POVEY speaking as one concerned with flour milling engineering pointed out that although by basing the flour extraction on clean wheat instead of according to present-day regulations it would be possible for millers to remove a great deal of rodent excreta with existing available plant a perfect separation would not be possible because the physical properties a t present employed as a basis of separation do not remain in the case of rodent excreta a constant factor.New plant and methods are however being devised employing entirely new principles by means of which it is hoped to effect a perfect separation, but this will take some time. I t should be appreciated that a t the present time even with an extraction based on clean wheat it would not be possible to produce a flour entirely free from rodent hairs. It is far better to remove rodent excreta in the whole state than to break them up and endeavour to remove the hairs; these attach themselves firmly to the bran skins and are most difficult to remove.This point is illustrated by the comparative high contamination of whole meal flour. Professor E. S. HAWKINS drew attention to the special importance of contamination in oriental grain, rodents being a more dangerous scourge in the East than here. Mr. E. G. RAYNES asked if the authors had any information as to the standards used by American authorities in rejecting foodstuffs exported from this country. Mr. C. H. MANLEY mentioned that a year ago he examined a large tin of dried full-cream milk that the purchaser suspected of containing m‘ouse dirt. About fifty dark particles about Q in. long were isolated from it. Some were single and some in pairs but they were not dark enough in colour to be mouse dirt, nor did they contain undigested wheat fibres.They had a reticulate surface and contained some small spiral vessels. Mr. D. M. FREELAND said that the authors’ figures indicate that wheat left standing some time before being milled showed increased counts of “impurities” in the flour. This seemed to call for improvement in the farmer’s technique. With biscuit flours the tests also showed appreciable quantities of sandy and earthy matter in flour; if millers could once more resort to wheat washing before milling much of this, together with excreta and insect fragments would be eliminated. Had the authors found that the pancreatin used varied much in quality and if so did they recommend the use of any particular brand? Mr. P. S. ELIAS in replying to questions said that the authors had no experience of seasonal variation in the hair content of rodent faeces.From the large number of such pellets examined the figure seemed to be reasonably constant. Whether the hairs came from faeces in the grain or from direct contact with rats and mice was of little consequence as there was bound to be contamination if rodents had access to flour. Mr. BRADSHAW said that taking into account the length of time necessary to make each count it was not practical or indeed desirable to spend additional time identifying the insect from which each fragment was derived. There was no evidence as far as he knew to show that rodent contamination of They were believed to be seeds but their origin and identity could not be ascertained TRAUTNER AND ROBERTS THE SEPARATION OF HYOSCXNE AND Fol.73 cereals suffered from any seasonal fluctuations. The distribution of rodent hairs throughout a bulk of flour was already under consideration and 25 samples each from the same bag of flour were being examined. As to variations in the quality of pancreatin there was no evidence to suggest that this had caused difficulties in the test. Mr. THACKRAY said that the authors had no experience of the chloral hydrate method suggested by Mr. Heron but he wondered whether this treatment would cause swelling of the hairs and undesirable distortion. He agreed that it was desirable to concentrate the dirt as far as possible but an area about 4 inches in diameter was as small as it was desirable to go to in view of the amount of bran especially in present-day flours. Quite a large number of larvae had been noticed including larvae from the house fly.About Mr. Manley’s observations on milk he thought that the absence of rodent hairs was conclusive evidence that material found in the milk did not contain rodent faeces. Dr. AMOS replying to Dr. Coppock’s query said that the data given in the paper showed that the presence of 4 to 5 rodent hairs per 100 g. of flour would correspond to the presence of one fragment of mouse excreta of about 20 mg. weight in about 6 lb. of wheat. Although this might seem to some people a high contamination he had recently seen in the West Country native English wheat which in the small sample examined contained one fragment of rodent excreta in each 300 to 400 g. of wheat. H e knew of no experi-mental evidence on the effects of passage through an Entoleter upon rodent hairs present in the stock, but he did not think it likely to break the hairs into small fragments.Insects however were likely to be disrupted on passing through an Entoleter with a consequent increase in the insect fragment count of the stock but trials were being made in America on wheat with strongly aspirated Entoleters with a view to removing the insect fragments produced by the machine. Results had been encouraging and developments along these lines might be expected. Dr. Amos said that the point raised by Mr. King was an interesting one but no information was available upon the relation between the rodent hair contamination and the bacterial population of flour. If a flour were grossly contaminated with rodent excreta it might exhibit a significantly high bacterial count but he did not think it likely that there would be a positive correlation between the two factors in normal commercial flours.Bacteriological studies which he had made some years ago revealed that by far the majority of the bacteria present in flour were epiphytic micro-organisms from the wheat and the numbers of such organisms on different types of wheat-and wheats substantially free from rodent excreta-varied so widely that the bacterial population of the resulting flour could not serve as a reliable index of rodent contamination. Dr. Amos said that he thought that Mr. Claremont was correct in his assumption that generally speaking the smaller and older mills would have a more difficult task than the large modern mills in maintaining the Contamination of their flour at a low level. Many of the older and smaller mills were constructed partly of wood and would be much more difficult to render rodent-proof than the brick and concrete mills built to modern design. Moreover in normal circumstances, many country mills would employ a considerably higher proportion of native wheat than would the large port mills and native wheat was the worst offender as a source of rodent excreta. In reply to Mr. Raynes, Dr. Amos said that the Food and Drug Administration in America had not divulged what standards they had adopted for rodent hair and insect fragment contamination. An American chemist had however, stated in a private communication,. that there was no tolerance. but there was reason to believe that at the moment exception would only be taken to the presence of more than 5 rodent hairs per lb. of flour. The data presented in the paper which included some American flours indicated that such a standard was at the present time not always being attained. Oriental grain had not so far been examined. As to the presence of eggs a few had been observed

ISSN:0003-2654    

DOI:10.1039/AN9487300128

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

140 TRAUTNER AND ROBERTS THE SEPARATION OF HYOSCXNE AND Fol. 73 The Separation of Hyoscine and Hyoscyamine and the Alkaloidal Assay of Duboisia SPP. BY E. M. TRAUTNER" AND M. ROBERTS THE two alkaloids hyoscyamine (with which is included atropine) and hyoscine occur together in several of the Solanaceae and are usually determined as total alkaloids and calculated in terms of one or the other A survey of the literature indicates that little attention has been directed towards a procedure for the separation of such mixtures. Kuhn and Schafer,f taking advantage of the fact that hyoscine is a weaker base and more soluble in ether than hyoscyamine claim that if an acid solution of the mixed alkaloids be made slightly alkaline with sodium bicarbonate and extracted three times with ether then the combined ether extracts contain the whole of the hyoscine together with a small proportion of the hyoscyamine.The latter can be removed by evaporating the ether solution to dryness and repeating the procedure twice after which the final ether extract will contain all the hyoscine in a pure state. Rowson2 found this procedure to be unsatisfactory and proposed a process of fractional * Department of Physiology University of Melbourne Australia March 19481 HYOSCYAMINE AND THE ALKALOIDAL ASSAY OF PUBOZSIA SPP. 141 liberation of the hyoscine the extraction being repeated until a sharp transition was reached between an oily alkaloidal residue (hyoscine) and a crystalline alkaloidal residue (hyoscyamine -atropine). Besides being of doubtful accuracy this method is not applicable to quantities of hyoscine less than 20 mg.Two methods are described in the present paper first an approximately quantitative separation of the alkaloids by means of chromatographic adsorption on activated silica and subsequent fractional elution and second the separation and identification of the components of a mixture of alkaloids by fractional precipitation of their picrates. EXPERIMENTAL (i) Fractionation of hyoscine and hyoscyamine on a silica column-It has been found that 6 to 10mg. of the mixed alkaloids can be satisfactorily separated on a silica column; both hyoscine and hyoscyamine are strongly adsorbed from bedzene solution but whereas hyoscine is rapidly eluted by absolute alcohol this solvent moves hyoscyamine only slowly.COLOUR CODE HYOXY-AMINE (5 m9.1 SILICA COWMNS 12 )r I cm. Fig. 1. Hyoscyamine-bearing Duboisia Leichhardtii extracts on alumina and silica. The extracts were prepared by treating the powdered material with dilute sodium carbonate and percolating with benzene. The silica columns are divided the left-hand side showing actual positions and colours of adsorbed leaf pigments the right-hand side the additional red and yellow zones made visible by dimethyl yellow. Column (a) zones after adsorption of extract from benzene. Column ( b ) zones after development with 10 ml. of benzene - ether mixture (1 + l) showing adsorption-free space between alkaloids and shifted pigments. Column ( c ) zones after washing with a little alcohol which quickly elutes the bulk of the pigments but leaves a dirty green-brown band on top of the silica.Columns (d) and (e) demonstrate the removal of this dirty green-brown band by a short alumina layer (indicator added to the silica only). Column (d) zones after adsorption of benzene extract. Column (e) zones after washing with 16 to 20 ml. of absolute alcohol. Most of the pigments are eluted through both columns by alcohol but the silica retains up to about 4 to 5 mg. of hyoscyamine in an extended zone. Roberts and James3 experienced some difficulty with this procedure for neither alkaloid can be detected on the column by viewing in visible or ultra-violet light. This was overcome and the whole investigation greatly facilitated by the observation that if a trace of dimethyl-amino-azo-benzene (butter yellow dimethyl yellow C.I.19) is dissolved in the benzene solution of the alkaloids the dye is weakly adsorbed by the silica to give a brilliant red colour, except where the alkaloids are preferentially adsorbed and there a yellow band of the un-absorbed dye is visible By elution with ether or absolute alcohol the dye is rapidly removed; if these solvents are then replaced by benzene or better light petroleum containing a little dye the adsorption zones reappear and it can be seen which have been eluted separated or spread. In this way the different stages of the separation of the alkaloids from a benzene extract of a hyoscyamine-bearing Duboisia Leichhardtii on a silica column can be demonstrate 142 (Fig. 1). The dirty green-brown band at the top of the silica column is not removed by absolute alcohol; this band is retained on the alumina if the composite alumina - silica column of Roberts and James3 is used (Fig.1 ( d ) and ( e ) ) The most satisfactory f o m of silica has been found to be “Granulated Neosyl” (Peter Spence & Sons Ltd. Widnes) in SO/lOO mesh. Before use this should be carefully washed with a 50 per cent. aqueous solution of acetic acid followed by water and after drying, activated by calcining for 12 hours. Water and moist solvents inactivate the silica rapidly and irreversibly ; hence all such materials should be thoroughly dried before use. Commercial “crystallisable ” benzene is not satisfactory for use for it occasionally gives a considerable yellow adsorption band at the top of the silica column owing to the presence of pyrroles and other impurities ; these Contaminate the alkaloidal fractions and prevent clean crystallisa-tion of the picrates.It is advisable to test all solvents used by passing a small portion through a silica column; if any visible adsorption takes place the contaminated material should be purified by passage through the column. The efficiency of the separation of hyoscine and hyoscyamine by fractional elution from a silica column with absolute alcohol is dependent to some extent upon the dimensions of the column. That generally used in these experiments (12 cm. x 1 cm.) will allow the removal of as much as 10 to 12 mg. of hyoscine in the first 20 ml. of alcohol while retaining up to about 4mg. of hyoscyamine even if the volume of eluant is increased to 30ml.If conditions are suitable the first 15 ml. of alcohol contains the bulk of the hyoscine; the fractions between 15 and 25 or 30 ml. are almost free from bases (usually less than 0.1 mg. per 5ml.) while hyoscyamine begins to be eluted as the volume of solvent exceeds 30ml. (at the rate of about 0.5 to 1 mg. per 5 ml.). Removal of the hyoscyamine is more efficiently carried out by de-activating the silica with 3 to 4 ml. of 20 per cent. ammonia solution and eluting with 30 to 40ml. of chl~rofom.~ With careful manipulation the total recovery of alkaloids by the elutions with absolute alcohol and ammoniacal chloroform combined is within 3 per cent. of the correct amount, although if the elution be carried out in small fractions and these are determined separately, the errors of micro-titration or of colorimetry may add up to a discrepancy of 5 to 10 per cent.Again whilst hyoscyamine is quantitatively recovered from a silica column by elution with ammoniacal chlorofonn there is a small fraction of hyoscine that is not eluted by absolute alcohol although it is readily removed by ammoniacal chloroform. The amount of hyoscine so held appears to depend upon the quantity and quality of the silica used; it is consider-ably reduced in the presence of hyoscyamine. Thus with the column described above (12 cm. x 1 cm.) this amount varies from about 0.9 mg. for pure hyoscine to 0.15 to 0.3 mg. in the presence of 3 or 4 mg. of hyoscyamine. For the most efficient separation it is advisable, therefore to arrange that the total alkaloids submitted to the separation procedure should contain between 3 and 4 mg.of hyoscyamine; even so the figure obtained for the hyoscyamine content will tend to be slightly high. The best results are obtained by using mixtures of alkaloids in which the ratio of the amount of hyoscine to that of hyoscyamine lies between the limits 1 4 and 6 1. The fractions obtained are pure enough to give crystalline picrates by the method described below even when only 1 or 2 mg. of alkaloid are present. From the above considerations it follows that a mixture of hyoscine and hyoscyamine containing less than 10 per cent. of the former cannot be separated on a silica column unless it be first submitted to a partial fractionation by some method such as that of Kuhn and Schafer.l An extract of belladonna for example gives the total alkaloids in the hyoscyamine fra~tion,~ there usually being not more than a few per cent.of hyoscine in the total alkaloids extracted from this drug. Results obtained by submitting mixtures of hyoscine and hyoscyamine in varying proportions to the chromatographic separation are shown diagrammatically in Fig. 2. The alkaloid in the separate fractions was determined by adding a measured excess of 0.02 M sulphuric acid warming to remove excess of alcohol and any remaining benzene and titrating the excess of acid with 0.01 N sodium hydroxide using B.D.H. “4460” indicator. When extracts of solanaceous drugs are submitted to the fractionation procedure it is advisable to examine the hyoscyamine fractions titrimetrically and in addition by the method of Allport and Wil~on,~ employing a modified Vitali reaction since all the stronger bases collect in the hyoscyamine fraction.This is particularly true of Duboisia spP. since here the pro-portion of alkaloids other than hyoscine and hyoscyamine is of ten considerable and cannot be neglected. TRAUTNER AND ROBERTS THE SEPARATION OF HYOSCINE AND [Vol. 7 March 19481 HYOSCYAMINE AND THE ALKALOIDAL ASSAY OF DUBOZSZA SPP. 143 (ii) Fractional precipitation of crystalline eicrates from a mixture of hyoscine and hyoscyamine-It has been observed by Trautner Neufeld and Rodwells that if a chloroform solution containing hyoscine and hyoscyamine (not less than 6 mg. of each per ml.) be titrated with a 0.05 N solution of picric acid in chloroform using dimethyl yellow as indicator and slightly over-titrating to the formation of a distinct orange colour well-formed needles of hyoscine picrate separate immediately while hyoscyarnine picrate remains in solution and can only be induced to crystallise by addition of considerable amounts of ether or light petroleum.Using trichloroethylene as solvent these workers describe a rapid method for the assay of hyoscine - hyoscyamine mixtures based on this principle; they found that if the concentration of the bases was about 0.1 N reasonably accurate results could be obtained by weighing the precipitated picrates. IIr--- 5mL. alcohol fractions 5 I0 IS 20 2s p 5 rnl. alcohol fractlons 3 0 9 2 x 9 2 3 9 % % m d F' gl ' 5 10 I5 20 25 0 4 5-0 L fractions 5 mt.alcohol fractions Fig. 2. Separation of hyoscine and hyoscyamine in varying proportions on silica columns (12 cm x The alkaloids were adsorbed from benzene hyoscine was washed out with 25 ml. of absolute alcohol Hyoscyamine and any retained hyoscine were eluted with Titration values are represented by blocks, The mixtures used 1 cm.) . and collected in 5-ml. fractions for titration. ammoniacal chloroform and estimated after removal of solvent. shaded for hyoscine and unshaded for the fraction eluted by ammoniacal chloroform. in the experiments had the following composition given in mg. hyoscine + mg. hyoscyamine: (a) 1-03 + 4.02 (total alkaloids recovered 4-90mg.). (b) 2.06 + 3.22 (recovered 5-15 mg.). (c) 4.11 + 2-41 (recovered 6-36 mg.).(d) 5-14 + 1.61 (recovered 6-47 mg.). (e) 7.20 + 0.80 (recovered 7.46 mg.). If this procedure is applied to a solution of hyoscine in chloroform containing 0-5 mg. per ml. no precipitation of the picrate takes place; however addition of an equal volume of benzene (AnalaR grade) causes small clusters of crystals to be deposited within 24 or 48 hours and the separation is usually quantitative. A similar treatment applied to a solution of hyoscyamine in chloroform containing the highest concentration possible in a small-scale assay about 5 mg. per ml. does not cause any precipitation even when the proportion of benzene is increased three or fourfold. To precipitate hyoscyamine picrate it is necessary to add sufficient ether or light petroleum to produce a persistent milkiness and then on standing an initial crop of stout prismatic crystals foms in clusters; if the base is in the racemic form (atropine) the picrate crystallises similarly in thin blades.The separation of hyoscyamine picrate under these conditions is not quantitative; further crops of crystals are obtained on continued addition of ether or light petroleum and a total of three to fou 144 TRAUTNER AND ROBERTS THE SEPARATION OF HYOSCINE AND tvoi. 73 volumes of light petroleum are necessary to give almost complete precipitation but it is not advisable to add this amount of solvent at one time because this tends to cause the hyoscine picrate to separate as an oil which crystallises slowly and badly. A solution containing only 0-3 mg.of hyoscine per ml. will give a satisfactory separation of the picrate but if hyoscyamine or other solanaceous alkaloids are present this minimum concentration may rise to as much as 2 mg. per ml. according to the relative proportions of the bases (see Table I). The alkaloid fractions obtained by the separation of a mixture with a silica column are sufficiently pure to form picrates that are readily identifiable by melting point if not less-than about 0.5 to 1.0 mg. of total bases is present. After washing with fresh portions of the same solvent mixture as that from which precipitation occurred followed by drying at 105" C. hyoscine picrate usually melts at the correct temperature 187" to 188" C . ; the hyoscyamine picrate is frequently less pure and may melt at a temperature several degrees lower than the correct value 165" to 166" C.TABLE I Minimum concentration of hyoscine separable as picrate Proportions of hyoscine to hyoscyamine mg. per ml. 10 0 0.30 (pure hyoscine) 7 3 0.36 6 6 0.50 3:7 1.0 1 9 1.0-2.0 In their unpublished work on Dzlboisia sp$. Trautner and Rodwell developed an alter-native procedure in which the picrates are crystallised from a two-phase system. The mixture of alkaloids in ether solution is poured carefully over an equal or smaller volume of water containing excess of picric acid. A cloud forms at the junction of the layers and, on standing overnight well-shaped crystal clusters separate at the interface and on the walls of the containing vessel in both phases. This method is useful in certain circumstances because it effects a partial separation from minor alkaloids and allows crystallisation of the important bases when with a single-phase system only oily products are formed.By this two-phase procedure nor-hyoscyamine has occasionally been found in hyoscyam me fractions but with less than 30 to 50mg. of alkaloids reliable results cannot be obtained. The separation of hyoscine and hyoscyamine picrates as described above is too slow t o be of practical analytical importance since a better and more rapid fractionation can be achieved with a silica column. It is however useful if it is necessary to establish the identity of the main alkaloid present in the hyoscyamine fraction. APPLICATIONS (i) Assay of a sample of Duboisia myofioroides (Qzceensland Australia)-About 0.5 g., accurately weighed of powdered leaf was moistened with dilute sulphuric acid and washed with ether to remove the greater part of the ether-soluble matter and the alkaloids were extracted by treating the washed drug with a mixture of equal volumes of chloroform, previously saturated with ammonia gas and ether.The extract was evaporated to dryness, the residue dissolved in chloroform the solvent removed and the residue again dissolved in chlorofonn. The proportion of non-volatile bases present was approximately determined by titration with $-toluene sulphonic acid in chloroform using dimethyl yellow as indicator. The end-point was not sharp but the volume of acid used corresponded to between 17 and 20mg. of total alkaloids calculated as hyoscine.After a further purifikation of the total alkaloids by transferring to dilute acid and then to ether the mixed ether extracts were dried, the solvent was removed and the residue dissolved in 25 ml. of benzene. The alkaloids were separated by transferring 10 ml. of this benzene solution to a chromato-graph column* consisting of a 2-5-cm. layer of activated alumina (type H from Peter Spence & Sons Ltd. Widnes; activated by treating with 50 per cent. acetic acid washing with distilled water and after drying calcining for 24 hours) arranged above a column of activated silica the dimensions of which approximate to 12 cm. x 1 cm. The alumina does not retain the alkaloids from alcohol but adsorbs colouring matter and much other material. Th Much 19481 HYOSCYAMINE AND THE ALKALOIDAL ASSAY OF DUBOISZA SPP.145 combined column was eluted with one 15-ml. portion and two 5-ml. portions of absolute alcohol. The second and third fractions were almost free from bases (less than the equivalent of one drop of 0.05 N acid) and were discarded. The layer of alumina was then removed and the silica eluted with 44 ml. of ammoniacal chloroform. The alcohol fraction was diluted to 25 ml. and the tropic esters determined on a 1-ml. diquot part by the colorimetric method of Allport and Wilson4; this gave a value of 1.26 mg. per 10 ml. of original benzene extract of the drug calculated as hyoscine. The remainder of the fraction was quickly evaporated to dryness under reduced pressure dissolved in 2 ml. of chloroform and slightly over-titrated with 0.05 N picric acid in chlorofonn.An equal volume of benzene was then added. No cloudiness appeared and after a few hours several drops of light petroleum were added. On allowing to stand overnight clusters of small needles separated which after washing with a mixture of equal volumes of chlorofonn and benzene containing several drops of light petroleum and drying at 105" C. melted at 186" to 188" C. ; after admixture with stock hyoscine picrate the melting point was 185" to 188" C. The ammoniacal chloroform eluate was made up to exactly 50ml. with chloroform and 1 ml. assayed by the modified Vitali reaction4; this indicated a total alkaloid content of 4.1 mg. per 10 ml. of the original benzene extract calculated as hyoscyamine. The remaining 49 ml.of the eluate was divided into two portions of 25 and 24 ml. ; the 25-ml. portion was evaporated to dryness the residue dissolved in a little alcohol and the bases titrated giving a figure equivalent to 4-5mg. per 101111. of the original benzene solution calculated as hyoscyamine ; the 24-ml. portion was evaporated to dryness re-dissolved in chloroform , just over-titrated with picric acid as above and after addition of one volume of ether and one volume of light petroleum the milky mixture was left overnight. A few oily drops collected at the bottom of the container and several clusters of stout prisms were deposited on the walls. The latter after washing and drying as described above melted at 163" to 164" C. and the mixed melting point with stock hyoscyamine picrate was 164" to 165" C.The figures obtained above indicate the presence in 1 g. of original drug of 6.3 mg. of hyoscine by the colorimetric procedure 20.6mg. of hyoscyamine by the same method and, from the difference between the colorimetric and titritmetric assays applied to the ammoniacal chloroform eluate about 2 mg. of bases not esterified with tropic acid. Two small fractions containing possibly between 1 and 2mg. of alkaloid (calculated for 1 g. of drug) were dis-carded. Since a small loss of hyoscine is usually incurred it can be concluded that the sample of Duboisia myoporoides contained about 2 per cent. of hyoscyamine 0.7 per cent. of hyoscine and 0.2 per cent. of other alkaloids. (ii) Starvation experiment on leaves of Atropa belladonna-(This experiment is taken from a series of investigations carried out by Dr.W. 0. James Oxford Medicinal Plants Scheme Department of Botany University of Oxford. The present report deals only with the isolation and identification of the alkaloids.) Detached leaves of Atropa belladonna were kept in the dark in water until they showed distinct yellowing; the material was then dried and powdered. Two portions each 0.5 g., of the powdered drug were assayed by the method of Roberts and James,3 the total alkaloid content being determined by titration and the tropic ester content by the colorimetric procedure. The results of the two assays were identical and little different from the values for the untreated leaves. The portion used for the titration was made alkaline the alkaloids were extracted with several portions of chlorofonn and the combined extracts evaporated to a small bulk and slightly over-titrated with picric acid as described above.On standing no precipitation took place even after mixing with one volume of benzene and one-quarter volume of light petroleum. On addition of sufficient light petroleum to produce a distinct cloudiness oily drops separated on the glass walls and on replacing the supernatant liquid by a mixture of chloroform ether and light petroleum having the same composition and leaving overnight, these oily drops crystallised in clusters of stout prisms. The fluid was decanted and a further quantity of light petroleum was added to it ; this produced an additional crop of small prisms. A further crop could not be obtained.After washing and drying a s already described the crystals from both crops had an identical melting point 164" to 165" C. which was slightly raised by admixture with stock hyoscyamine picrate. The above results suggest that under the conditions of the experiment i.e. starvation to the point of incipient proteolysis the hyoscyamine content of leaves of Atropa belladonna is unchanged and neither hydrolysis nor dernethylation takes place to any appreciable extent 146 WHITE THOMPSON AND BRICE APPLICATION OF THE DUMAS SUMMARY The adsorption zones of the solanaceous alkaloids and other colourless bases can be demonstrated on columns of activated silica by displacement against dimethylamino-azo-benzene (dimethyl yellow). This dye is weakly adsorbed from benzene or light petroleum to give a brilliant red colour on the column; if however the dye solution also contains colourless bases or if the latter have previously been adsorbed from more polar solvents, yellow bands of unadsorbed or displaced dye indicate the position of the adsorbed bases on the column.Both hyoscine and hyoscyamine are strongly adsorbed from benzene solution by silica, but whereas the former is rapidly eluted by absolute alcohol the latter is moved only slowly. It is shown that making use of this principle hyoscine and hyoscyamine can be separated almost quantitatively so long as the hyoscine/hyoscyamine ratio lies between 1 4 and 6 1. The identity of 0.5 to 1 mg. of pure hyoscine or hyoscyamine can be established by preparing the picrates from chloroform solutions. By applying a preliminary chromato-graphic fractionation it is possible to separate and identify the components of a mixture of hyoscine and hyoscyamine when the amount of total alkaloid is between 5 and 10mg. The authors wish to thank Dr. W. 0. James for the opportunity to carry out this work in the laboratories of the Department of Botany Oxford. They would also like to express to Mr. N. L. Allport their appreciation of his interest in the investigation and to Mr. John Allen their thanks for his generous help during preparation of the manuscript for publication. Financial support was provided by the Oxford Medicinal Plants Scheme. REFERENCES [Vol. 73 1. 2. 3. 4. 6. Kuhn A. and Schafer G. Apotheker Z. 1938 53 406 424. Rowson J. M. Quarf. J . Pharm. 1944 17 226. Roberts M. and James W. O. Ibid. 1947 20 1. Allport N. L. and Wilson E. S. Ibid. 1938 12 399. Trautner E. M. Neufeld O. and Rodwell C. N. Australian Chem. Inst. J. 1948 15 52. OXFORD MEDICINAL PLANTS SCHEME DEPARTMENT OF BOTANY THE UNIVERSITY OXFORD October 194

ISSN:0003-2654    

DOI:10.1039/AN9487300140

出版商:RSC    

年代:1948

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/AN9487300146

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9487300149

出版商:RSC    

年代:1948

数据来源: RSC

摘要:

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

ISSN:0003-2654    

DOI:10.1039/AN9487300152

出版商:RSC    

年代:1948

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/AN9487300157

出版商:RSC    

年代:1948

数据来源: RSC