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DECEMBER 1906 Vol. XXXI. NO. 369. THE ANALYST. THE ANALYST AND THE MEDICAL MAN. BY F. GOWLAND HOPKINS M.A. M.B. D.Sc. F.R.S. (Read at the Meeting November 7 1906.) IN venturing to address you this evening I am deeply impressed with the sense that the excuse for my intrusion is a small one. Seldom 1 imagine has this learned Society welcomed a visitor less obviously entitled to occupy its time. So fully do I realize this that I must ask you at the outset to listen to a few words of explana-tion the personal aspects of which you will kindly excuse. My appearance here primarily takes origin from the circumstance that I am at the moment Examiner in Pharmacology and Therapeutics at the Institute o 386 THE ANALYST. Chemistry happy in occupying the position of such distinguished predecessors as Sir Thomas Stevenson and Dr.Arthur Luff. Now it is an open secret that the officials of the Institute and the great majority of professional chemists interested in its examinations were far from welcoming the imposition of this particular test. I t was prescribed by an all-powerful Government Department and accepted by the Institute as a pill is swallowed by a disbelieving patient. Convinced of the utility of the examination but believing that some modifications in its details had become desirable I was allowed to approach the Council of the Institute with some suggestions towards such modifications ; and though I did not dare ask for all I should have liked and though my eloquence was not equal to obtaining quite all that I did ask for yet it was felt by my good friend the honoured Registrar of the Institute that the views I ventured to lay before the Council might perhaps interest a wider audience and at his suggestion your president and your senior secretary Mr.Chapman ofl'ered me on your behalf the in-dulgence of a hearing. The flattery of this invitation committed me to the effort of addressing you. But consideration made it evident that anything I might have to say about the examination referred to could not be made to occupy your time with advantage for more than a few minutes and I felt I must expand this narrow text into something wider which should more or less naturally arise from it. II came to the conclusion that the only real qualifications I had for coming before you were those possessed by an individual who having been trained for your own profes-sion and having acquired some knowledge of its aims and claims sought later a training in the profession of medicine and so gained similar knowledge with regard to it.I am of course very far from standing alone in this experience ; but, unlike many who with the same doubled training have practised one or other of these professions with distinction and still more unlike those who have contrived to practise both it has been my fate never at any time to practise either. Even so my case is doubtless not unique but if anything worth saying can be said about the relations of these two professions the circumstances at any rate give me a claim to speak without prejudice. With no other endowment than what I have indicated, I venture for lack of other text to say a few words on the relations present and future between the analyst and the medical man.There is no need I think to repeat the indisputable statement that the doctor and the analyst share between them-not forgetting the work of the sanitary engineer -almost the entire burden of the maintenance of public health. It would be but repeating the obvious moreover to say that these two professions having such common aims should possess full sympathy and mutual understanding. But although we may believe that the sympathy is always present yet the understanding is not quite always complete and the lack of it hag now and again-we rejoice to know, not often-led to some friction at points of contact. When such small differences arise it must be admitted that the medical profession has this great advantage over yours-that its claims and its merits are so much more easily understood by the general public.This should a need for judgment arise somewhat unfairly strengthens the hands of the one disputant. It must unfortunately be recognised that even now after all the years during which the Public Analyst has served the community THE ANALYST. 387 the layman has a most imperfect knowledge of what his work entails. The services of the engineer are understood those of the doctor are appreciated but the skill expended in the analytical laboratory is understood and appreciated but little. This, to you is again a commonplace; but I bdieve I am justified in adding to it the really regrettable statement that even the average medical man is not greatly different from the man in the street in this respect,.He has at one time known a little chemistry but he possesses no standard to measure what is required of the skilled analyst. I am going to take the risk of making a bold generalization here which I must justify afterwards. I believe that of those professional men who in any sense apply science to practical affairs the average doctor is among the least scientific while the professional chemist is among the most scientific. I hope I am not making this statement gratuitously and I am certainly not urging the contrast to ingratiate myself here or to cast a slur upon the medical profession. There are many in the latter who are using high scientific knowledge and applying it in the most difficult of all regions the treatment of disease ; but nowadays the medical man with a real scientific bent tends to cleave off from the profession as a pathologist or physiologist.It is even the fashion once more for distinguished medical teachers to urge upon their students that the art rather than the science of their calling is the important thing; and we must all iudeed recognise that in practical medicine skilled and wise empiricism based upon experience is a much better endowment than ill-digested science. The progress o! medicine depends upon science but its practice does not demand scientific interests properly so called on the part of the practitioner. You must not I think expect that your work will be understood or fully appreciated, by the doctor merely because he has passed through the medical curriculum.But you will be inclined to say here the predilections of the doctor as a clinician are of small importance to the analyst save when the latter as one of the general public is sick and under his hands. The analyst in the exercise of his own profession has little to do with the practising doctor; it is with the specialized medical officer of health that his duties bring him more or less into direct contact. This is true and though it will prove the chief burden of my paper to urge that in the future the professional chemist and the clinician will be in closer contact the present attitude of the Medical Officer of Health towards the Public Analyst claims first attention.There is no doubt that in the great majority of cases these two coequal and independent officers of a sanitary authority work together harmoniously but there have been in the past sufficient instances of misunderstanding to make it justifiable to take one’s courage in hand and say a word about them though on such a subject it is difficult perhaps to do more than givevent to obiter dicta with the risk of being misunderstood. The Medical Officer of Health is a man whose education has been wide and various and who has submitted himself to tests of efficiency which are without doubt rigorous. But although among many other things he has been taught more chemistry than the less specialized members of his profession I venture to think that even he does not-at any rate at the outset of his career-possess enough chemistry I t should be understood that I speak of average cases only 388 THE ANALYST.to appraise the high claims of the skilled analyst or to gain the full respect for the latter which comes with knowledge. He does not always recognise as he should, that the consulting chemist and the analyst belong to a profession in which education is as prolonged and in which personal ability and skill are as essential as in his own. I feel that this lack of knowledge on the side of the medical officer is certainly one of the causes leading to misunderstanding. The Public Analyst on his side should not, of course forget that the Medical Officer of Health is a man of multifarious and responsible duties whose accomplishments are not to be measured by his knowledge or ignorance of special laboratory problems; he must demand only that these laboratory problems be viewed with a due sense of proportion.Now we all know that one bone of contention has been the matter of water analyses which either officer concerned may legally carry out. I believe this is really a somewhat small bone not really important to the nutrition of either combatant but it has given rise to some growls. I have in my time taught water analysis to medical students in an official public health course and if you ask me whether the average man having finished such a course and having weathered the examination at the end of it is equal in practice to examining and reporting upon a. series of drinking waters I must certainly answer No ! The real value of such practical work as he does in class is in enabling him the better to appreciate the significance of analytical data when they come before him.If he subsequently argues to himself “ I have been to the trouble and expense of learning water analysis and I am stamped by the examiner as efficient why should my knowledge not add to my guineas?” then so arguing he shows himself a man without sense of proportion. But remember there are individual Medical Officers of Health who owing to special tastes and opportunities do try subsequently to make themselves efficient in this connection and it is going much beyond the facts to assert that an intelligent man pre-eminently in touch with practical problems having carried out routine analyses of a score or so of water samples is not in a position to claim accuracy for his work so far as it is of this routine kind.You would if I mistake not accept the data obtained by your own junior assistants after similar experience. But the existence of these exceptional cases is beside the mark. To the normal medical officer even if he be possessed of some skill as a chemist the chemical laboratory and its pursuits are but an accident. He can enter it only seldom and if he come into it sample in hand it is usually to find standard solutions which time and accident have made unreliable and apparatus untested for weeks or months. Nine times out of ten therefore the analytical effort is a trying one and if the medical officer spend the time necessary for accuracy in a laboratory which is not strictly a going concern the enterprise is to him unprofitable.He should realize how much simpler it all is to the professional analyst in constant practice. No one I venture to assert has seen more of these things than I have and I certainly believe that the medical officer who does not refer all the water analyses which might come his way to his chemical colleague is a person neglecting other and to him more profit able opportunities. But into the controversy about water analyses there came some years ago THE ANALYST. 389 certain tu quoque argument and to the disint’erested outsider the position was even a little amusing. The examination of water is only partially complete without a bacteriological study ; and though it must be admitted that our power to dogmatize about the details of contamination has not yet been aided by bacteriology to the extent that was hoped for yet it is certain that the water expert must be on special and limited lines at any rate a bacteriological expert.But in bacteriological study the medical man for the most part preceded the analyst and Hands off I” at first seemed to him as legitimate an expression when uttered on his side of the boundary as when used on the other. The technique of bacteriology on its cultural and merely diagnostic side is much simpler more limited and more empirical than that of analytical chemistry; but the former subject like the latter requires something more than a formal knowledge of technique. I t is the development of certain special instincts only given by long contact with the problems which converts the amateur into the expert.The ordinary training of the medical officer or of the analyst gives in neither case this endowment as regards bacteriology. There is however I believe this fundamental difference between the intrusion of the Public Analyst into bacteriology and that of the medical officer into chemistry the analyst is first last and always a laboratory man while the medical man is not. The six years of laboratory life which must elapse before the professional chemist is looked upon as fully qualified make the attempt upon new laboratory ventures an easier task for him. This confinement to the laboratory is on the other hand the cause of some distinct disadvantages to the analyst.The four walls of his workshop hide him from the gaze of the public; he triumphs over diflficulties in secret and without appreciation. But he should at least reap the advantage of a recognition from those who know of the fact that his constant practical experience at the laboratory bench endows him with fundamental instincts for laboratory work in general which the occasional visitor to the laboratory can only very exceptionally possess. Some of you have doubtless been practical bacteriologists for as long a period as any pathologist can claim to have been but the question is now rather as to how far the student who intends to practise chemistry in the future shall spend time and energy on the study of bacteriological technique. It seems to me highly desirable that a certain proportion among chemical students should be encouraged to take an interest in the subject because of the enormous amount of purely chemical work to be done in connection with it and because of its growing importance in subjects quite other than medical ones.These are the students for whom Branch E of the Institute’s final examination with its admirable syllabus is intended. But as regards the future activity of those who become oficers of public sanitary authorities it is likely that specialization will increase and the bacteriological laboratory will become a unit. I think specialization will here become accentuated because of the familiar difficulty due to the intrusion of the pathogenic organism. I t is of course not possible to draw the line sharply between the study of these and the non-pathogenic groups.The B. coZi communis is an organism which must always concern the water specialist and yet its case is one which bridges any gulf between the pathogenic and the non-pathogenic. But to follow up the study of the pathogenic organisms full 390 THE ANALYST. requires the use of animal experiments with all their attendant difficulties. The rigour of the license system is likely to increase rather than diminish and only specialists working in a comparatively few licensed laboratories will be able to do useful work. This will lead to the emergence of the bacteriologist as a specialized officer of all sanitary authorities and since laboratory work is best grouped in accordance with the technique employed in it rather than in relation to its immediate aims the specialized laboratory is likely to attract all public bacteriological examina-tions to its domain This is my view of the future and though for reasons already mentioned I utterly disagree with Professor Hewlett for example when in a presidential address last year he declared that '' the present tendency of Public Analysts "-assuming this exists-" to undertake any and every form of bacteriological work is fraught with the greatest danger .. . ," yet I believe him to have been right in urging that the bacteriological specialist must emerge in the future. I t is highly desirable that the knowledge possessed by any expert should extend beyond the limits of his daily task and in fact that it should be as wide as the shortness of life permits; but it is equally desirable that in the application of expert knowledge to the public service specialization should go so far as Society and the State can afford.If in the future the Public Analyst is to be reminded by other specialists that his business is chemistry the medical officer will be treated on similar terms and I have firm faith myself that an increase in the analyst's activities on purely chemical lines will leave him well content as I hope in some sort to show later. There are it seems some grounds of complaint against medical officers in other and to my mind more serious connections than those yet dealt with. I t has occurred that the Medical Officer sf Health of a district has acted as though he were the superior of the Public Analyst in the sense of possessing a right to deal with the reports of the latter publishing them as though they emanated from a mere depart-mental oficer under his control.Such a distortion of fair conduct or anything analogous to it must be and remain rare and need not be discussed as though i t pertained to the normal. It could arise only from the existence of a complete mis-understanding of the situation. I am sure that every reasonable medical officer of health recognising that the analyst's appointment is a direct one and coequal with his own would wholly repudiate such a course. In such a case it would be well to see that the facts came to the knowledge of the medical press in which I am sure it would meet with right and egective comment. Leaving for the moment any further reference to the difficulties which have arisen between doctor and analyst let me now proceed to the more satisfactory task of indicating future developments which may tend to bring them together.I n pursuit of this side of my subject I find that I may logically begin by referriug to the Institute examination in pharmacology and therapeutics. When this was first established by fiat of the Local Government Board Sir Thomas Stevenson the firsti examiner very wisely established a standard which has since kept the range of the examination within certain narrow limits. The student has been expected to recognise by their naked-eye characteristics the various drugs of the British Pharma-copceia and to know roughly the practical uses of the more important drugs and the doses medicinal and fatal of such drugs as are presumably toxic THE ANALYST.391 Such limitations were very necessary on the first establishment of the subject, and the present view of the Council which with certain modifications should I think be respected by all wise examiners is in favour of the careful avoidance of any demand for knowledge within the proper province of the medical student. At the moment however things have arrived at this pass Either as a result of the growth of coaching or because of present organized facilities for handling pharmaceutical preparations not a single candidate now fails to be well versed in the recognition of drugs. I t is most rare to find a single individual who cannot with the aid of various ‘‘ tips ” and menzoria tcchnica recognise with unfailing accuracy every typical drug which he may be shown.His knowledge of doses is equally accurate for he comes provided with a short list which has been got by heart the night before and can be again consulted at the eleventh hour. Indeed on the some-what rare occasions when it becomes necessary to refer a candidate it is almost always in my experience because of weakness in the associated subject of inicroscopy, in the practical technique of which I have been surprised to find a chemical candidate inferior to the medical student of similar standing. NOW as examiner I certainly did not wish for more opportunities of referring candidates nor did I desire to increase the amount of work the student has to do. In asking for a somewhat more extended syllabus I had several considerations in view which I should like to submit to you.In the first place I found the candidates come up for this examination with feelings of considerable discomfort. So far as the matter of previous papers set on the lines defined above can guide them they succeed easily in making themselves letter perfect ; but they feel that between the boards of a text-book of pharmacology and therapeutics there are many things beyond these and though they understand they are not to be treated as medical students they yet feel uncertain as to what exactly may be sprung upon them to their no small distress. I n circumstances such as these a syllabus which seems to extend the subject may really limit the amount of reading to be done.Next it appeared to me that if a given subject is studied under compulsion, those parts of it which stimulate interest and are of educational value should cer-tainly not be eliminated and it seems to me that “spotting” drugs and learning doses by heart possess little of either of these qualities. Again there seemed to be aspects of pharmacology which really concern the professional chemist as much if not more than those hitherto emphasized. I have found for instance that candidates who can without hesitation distinguish between caraway and dill or rattle off a list of doses did not know that a man taking chloral hydrate excretes a product which by reducing Fehling’s solution has led to confusion with glycosuria. Yet he might quite conceivably be face to face with the results of this phenomenon in his laboratory and such matters as well as many analogous ones seemed to me to concern him even more than a knowledge of poisonous doses.Moreover if the fatal dose of a poisonous drug is supposed to be known there should certainly be the added knowledge of the influence of age idio-syncrasy and habituation as modifying such doses. Questions as t o whether a poisonous drug is rapidly eliminated or whether it i 392 THE ANALYST. accumulated in the body and whether when it has to be looked for it will be found unaltered or changed by the extraordinarily interesting processes to which the body may submit it are of import to the professional chemist; for though it is to be hoped that investigations concerning criminal toxicology may largely remain in the hands of specialists yet the help of the professional chemist in ordinary practice may often be sought in non-criminal cases.His help may indeed become more important and at the same time his task somewhat more difficult with the growing use of complex organic drugs. I t further seemed to me though I was not allowed by the Council to insert such matters in the syllabus that a chemical student who is compelled to learn pharma-cology at all might well have his attention called to the interesting relationships which exist between the chemical constitution of active substances and their effect upon the body. This knowledge and the synthetic work based upon it has certainly proved highly profitable to scientific chemists in Germany.Such knowledge as is asked for in the present syllabus can be got from almost any reasonably complete text-book by selecting a few special sections. It is not its bulk but its suggestiveness that gives it importance. Note that it has not hitherto been my purpose to discuss the wisdom of the actual institution of a professional examination in pharmacology and therapeutics ; but taking it as an accomplished fact I have wished to point out that without taxing the student’s time overmuch and without treating him in any sense as a medical student he may with great advantage be asked to know something more than the dry bones of the subject. But I believe further that just as the establishment of Branch F (biological chemistry) came at an opportune moment and will help to provide experts whose services will be of great value.to the State in the immediate future so the existence of a section in Branch E capable of giving some slight medical bias to the minds of even a few students will ultimately prove of no small service both to themselves and to the medical profession.This is my firm faith and this is why I have wished to see the examination deal with something lriore than the dead and unstimulating aspects of the subject I will try to explain why I hold this faith in the value of a medical bias just now. As many of you will have realized there has been enormously accentuated pro-gress in physiological chemistry during quite recent years. The new knowledge being gained is living stuff and of real practical importance.Now progress in physiology rapidly reacts upon pathology and pathology upon methods of diagnosis. Pathology is striking out some chemical paths of its own but it has not yet felt the effect of the unloading of chemical facts which physiology is preparingfor it. Sooner or later there will be activity on lines unknown to the physician at present. If we consider the question of urine analysis alone it is easy to prognosticate that there will be added to the study of the few constituents which are now troubled about that of a great number of excretives appearing in small amount but of great importance as measures of departures from the normal metabolism. The practical urine analyst of the future will have to cover an extensive ground. Even now with the physician only vaguely aware that the pathological chemistry of the past whic THE ANALYST 393 was too ill developed a subject to be of much use to him is giving way to something more real-even now there is some awakening to the importance of the laboratory.On the Continent at any rate and especially in France elaborate and very numerous analytical studies are continuously made by professional analysts from which characteristic curves are constructed these being supposed to give important indica-tions as to departures from normal health. Though many physicians in France attach much importance to these curves and attribute to them even a prognostic value I believe myself that much of this work is only pseudo-scientific; it is a little premature and undiscriminating but it is at any rate exceedingly profitable to the analyst the patient-if not the physician-cheerfully paying satisfactory fees.I n this country the medical profession is at any rate beginning to think more seriously of the professional laboratory as an aid to its work. This is evidenced by the astonishing success of certain medical investigation associations run upon business lines. Only part of their work is chemical however and as the complexity of the chemical problems grows the special difficulties of chemical technique will send the work more and more into the hands o€ individual experts. The average medical man while not yet aware of all that chemistry can do for him is also for reasons already indicated not yet clear as to whom he should turn to for help in those chemical problems which he has even at the present time in mind I have read recent elaborate medical monographs involving extraordinarily futile chemical investigations in which the author himself innocent of chemistry acknow-ledges his obligations to the pharmacy which is adjacent to him.Now it is no reflection upon an honourable calling to suggest that in such a case the doctor ought to have gone elsewhere. One can see that in these conjoint researches it was the good nature of the pharmacist and no worse motive which made him consent to the unprofitable partnership. But I believe it is not going too far to say that the rise of chemical pathology to its full importance will call almost for a new profession. I wish very much to make a point here which if it seems too remote at present from your practical interests may be considered as in parentheses.The care of the body in sickness with all the delicacies of human relationship which it involves must remain always an entire and carefully guarded prerogative of the physician ; but the innate respect of the public and even of the non-medical scientific public for the physician’s calling has led to a somewhat illogical attitude and has tended to make sacrosanct not only the calling of the physician but the scientific material which he deals with. There has been as it were an averting of the gaze whenever a region of knowledge is stamped as “medical.” Now I am certain that the progress of scientific medicine demands a change here. While a large part of future scientific medical studies must always be carried out by men who though medically qualified, have preferred the laboratory to practice and whose special qualification therefore, is that they have had personal touch with the problems offered by disease yet in a middle region these must be joined in their work by men whose primary qualifica-tions are non-medical-men who saved from the long years of clinical study are able to bring well-grounded laboratory knowledge and (I may add) a sufficient know-ledge of the literature of pathology which is open to all to join their medically qualified coizf&res in attacking the huge problems which await solution 394 THE ANALYST.Many of these must be organic chemists and to make a distinction which I will urge again later many of them must be also analysts.If it be felt that these are matters which concern those who aim at pure science and not the professional chemist it is yet certain that the amount of valuable analytical work to be done professionally and outside the research laboratory will greatly increase as a result of the tendencies indicated. My own calling compels me to know well the present position of physiological and pathological chemistry and I may claim to have had first-hand acquaintance with the large amount of paying work which is even now being done for the medical profession though not by individual professional analysts. And though I may not stop to prove my point further I yet reiterate my opinion that there will be in the near future an efficient source of income for many of the students in your laboratories if they are prepared to work on these lines.While upon the business of prophecy I am tempted to put another series of prognostications before you the credibility of which is at the present time perhaps, more obvious to the physiological chemist than to anybody else. I pass froin pathology to an aspect of dietetics. This is a subject in which the medical man is the recognised authority charged with instruction of the public but for a scientific knowledge of which he depends largely on the chemical physiologist and the an a1 y s t. Putting on one side the aspect of affairs which especially concerns this Society-the maintenance of purity and freedom from adulteration-and leaving out questions such as digestibility and the like the chief practical points which have hitherto been considered in relation to the daily rations of mankind are the total energy value requisite for maintenance the optimum ratio of fats and carbohydrates and the optimum supply of protein.Now these questions have recently received fresh attention and experimental work has been done lately yielding as you know some-what startling results tending at first sight to modify our views concerning maximal, minimal and optimum dietaries. But I am not going to discuss the work of Atwater or Chittenden proposing rather to put before you very briefly facts of another sort less known and seemingly academic. I believe however that my theme which is that of the influence of minimal qualitative variations in dietaries will one day become recognised as of great practical importance.Physiological chemistry chiefly owing to the work of Emil Fischer has recently gained the knowledge that individual proteins and among them those which contribute to human dietaries may each bear a special chemical stamp; that a given protein may differ so widely from another protein as to have quite possibly, a different nutritive value. I will illustrate this! first of all by a somewhat extreme case. A protein zein forming no inconsiderable proportion of the total nitrogenous constituents of maize is entirely deficient in at least one character-istic molecular grouping. I t yields on digestion no tryptophane the product which represents the indol group present in the molecule of most typical proteins.I n mentioning tryptophane I cannot deny myself a moment’s harmless gibe at your expense. The well-known colour reaction which you have used for so many years as a test for formaldehyde in milk is really a reaction due to this indol grou THE ANALYST. 395 of the casein. Now as it was a similar colour reaction which led some of us a t Cambridge to separate the tryptophane of protein for the first time I have felt that some of you being authorities on food-stuffs ought with proper enterprise to have anticipated us in this not unimportant discovery. Recently we have fed animals with this indol-free maize protein in such a way that it formed the only supply of protein though associated with abundant fat and carbohydrate and suitable salts. The diet wholly failed to maintain tissue growth in young animals which however grew at once when their zein was replaced by pure casein.When tryptophane was added to the zein diet there was still inability to maintain tissue growth doubtless because the zein has other deficiencies as a, protein. The animals which received the missing indol derivative in addition to the zein did not grow in fact continued to lose weight daily and were afterwards in rnuch better health than and long outlived those which had the zein alone. These experiments seem to show two important facts First that in an extreme case a particular protein may wholly fail to support life just as is the case with gelatin; and next that a group in the protein molecule may serve some purpose in the body other than that of forming tissue or supplying energy.The usual disci~ssions about food-stuffs attribute to &ern these two functions only-repair of the tissues and energy supply. But the body has other and more subtle needs equally urgent. Here there or elsewhere in the organs must appear special indispensable active substances which the tissues can only make from special precursors in the diet. The indol grouping in the protein molecule serves some such special purpose, quite distinct from its necessary function in tissue repair This matter of qualitative differences in proteins may be of no small significance in dietaries. It may account for what I believe is proved by experience-that rice may serve the races which rely upon it as an almost exclusive source of protein while wheat is only suitable for races that take a much more varied dietary.I t may explain many variations in nutritive values which at present we feel and recognise only vaguely I n the future the analyst will be asked to do more than determine the total protein of a food-stuff; he must essay the more difficult task of a discriminative analysis. But further no animal can live upon a mixture of pure protein fat and carbo-hydrate andeven when the necessary inorganic material is carefully supplied the animal still cannot flourish. The animal body is adjusted to live either upon plant tissues or the tissues cjf other animals and these contain countless substances other than hhe proteins carbohydrates and fats. Physiological evolution I believe has made some of these well-nigh as essential as are the basal constituents of diet.Lecithin for instance has been repeatedly shown to have a marked influence upon nutrition and this just happens to be sumething already familiar and a substance that happens to have been tried. The field is almost unexplored ; only is t certain that theye are many minor factors in all diets of which the body takes account. I n diseases such as rickets and particularly in scurvy we have had for long years knowledge of a dietetic factor ; but though we know how to benefit these con-ditions empirically the real errors in the diet are to this day quite obscure. They But now an interesting fact came to light 396 THE ANALYST, are however certainly of the kind which comprises these minimal qualitative factors that I am considering.Scurvy and rickets are conditions so severe that they force themselves upon our attention; but many other nutritive errors affect the health of individuals to a degree most important to themselves and some of them depend upon unsuspected dietetic fact ors. I can do no more than hint at these matters but I can assert that later develop-ments of the science of dietetics will deal with factors highly complex and at present) unknown. But am I at present justified in troubling you as practical men with such matters-you who are interested in professional chemistry and not in what is still more or less academic physiology ? First it is abundantly clear that the foundation of future progress in chemical pathology and dietetics on the lines I have been indicating calls for large efforts in purely analytical chemistry-efforts which have been too long delayed.And the delay has arisen from a circum-stance of no small interest and importance. The scientific chemist -unlike his predecessors the pioneers of sixty or seventy years ago-has long ceased to be much interested in the animal or the plant. Further the triumph of synthetic work in advancing theory has led the pure chemist away from the especial difficulties of analytical work. His extra-ordinary developed technique concerns itself only secondarily and imperfectly with analytical studies of the kind still necessary in physiological problems. I mean the endeavours to identify and separate unknown substances with unknown pro-perties present in complex mixtures.Only now and again has he made special efforts in this direction such as that with which Fischer started his work upon proteins. Such work really requires special instincts and the pure chemist has largely lost them. He is but; a poor analyst as the physiological explorer finds on turning to him for help. I feel that this help so far as the immediate future is concerned will have to come from the pupils primarily trained in your own labora-tories where the analytical instinct is developed. Some of your students it is to be hoped will have their attention turned in this direction and to at least a few there may ultimately come opportunities for research ; for research in all callings even that of the academic teacher is only to be snatched from leisure.There are the beginnings just now of a renewed interest in biology on the part of all chemists, May the analyst feel this too. It is not only the manufacturer and the sanitary authority that require his help. I n the second place I am not afraid to assert that progress in dietetics no less than in chemical pathology is about to react largely on pofessional chemical practice. Fresh problems and new ideas will unfailingly extend the field of professional operations. All progress of the kind I have been hinting at cannot fail to be of the greatest importance to the doctor; and if I may seem to have maligned him in previous paragraphs I know well how ready and able he is to make use of all knowledge that he believes to yield advantage to his patients. I have been led to do so from two considerations THE ANALYST 397 I see abundant reasons for believing that in the near future events will march to -the consummation of mutual appreciation and helpfulness and to the disappearance of all misunderstanding in the relations between analyst and medical man.DISCUSSION. At the invitation of the President the discussion was opened by Dr. BUCHANAN of the Local Government Board who endorsed the remarks of Dr. Hopkins as to the advantages which might be derived from a closer association of the analyst with the medical consultant and the medical practitioner. Dr. Hopkins also saw as probably they all did many opportunities for a greater use of the chemist in matters relating to the public health. He might make a few observations on this matter although it was not perhaps the part of the paper on which Dr.Hopkins would wish to lay greatest stress. Some of the considerations to which reference had been made-the lack of appreciation of the work of Public Analysts under present circumstances the isolation of the analyst as a ‘( laboratory man,” and especially the limited use that was at present made of chemistry in relation to public health questions-were it should be remembered arguments that were used in support of the suggestion that was very frequently made in the larger munici-palities and was coming more and more to the front for the appointment of whole-time nlunicipal chemists and analysts. Those authorities said that they would like t o put their chemical service on the same footing as other expert services and to have a chemical officer on the spot who would not only do formal work under the Sale of Food and Drugs Acts but would undertake research work and other chemical work for the municipality and would be able to advise and confer with the executive officers as to the collection of sampIes interpretation of analytical results and so forth.I t must be recognised that in some aspects there were advantages in this solution of the question. He was far from saying that it was the right one even for -the larger cities and boroughs but he thought that one of the legitimate reasons for this proposal was that under such an arrangement better use might be made of chemistry in relation to public health. Assuming however that the Public Analyst continued as now to occupy a position which in many ways stood apart from that of other municipal expert officers the question arose How could his work best be utilized and developed in the interests of the public health? The olovious answer seemed to be By full and cordial co-operation between the analyst and the medical officer of health who was on the spot.I?r. Hopkins had said that medical men of scientific bent were wont to specialize-in physiology pathology and so forth. There was another thing in which they specialized namely public health administra-fion and where the analyst had the opportunity of working with a trained officer of that kind it was of the utmost benefit to both that their mutual relations should be as cordial as possible and that they should help one another.If he might find just a little fault with this most admirable paper it was that it seemed to him in the first part to go a little out of the way not to emphasize the necessity for such co-operation but to draw attention to small and admittedly trivial points of divergence and difference between Medical Officers of Health and Public Analysts. With regard for instance to water analyses he ventured to say (speaking for th 398 THE ANALYST, moment of those not holding combined appointments) that no Medical Officer of Health undertook water analysis willingly. He would much rather leave it to the Public Analyst. But in many cases the position was forced upon him by the local authority and this was not a grievance against the Medical Officer of Health but against the local authority.Occasional differences and even stupidities did of course, occur as he himself knew from both sides. For example there was the Medical Officer of Health who said to himself-say in reference to samples of canned meat-“ I will give the Public Analyst no information at all,” and straightway stripped the tins of all their labels and sent them to the Public Analyst under mere numbers ; whereas of course the whole point was to get information and get the views of the Public Analyst and to let him have every possible help and information. On the other hand there was the analyst who said ‘‘ I am not going to supply the medical of3ker with any information or to tell him what my results are for individual milk samples and in fact am not going to send him any reports at all because it is not laid down in the Sale of Food and Drugs Acts.” Just now when the assistance which chemistry was able to aftord in regard to public health mas becoming more and more apparent and when the medical officer and the Public Analyst were coming more into contact these points of friction occasionally arose but he thought they were much more trivial than to the people immediately concerned they sometimes appeared.He thought that Dr. Hopkins quite realized that they were exceptions, and although they received a good deal of attention momentarily he did hope that too much stress would not be laid upon them. He believed that Medical Officers of Health and Public Analysts as a whole were fully alive to the necessity for “ give and take,” and that they would not allow friction to arise which would hinder the work which they did for their mutual benefit and that of the public.He was very glad to have had the opportunity of hearing Dr. Hopkins’ obsevvations on the probable development of the work of the analytical chemist in the investigation of proteid food constituents. The paper had in many ways given them a great deal to think about. Professor R. T. HEWLETT (King’s College London) said that on the whole he was in cordial agreement with Dr. Hopkins’ remarks and any criticism of them that he would have been disposed to make had been admirably put by Dr. Ruchanan. With regard to his recent presidential address which had been referred to he did not. think that Dr. liopkins’ quotation was altogether fair because the remarks quoted were very much qualified by what followed them.The view which he took was that the analyst was not in a position to deal with pathological problems. I t seemed to him that many chemists had no biological training at all and most had certainly no training in pathology; and when problems of disease had to be dealt with as was the case in many of the examinations that had to be made to-day he thought it distinctly dangerous to the public health that those examinations should be under-taken by anyone who could not view pathological problems in the light afforded by a medical training. He believed that the position had been partly thrust upon the analyst. One instance which he had in mind was that of a veryimportant city which insisted that its recently appointed Public *4nalyst should undertake examinations €or diphtheria typhoid tubercle etc.I t seemed to him To his mind that was wrong THE ANALYST 399 that in an ideal sanitary administration each department should have its analyst-Lac. that there should be both a chemical analyst and a bacteriological analyst and for the latter a medical training mould probably be desirable. The work of the analysts with that of the sanitary engineering staff would be co-ordinated by the Medical Officer of Health With regard to the examinations of the Institute of Chemistry there was just one addition that he should like to see made to the excel-lent syllabus of the examination in biological chemistry. As matters stood at present, candidates could enter for the examination without previous biological training.Such training was essential to. the prcper taking up of work of that kind and he thought that the Institute would be well advised to insist upon it. Mr. HEHNER said that analysts owed gratitude to Dr. Hopkins for having pointed out directions for research and means by which their professional knowledge could be more useful to physiologists and their medical colleagues. I t was singular that as far as he knew not a single University chair had been established for the teaching of analytical chemistry in this country; and as one who had always insisted that the analytical chemist in order to take his proper place amongst chemists must be a highly-cultured scientific man he deplored the fact that at the Universities no specific notice had been taken of the claims of analytical chemistry as a science.He thought that the cases referred to by Dr. Hewlett in which analysts were forced by ignorant local authorities to undertake pathological work, must be very rare; and that if the medical profession which was generally well represented on local authorities were 90 minded they could easily prevent such undesirable appointments. Analysts did not want to do work outside their function, but if it were forced on them they would in some cases submit just as Medical Officers of Health had sometimes perforce to undertake chemical analytical work against their inclination. The time when every local authority of sufficient magnitude would have a chemical officer as well as a medical officer was beyond doubt approaching.Although its advent might damage some members of the analytical profession as at present constituted the damage would be insignificant compared with the resulting public benefit. The analyst had a claim to be recognised as an independent officer of public authorities working whenever the subject demanded in conjunction with the medical department but dealing in a great number of cases with chemical problems quite foreign to medical or public health matters. He (Mr. Hehner) had always been most anxious that the analytical profession should maintain as many points of contact as possible with their medical friends and colleagues but that under no circumstances should a chemist be considered as an officer working under the Medical OEicer of Health and that in an age which owed at least' as much to chemistry as to medicine the chemist was entitled to have the recognition of his independent position.The sooner combined medical and analytical practices were things of the past the better. Only on one point was he inclined to differ from Dr. Hopkins. While it was quite true that the ignorant public had still a great deal to learn about the useful services which the analytical profession could render and that many people instead of going to the chemist direct still referred questions to the medical man on which he at best could have but second-hand information the fact nevertheless remained that in th 400 THE ANALYST. twenty years durigg which the profession of chemistry had existed in this country, enormous strides had been made.The position of the chemist at the present time, compared with that before the foundation of the Institute of Chemistry was incomparably better. The extent to which practising chemists had multiplied and the fact that they were as a whole at least as prosperous as the average medical practitioner afforded proof of the progress made. Professor Bos~ocri KILL said that he happened to be a county Medical Officer of Health and a Professor of Hygiene but he had also been a Public Analyst for over thirty years and therefore felt that he might perhaps look at this matter from points of view that were not open to some others of the members of the Society. He should like to say how much he appreciated practically all that Dr.Hopkins had said. He thought that if any jealousy existed between the medical man and the analyst it was largely due to two factors Firstly the special work of the Public Analyst was largely an inheritance of work that had originally been done-what little of it was done-by members of the medical profession. One could not forget that in the early days much of the work that formed the basis of the modern Public Analyst’s work was done by medical men of whom Hassall Letheby and many others might be mentioned as notable examples. Another factor wag to use Mr. Hehner’s words the profound ignorance not only of the public but also of medical men a5 to the duties of the analyst and sometimes he believed ignorance on the part of the analyst as to the functions of the medical man.The public had been accustomed to look upon the medical inan as almost the symbol of scientific work and on that account expected him to do things quite outside his province. The Medical Officer of Health who could be taken as the type of medical inan chiefly concerned in this discussion might be said to be in a state of transition-to be under-going evolution. When Medical Officers of Health were first appointed their work had practically to be developed by themselves. Now their work was on a fairly firm basis and was developing on many lines. The same might be said in the case of the Public Analyst. He (the speaker) did not think that there should be the least jealousy between the two. If any had arisen it wits largely through their want of appreciation of each other’s work.If the Medical Officer of Health sometimes assumed an attitude of apparent superiority towards the Public Analyst it was not altogether surprising when it was remembered that at the present day whether rightly or not the Public Analyst was practically a worker in the department of the Medical Officer of Health as far as public health work was concerned. Therefore in deciding for instance what samples should be taken it was only natural under present circumstances that in the case of a large authority the Medical Officer of Health should have control without of course in any way interfering as regards the results or conclusions of the chemical work. As one in touch with medical teaching, he felt convinced that while the Public Analyst might do certain bacteriological work with advantage to himself and to the public yet any entry of his into work of a pathological kind would be resented by the medical profession and would not lead to any good.Attempts were certainly made in this direction; and he knew at the present time a Public Analyst who willy-nilly had to do all kinds of pathological work that might be sent to him from a very wide area. I t was not easy for the analyst to refuse and such cases could probably only be met by a strong professiona THE ANALYST. 401 feeling that work appertaining to those sciences comprised in the medical man’s work should be kept at all events in the medical branch of the profession. He had had some experience of examinations in pharmacology etc. and he thought that in the case of the Institute examination in its present form a man might given a fair amount of daily time learn all that was required for the therapeutical part in three or four weeks.That a man should be labelled as having a knowledge of therapeutics after so short a period of necessary work was he thought not at all of value to the profession of chemistry. Mr. F. J. LLOYD said that he ventured to think that it was quite as difficult for the Medical Officer of Health as for the Public Analyst to undertake pathological bacteriological work and his own view was that in the future such work ought not to be put upon the shoulders of either but ought all to go to specialists. There was, however a large quantity of non-pathological bacteriological work that could be done by either the one or the other ; and he agreed with Dr.Hopkins that the man who was always in the laboratory was better able to undertake that work than one who must necessarily leave his laboratory very frequently and perhaps for long periods. He thought therefore that in the education of the analyst non-pathological bacteriology should be given a prominent place. Dr. Hopkins had made some interesting and valuable suggestions as to the need for investigation in certain directions. He (Mr. Lloyd) would like to mention one instance showing how difficult such investigation was. There was abundant evidence that the disease known as (( Barlow’s disease ” resulted from the feeding of children upon boiled milk, and entirely disappeared on reverting to the consumption of fresh milk.Now the analytical differences between boiled and unboiled milk were very slight indeed and their investigation would probably require some years of very careful work at great pecuniary expense. Could any analyst dependent for his income on his analytical practice be expected to give the necessary time and money to such a research? He thought not and therefore agreed with Mr. Hehner that it could not be hoped that such recondite subjects would be fully investigated until the Universities were able to appoint profeesors charged with the duty of investigating and of training others to investigate analytical problems which were far beyond the ordinary routine work of the profession. Dr. VOELCKEIC said that he was hardly in agreement with Dr.Buchanan in thinking that the points touched upon in the first part of the paper were perhaps somewhat trivial. These were the points which really came into prominence when the relations between the medical man and the analyst were discussed and for a considerable time they had been a came of agitation. The remedy for them and for the harm caused by the continual search after cheapness must as had been pointed out be looked for in the better education of the public. In this connection it would be wrong not to take the opportunity of acknowledging the work of the Institute of Chemistry in emphasizing the need for keeping separate these two classes of work, and for urging that the claims of both should be fairly represented. The Institute, urged on by its energetic Registrar (whose presence they were glad to have at that meeting) had been steadily insisting on the importance of this matter and hadmade repeated representations on it to the Local Government Board.The tendency wa 402 THE ANALYST. for a man to rise to what was expected of him and to try as best he could to do what the public or the local authority thought he ought to be able to do. The result how-ever was often unsatisfactory. It might be pointed out that the Institute’s examina-tion in branch ‘( E ” was framed in accordance with the desire of the Local Govern-ment Board. I t would however be wrong for anybody to take advantage of having passed that examination and say that he was therefore qualified to take up bacterio-logical and similar work. The chemist could not afford to ignore the help that was to be obtained from bacteriological study but it was quite another thing to pose as an authority on the subject ; at the same time it was true that the chemist from his constant work in the laboratory had better opportunities of learning bacteriological methods and applying them than the medical man had of picking up the details of chemical analysis.Mr. FAIRLEY remarked that while the analytical profession was undoubtedly indebted to the work of medical men in the past it was equally true that much help had been given to medical science by chemists. Pasteur was a conspicuous instance, and there were many others. With regard to the 6fclinical research associations ” which had been referred to he thought that the very success of these institutions, where the reports of the work done by various professional men were sent out merely signed by a secretary must tend to deter young chemists from giving attention to problems of pathological chemistry.Mr. C. T. KINGZETT said that although neither a Public Analyst nor a Medical Officer of Health he had devoted a good deal of attention to public health questions ; and he felt very strongly that all chemical matters should be referred to the chemical officer and that the medical officer should no more encroach upon the domain of the chemist than the latter should encroach upon the domain of the medical officer. He thought that a good deal of confusion arose in this matter from a misuse of terms. I t was most regrettable that the Public Analyst should be so called ; he ought to be styled the Chemical Officer.The subject of chemistry was so wide and covered such a large range of knowledge that to call a man a Public Analyst did not adequately describe the position which he ought to occupy in relation to public health. Dr. Hopkins seemed to consider that the acquaintance of medical students with bacteriological work must be more intimate and thorough than that of the chemist. He (Mr. Kingzett) did not think that that was at all the case. He thought that the chemist who followed bacteriological work was much more likely to have an adequate knowledge of it than the ordinary medical student or practitioner. The difference between the effects produced by so-called pathogenic and by non-pathogenic organisms was all a matter of chemistry and the chemical knowledge which the medical man obtained from his ordinary course of instruction was absolutely inadequate to enable him to draw any sound conclusions in this branch of work.The work of the medical officer should if possible be restricted to matters pertaining to the outbreak and prevention of the spread of disease ; and if there must be an oflticer in a position of control he should be an ‘‘ Officer of Health ”-not necessarily medical but at least an expert capable of assimilating the knowledge to be derived from both sources, and of presenting it in a proper and digested form to the municipal authority. The P~EBIDENT (Mr. Bevan) said that he was very glad that Dr. Hopkins had lai THE ANALYST. 403 so lihtle stress upon the so-called antagonism between the Medical Officer of Health and the Public Analyst which he thought was very much overrated.Certainly it had never occurred in his own work and he thought that a good deal of it was due to petty jealousies that ought not to exist. Although not disposed to go so far as Dr. Hewlett, he agreed with Dr. Hewlett in thinking that Public Analysts had no right to trench upon the province of bacteriology; but he did consider that they ought all to be acquainted with what might be called the more rudimentary methods of bacteriological examination. He was glad also that so little had been said about dual appointments. He was free to confess and did so with a full sense of responsibility that the ideal Public Analyst was a medical man with a great knowledge of chemistry But men like Sir Thomas Stevenson were very rare and in these days of specialization were likely to be rarer still so that it was highly important that the two offices should now be kept distinct.Dr. HOPKINS in reply said that he had felt considerable compunction in reading this paper before the Society even after it had been written. He had a strong feeling that while the first half was made up of platitudes and indiscretions the second consisted of an academic lecture. Still as regards the points first touched upon it wag perhaps difficult to utter other than platitudes while he was bound to say that he did not wholly regret the second part for if anything gave him pleasure, it was to talk academically to practical men.He might have made too much of the points of difference between analysts and medical men but he had been tempted to try and make a contrast between the present state of things and the Utopia which might exist. Although he still did not agree with Dr. Hewlett he owed him some apology for having concluded his quotation marks a little too soon. Dr. Hewlett had gone on to say that bacteriology in the hands of the Public Analyst would be a very dangerous thing ‘( unless the chemist made himself a biologist or employed in the laboratory those who had had biological experience. ’’ That addition to the quotation perhaps made all the difference but he still thought that there was not the least danger in trusting the Public Analyst with a pathogenic organism for the reason that he believed a laboratory man to be a safe person.I t was quite right as Dr. Hill had said to recognise what the medical profession had done in the past but the time had long gone by when the medical nian was the only scientific man available. The question of the Institute examination was of course one which he had very much at heart and with regard to the views thereon of Dr. Voelcker and Dr. Hill he should rather like to know whether it was before or after his suggested alterations that they did not think much of i t ! With regard to the difficulties of entering into research to which Mr. Lloyd had referred he had felt that the original work that W ~ B done in strictly analytical laboratories was perhaps in too few hands. The provision of chairs of analytical chemistry at the Universities was he believed at any rate as far as Cambridge was concerned merely a question of money. But research in any event had to be stimulated and he thought it important that students of analytical chemistry should be encouraged as part of their advanced work to make original investigations bearing upon their special branch of applied science, One would wish that the Institute of Chemistry might ultimately see its way to making some sort of award for the encouragement of research 404 THE ANALYST. The PRESIDENT remarked that under the research scheme initiated some time ago by the Society’s Council there had been sent to various Universities a great many problems the investigation of which had been undertaken under the guidance of their professors by senior students. He then moved a vote of thanks to Dr. Hopkins, which wa8 heartily carried

ISSN:0003-2654    

DOI:10.1039/AN906310385b

出版商:RSC    

年代:1906

数据来源: RSC

摘要:

404 THE ANALYST. ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. On the Sugar contained in Milk. J. Sebelien. (Festschrift xum 65-j~ihr. Geburtstay von OLaj Hammarsten, No. 17; through Chem. Ztg., 1906, xxx., Rep., 337.)-The author shows that a. pentose, probably arabinose, is present in milk to the extent of about 20 to 40 mgms. per 100 C.C. of milk. Other unknown carbo- hydrates must also be present to explain the differences always found between the gravirnetric and polarimetric determinations made on the milk serum free from proteid, and the different values found when the quantities of Fehling solution used are varied. A. G. L. A Rapid Method of Removing Alcohol from Ether. P. Guigues. (Journ. Pharm. Chinz,., 1906, xxiv., 204.)-When a mixture of alcohol and ether is distilled with a resin such as colophony, the alcohol is retained by the pasty residue left in the flask.Thus, on distilling a litre of ether containing about 1 per cent. of alcohol with about 50 grams of colophony, a distillate is obtained free from alcohol. C. A. M. Formic Acid as Preservative. G. Lebbin. (Chem. Ztg., 1906, xxx., 1009.)- From the author’s experiments it appears that the addition of 0.15 per cent. of anhydrous formic acid acts as a perfect preservative for all manner of food-stuffs, more especially fruit extracts and syrups. I n most cases 0.10 per cent. even is quite sufiicient. As regards toxic properties, reasoning from experiments on rabbits, the author finds that it would take a dose of 3.5 grams of formic acid to produoe harmful results on an adult human being.From actual experiments on himself and his assistants, he finds that a daily dose of 0.5 gram formic acid, taken regularly in the form of lemonade for two to four weeks, was without the slightest effect. He believes that it ie perfectly safe to assume that formic acid is not more than twice as poisonous as acetic acid. A. G. L. The Action and Efficacy of Preservatives. A. Behre and A. Segin. (zeit. Untenuch. Nahr. Genussm., 1906, xii., 461-467.)-Tabulated results of experiments with various preservatives are given. Definite quantities of the preservatives were added to unsterilieed meat-juice diluted with water, and observations made as to theTHE ANALYST. 405 change in colour of the solutions as well as to the time taken before an odour of decomposition was noticeable.The results show that formaldehyde has by far the most powerful preserving action, that benzoic acid is a better preservative than salicylic and boric acids, and that sodium benzoate is about equal to boric acid, whilst sodium thiosulphate and sulphite are very feeble preservatives. W. P. S. Gravimetrie Determination of Potassium Nitrate in Meat. C. Paal and G. Mehrtens. (Zeit. Untersuch. Nahr. Gewussm., 1906, xii., 410-416.)-The method described is an application of Busch’s process for the determination of nitric acid by means of ‘‘ nitron ” (see ANALYST, 1905, p. 256). Fifty grams of the finely-minced meat are agitated with warm water for about two hours, the mixture being then brought to boiling and the solution filtered. The residue is boiled out with several successive small quantities of water until the extracts no longer give a reaction with diphenylamine, and the united extracts are then diluted to a volume of 500 C.C.Two hundred C.C. of the solution are now evaporated to a volume of about 50 C.C. When quite cold, 3 drops of ammonia and a slight excess of neutral lead acetate solution are added, the mixture is boiled, again cooled, filtered, and the precipitate washed. The filtrate is acidified with acetic acid and boiled, sufficient L L nitron ” dissolved in acetic acid being added to precipitate all the nitrate present. The vessel containing the mixture is kept in ice-water for three hours, after which period the precipitate of L L nitron ” nitrate is collected on a, filter, washed with 10 to 12 C.C.of ice-water, and dried at a temperature of 110” C. The weight of the precipitate multiplied by 0-26933 gives the amount of potassium nitrate in the 200 C.C. of solution taken for the determination. Basic lead acetate must not be used for clarifying the meat decoction, as its use tends to give low results; sodium chloride, even when present in the meat in considerable quantity, does not interfere with the determination, as most of it is removed with the lead precipitate. w. P. s. The Determination of Unaltered Casein in Cheese. A. Trillat and Sawton. (Ann. de Chin?,. Anal., 1906, vol. 11, 363-365.)-The unaltered casein in cheese forms an insoluble product with formaldehyde (ANALYST, xxxi., 260), whilst the broken-down products formed from the casein as the cheese matures remain soluble.Two grams of the sample are triturated with 10 C.C. of hot water, the mixture treated little by little with 50 C.C. more of w.ater (very faintly ammoniacal water in the case of hard cheese), and boiled for five minutes. I t is next treated with 0.5 C.C. of commercial formalin, boiled for three minutes longer, and allowed to stand for five minutes, for the fat to rise to the surface. The casein is then pre- cipitated by means of 5 drops of pure acetic acid, and the precipitate collected, extracted with acetone, dried, and weighed as described in the previous communica- tion. The following percentages of casein were thus obtained with commercial samples of cheese : Camembert, 18.20 ; Gruydre, 31.34 ; Gervais, 6.41 ; Brie, 22.93 ; Roquefort (half-ripe), 11.65 ; Roquefort (very ripe), 7.10 ; and Dutch, 31.5.Tho process of ripening may also be followed, and the ratio between the amounts of original and altered casein determined. Thus a sample of fresh Roquefort cheese gave the following results : Original cheese, 19.48 ; after eight days, 18-12 ; after4Q6 THE ANALYST. fifteen days, 11.65; after thirty days, 8 ; and after sixty days, 7.10 per cent. of unaltered casein. The authors have proved by control experiments that the casein separated by this method does not contain any foreign substances, and that it has the composition of milk casein ; also that any peptones or albumoses formed are not rendered insoluble by formaldehyde. They have obtained similar results in the artificial digestion of casein with pepsin.C. A. M. On the Carbohydrates occurring in Spices. 1. In Canella Bark. J. Hanus and F. Bien. (Zeit. Untemuch. Nnlzr. Genussm., 1906, xii., 395-40’7.)- The quantity of pentosan occurring in spices is fairly constant for each kind of spice ; the largest amount (18.28 per cent. on the dry substance) being found in canella bark and the least in those spices which consist of the flowers of the plant. The quantity of crude fibre yielded by a spice is proportional to the pentosan content. The pentosans found in canella bark are not completely hydrolysed by 8 per cent. sulphuric acid, a considerable portion, closely resembling cellulose, remaining unattacked. Canella bark contains about 8 per cent.of mannite, and, on treating the bark with water under pressure, araban, galactan, and small quantities of xylan go into solution. The residue from the aqueous extraction still contains xylan and, possibly, dextrosan, these two polysaccharides dissolving when the residue is treated with 5 per cent. sulphuric acid. w. P. s. The Quantity of Tin in Tinned Tomatoes. C. Formenti and A. Scipiotti. (Zeit. Untersuch. Nahr. GenzzLssrn., 1906, xii., 290-293.)-From 0.091 to 0-128 per cent. of tin was found in six samples of tinned tomato pulp, the determinations being made immediately after the tins were opened. I n two cases the pulp was left in the tins for five days, and the tin content of the pulp again determined. I n one sample the quantity of tin increased from 0.091 to 0.324 per cent,, and in the other from 0.093 to 0.169 per cent.As Ungar (Zeit. fiir Hygiene, 1887, ii., 241), Gunther (Rec. intern. fulsif., 1887), and others have published results showing the injurious effect of tin compounds on animals, it is important that the dissolving action of fruit acids on tin should be prevented as far as possible, either by varnishing the interior of all tins in which fruits, etc., are preserved, or by removing the fruit from the tin as soon as the latter is opened. w. P. s. Determination of Cellulose, Lignin, and Cutin in ‘‘ Crude Fibre.” J. Konig. (Zeit. Untersuch. Nahr. Genussm., 1906, xii., 385-395.)-Methods have already been given for the determination of cellulose and lignin in ‘‘ crude fibre ” (ANALYST, 1903, p. 318), and it is now shown that the “cellulose” thus obtained may be further split up, by treatment with ammoniacal copper solution, into pure cellulose and cutin.The ‘‘ crude fibre ” is determined as already described, and a, second portion of the sample is treated according to the process given previously, that is, with glycerol and sulphuric acid, and afterwards with ammoniacal hydrogen peroxide. The residue obtained is, together with the asbestos filter, now treated for two hours with 75 C.C. of ammoniacal copper solution, prepared by saturating 24 per cent. ammonia with hydrated cupric oxide (Merck). The mixture is then gentlyTHE ANALYST 407 warmed and filtered through asbestos, the residue is washed with water, dried on the filter at 110’ C., and weighed. After ignition, the filter is re-weighed, the difference in the two weighings giving the weight of the cutin.Three hundred C.C. of 80 per cent. alcohol are next added to the filtrate from the cutin residue ; on stirring the mixture, the cellulose separates out and is collected on an asbestos filter, dried at llO°C., and weighed. The difference between the quantity of “crude fibre” and the sum of cellulose and cutin gives the amount of the oxidizable part of the ‘‘ crude fibre,” the so-called lignin. w. P. s. Further Simplification of the Determination of ‘‘ Pepsin-Soluble ” Nitrogen in Feeding-Stuffs. A. Stutzer, H. Wangnick, and W. Rothe. (JOZLT7L. L a m . , 1906, vol. 54, p. 365 ; through Cheiiz. Zty., 1906, xxx., Rep., 338.)- A strong extract for determining the pepsin-soluble nitrogen in feeding-stuffs is prepared by cutting up the inner mucous coat of at least six pig stomachs and allowing the fragments to stand, with occasional agitation, in 0.2 per cent.hydro- chloric acid for twenty-four hours in a cool place, 2.5 litres of liquid being taken for every stomach used. The extract obtained is filtered first through flannel and then through paper. So much chloroform is then added that a portion retnains undis- solved, and the liquid is kept in a cool place. A. G. L. Determination of Digestible Proteids in Feeding-Stuffs. A. Stutzer. (Journ. Landw., 1906, vol. 54, p. 235; through Chcqn. Ztg., 1906, xxx., Rep., 338.)- The separation of proteids from non-proteids by means of copper hydroxide has been proved to work well, both when previously prepared copper hjrdroxide or when a mixture of copper sulphate and sodium hydroxide is used.In both cases the liquid should be kept slightly acid; this may be done by adding a few C.C. of strong alum solution, or by employing an excess of copper sulphate solution. To determine “ pepsin-solubls ” nitrogen, 2 grams of the feeding-stuff are digested for forty-eight hours at blood temperature with 500 C.C. of gastric juice prepared according to the author’s old, or 250 C.C. according to his new, prescription (see preceding abstract). The amount of proteid actually digested by the animal stomach is, however, often diiferent from that indicated by the quantity of ‘‘ pepsin-soluble ” nitrogen found. A. G. L. Characteristics of Annam Beeswax. J. Bellier.(Ann. de Chim. Aital., 1906, vol. 77, pp. 366-368.)-The sample of this wax examined by the author was in the form of prismatic cakes containing 5 02 per ccnt. of water, 0.5 per cent. of substances insoluble in benzene, and 0.08 per cent. of ash. The wax itself, when melted and filtered, resembled European waxes in appearance. It gave the following results on analysis : Specific gravity, 0.964 ; melting-point, 61” C. ; acid value, 7.8 ; ester value, 86.6 ; ratio of acid value to ester value, 11 ; iodine value, 6 ; hydrogen liberated at 250’ C. by potash-lime, 60.3 C.C. per grain at 0” C. and 760 mm.; and hydro- carbons unsaponifiable at 250’ C., 10.5. The wax thus differs from European waxes in having a higher iodine value, and containing less free acids and more combined acids, so that the ratio is 11 instead of the usual 3.8.The amount-of hydrogen liberated is also much greater. On the other hand, these constants are very similar408 THE ANALYST, to those of Indian waxes, and in particular of that of Apis dorsata (see ANALYST, xxx., 57). C. A. M. The Characteristics of Essential Oil of Juniperus Phaenicea. J. Rodie. (BUZZ. SOC. Chim., 1906, xxxv., 922-925).-This oil is stated to be sold in France in place of savin oil (JzLnzperus sabinus), which it closely resembles. The pharma- ceutical and chemical differences were studied by Umney and Bennett (Pharm. Journ., lxxv., 827), who found that the substitute had a specific gravity of 0.892 at 15" C. and an optical rotation of + 4" 30' in a 100 mm. tube. Five samples of the oil of undoubted purity examined by the author had a specific gravity of 0.867 to 0.868 at 15' C., and an optical rotation of + 2" 54' to + 4" 10'.The low specific gravity of some of these samples was attributed to there being a larger proportion of terpenes in oil from younger trees and differences in the mode of distillation. Umney and Bennett found only 64 per cent, of constituents boiling below 165' C., whilst a sample distilled by the author yielded 92.3 per cent. of a, terpene fraction boiling between 154" and 180" C., nearly the whole passing over between 155" and 160" C. In addition to pinene, already identified by the English chemists, this fraction was found to contain traces of camphene and phellandrene. C. A. M. Characteristics and Reactions of Oil of Cade.C. Pepin. (Jounz. Pham. Chim., 1906, xxiv., 248-259.)- From an examination of samples of known purity the author concludes that genuine oil of cade derived from Juniperus oxycedrus should have the following characteristics : It should be fluid, have an unmistakable odour of smoke, and a, specific gravity slightly less than that of water. Its acidity, in terms of acetic mid, should be less than 1.5 per cent. When distilled under the ordinary pressure it should yield at least 65 per cent. of distillate between 150' and 300" C., and at least 70 to 75 per cent. between 10" and 215' C., on distillation under a pressure of 0.065 mm. A sample of pine-tar oil had an acidity of 1-555 per cent., and gave 15.2 per cent, of distillate between 150" and 300" C.under the ordinary pressure, and 23-2 per cent. between 10" and 215" C. under the reduced pressure. Pure oil of cade should always give a brown coloration in the test for pine-tar oil with petroleum spirit and copper acetate (ANALYST, xxxi., 302). In the author's opinion, no reliance can be placed on the colour reactions given by Hirschsohn and Adam, or in the results of the tests for furfural or pyrocatechol, which, according to Kauffeisen, are present in pine-tar oil, but not in aqueous solutions of true oil of cade. All the samples examined by the author gave the reactions for both substances. C. A. M. Determination of Minute Quantities of Morphine. C. Mai and C. Rath. (Aychiu Pharm., ccxl., 300; through Pharm. Jount., 1906, vol. lxxvii., p. 413.)- With a view of obtaining a means for determining quantities of morphine of less than 1 mgm.in weight, the authors have investigated the iodic acid reaction, the colora- tion with Frohde's reagent and that with Marquis's reagent. The latter consists of a mixture of 2 drops of 40 per cent. formaldehyde solution with 3 C.C. of sulphuric acid. Of these reactions that with Marquis's reagent was the only one that provedTHE ANALYST. 409 to be practicable. I t is carried out as follows : One C.C. of a 0.1 per cent. morphine hydrochloride solution is evaporated to dryness in a basin, and the residue mixed with 1 C.C. of the reagent. The liquid is transferred to a small test-tube, and the basin rinsed with 4 C.C. of sulphuric acid. With 0.001 gram of the alkaloid the mixture assumes a deep violet-blue colour ; with smaller quantities the coloration is less intense and is easily comparable colorirnetrically. The limit of morphine that can be determined is 0.00003 gram.TV. P. s. TOXICOLOGICAL ANALYSIS. A Simple Method of Differentiating the Blood of Different Animals. Piorkowski. (Ber. d. phaym. Ges., 1906, 226; through J0ur.n. Pharna. Cham., 1906, xxiv., 272, 273.)-The following simple method of applying the serum test for blood has been devised by the author : One C.C. of hydrocele liquid, ascites fluid, or of human serum, is introduced into each of a series of test-tubes (6 c.m. long by 0.8 c.m. in diameter), then one drop (0.04 c.c.) of the fresh blood of different animals diluted ten to fifty times, or better, of the dried blood previously dissolved in a physiological solution of salt. Hydrocele fluid forms the best reagent, and the blood must be allowed to fall from the pipette so as to form a layer on the surface of the other liquid. The tubes are examined thirty to forty-five minutes after the introduclion of the blood, and if the latter is of human origin a faint red precipitate (of coagulated blood) will be observed, while the supernatant liquid will have remained clear. On the other hand, the blood of other species will have dissolved in the human serum, colouring it red. If the tubes are charged, in the first place, with serum of the horse, ox, or other animal, the corresponding blood is coagulated, while chat of any other animal dissolves. The reactions are rendered more conclusive by cautiously shaking the tubes every half-hour after the coagulation has taken place, a fresh precipitate being formed each time. In preparing the solution of blood, the action of the sodium chloride (or sodium carbonate) upon the stain, etc., iff continued until the liquid is manifestly yellow, aftcr which it is filtered and tested as described. C. A. M.

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DOI:10.1039/AN9063100404

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年代:1906

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THE ANALYST. 409 ORGANIC ANALYSIS. Detection of Methyl Alcohol. H. Scudder and R. B. Riggs. (Jozm. Anzer. C'h~wz. Soc., 1906, xxviii., 1202-1204.)-0xidation of the solution by a hot copper spiral, subsequently testing for formaldehyde by heating with milk and HC1 containing Fe,CI,, is unreliable for the detection of methyl alcohol, 10 per cent. aqueous solutions of ethyl alcohol, acetic acid, and acetone, all giving reactions indistinguishable from that obtained with pure methyl alcohol. The following modification of the Sang% Ferribre-Cuniasse test shows 2 to 3 per cent. of methyl alcohol in ethyl alcohol. To 10 C.C. of the aqueous solution to be tested add 0.5 C.C. concentrated H,SO,, and 5 C.C. of a saturated solution of KMnO,, the temperature being maintained at 20' to 25' C.After two minutes add sufficient sulphurous acid to give a colourless solution, boil till free from SO, or acetaldehyde, and apply the resorcinol test for formaldehyde. The production of a pink ring is usually sufficiently characteristic to prove the presence of methyl alcohol, but the appearance of flocks, which can often be developed410 THE ANALYST. by standing for one or two hours and then heating the upper layer to boiling, affords positive evidence of its presence. The use of HC1 instead of,H,SO, in the resorcinol test prevents any darkening due to overheating or charring, but lessens the delicacy .of the reaction. W. H. S. The Formation of Formaldehyde in the Caramelization of Sugar. A. Trillat. (Bull. Xoc. Chim., 1906, xxxv., 681-685.)-0n heating sugar, traces of formaldehyde are given off even at 125" C., and at 150" C. the aldehyde is liberatea in greater quantity.Analyses of the vapours emitted at 200" C. showed the presence of 0.2 to 5.7 per cent. of formaldehyde, and the residual caramel contained up to 0.27 per cent. of polymerized formaldehyde, probably in the state of trioxymethylene. The amounts produeed were found to vary with the method of heating, the nature of the vessel, and the purity of the sugar. Experiments with five samples of commercial caramel showed that two were free from formaldehyde, whilst the others contained from 0.030 to 0.325 per cent. The author points out that this accounts for the antiseptic properties of caramel. Fresh urine, for example, treated with a sufficient quantity of caramel no longer putrefies.The Bacillus coZi comrnunis was destroyed by being left for fourteen hours in contact with a 10 per cent. solution of caramel. c. A. Rl. The Determination of Formic Acid by Potassium Permanganate. J. Klein. (Bey., 1906, vol. 39, p. 2640 ; through Chent. Ztg., 1906, XXX., Eep., 329.) -Grossmann and Aufrecht's recent paper on this subject has caused the author to refer to his method, published nearly twenty years ago. It consists in oxidizing formic acid in a boiling alkaline solution by means of potassium permanganate, then adding an excess of oxalic acid and dilute sulphuric acid, and finally titrating the excess of oxalic acid with permanganate. A. G. L. On the Determination of Malic Acid. H. Cantoni and M. Basadonna. (BuEE.SOC. Chim,, 1906, xxxv., 727-737.)---The determination of malie acid by oxida- tion with potassium permanganate in acid solution has yielded absolutely discordant results in the authors' hands, whatever modification of the method was employed. They have also obtained bad results with the various methods of precipitating the acid by means of lead acetate, the highest yield being 91.41 per cent. of the theoretical amount. I n their opinion, there is as yet no method capable of deter- mining malic acid in the presence of other organic acids, and they recommend the study of the solubility of rnalates in different solvents to find the basis for a reliable process. They themselves have determined the solubility of malatcs of the alkaline earths in water. The strontium salt is less soluble at 20" to 30" C., but much more soluble at higher temperatures than the calcium and barium salts, and its solubility increases enormously with the rise in the temperature.Calcium malate is the least soluble of the three salts at 35' C., and its solubility decreases with the rise in temperature. The barium salt is slightly more soluble in hot than in cold water (cf. ANALYST, xxxi., 300). C. A. M.THE ANALYST. 411 On Melezitose and Turanose. G. Tanret. (BUZZ. SOC. Chinz., 1906, xxsv., 816-825.)-The melezitose prepared by the author from Taschkent manna had a composition correspondiog with the formula CISHDSOI,',, 2H,!O, and did not lose the whole of its water of crystallization at 1300 to 135" C. Its optical rotation, calculated on the anhydrous sugar, was al) = + 89.3. When hydrolysed by means of a dilute acid, it yielded one molecule of turanose and one molecule of dextrose, the former being decomposed on further hydrolysis into one molecule of dextrose and one molecule of I~vulose, and not, as commonly accepted, into two molecules of dextrose.The turanose separated from the products of the restricted hSdrolysis of melezitose had the formula CI.LH23011, and was the first known isomer of cane-sugar. I t was very sweet and soluble in all proportions in water and methyl alcohol. I t s optical rotation was aD = + 71.8 (calculated 72.8). I t was fermented by beer-yeast, but only very slowly. From 5 to 10 per cent. of sugar remained unfermented in an experimenr; that was continued for five months.C. A. &I. Determination of Lead Number of Maple Syrup and Maple Sugar, A. E. Winton and J. L. Kreider. (Jozim. Anzey. Chem. SOC., 1906, xxviii., 1204- 1209.)-The proportion of lead in the precipitate produced by treatment of maple products with basic lead acetate solution is approximately constant, and furnishes a means of determining the presence of cane-sugar. For its estimation the authors recommend an indirect method, using a definite volume of standard lead subacetate, and determining the lead remaining in the solution after precipitation. Twenty-five grams of the material ic; weighed into a 100 C.C. flask, 25 C.C. lead subacetate solution added, and the volume made up with water to 100 c.c., the rxixture shaken, allowed to stand one hour, and filtered.Ten C.C. of the clear filtrate are diluted to 50 c.c., a moderate excess of H,SO, and 100 C.C. of 95 per cent. alcohol added, and the whole allowed to stand overnight. The precipitate is then filtered on a Gooch crucible, washed with 95 per cent. alcohol, dried at a moderate heat, ignited at low redness for three minutes and weighed, the difference between the amount of lead thus found and that present in 2.5 C.C. of the standard solution, when divided by 2.5, giving the '' lead ~tuvzbe~." The lead subacetate solution used is prepared by boiling for half an hour 430 grams lead acetate, and 130 grams litharge, with 1,000 c.c. water, and after cooling and allowing to settle, diluting the supernatant liquid to a density of 1-25. To a measured volume of this solution, 4 volumes of water are added, filtering if not perfectly clear.The lead number for maple syrup is found to vary from 1.19 to 1-77, the last figure being obtained with a poor quality, and that for maple sugar from 1.84 to 2-48, falling in the case of adulterated samples to as low as 0.10, and in one case 0.02. W. H. S. On a Method for the Separation of Cholesterol and Phytosterol. A. Windaus. (Chem. ZQ., 1906, xxx. , 101l.)-Cholesterol dibromide is difficultly soluble in i ) ~ mixture of glacial acetic acid and ether, a mixture of 50 c.c. of acetic acid and 50 C.C. ether dissolving only 0-6 gram of the substance at 20" C. Phytos- terol dibromide, on the other hand, is much more readily soluble, and, moreover, does not crystallize at all easily. The author proposes a method of separation based412 THE ANALYST.on these facts, and describes the treatment of mixtares of 4, 8 and 0.4 gram cholesterol with 4, 0.8 and 4 grams respectively of phytosterol, the mixtures being dissolved in each case in 10 parts of ether and treated with the same quantity of glacial acetic acid containing 5 per cent. of bromine. I n each case products were obtained which permitted of ready identification as cholesterol and phytosterol derivatives. The dibromides can be readily reconverted into the original alcohols by freatment with a reducing agent (zinc dust or sodium amalgam). A. G. L. The Action of Ozone on Oils and Fats. E. Molinari and E. Soncini. (Berichte, 1906, xxxix., 2735-2744.)-Ozone is absorbed quantitatively by unsaturated fatty acids, and the increase in weight corresponds with the ozone value calculated from the iodine value.Oils become very viscous under the action of the gas, and a good solvent for modifying the violence of the reaction has been found in hexane from petroleum, which can subsequently be easily eliminated by means of a current of ozone. The author has determined the ozone values of linseed, maize, castor, olive, and rape oils, etc., and has obtained results agreeing well with the iodine values. Linseed-oil, for instance, with an iodine value of 171 gave an ozone value of 30 a s against the theoretical 32.3. Pure oleic acid (iodine value 9G.03) absorbed ozone in the proportion of 1 molecule to 1 molecule (03). The ozonide was a viscous, almost colourless liquid, heavier than water, and decomposing without melting when heated above 90" C. Its elementary composition and molecular weight corresponded with the formula C,,H,,O,.When decomposed by dry or moist heat it yielded nonylic, azelaic, and two other fatty acids, and an oily product boiling at about 190" C. From a study of these decomposition products the authors conclude that the ozonide must have the constitutional formula- C H, [ C Ha] 7. CH - C H. [ C H,] 7. C 0 0 H '0.06 aud that oleic acid absorbs 3 atoms of oxygen when acted upon by ozone, and not 4 as asserted by Harries (Berichte, xxxviii., 1630). Xezo Xethod of Determining Oxom.-When ozone is passed through ordinary olein the increase in weight corresponds to the amount of the gas absorbed. C. A. M. On the Ozonides of Oleic Acid, C.Harries and C. Thieme. (Bei-icILte, 1906, xxxix., 2844-2846.)-I.n a previous communication ( A m . d. Chenz., 1906, 318) it was found by the authors that when ozone acted upon a solution of oleic acid in acetic acid or chloroform it yielded a viscous oil, which, when purified by being dissolved in acetic ether and precipitation by petroleum spirit, was a colourless product containing 4 atoms of oxygen. They now find that if this substance he washed with water and sodium bicarbonate solution and extracted with ether, it gives a product containing only 3 atoms of oxygen. They propose to term this normal oleic acid ozonide, and their former preparation oleic acid perozonide. Both ozonides yield the same products when decomposed by water, and the chief difference between them is that when equal quantities are boiled for the same lengthTHE ANALYST+ 413 of time with water a much more intense reaction for hydroxgen peroxide is obtained in the case of the perozonide.The formula assigned by the author to the normal ozonide is the same as that given by Molinari and Soncini (see preceding abstract). C. A. M. Notes on some Conifer Oils. R. E. Hanson and E. N. Babeoek. ( J o u r ~ Amcr. Chern. Soc., 1906, xxviii. 1198-1201.)--Several oils distilled by the authors from authentic materials have been examined with the following results : Oil of Black Spruce Hemlock (1) Cat Spruce, Cat Spruce, Red Spruce, 7, (2) leaves cones leaves Red Spruce, cones A m e r i c a n Larch Pitch Pine Red Pine Juniper Virginia leaves leaves j Juniper, Yield, Per Cent._ _ 0.57 0.4 0-46 0.103 0-25 0,204 0.38 0.149 0.001 0.001 0.18 0.9274 ati 19" 09238 7 , 15" 0.9273 ), 15' 0.9216 ) ) 15" 0.899 ) ) 15" 0.9539 ), 16" 0.8600 ), 15" 0.8816 7 7 15" i 0.8531 a t 20" I - 0.900 7 > 16" . - - Odour suggests limonene or dipentene Yellow colour, pronounced limonene-like odour Free borneol, 7-76 pel- cent. odour of bornyl acetate Golden-yellow colour, fir- balsam-like odour Remainder largely pinene Yellow colour, pungent odour Brownish - red colour, pungent and disagree- able odour Light yellow colour, juniper odour - W. H. S. The Phosphomolybdic Aeid (Welman's) Test for Vegetable Oils. B. Kuhn and G. Malfpaap. (&it. Untersuch. Nahr. Gcnussm., 1906, xii., 449-455.)-This test is qzite useless for detecting the presence of vegetable oils in oleo-margarine and in tallow, as these two fats themselves give a dark green coloration with the reagent, but it may be employed for the detection of vegetable oil in lard.With very few exceptions, lards do not give a coloration. The constituent of vegetable oils which gives the coloration is, apparently, a decomposition product of albumin ; it is non- volatile, easily oxidizable, and is readily removed from the oils by extraction with414 THE ANALYST. alcohol, but not with hydrochloric acid. Owing to the fact that this active constituent is destroyed by heat, direct sunlight and oxidizing agents, a negative reaction does not prove the absence of vegetable oils (cf. ANALYST, 1895, p. 62). w. P. s. The Analysis of Turkey-red Oils.W. Herbig. (Chem. I k u . Fett-?i. Haw- Ind. , 1906, xiii., 187-190, 211-213, 241-244).--There is considerable confusion in commerce as to the meaning of the term '' 50 per cent. Turkey-red oil," etc., when applied to these products, and to obviate this the author suggests that it shall invariably be taken to refer to the amount of total fat. He has made comparative experiments with different methods, and recommends the following simple method of determining the total fat and combined sulphuric acid : Ten grams of the sample are heated with 50 C.C. of water, and the resulting solution treated with 25 C.C. of dilute hydrochloric acid (strength not given), and boiled for three to five minutes. Whenxold it is transferred to a separating funnel, the flask being rinsed out with water and ether, and then shaken with about 200 c.c.of ether. The aqueous layer is drawn off, and the ethereal solution thoroughly washed three times with water, which will take from thirty minutes to an hour. The washings are added to the original aqueous layer, the mixture boiled to expel all ether, and the sulphuric acid precipitated in the usual way as barium sulphate. The ethereal solution is now concentrated by distillation at a low teniperature, the residue then transferred to a weighed beaker, and the rest of the ether allowed to evaporate spontaneously. Fi.nally $he fat is heated for a minute or so over a free flame (till no more bubbles appear), and is then dried for thirty minutes at 105" C., and weighed. Tables of experimental results are given in detail, and it is also shown that the results for the total fat obtained by decomposing Turkey-red oils with cold hydrochloric acid differ but slightly from those obtained by treating the oils with boiling acid.C. A. M. A Method of Distinguishing between True Albumin and Mucinoid Substance in Urine. L. Grimbert and E. Dufau. (Jounz. Y h n m . CIZZ"IYL., 1906, xxiv., 193-199.)-A little of the filtered urine is allowed to run from a narrow pipette on to a few C.C. of a solution of 100 grams of citric acid in 75 C.C. of water. When only mucinoid substance is present, a more or less nebulous zone is formed near the juncture of the liquids, attaining its maximum intensity after the lapse of one or two minutes. On the other hand, urine containing only pathological albumin (even as much as 6 to 8 grams per litre) gives no such turbidity.Again, when the urine is allowed $0 flow on to the surface of nitric acid (Heller's reaction), pathological urine produces a sharp ring at the contact-zone, whilst mucinoid substance gives no ring, but a, turbidity above the zone of contact. I n the case of urine containing both substances, the ring and turbidity will both appear, with a clear zone between them. When Heller's reaction gives a positive result, it will be necessary to confirm by other tests the nature of the proteid found. C. A. M. Note on the Analysis of Hungarian Leather. F. Jean. (dnn. de Chinz. Anal., 1906,, voL 7fl, pp. 361-363.)-Tne commissariat of the French Army requiresTHE ANALYST.415 the white skins intended for military accoutrements to contain not more than 10 per cent. of water, from 10 to 15 per cent. of alum, 5 per cent. of sodium chloride, and 25 to 33 per cent. of grease. By " alum " is understood potassium aluminium sulphate containing twenty-four equivalents of water. Three samples of such leather examined by the author gave the following results : Water (loss at 105" C.), 25.4 to 26-2 ; fat, 21.5 to 23.6 ; sodium chloride, 4-1 to 5.6 ; sulphuric acid (SO,), 6.7 to 9.3 ; water in ammonium sulphate, 0.25 to 0.31 ; ammonia, 0.47 to 0.49 ; alumina, 2.4 to 3.9, and hide substance (N x 5*62), 32.7 to 36.3 per cent. Calculation of the amount of ammonium alum (containing twenty-four equivalents of water) : (1) from the amount of alumina; (2) from the total sulphuric acid; and (3) from the ammonia, gave the following figures : 1 2 0 Pcr Cent.Per Cent. Per Cent. From the alumina ... ... 21.5 26.7 34 ,, sulphuric acid . . . ... 19.19 19.54 26-29 ,, ammonia ... . .. 12-78 12.60 15-77 The author's explanation of these discordant results is that in hides whitened with alum and salt the aluminium is no longer present in the form of alum, but that there has been dissociation of the salt into a more or lass basic aluminium sulphate fixed by the hide, with partial elimination of ammonium sulphate in the baths. I t will be necessary for the military specifications to be modified, since ordinary alum has now been generally replaced by ammonium or sodium alums in the preparation of Hungarian white skins. C.A. M. On the Balsam of Hardwiekia Pinnata. G. Weigel. (Phnrm. Ccntralh., 1906, vol. 47, p. 773; through C'lzem. Ztg., 1906, xxx., Rep., 345.)-This East Indian balsam appears capable of replacing copaiva balsam in the painting of porcelain, varnish-making, etc. The balsam contains 48.5 per cent. of ethereal oil and 51.5 per cent. of resinous bodies (48.3 per cent. saponifiable and 3.2 per cent. unsaponifiable). A. G. L. The Determination of the Calorifie Value of Liquid Fuels by Means of the Junker Calorimeter. E. Glinzer. (Zeits. angezo. Ghem., 1906, xix., 1422.)- The author mentions the excellent results obtained by means of the Junker calori- meter in the case of gaseous fuels, and its increasing application to liquid com- bustibles. Under special conditions oils with a boiling-point of even 400" C. may be burnt in it, and in the ordinary way the calorimeter may be used for oils with a boiling-point not exceeding 250' C. For such oils the burner shown in the figure is used, the principle of the burner being similar to that of the well-known "Primus" burners for gasolene and petroleuni. The burner is suspended from one arm of a, balance, and nearly balanced by weights placed on a scale-pan depending from the other arm. The oil-vapour is then lighted, the nozzle placed in the calorimeter, the water is turned on, and the temperatures of the in-going and out-coming water are allowed to become constant. When so much oil has been burnt that the burner is exactly balanced, a small weight (10 or 2C grams) is placed in a small scale-pan below the burner so as to depress the latter, and the experiment is continued until the416 THE ANALYST, burner is again in exact equilibrium, showing that a quantity of oil corresponding to the added weight has been burnt. The water passing through the calorimeter during this time is, of course, collected and measured. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9063100409

出版商:RSC    

年代:1906

数据来源: RSC

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416 THE ANALYST, INORGANIC ANALYSIS. A Delicate Colour Reaction for Copper, and a Miero-chemical Test for Zinc. Harold C. Bradley. ( A w z e T . Jozm. Sci., xxii., No. 130; through Chem. News, 1906, vol. 94, p. 189.)--It has long been known that hsmatoxylin (the unoxidized extract of logwood) gives a dark blue colour with copper salts. The author has found that the reaction is exceedingly delicate, solutions containing only 0~0000001 per cent. of copper still giving a blue colour, whilst the limit with ferro- cyanide is 0.001 and with potassium iodide 0.0001 per cent. The absolute quantities taken are not stated. Zinc can be readily identified in the presence of other bodies by its character- istically crystalline nitro-prusside, all the other heavy metals giving amorphous, slimy nitro-prussides.Thus, zinc was recognised in the blood of certain molluscs by incinerating a small quantity, preparing a roughly 10 per cent. solution of the ash, removing copper by means of sulphuretted hydrogen, evaporating the filtrate to a small bulk, and digesting 1 drop of the solution on a microscope slide with 1 drop of a fresh solution of nitro-prusside. On cooling, the rectangular plates and prisms of zinc nitro-prusside could be readily seen under the microscope, A. G. L. Estimation of Copper by Titanium Chloride. Ezra Lobb Rhead. (Journ. Chewz. SOC., 1906, vol. lxxxix., p. 1491:)-1n presence of potassium thiocyanate, copper is quantitatively reduced from the cupric to the cuprous state by a solution of titanium trichloride. The reaction takes place in either sulphuric acid or hydrochloric acid solutions.As indicator a little ferrous sulphate is added, which is oxidized by the cupric salt to the ferric salt, the latter giving the well-known red colour of ferric thiocyanate to the solution; the disappearance of this colour marks the end of the reaction. The titration must be carried out below 30" C. and in an atmosphere of hydrogen or other inert gas, as titanium trichloride oxidizes readily in air. Ferric salts must he absent or else their amount known and allowed for ; nitric acid must also be absent. The results given by the method are good. A. G. L. The Determination of Arsenic Acid. L. Rosenthaler. (Zeit. uml. Chem. , 1906, xlv., 596-599.)-The method is based on the following reaction (the converse of that in general use in the determination of arsenious acid) : 2H,AsO, + 4KI + 4HC1= As,O, + 41 + 4KCl+ 5H,O.I n the presence of a large excess of acid, the reaction begins without the application of heat, and is complete in ten to fifteen minutes, after which the liberated iodine can be titrated with FG thiosulphate solution, each C.C. of which corresponds to 9 mgms. of potassium arsenate. I n making a determination, the potassium arsenateTHE ANALYST. 417 is dissolved in water, 2 grams of potassium iodide introduced, and hydrochloric acid (25 per cent. strength) added until a precipitate results. This is dissolved by the addition of the smallest possible amount of water, and the liquid allowed to stand ten to fifteen minutes before titration of the iodine.Sulphuric acid can be used in place of hydrochloric acid with equally satisfactory resalts. For the simultaneous determination of arsenic and arsenious acids, the latter is first titrated in the usual way with iodine solution. The liquid is then treated with 1 to 2 grams of potassium iodide, and fuming hydrochloric acid and 50 per cent. sulphuric acid (proportions not given) introduced until the precipitate forms, after which the determination is completed as above described. The method can also be used in the determination of arsenic, the latter being first oxidized into arsenic acid. C. A. M. Determination of Minute Quantities of Arsenic. W. Thomson. (Chem. News, 1906, vol. xciv., pp. 156, 157, and 166, 167.)-The author points out that all nitrous compounds formed in the destruction of organic matter must be completely removed by repeated evaporation in order to obtain the proper size and depth of the arsenic mirror when the electrolytic process is employed far the determination.With the Marsh-Berzelius method the presence of some nitrous compounds does not materially affect the results. Results of experiments are also given to show that l e d cathodes are the most efficient in reducing arsenic compounds, in the presence of nitric or nitrous acid, to the state of arseniuretted hydrogen. From experiments with insensitive zinc in the Marsh-Berzelius process the author concludes that the addition of cadmium sulphate does not always have the effect ascribed to it by Chapman and Law (ANALYST, 1906, p. 3). w. P. s.Investigations on Red Phosphorus. A. Siemens. (Arb. am d. &is. Geszindheitsamte ; through Chem. Ztg., 1906, XXX., Rep., 349.)-The author shows that every sample of red phosphorus can be made to give indications of the presence of yellow phosphorus in the Mitscherlich test, if only the boiling is sufficiently rapid (under somewhat reduced pressure), and a current of hot oxygen is employed. The '' glowing " of phosphorus appears to be due to the formation of a volatile lower oxide, which is formed from red phosphorus at 90" C. at the same rate as from yellow phosphorus in the cold. The author has worked out a method for the detec- tion of yellow in red phosphorus, which depends on the reduction to metal of certain metallic salt solutions by means of the dissolved phosphorus.He also shows the view that concussion changes red into yellow phosphorus to be untenable; the red phosphorus is only changed into a, more finely divided modification, in which state it is more easily acted on by reagents and more readily soluble. A. G. L. The Detection of Ozone. F. Fischer and H. Marx. (Bcrichte, 1906, xxxix., 2555-2557.)-Paper dipped in an alcoholic solution of tetramethyl-p-diamido-diphenyl- amine becomes violet when brought in a moist condition into contact with ozone. Oxides of nitrogen colour this 6' tetramethyl base " paper a straw yellow, whilst mixtures of nitrous oxides and ozone give dirty-brown intermediate shades. It is418 THE ANALYST. essential to have the test-paper moist, since the dry paper is coloured yellow by the long-continued (thirty minutes) action of ozone.If either the nitrous oxide or the ozone largely predominates in a mixture of the gases, the paper gives the colour characteristic of the gas that is in excess. Paper that is coloured violet by ozone becomes yellow if subsequently exposed to the action of nitrous oxides, and vice cemd. A trace of nitric oxide in ozone may be detected by conducting the mixed gases into liquid air, when the ozone dissolves and the nitric oxide solidifies in flakes which can be separated by filtration, while the ozone remains in the filtrate. C. A. M. The Examination of Liquid Carbon Dioxide. Werder. (Cherm. Ztg., 1906, xxx., 1021.)-According to the author, the spread of the total abstinence movement has led to a considerable increase in the quantity of liquid carbon dioxide used in the manufacture of aerated waters and fruit syrups.The quantity of liquid carbon dioxide made in Switzerland is estimated for the year 1906 at 300,000 to 350,000 kilogms., the greater part being €or human consumption. The carbon dioxide is made in three ways : from coke, potassium bicarbonate being an intermediate product ; by heating magnesite or other carbonates ; and from breweries. The author proposes the following specification for the liquid : There should be no pungent or empyreumatic odour. The quantity of carbon dioxide present should not be less than 98 per cent., that of carbon monoxide not more than 0.5 per cent. Sulphurous and nitrous acids must be absent. Or, leading the gas for fifteerl minutes through 100 C.C.of a warm potassium permanganate solution containing sulphuric acid, no appreciable decolorization should take place ; nor should it produce a precipitate in the same time in 100 C.C. of a & silver nitrate solution acidified with nitric acid. In taking a sample of the gas, the bottle should always be in the horizontal position ; otherwise the quantity of air in the sample taken is excessive. The carbon dioxide, oxygen, and carbon monoxide present are best determined in an Orsat apparatus, the measuring vessel of which is narrowed in its upper part, so that 20 C.C. can be read to qD C.C. The measuring vessel is filled ten or twenty times with the gas, the carbon dioxide being absorbed each time, and the united residues are then analyeed for oxygen (0.01 to 0.05 per cent.) and carbon monoxide (0.05 to 0.20 per cent.).Communication between the Orsat apparatus and the reducing valve of the bottle is conveniently made by a tube carrying a three-way tap. The taste should be purely acid. A. G. L. Determination of Nitrates. Frank Sturdy Sinnatt. (Proc. Chenz. Xoc., 1906, vol. 22, p. 255.)-Knecht and Hibbert's method for the determination of picric acid (Bey., 1903, xxxvi., 1549) was applied to the determination of potassium nitrate as follows : Ten C.C. of a 0.1 per cent. solution of potassium nitrate mere evaporated to dryness, and the residue heated for thirty minutes in a steam-oven with 5 C.C. of a solution of phenol-sulphonic acid. The whole was then washed into a flask, hydro- chloric acid added, and titrated with titanium trichloride.Three titrations carried out in this way gave 0*009788, 0.009948, and 0.009817 gram of potassium nitrate respectively, instead of the 0.01 gram taken. A. G. L.THE ANALYST, 419 The Determination of Hydrosulphurous Acid in Hydrosulphites and in their Combinations with Formaldehyde. A. Seyewetz and &loch. (BztZZ. SOC. C'him., 1906, xxxv., 293-297.)-TThe method is based upon the fact that hydro- sulphurous acids and hydrosulphites reduce silver halides to metallic silver. The hydrosulphite is dissolved in boiled distilled water, with precautions to exclude atmospheric oxygen, and is immediately introduced into an ammoniacal solution of silver chloride containing four or five times the theoretical amount of silver salt for the reduction, The precipitated silver is collected, washed with ammoniacal water, ignited, and weighed.The reaction may be expressed by the equation :++ 2AgC1+ 4NH, + Na,S,O, + R,O = 2NaCl+ 2(NH,),SO, + Ag,. The results quoted show that the method gives better results thau those obtained by titration with indigo carmine. The commercial product hyraldite (a mixture in varying proportions of sodium hydrosulphite-formaldehyde and sodium bisulphite-formaldehyde) cannot be titrated with indigo carmine. In aqueous solution it only reduces amnioniacd silver chloride slowly, but the reduction is immediate and complete at 80" C. The solution of hyraldite sliould be boiled for four or five minutes with four times the required amount of the reagent, and the precipitated silver weighed as in the case of hydrosulphites.Assuming that a molecule of pure hyraldite (NaHSO, + CH,O + 2H,O) reduces 2 molecules of silver chloride, the commercial hyraldite, C, of the Lyons manufac- turers contains from 84.42 to 86 per cent. of the pure compound. The formaldehyde has no action upon the ammoniacal silver chloride, and is itself transformed in the reaction into hexamethylene- tetramine. C. A. M. The Action of Sulphides on Nitroprussides. J. F. Virgili. (Zeit. a n d Chenz., 1906, xlv., 409-439.)-A soluble sulphide acting on sodium nitroprusside, or, in general, on any soluble or insoluble nitroprusside, yields a blue substance, which the author concludes to be a molecular addition compound. The presence of free alkali or of alkaline earths prevents the formation of this blue coloration, and certain salts of weak acids which can yield alkalies on hydrolysis-e.g., silicates, phosphates, and borates-also interfere with the reaction.Ammonia, and its salts have less influence. If an excess of ,z soluble nitroprusside act upon a soluble sulphide in the presence of a sufficient quantity of free alkali, a red coloration is obtained. The author attributes the reddish-yellow, red, purple and violet colorations that are frequently obtained to the simultaneous production of the blue compound between the sulphide and nitro- prusside, and of a yellow substance formed by the action of alkali or alkaline earth upon the nitroprusside. As regards the use of nitroprusaides in analysis, the conclusion is arrived at that they are not reagents for the sulphide ion, but for the unionized sulphide molecule, and are hence less sensitive than the solutions of certain metallic salts--e.g., neutral or alkaline lead salts-which act upon the sulphide ion.The sensitiveness of sodium nitroprusside as a reagent for sulphides is increased by the use of solvents-e.g., glycerin or alcohol-which prevent or check the ionization, and also by the addition of an excess of the reagent, or by the intro- * Assuming that, in the indigo process, one molecule ( 3 ) Na,S,04 -k SH,O (forrnula of I3ernthsen) liberates I€,.420 THE ANALYST, duction of other ions, for which purpose neutral salts, and in particular alkali carbonates, are suitable. The addition of alkali greatly increases the sensitiveness of the test, fixed alkalies being more effective than ammonia.If the sulphide solution containing the nitroprusside, but not an excess of alkali, be cooled to the freezing-point, the sensitiveness of the reaction is almost doubled, but even then falls short of that shown by reagents acting directly upon the sulphide ion. The maximum of sensitive- ness is reached with an excess of alkali in the frozen solution, but the presence of the alkali prevents a distinction being made between sulphides and hydrogen sulphide. I t is not possible to differentiate sulphides from sulphydrates by means of the nitro- prusside reaction ; nor can a coloritnetric determination of sulphides be made, owing to the difficulty of obtaining coniparabie coloured solutions and the want of sensitive- ness of the reagent. C.A. M. The Determination of Halogen. James Moir. (Proc. Chem. Xoc., 1906, V O ~ . 22, p. 261.)-The substance to be analysed is weighed into a tall nickel crucible, 10 drops of water and 5 to 7 ‘( pastilles ’’ of pure potassium hydrate are added, and the mixture stirred with a platinum wire whilst it is heated on a steam-bath ; when it is uniform, 0.5 to 1 gram of finely-powdered potassium pernianganate is gradually stirred in; the heating is then continued until the mixture is dry, care being used to prevent frothing; the crucible is next heated to redness over a burner, until the reaction between carbon and manganese dioxide is over. The cool crucible is next placed in a warm dilute solution of potassium bisulphite; the solution obtained is acidified with acetic acid, and filtered into a solution of silver nitrate, the silver halide precipitated being treated as usual.Or the contents of the crucible may be dis- solved in water, and acetic acid added until the manganate has been converted into perrnanganate ; the latter is destroyed by adding barium dioxide, and the filtered solution is neutralized with sodium bicarbonate and titrated, using chromate as an indicator. A. G, L. Modification of the Hanging-Drop Fluoride Test. C. D. Howard. ( JouY?~. - h e r . Chem. SOC., 1906, xxviii., 1238, 1239.)-A test-tube of small bore, about 2 inches long, is fitted with a, rubber stopper, into the bottom of which passes a small piece of glass-tubing closed at one end, its open end extending about 3 mm.into the tube. Tho precipitate of CaCO, and CaF,, ignited until nearly free from carbonate, is well mixed with about 0-1 gram of precipitated silica, and introduced into the dry test- tube, the glass tubing nearly filled with two or three drops of water, the bottom of the stopper thoroughly dried, and the stopper inserted immediately after the addition of 1 to 2 C.C. strong H,SO,. The tube is then immersed in a beaker of boiling water for fifteen to thirty minutes, when, if the solution under examination contains any appreciable quantity of fluoride, a heavy gelatinous ring will be formed in the small tube projecting from the stopper. By comparison with tubes containing known amounts of fluoride, the process may be made roughly quantitative. W. H. S.Back Reactions in Iodine Titrations. J. H. Davies and E. P. Perman. (Chem. News, 1906, 93, p. 235.)-The ‘( back reaction ” often observed in the titrationTHE ANALYST, 421 of iodine liberated from potassium iodide, using starch as indicator, is found to depend on the concentration of the potassium iodide in solut.ion, and is most marked when the iodine is liberated by copper sulphate or potassium bichromate, but only very slight when bleaching-powder or permanganate is used. I t appears to be due to the comparative slowness and incompleteness of the liberation of iodine, and may be overcome by increasing the concentration of the iodide solution to 1 gram in 10 C.C. water for 25 C.C. & K,Cr,07 and 2 grams jn 20 C.C. water for 1 gram of CuSO,SH,O in 50 C.C.water. W. H. S. The Separation of Silica in the Determination of Citric-Acid-Soluble Phosphoric Acid. J. Hasenbaumer. (Clzem. Zeit., 1906, xxx., 665, 666).-The author finds that the magnesium pyrophosphate obtained in determinations of the citric-acid-soluble phosphoric acid in Thomas slag does not contain silica, and consequently the high results found when the silica has not been separated previously are not due to occluded silica. Further experiments make it appear probable that the higher results obtained when the silica has not been separated are due in part to the possible retention of phosphoric acid by the gelatinous silica, and also to the fact that the magnesium - ammonium phosphate has a slightly varying composition, depending on the previous separation of the silica.The ratio of magnesia to phosphoric acid is 1 : 2.02 when the silica has not been separated previously, and 1 : 1.95 in cases where the silica has been removed. w. P. s. New Method for Preparation of Standard Solutions. S. F. Acree and R. F. Brunel. (Amer. Chenz. Joz~m., 1906, vol. 36, pp. 117-123.)-For the prepara- tion of solutions of HC1 and NH,OH the authors recommend passing the purified, and well-dried gases into a tared graduated flask, nearly filled with conductivity water, until the necessary weight is dissolved, the solution being then made up to the mark with water. The titration of solutions of HC1 and H,SO, with recrystallized NaHCO,, weighing the resultant NaCl or Na,SO,, is considered preferable to the silver chloride and barium sulphate methods, while the unknown strengths of an acid and of an alkaline solution can be determined simultaneously by neutralizing one with the other and evaporating to dryness, the weight of the dry salt and the- volumes of acid and alkali solutions used furnishing the necessary data.w. H. s. On Nessler’s Reaction. A. Buisson. ( J o z m . Pharm. Chim., 1906, xxiv., 289-294.)-It is shown experimentally that the reaction of ammonia with Nessler’s reagent is incomplete, and that a state of equilibrium is established between the different substances. The animonia is not completely precipitated, and on filtering off’ the precipitate and distilling the filtrate, the distillate will give a fresh reaction with Nessler’s solution. Thus, in one experiment in which a solution containing 0.189 gram of ammonium chloride in 40 litres was treated in this way, the distillate contained 0.040 gram of amiiiouia, representing 21 per cent. upon which the reagent had not acted in the first instance.The author also finds that the precipitate has not the composition usually attributed to it. The simplest formula corresponding422 THE ANALYST. with his analytical results is Hg,N,I,. The compound is a brown amorphous body, insoluble in neutral solvents, but soluble in excess of potassium iodide solution, which liberates the whole of its nitrogen in the form of ammonia-HgN,I, + 12KI + 12H,O = 9Rg1, + 4NH, + 12KOH. I n the colorimetric method only a portion of the ammonia contributes to the formation of the colour, and, in the author's opinion, it is probable that the intensity of the resction in the standard solution and in the unknown solution is liable to vary in different fashion under the influence of different factors that affect the equilibrium, such as heat, dilution, etc.C. A. M. The Differentiation of Natural and Artificial Mineral Waters. D. Negreano. (Comptes Rendzcs, 1906, cxliii., 257, 258.)-The electrical resistance of a natural mineral water is almost a physical constant for each kind of water, and serves to distinguish it from other waters. Thus the author obtained the following results in ohms-c.c. at 18" C. : Caciulata water (Roumania), 328 ; Slanic water, 48 ; Vichy water, 140; Vittel water, 500; and Gvian water, 1,280. I n determining the resistance at different temperatures, it was found that it diminished with the tempera- ture. When the interval between the temperatures was not too great the resistance R, at a temperature t could be calculated to 18" C. by means of the formula- where a represents the coefficient of variation, and is approximately 0.02. The values of a in the case of waters mentioned above ranged from 0.019 to 0.027. The resistance of an artificial water made up to imitate the natural mineral water differs materially from that of the latter at the same temperature. For instance, water from the Cblestine spring at Vichy showed a resistance of 140 ohms at 18' C., as against 112 ohms by an artificial Vichy water. The resistance of water of natural Avian water was 1,280 ohms, whilst that of an artificial water was only 1,120 ohms at 18" c. C. A. M. R,=RIS [I -a(t - l8)],

ISSN:0003-2654    

DOI:10.1039/AN9063100416

出版商:RSC    

年代:1906

数据来源: RSC

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422 THE ANALYST. APPARATUS. On a Petroleum Coke for Metallwrgieal Laboratory Use. F. 0, Doeltz. (Clzem. Ztg., 1906, xxx., 585.)-The Celle-Wietze Petroleum Company in Hanover are supplying a petroleum coke well suited for many uses in the laboratory and for the manufacture of electrodes. I t forms a pitch-black, shining, porous mass of consider- able mechanical strength. Its calorific value was determined at 7,330 calories ; its ash content varies from 0.21 to 0.53 per cent. The ash shows a tendency to fuse from the presence of alkali. The production in the year 1905 was 55,000 kilogms. of the coke, its present price being 5 marks per 100 kilogms. A. G. L. A New Method for the Standardization of Thermometers below 0" C. T. W. Richards and F. G. Jackson. (Proc. Amer. Acad., 1906, vol.41, p. 21; through Chern. Ztg., 1906, xxx., Rep., 261.)-The thermometer is standardized by means of solutions of known melting-points. For this purpose the thermometer is placed in a, mixture of ice and water. The substance is then added and the thermo- metric reading obtained noted. Finally, the concentration of the substance added isTHE ANALYST. 423 determined analytically in the solution obtained, the real melting-point of a solution of this strength being then ascertained by reference to a table. I n this way any number of points may be determined, and a curve of correction for the particular thermometer may be constructed, A. G. L. A New Sodium Burner, (Chem. Ztg., 1906, XXX., 835.)-The new burner, which is made by Carl Zeiss, consists essentially of a Bunsen burner provided with a nozzle (C), and a small salt tray, which can be adjusted at the edge of the flame by a screw ( J ) .The tray consists of plate of pumice, 4 x 1 x $ cm., which is soaked in a solution of salt before use. The light from the flame passes through a rectangular hole ( L ) , 4 x 5 cm., cut in the screen (K), so as to yield a steady iinage of even intensity. ' A. G. L. On a New Electrically-heated Microscope Stage. J. Zwintz and C. Thien. (Zeiztralbl. Bakter.ioZ., 1906, [l], vol. 42, p. 179 ; through Chem. Ztg., 1906, xxx., Bep., 341.)-The stage is heated electrically and provided with an automatic regulator. This consists practically of an air manometer, one limb of which is closed at one end and connectedto a U-tube containing mercury at the other, At the bend of the U-tube a platinum contact-piece is sealed through the glass, whilst a graduated metallic rod is pushed to a certain depth into the open limb of the U-tube.If now the stage is heated to the desired temperature, the air in the closed limb of the manometer expands, pushing the mercury in the U-tube before it, and so making contact between the platinum contact-piece and the metallic rod. This closes the circuit of a battery which works a contact-breaker included in the heating circuit, and thus cuts off the latter. A. G. L. Weighing Bottle for Liquids. K. Buschmann. (Chenz. Ztg., 1906, xxx., 1060.)-To use the weighing bottle shown in the figure, some of the liquid is poured into it, and the hollow stopper is inserted so that the hole (e) in the stopper is not opposite the groove (a) in the neck of the bottle. The bottle is then weighed, the stopper turned so as to bring (e) opposite (a), and some of the liquid is forced out by compressing the india-rubber ball on the stopper, which is then again turned into its first position, after which the bottle is again weighed. The bottle may be obtained from F. A. Kiihnlenz, Frauenwalde i. Th., Germany. A. G. L.

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DOI:10.1039/AN9063100422

出版商:RSC    

年代:1906

数据来源: RSC

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424 THE ANALYST+ REVIEW. TOXINS SND AKTITOXINS. (London: VERY few books of the size (250 pages) contain such a mass of detailed information upon any subject as has been crowded by the authors into this volume. There are innumerable references in the text and in the footnotes, and an excellent bibliography at the end. The book is difficult to read, but this is not so much the fault of the authors as of the subject. Since the existence of toxins and antitoxins was first surmised numerous workers hare been engaged in isolating and studying them, and most complex theories have been evoked to explain their actior,s and inter- actions. At present we are threading an apparently most intricate maze, and much further exploration is necessary before we can say with certainty that the key to it has been found.The authors endeavour to simplify their labours by being very precise in their definitions. According to them a toxin is not a ptomaine or a tox- albumin, nor yet a proteid, but a complex body whose chemical structure is absolutely unknown, and which shows many remarkably close analogies with ferments. They have a specific physiological action, and each true toxin has its corresponding true antitoxin. Moreover, the authors appear to accept Ehrlich’s theory in its entirety, and “rigorously exclude from the toxins any poisonous substance that is not a haptine.” By this rigorous system of exclusion the number of bodies to be considered is reduced to a minimum. Section 3 is devoted to the True Toxins, Section 3 to the Vegetable Toxins (phytotoxins), and Section 4 to the Animal Toxins (zootoxins), whilst Section 2 deals with Endotoxins and other bacterial poisons.To the bacteriologist and pathologist the work must be of the greatest value, but to the practical chemist or Public Analyst it can have but little interest. As there are no chemical tests whereby a toxin can be identified or even tho presence of a toxin determined, their isolation can oiily be attempted by those who are licensed to experimen t on animals. Details are given here and there for the isolation of certain of the bodies under consideration, but no reference is made to poisons formed in articles of food or to food-poisoning. The very last paragraph, however, is interesting in the light of the recent revelations with reference to the slaughter of animals for canning purposes.Weichart has shown that the muscles of over-fatigued animals contain an apparently true toxin, which in large doses is fatal. It would appear, therefore, to be desirable that all animals should enjoy a period of rest before being slaughtered. By C. OPPENHEIRIER and C. A. MITCHELL. C. Griffin and CoEpany, Ltd. Crown 8170. ; cloth. Price 7s. 6d. net.) J. C. T. + & * * * INSTITUTE OF CHEMISTRY OF GREAT BRITAIN AND IRELAND. AN examination in biological chemistry was held on October 23 to 26, 1906. Two Associates who were examined for the Certificate passed : Clarke, Robert William, A.I.C. ; Filmer, Reginald Mead, B.Sc. (Lond.), A.I.C. Two candidates examined for the Associateship passed : Gimingham, Conrad Theodore, University College, London ; Whatmough, Wilfred Ambrose, King’s College, London, and under A. H. M. Muter, F.I.C. The examiner in biological chemistry was Arthur Harden, Esq., D.Sc. (Vict.), Ph-D. (Erlangen), F.I.C. The examiners in chemistry were Walter William Fisher, Esq., M.A. (Oxon), F.I.C., and Professor George Gerald Henderson, M.A., D.Sc. (Glasgow), F.I.C.

ISSN:0003-2654    

DOI:10.1039/AN9063100424

出版商:RSC    

年代:1906

数据来源: RSC