摘要:

MARCH, 1913. Vol. XXXVIII., No. 444. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE annual general meeting of the Society wits held on Wednesday evening, February 5, in the Chemical Society's Rooms, Burlington House. The President, Mr. L. Archbutt, F.I.C., occupied the chair, The minutes of the previous annual general meeting were read and confirmed.Messrs. N. Evers, B.Sc., and W. H. Simmons were appointed scrutators of the ballot papers for the election of officers and Council for 1913. The HON. TREASURER presented the accounts of the Society for the year 1912. Therae were adopted, and votes of thanks were passed to the Hon. Treasurer, Hon. Secretaries, and Auditors. On the motion of the PRESIDENT, a, vote of thanks was passed to the President and Council of the Chemical Society for their kindness in allowing the Society the use of their rooms at Burlington House during the past year.The PRESIDENT delivered his Annual Address. Mr. E. W. VOELCKER moved that a hearty vote of thanks be accorded to the President for his address and for his services in the chair during the year, and that his permission be asked to print the address in the ANALYST.Dr. MONIER- WILLIAMS seconded, and the motion was carried unanimously. The PRESIDENT, having received the report of the scrutators, announced that the officers and Council for 1913 had been elected in accordance with the Council's nominations, the list being as follows : President .-Leonard Archbut t, F. I. C. Past-Presidents serving on the Council (limited by the Society's Articles of Association to eight in number).-Edward J.Beven, F.I.C. ; Bernard Dyer, D.Sc., F.I.C.; Thomas Fairley, F.I.C. ; W. W. Fisher, M.A., F.I.C.; Otto Hehner, F.I.C.; R. R. Tatlock, F.I.C. ; E. W. Voelcker, A.R.S.M., F.I.C. ; J. Augustus Voelcker, M.A., B.Sc., Ph.D., F.I.C. Vice-presidents.- George Embrey, F.I.C. ; J. T. Hewitt, M.A., D.Sc., Ph.D., F.R.S.; W.H. Willcox, M.D., B.Sc., M.R.C.P., F.I.C. Hon. Treasurer.-Edward Hinks, B.Sc., F.I.C. Hon. Secretaries.-A. Chaston Chapman, F.T.C. ; P. A. Ellis Richards, F.I.C. Other Members of Cozcncil.-R. M. Clark, B.Sc., F.T.C. ; James Connah, B.Sc., F.I.C.; John Evans, F.T.C.; George T. Holloway, A.R.C.Sc., F.T.C.; G. D. Lander,88 ANNUAL ADDRESS OF THE PRESIDENT D.Sc., F.I.C.; Thomas Macara, F.I.C. ; G. W. Monier-Williams, M.A., Ph.D., F.I.C. ; Cecil Revis ; Harry Silvester, B.Sc., F.I.C. ; F. Wallis Stoddart, F.I.C. ; Arnold R. Tankard, F.I.C. ; John White, F.I.C. Messrs. R. G. Grimwood and Harley F. Knight were appointed auditors of the Society’s accounts for 1913. The ordinary monthly meeting followed the annual meeting, the President occupying the chair.The minutes of the previous ordinary meeting were read and confirmed. Certificates of proposal for election to membership in favour of Messrs. J. A. Goodson, F.I.C., F. W. Skevington, and J. C. White, A.I.C., were read for the second time; and certificates in favour of Messrs. Arthur Cecil Bescoby, M.A. (Cantab.), 24, Saumarez Street, Guernsey, Official Analyst to the States of Guernsey ; Thomas Walter Frith Clark, 11, Quadrant Road, Canonbury, N., Chemist to Messrs.Barnett and Foster, Manufacturing Chemists ; Frank Edward Day, B.Sc. (Lond.), A.I.C., Lansdowne, Limerick, Chemist to the Condensed Milk Company of Ireland ; and James Fowler Tocher, B.Sc., F.I.C., 414, Union Street, Aberdeen, Official Agricultural Analyst for the County of Aberdeen, Public Analyst for the Counties of Aberdeen and Banff.Dr. George T. Beilby, F.R.S., F.I.C., was elected an honorary member of the Society ; and Messrs. S. Elliott, A.I.C., T. R. Greenough, B.A., A.I.C., H. Lowe, M.Sc., A.I.C., J. P. Ogilvie, and J. A. L. Sutcliffe, A.I.C., were elected members. The following papers were read : ‘( Antipyrin in Toxicological Analysis,” by G. D. Lander, D.Sc., F.I.C., and H. W. Winter; ‘( A New Method for the Volu- metric Estimation of Chromium, Vanadium, and Iron in Admixture,” by Frederick W. Atack, M.Sc. ; and a “ Note on Hardened Oils,” by Arthur W. Knapp, B.Sc., F.I.C.

ISSN:0003-2654    

DOI:10.1039/AN9133800087

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

88 ANNUAL ADDRESS OF THE PRESIDENT ANNUAL ADDRESS OF THE PRESIDENT. (Delivered at the Annual General Meeting, February 5, 1913.) WHEN I allowed myself to be nominated as your President, I am afraid I did not sufficiently realise the difficulty of a non-Public Analyst, and one who is not even in private practice, holding the Presidency of a Society which, in spite of the extension of its title, still is, and must always be, so closely indentified with the Public Analyst and his work, If, therefore, my remarks do not adequately deal with matters which are uppermost in the mind of the Public Analyst, I must crave the indulgence of that branch of our members.The field of analytical chemistry is so vast and varied that it becomes more and more difficult to keep in touch with all branches of it; one can, in fact, picture the Society in the future divided into sections, and its roll of member- ship immensely wider than it is at the present time.I am pleased to report that during the past year we have elected nineteen new ordinary members, including one lady member, and your Council has reinstated oneANNUAL ADDRESS OF THE PRESIDENT 89 old member who elected to pay five annual subscriptions which were in arrear instead of being renominated, a tribute to thevalue of our journal.Three names have been removed from the roll owing to resignations and non-payment of subscriptions ; and five, I regret to say, by death. Our total membership has, therefore, increased during the year from 397 to 411, and now includes thirteen honorary and 398 ordinary members.As I have already hinted, I think we ought to have a much larger membership. I am afraid the amplification of our title which was made wben the Society was incorporated in 1907 has not entirely removed the misconception that we are essentially a Society of Public Analysts. I hope, however, that the honour you have done me in electing me as your President will be understood, as it was doubtless intended, to be a recognition of the fact that our members include representatives of all branches of the analytical profession, and that we welcome to our ranks all qualified analytical chemists.That this was the intention of the founders of the Society can be in no possible doubt, for I find by reference to the first volume of our *‘ Proceedings,” dated 1876, the following words on page 6 : ‘‘ By the constitution of ‘ The Society of Public Analysts,’ all analytical chemists, but no others, are eligible for membership ” (the words in italics are so printed in the original).If all analytical chemists would join our Society and communicate their purely analytical papers to us, it would be one step towards that classification of chemical literature which is so desirable and will very soon become imperative.I regret to find that even our own members do not always bring their analytical papers here, and I commend to them the suggestion that they should make a point of doing so whenever possible, and should ask their friends to join us and do the same. I do not urge this from a selfish point of view, but in view of the convenience of having all analytical papers in one journal.It is with great regret that I have to record the loss by death of five members : Arthur Edwaid Ekins, John Pattinson, Benjamin Edward Reina Newlands, Henry de Mosenthal, and Arthur Crozier Claudet. Mr. Ekins, who was elected a, member in 1882, served twice on the Council and also as a vice-president, was one of those men of extraordinary energy who do not seem to allow themselves sufficient rest.He was a, very regular attendant at our meetings, and personally I miss very much his genial presence. Mr. John Pattinson must, I think, have been an original member. He was one of the first Public Analysts appointed and a vice-president of our Society in 1896-97, but he was probably most widely known among chemists by his volumetric method for the estimation of manganese.Mr. Newlands was not a Public Analyst, but a technical chemist of great repute, who, though a, member of our Society, was seldom seen a t our meetings. The same remarks apply to Mr. de Mosenthal, who distinguished himself chiefly in connection with the chemistry of explosives.Mr. Claudet was one of our best known Rnd most widely respected metallurgical chemists, assayer to the Bank of England and the Royal Mint. He took a great interest in various educational movements connected with metallurgical chemistry, to which he freely gave his time, and many of which he generously helped financially. During the past session thirty-one papers were read at our seven meetings, of90 ANNUAL ADDRESS OF THE PRESIDENT which thirty have been published in our journal ; five other papers were communicated during the recess, making thirty-five published papers altogether, of which nine are on food and drugs and twenty-six on general subjects.Seven of the latter papers have contained the results of work carried on under the Society’s Analytical Investigation Scheme; and as we do not present a medal or give prizes for this work, I feel sure I am interpreting your wishes in giving the titles of these papers, and thanking their authors from this chair for their work.They are : ‘‘ The Separation of Arsenic from Antimony and other Metals, with some Appli- cations to Toxicological Work.” By Stanley W. Collins, B.Sc., F.I.C.‘‘ The Analysis of Lithopone.” By W. L, Austin and Charles A. Keane, D.Sc., Ph. D., F. I. C. “ On the Effect of Lime on the Ammonium Molybdate Method of Lead Assay.” By C. 0. Bannister, A.R.S.M., and W. McNamara. “Solubilities of the Lead Salts of the Higher Fatty Acids in Ether and in Petroleum Ether.” By G. A. Neave, M.A., D.Sc. ‘‘ The Detection and Estimation of Arachis Oil.” By Norman Evers, B.Sc., A.I.C.“Alcoholysis and the Composition of Cocoanut Oil.’’ By G. I). Elsdon, B.Sc., A.I.C. ‘‘ The Estimation of Citric Acid in the Presence of Certain Other Acids.” By L. Gowing-Scopes. In selecting these papers for special mention, my only desire is to encourage our younger members to offer their services for this very useful investigation work. We are, of course, equally indebted to all who contribute to our proceedings and assist in the progress of analytical chemistry.Mr. Chapman, who, as you know, originally suggested the investigation scheme, asks me to state that several investiga- tions are still in hand, the results of which will be published in due course. Among other papers read during the session, mention should be made of the valuable contribution to our knowledge of Chinese and Japanese wood-oils contained in the paper by Chapman.The differences in character between these two remark- able oils are clearly established by this paper, and we now have a much more exact knowledge than hitherto existed of their characteristic features and range of analytical values. I should like also to refer to the paper by Levy, published in our journal during the recess, in which the author shows that the slightly higher results obtained when the carbon in steel is determined by direct combustion than when the indirect method is used are due to the presence in the metal of dissolved carbonaceous gases.Although the point is more of academic interest than practical importance in the great majority of cases, it is satisfactory to have an explanation of the slightly different results obtained by the two methods ; and Mr.Levy has done good service in calling attention to the matter, as the examples he gives show that in exceptional cai3es it may be of real importance. A point of kindred nature, relating to the influence on analytical processes of gases occluded by or dissolved in metals, has been raised by Heath (J.Ird. Eng. Chern., 1912, 4, 402; ANALYST, 1912, 37, 376), who shows that error may arise in the determination of oxygen in copper by direct combustion owing to the occlusionANNUAL ADDRESS OF THE PRESIDENT 91 of hydrogen and other gases by the copper, and he has propoaed a most elaborate method for obviating this error.Heath’s method is so elaborate that it would be a very serious matter to have to use such a process in commercial work. I n the paper which I read before the Society in 1900 there was no indication of any such error in the assay for oxygen of 4 4 tough-pitch ’’ copper, since the loss of weight of such copper by simple heating to redness in hydrogen agreed very closely with the oxygen calculated from the weight of water found.As, however, the results obtained by analysts in the estimation of oxygen in copper have been called into serious question on several occasions recently, I think the subject is one which might be usefully investigated under our Analytical Investigation Scheme. It is very satisfactory to know that in spite of the depreciation of our securities, and increased expenditure, our financial position is better than last year by about 290, and that the increased expenditure includes a small salary for much-needed clerical assistance to our Hon.Secretaries. Mr. Richmond informs me that we now have about 6200 available for investment from the income of the past three years, after providing 675 towards the cost of the next General Index, and we are much indebted to him for the very careful way in which he has husbanded our resources.In his successor, Mr. Hinks, we have a member who has the interests of the Society at heart, and will, 1 am sure, serve us well. There is another matter connected with the accounts to which I wish to refer. The Research Fund, you will notice, shows a, deficit-small, it is true, but if we had not had a considerable balance over from last year the deficit would have been much larger.Mr. Richmond thinks, and I agree with him, that we ought to try and raise a, larger sum than $100 for this fund, as the interest on this is not sufficient to carry on the work, and it is not desirable that we should have to encroach upon the capital. I would therefore appeal to those members who appreciate the work that is being done, and realise the importance of it to the Society, to help us in raising a larger capital sum for this fund.I t is satisfactory to know that our journal has cost very little more than last year, and that the increased cost has been more than balanced by the increased revenue of the Society. The value of the journal has been fully maintained, every analytical paper of importance which has appeared in other journals having been abstracted.We are much indebted to our editor, Mr. Julian L. Baker, and the Publication Committee for the care and attention bestowed upon this, the principal asset of the Society. There is one point about the journal which particularly strikes me, and that is that the reviewers really do read the books sent to them for review.Whether one agrees or not with the trenchant criticisms of booke which appear from time to time in the pages of the ANALYST, one does feel that they are at any rate honest attempts to tell what the reviewer believes to be the truth, and what he feels that the reader desires to know. The estimation in which the journal is held is shown by the fact that we have 153 subscribers outside the Society, besides about 35 copies which are sent as exchanges, and to institutions, etc.The Chemical Society having invited ue to send delegatee to a Conference convened for the purpose of considering whether the present system of duplication Our Hon. Treasurer is to be congratulated on the excellence of his report.92 ANNUAL ADDRESS OF THE PRESIDENT of abstracts could be avoided, Mr.Hehner and I attended a meeting held in July last, at which certain preliminary inquiries were agreed upon. There is necessarily some difference of opinion as to what an abstract should give; some favour very brief abstracts, considering that those who wish for fuller information should consult the original papers; others feel that fuller abstracts are required for the benefit of those who have not the time and sometimes not even the opportunity of consulting the original.I n either case the present system of duplication is wasteful, and it is devoutly to be hoped that the Conference may lead to some way of avoiding it. I gather from Mr. Blount, to whom our thanks are due for representing us a t the Eighth International Congress of Applied Chemistry held in New York in September last, that no analytical papers of striking importance were read.Those which appeared to be of sufficient merit have been secured by our editor for abstraction into the ANALYST. I hope we shall have some good papers during the ensuing session, and I would appeal to all our members to ask themselves whether there is not some subject on which they could contribute to our proceedings.To mention only a few problems awaiting solution in connection with my own practice, a reliable method for the direct estimation of rubber in vulcanised rubber goods is much needed. A good summary of our present knowledge in regard to this is contained in a recent paper by W.A. Ducca in the JozLrnal of Ind. and Eng. Chem., reprinted in the Chemical News of January 3, 1913. Notwithstanding the valuable work done by Henriques, Weber, and others, our present methods of analysis of manufactured rubber goods are cumbrous and far from satisfactory. One has only to peruse the paper by Beadle and Stevens in volume xxxv., page 11, of our journal to perceive the pitfalls which await the unwary.The advance must come from those who are in touch with manufacturing operations, and these are guarded with jealous secrecy. I cannot think, however, that manufacturers would lose by assisting in the elucidation of analytical problems. I hope before long we may have some further papers from those of our members who specialise in this difficult branch of analytical work.Another direction in which progress is needed is in methods for the estimation of oxides and other non-metallic impurities in metals and alloys. Professor Turner has shown recently, in a paper read before the Institute of Metals, that there is no method for estimating oxygen in brass. Mr. E. F. Law has frequently called atten- tion in papers read before the Metallurgical Societies to the neglect by analysts of the non-metallic impurities which are so plainly seen in micro-sections of metals and alloys, and which may have a quite important influence in obscure cases of corrosion, fracture, etc.In the analysis of lubricating oils there is room for much improvement. I n spite of the enormous extent to which gas and oil engines and super-heated steam engines are now used, and the consequent demand for oils which will lubricate a t high temperatures without decomposing and forming serious deposits of carbon and hydrocarbons in the cylinders and valve chests, there is no recognised reliable laboratory method for ascertaining quantitatively what the behaviour of an oil will be under these exacting conditions.High viscosity does not seem to be so im- There is no lack of matter.ANNUAL ADDRESS OF THE PRESIDENT 93 portant for such oils as sufficient volatility for the oil to evaporate when it has done its work.Viscosities of lubricating oils should be stated in absolute measure and in the form of a temperature curve, as recently urged by Messrs. Dunstan and Stevens, though the same thing was advocated by Mr.Deeley and myself twelve years ago, and a method described for calibrating commercial viscometers with mixtures of glycerol and water of known viscosity, so as to enable the viscosities of lubricating oils to be determined by means of such simple instruments. We published a table giving the viscosities in absolute measure of glycerol, water, and mixtures of the two in all proportionq which has never, so far as I am aware, been checked by other observers.It is desirable that this should be done, and that others should test our suggested method of determining absolute viscosities with commercial instruments, as Ostwald’s viscometer is not a convenient instrument to use for commercial work. It is also important to bear in mind that unless the capillary tube of the viscometer sold as Ostwald’s complies with certain necessary dimensions, the results obtained by it will not be correct.So long as the present system of reporting 6 t times of efflux” instead of “viscosities ” is adhered to, ihe accurate calibration and standardisation of com- mercial viscometers is a pressing need. In this country the Redwood viscometer is the standard, and very large numbers of these instruments are in use, but unfor- tunately there is a lamentable want of agreement between their indications.I am glad to know that the National Physical Laboratory has this very difficult matter in hand at the present time, and I hope before long they will undertake the standard- isation of these instruments. I may mention that this work is being done in connec- tion with the International Commission for the Unification of Tests on Petroleum Products, and that a most interesting report on flash-point apparatus by Dr.Harker and Mr. Higgins was issued in 1911. Everyone who has to determine flashing-points of oils should study this report. Among the subjects which have engaged the attention of the Council during the year has been the question of the fees paid for public analytical work and the tendency to reduce rather than increase the already inadequate remuneration offered for such work by public bodies.A glaring instance occurred in the early part of last year in connection with the appointments of Public Analysts for the Metropolitan Boroughs of Lambeth and Wandsworth and the County of Antrim.In the two former cases the fees offered amounted to 5s. per sample, the analyst being required to provide his own laboratory and equipment as well as a competent deputy during absence; and in the latter case the princely salary of 6150 per annum was offered for the analysis of an indefinite number of samples-probably exceeding 800 per annum. It being obvious that the fees offered were insufficient to pay for the adequate performance of the work, the honorary secretaries were instructed to write to the two Borough Councils on the subject, and so serious did the matter appear that the Council of the Institute of Chemistry were led to move in the matter, and not only issued a public protest, but urged every Fellow of the Institute to refrain from applying for or accepting either of the three appointments.This led to the withdrawal of all the candidates except three for Lambeth and two for Wandsworth,94 ANNUAL ADDRESS OP THE PRESIDENT of whom one was eventually appointed. Our letter of protest merely received a formal acknowledgment, and all the efforts of the Institute of Chemistry to obtain interviews with the Borough Councils and the Local Government Board failed, the latter being apparently satisfied with some private information which led them to regard the arrangements eventually made as satisfactory.In the case of Antrim an analyst was appointed, but subsequently resigned, as indeed he must do, unless he were prepared to give both his services and his privste income for the benefit of the community. He has since been re-appointed on somewhat better terms.The state of affairs thus disclosed is most unsatisfactory, quite as much so from the public point of view as from that of our profession. Men of the necessary high standing and qualification will not offer their services for inadequate pay, or if they do SO, it is only because the appointments bring other work, and thus in the end private individuals have to pay for public work, which is quite wrong in principle.The acceptance of public appointments at inadequate fees tends to lower the analyst in the public estimation, and prejudices also the interest of the industrial chemist, who is already in many cases most inadequately paid. Matters seem to be far worse in Scotland than in England, and shockingly bad in Ireland.The Association of Public Analysts of Scotland, I am glad to say, have addressed a strongly worded and able statement of their case to the President of the Scotch Local Government Board, in which they allege that the low fees in that part of the country are not wholly unconnected with a desire on the part of certain members of the local authorities that the Adulteration Acts should not be worked, lest their trade should be interfered with.Whatever the reason may be, the persistent opposition to the working of the Acts in Scotland disclosed by the Scotch circular is a grave scandal, and the Local Government Board will fail in its duty to the public if full inquiry is not made into the facts and every support given to the analysts if their complaints are found to be justified.One reason why analysts are so badly paid arises, no doubt, from the general ignorance which prevails in regard to our work, even in quarters where one would expect a more intelligent appreciation of it. How frequently it happens that the salary offered to a chemist entering a works is so meagre as to suggest that the main object is to pay the chemist as little as possible rather than to secure the services of a really capable man ! Public Analysts rightly object to any interference with their work on the part of Medical OfIicers of Health, and to any encouragement being given to this by the Local Government Board, as contrary to the intention of the Act j but if frequently happens in industrial concerns that chemists holding some- what similar, though not official, positions are subordinated to other officers, instead of being placed upon a footing of equality with them in relation to the board of management. It is, in my opinion, the duty of every chemist, official or otherwise, to take every opportunity of claiming the same recognition for his profession as is accorded to the professions of medicine, the law, and engineering.It is of great importance to the well-being of the community that the statuo as well as the remuneration of chemists should be such as to attract to the profession men of the requisite ability, standing, and integrity. The time having come when, in the opinion of the Council, an attempt might beANNUAL ADDRESS OF THE PRESIDENT 95 made to formulate a statement indicating the minimum fee or fees which should be accepted by analysts applying for appointments under the Sale of Food and Drugs Acts, a committee was appointed to consider the matter, and inquiries were addressed fo all Public Analysts in the United Kingdom asking for information as to the number of samples analysed by them per annum, and the fees and other remunerations received in respect thereof.The Council wish to thank the large number of analysts who replied to these inquiries. The conclusions of the committee, arrived at after careful consideration of the whole subject, have been adopted by the Council; but as the question is merged in one of wider scope which is being considered by the Council of the Institute of Chemistry as a result of the Conference which was held in June last, it was decided to send a copy of your Council’s report to the Registrar of the Institute, and to await the result of the deliberations of that body before making the conclusions public.A matter of considerable importance has been called attention to by Dr. Dunn in a letter to the Hon. Secretaries, to which it is the desire of the Council that I should refer.I n the terms of appointment of the Public Analyst for Lambeth and Wandsworth a distinction was made between “ formal ” and 4 6 inlormal ” samples, and one of the candidates is reported to have remarked that the unofficial (or informal) samples wonld not demand so much time or trouble a8 the official samples. It seenis to me very unfortunate that the taking of unofficial samples should ever have been encouraged.The only difference between them and the official samples is that if adulteration is detected the percentage of adulterant does not need to be determined in the case of the informal sample; but just as much care is needed in the one case as in the other to detect the adulteration.Supposing, for example, the percentage of adulterated samples is 10, it follows that 90 per cent. of all the samples, formal and informal, would have to be put through precisely the same tests, and would occupy exactly the same amount of time and trouble. The impression that informal samples can be easily dealt with appears to be held even by the Local Government Board, who in one of their recent circulars refer to examination by “ rough sorting methods.” The fallacy that an analyst nowadays can do his duty to his employers, public or private, by the use of “ rough sorting methods ” should have been exploded long ago.The matter has been very well put by the Lancet : “ No analyst nowadays, if he is an honest man, dare certify that a sample, say, of butter, is genuine without determining not only the amount of butter-fat present, but the nature of the fat also, a process which involves considerable skill and attention.Then he will estimate the amount of water, curd, salt, and will search for preservatives, of which there are so many, and when found he will be bound to estimate the quantity in order to be able to say whether that is permissible. . . . The days when 10s. 6d. was an ample reward for casting a specimen of suspect coffee upon the surface of water and noting whether some of the particles rapidly sank, colouring the water on their downward way, which means the presence of chicory, are gone. The Public Analyst’s work now is work of the highest scientific order; it must be done by a competent and conscientious man, otherwise the administration of the food laws must soon fall into disrepute. Slovenly practice must be impossible if discredit of the public analytical service is to be prevented. And there should be no temptation, in the shape of96 ANNIVERSARY DINNER totally inadequate pay, to shirk the carrying out of a duty in a thorough and effective manner.” I commend these words to our public authorities, Government and other. Scientific adulteration is most successful in eluding detection by ‘‘ rough sorting methods,” and the fees which are adequate to pay only for the use of such methods might as well be saved altogether. In concluding this address, I wish to sincerely thank our Ron. Secretaries, and especially Mr. Chapman, for the kind way in which they have helped me to fill this chair during the past year. One needs to pass through the presidential chair to fully realise what the honorary officers do for the Society, and how deeply we are indebted to them for the voluntary time and labour which they so freely give.

ISSN:0003-2654    

DOI:10.1039/AN9133800088

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

96 ANNIVERSARY DINNER ANNIVERSARY DINNER. THE Anniversary Dinner of the Society took place on Tuesday evening, February 4, at the Trocadero Restaurant, under the chairmanship of the President, Mr. L. Archbutt. There were present about eighty members and guests, among the latter being Professor R. Meldola, D.Sc., F.R.S. (President of the Institute of Chemistry), Dr. Bramley Taylor (Master of the Society of Apothecaries), Dr.R. T. Glazebrook, C.B., F.R.S. (Director of the National Physical Laboratory and President of the Faraday Society), Dr. A. W. J. MacFadden (Chief Inspector of Foods, Local Govern- ment Board), Dr. Frank Clowes (Chemist to the London County Council), Dr. R, Messel, F.R. S. (Acting President of the Society of Chemical Industry), Dr. Alexander Scott, F.R.S. (Treasurer of the Chemical Society), Professor A.W. Crossley, D.Sc., F.R.S. (Hon. Secretary of the Chemical Society), Professor A. K. Huntington (Acting President of the Instibute of Metals), Professor H. G. Greenish, Dr. Arthur Voelcker, F.R.C.P., Mr. R. B. Pilcher (Registrar of the Institute of Chemistry), Mr. F. W. Beck, and Mr. Aubrey W. Rake. After the loyal toasts had been duly honoured, the following toasts were proposed : ( ( Government Departments,” by Sir William A. Tilden, D.Sc., F.R. S., responded to by Dr. MacFadden; “The Society of Public Analysts and Other Analytical Chemists,” by Professor Meldola, responded to by the President ; and ‘6 The Guests,” by Sir William Ramsay, K.C.B., F.R.S., responded to by Dr. Messel and Dr. Glazebrook.

ISSN:0003-2654    

DOI:10.1039/AN9133800096

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

LANDER AND WINTER : ANTIPYRIN IN TOXICOLOGICAL ANALYSIS 97 ANTIPYRIN IN TOXICOLOGICAL ANALYSIS. BY G. D. LANDER, D.Sc., F.I.C., AND H. W. WINTER. INVESTIGATION CARRIED OUT UNDER THE SOCIETY’S ANALYTICAL INVESTIGATION SCHEME. (Read at the Meeting, February 5, 1913.) SUCCESSFUL toxicological analysis depends very greatly on the existence of good characteristic tests. The absence of such tests proves a most serious difficulty in the cases of veronal and sulphonal and its allies.Fortunately an excellent charac- teristic test for antipyrin is afforded by F. A. Steensma’s reagent (Pharrn. Zeit., 1907, 52,851 ; ANALYST, 1908,33, 14), which is prepared by dissolving 1 grm. of p-dimethyl- aminobenzaldehyde in 100 C.C. of a solution of 5 C.C. of 25 per cent. hydrochloric acid in 100 C.C.of absolute alcohol. When a liquid containing a trace of antipyrin is evaporated to dryness, together with 5 C.C. of this reagent, a beautiful rose-red colour is developed. The colour is fairly permanent ; it is dissipated by warming with sulphuric acid, but reappears on dilution. No reaction is given by commonly occurring substances, such as methyl alcohol, acetone, acetic acid, light petroleum, aniline, ethyl acetate, aldehyde, or formalin.Commercial amyl alcohol, however, yields a faint pink colour, as also does undenatured spirit, and this fact ought to be borne in mind when testing for antipyrin. Extraction of Alztipyrin.-The best solvent for extracting antipyrin is chloroform. A solution of 10 mgrms. antipyrin in 20 C.C. of water yielded, on extraction with 15 C.C.of chloroform, 8 mgrms. from the neutral or ammoniacal solution, and 5 mgrms. from the solution acidified by hydrochloric acid. Similar experiments showed that light petroleum does not extract antipyrin, and that ether, ethyl acetate, and benzene, do so only in small proportions as com- pared with chloroform. Extraction from Urine.-The following experiments illustrate the nature of the results obtained on extraction from urine without submitting the liquid to any process of purification, such as by means of basic lead acetate. Five mgrms.of antipyrin were dissolved in 50 C.C. of human urine, rendered acid with tartaric acid, and extracted by the solvent mentioned in the tables. ACID SOLUTION, 50 C.C. Solvent. 1 Nature of Residue.(Reaction with Steensma’s Reagent. Light petroleum, 25 C.C. ... Ether, 25 C.C. ... ... Ethyl acetate, 25 C.C. ... Chloroform, 15 C.C. ... I nil dirty red dirty brown fairly clean nil yellow yellow yellow, red at edge I98 LANDER AND WINTER : ANTIPYRIN IN TOXICOLOGICAL ANALYSIS Solvent, AMMONIACAL SOLUTION, 50 C.C. Reaction with Steonsma’s Reagent. 1 Nature of Residue.Light petroleum, 25 C.C. ... Ether, 25 C.C. ... . . . Ethyl acetate, 25 C.C. ... Chloroform, 15 C.C. ... colourless nil nearly colourless, crystalline rather dirty, crystalline yellow, red at edge yellow, red at edge slightly green distinctly red Parallel experiments with normal urine, carried out in precisely the same way, showed that the nature of the various residues is very similar to that indicated above.On testing with the reagent, the colours obtained vary from yellow to dark brown when hot, fading in most cases to yellow when cold. The ether and ethyl acetate residues from the ammoniacal extraction sometimes give a pale red colour at the edges, which can be distinguished from the antipyrin coloration which forms in the liquid during evaporation.In a case of doubt it is advisable to make a parallel test with a portion of the residue to which a trace of antipyrin has been added. Extraction from Viscera.-Four mgrms. of antipyrin were added to 4 ounces of putrid intestine of a dog and extracted with 300 C.C. of pure spirit and 3 grms, of tartaric acid for twelve hours in the cold. After removal of the alcohol in a vacuum the residue was taken up with 20 C.C.of water, filtered, and extracted twice with 20 C.C. of ether. The solution was then made ammoniacal and extracted with 20 C.C. of ethyl acetate, and then with 20 C.C. of benzene. The combined residues from ether were very dirty, but gave the red coloration distinctly. The residues from ethyl acetate and benzene were in both cases fairly clean, and gave a good positive colour reaction.This experiment shows that in the proportion given no difficulty need be experienced as regards the recovery of unaltered antipyrin in a routine Stas-Otto separation. We then made a, similar expe:iment, adding 1 mgrm. of antipyrin to 4 ounces of fresh intestine. The final solution was, however, extracted successively with light petroleum, ether, ethyl acetate, and chloroform, both from acid and ammoniacal solution. Ether and ethyl acetate remove most of the dirt, and the residues from chloroform extraction each gave a positive antipyrin test, that from ammoniacal being more intense than that from acid extraction. The observations were repeated with 0.2 mgrm. of antipyrin to 4 ounces of intes- tine, In this case the results were negative. Our observations show that Steensma’s reagent serves to recognise antipyrin extracted from viscera according to the Stas-Otto process with certainty when as little as 1 mgrm. in 4 ounces is present; below this amount the results are doubtful or negative.

ISSN:0003-2654    

DOI:10.1039/AN9133800097

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

VOLUMETRIC ESTIMATION OF CHROMIUM, VANADIUM, AND IRON 99 A NEW METHOD FOR THE VOLUMETRIC ESTIMATION OF CHROMIUM, VANADIUM, AND IRON, IN PRESENCE OF ONE ANOTHER. BY FREDERICK WILLIAM ATACK, M.SC.TECH., B.Sc., A.I.C. (Read at the Meeting, February 5, 1913.) ATTEMPTS have been made to apply to the estimation of chromium and vanadium the method of reducing with zinc and hydrochloric acid, subsequently titrating with standard methylene blue solution, as used by Knecht and Atack for the estimation of molybdenum (ANALYST, 1911, 36, 98), and by Atack for the estimation of tin in presence of antimony (J.SOC. Dyers and Col., 1913, 29, 9), It was not found possible to obtain a process for the estimation of vanadium based on the oxidation of VCl, to VCI, by methylene blue, owing to the slow rate at which the VCl, first formed is oxidised to VCl, ; indeed, the VCl, stage could be roughly distinguished by the change from rapid to slow disappearance of the methylene blue colour.The results obtained made it evident that the state of oxidation represented by V,O, is stable in presence of methylene white, and the method now suggested is based on the oxidation of the leuco-dyestuff (methylene white) by means of vanadate (V,O,), resulting in the formation of methylene blue and V,O,.The amount of dyestuff so formed is then estimated, and corresponds to the oxygen available in the following equation : 2V20, = 2V,O, + 0,. Similarly, chromitlm cannot be estimated by reduction to chromous chloride, owing to the unstable character of this compound even in presence of a large amount of hydrochloric acid, but it has been found possible to use quantitatively the reduction of chromates to chromic salts on adding to methylene white : KkO, = 2Cr20, + 30,.This method of oxidising a leuco-compound and estimating the dye produced is also available for the estimation of ferric salts, which are quantitatively reduced by methylene white to ferrous salts, and it has been found possible to combine the processes into a method for the estimation of chromium, vanadium, and iron, in presence of each other.In estimations in which leuco-methylene blue is used, nitric acid must not be present in the solution. A convenient strength for the standard dyestuff solution is 4 grms. of fairly pure methylene blue (hydrochloride free from zinc) per litre.This approximately solution is readily standardised by one of the methods described elsewhere by the present author (Zoc. cit.), according to the reagents available. The method in which pure potassium chlorate is employed as the standard is to be recommended, a process identical with that described below for the estimation of chromate. A known volume of the standard methylene blue solution is heated to boiling with dilute hydrochloric acid in a current of carbon dioxide, and is then titrated whilst warm with titanous chloride solution until colourless.By this titration the titanous chloride solution is standardised, and the methylene white solution in the flask is ready for the addition of the oxidising agent to be estimated, standardisation and estimation being thus100 ATACK: A NEW METHOD FOR THE VOLUMETRIC ESTIMATION OF effected in the same flask.I t is essential that an excess of methylene white be present to prevent the formation of:chlorine and the consequent destruction of some of the methylene blue. Moreover, all methylene blue titrations must be carried out in an atmosphere of carbon dioxide, and in warm solution (over 40" C.) in order to obtain a sharp end-point.On account of the high tinctorial power of the methylene blue, the end-point is quite sharp, even if & solution of the dyestuff and of titanous chloride are employed. Estimation of Chromium.-The chromium salt is converted into chromate by oxidising with sodium peroxide, boiling to destroy the excess of the sodium peroxide, and then adding an aliquot portion of the chromate solution so obtained to a solution of methylene white prepared as above.The methylene blue 80 formed is estimated by titration with titanous chloride. The method has been tested on the purest Kahlbaum potassium dichromate, of which 1.3674 grms. were taken, dissolved in water, reduced with sulphur dioxide in presence of sulphuric acid, and made up to a litre after oxidising with sodium peroxide, the excess of which was destroyed by boiling. Fifty C.C.of standard methylene blue (1 C.C. = 0.00018 grin. oxygen) required 69 C.C. of titanous chloride, and on addition of 25 C.C. of the chromate solution further required 42-15 C.C. of titanous chloride for the methylene blue so formed.Addition of a further 25 C.C. of the chromate solution produced methylene blue equivalent to 42.2 C.C. of titanous chloride. One hundred and four C.C. of chromium are equivalent to 48 C.C. of oxygen. Thus, according to this method the sample contained 99.9 per cent. K,Cr,07. Chromium in Presence of Iron.-Solutions containing iron and chromium are oxidised with sodium peroxide, boiled to destroy the excess of this reagent, and the precipitate dissolved by addition of dilute sulphuric acid.The solution is then made up to a known volume, and an aliquot portion added to rnethylene white solution, titration with titanous chloride then giving iron as ferric salt plus chromium as chromate. The iron is estimated by boiling a known volume of the solution with concentrated hydrochloric acid until the chromate has been completely reduced, making up to a known volume, and adding to methylene white.The method gave very satisfactory results with mixtures of standard iron alum and potassium dichromate. (See complete table later.) The method is available for the analysis of ferrochrome and of chromium steel. The powdered ferrochrome or chromium steel in the form of fine drillings are fused with caustic soda and sodium peroxide, and the melt extracted with water.The ferric hydroxide may be filtered off' and the chromate estimated in the filtrate by addition to methylene white, or the iron and chromium may both be estimated by the process described above, in which case the chromium is determined by difference. The results of analyses of ferrochrome obtained by these processes agreed to within 0.2 to 0.3 per cent, on the chromium found.Estimation of Vanadium.-The process employed is identical with that described above for chromium, oxidation being effected by sodium peroxide. The method has been tested on a pure (Kahlbaum I) ammonium metavanadate, NH,VO,, which should contain 77.8 per cent, V,O,.The sample was found to contain 77.6 per cent. V,O,.CHROMIUM, VANADIUM, AND IRON, I N PRESENCE OF ONE ANOTHER 101 Vanadium in Presence of Iron.-The process employed is similar to that used for the estimation of chromium in the presence of iron, the vanadium being estimated by difference. The method was tested on mixtures of known volumes of standard iron alum and ammonium vanadate solutions, and gave satisfactory results.(See complete table later.) Chromium, Vanadium, and Iron.--It has been found possible to apply the above methods to the estimation of chromium, vanadium, and iron, in solution. The solution is oxidised with sodium peroxide, boiled, and made up to a known volume after addition of dilute sulphuric acid. (1) A suitable volume of the solution is added to methylene white, the methylene blue formed being titrated with titanous chloride.This gives the amount of chromate, vanadate, and ferric salt present. (2) Another portion is evaporated with concentrated hydrochloric acid to reduce the chromate and vanadate, the ferric salt remaining being estimated by addition to methylene white solution. (3) Finally vanadium, together with ferric salt, are estimated by reduction of a fresh portion of the solution with sulphur dioxide, boiling for a few moments, and then further replacing the sulphur dioxide by passage of a current of carbon dioxide through the liquid for a short time.There is no necessity to attempt a complete removal of the sulphur dioxide in this manner, as the solution is next oxidised with permanganate until it acquires a pink tinge, made up to a known volume, and the vanadate plus ferric salt estimated by addition of an aliquot portion to methylene white.The following results were obtained, using standard iron alum, ammonium vanadate, and potassium bichromate solutions : Vanadium Chromium Iron ... Vanadium Chromium Iron ... Vanadium Chromium Iron ...... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... FOUlld. Grm. 0.01750 0*00606 0.01486 0.01747 0.02413 0.00745 0 -01 7 76 0.01045 0-01856 Present. Grm. 0.01752 0.00604 0.01483 0.01752 0.02414 0.00742 0.01773 0.01050 0.01850 I n the analysis of chromium vanadium steel by these methods, the iron must be removed as hydroxide and estimated after solution in hydrochloric acid.It has been found possible to obtain a complete separation of the iron by fusing fine drillings of the steel with caustic soda and sodium peroxide. The melt is extracted with water, the whole being digested on a water-bath for some time, and then filtered through hardened filter-paper, finally washing with hot water. The filtrate contains the whole of the vanadium and chromium in the condition of vanadate and chromate, which are estimated by addition to methylene white of a portion of the solution.Another portion of the solution is acidified with sulphuric acid, filtered to remove silica if precipitated, reduced with sulphur dioxide, and then boiled for a short time. A current of carbon dioxide is passed through the solution, which is then oxidised with permanganate solution.A portion of this oxidised solution is added toLO2 KNAPP : NOTE ON " HARDENED " OILS methylene white to estimate the vanadium present. obtained in three estimations of chromium and vanadium in a sample of steel : Fairly concordant results were 1. 2. 3. Vanadium, per cent. ... ... 0.538 0.540 0.537 Chromium, per cent. ... ... 1.17 1-18 1.18 The presence of tungsten or molybdenum would vitiate the result. Methods in which methylene blue is used have the advantage that this reagent may be used quantitatively in presence of hydrochloric as well as sulphuric acid. Moreover, owing to the excellent character of the end-point with titanous chloride i n warm solutions, very small quantities of substance may be rapidly and accurately estimated by suitable adjustment of the strength of the titanous choride and methy- lene blue solutions used. In conclusion, the author desires to thank Professor Knecht for the facilities placed at his disposal in carrying out this work. CHEMICAL DEPARTMENT, FACULTY OF TECHNOLOGY, MANCHESTER UNIVERSITY.

ISSN:0003-2654    

DOI:10.1039/AN9133800099

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

LO2 KNAPP : NOTE ON " HARDENED " OILS NOTE ON '' HARDENED " OILS. BY ARTHUR W. KNAPP, B.Sc., F.I.C. (Read at the Meeting, February 5, 1913.) IT is possibly a convenient time for calling the attention of analysts to the fact that in the immediate future they will be called upon to analyse certain new artificial fats, and, not improbably, to detect their presence as adulterants. For many years attempts have been made to convert into stearic acid the oleic acid which is produced in such large quantities as a by-product in the manufacture of '' stearine " candles.The chemical reaction appears to be a simple one-the mere addition of hydrogen. This has at last been accomplished by making use of the catalytic action of platinum, palladium, or nickel. The same reaction which converts oleic acid into stearic acid also converts triolein into tristearin. Thus, for example, starting with olive oil, as the absorption of hydrogen proceeds, a turbid oil, then a liquid mess, then EL soft fat, and finally a hard fat, is obtained.A similar change occurs with ell oils containing glycerides of unsaturated acids. This rise in the melting-point is naturally accompanied by a decrease in the iodine value and refractive index.I obtained, amongst others, the following results with cottonseed oil, hardened with the help of a nickel catalyst (see p. 103). Fats have been prepared in this way from cottonseed oil with iodine values as low as 5, and if desired the iodine value could doubtless be reduced to 0, and the melting-point raised to 60' to 70' C.Whilst it is too costly for commercial purposes to carry the saturation of the unsaturated glycerides to completion, it might be of value in the laboratory as an aid to determining the component glycerides in a pure oil. Not only the oils containing glycerides of oleic acid can be hardened, but alsoENAPP : NOTE ON " HARDENED') OILS 103 those ctontaining glycerides of linolic acid and linoleic acid (the drying oils), and even of such highly reduced acids as clupanodonic (in whale oil).Anyone who has seen a malodorous oil converted into a bland odourless tallow realises the commercial possibilities of the prccess. And when it is remembered that the process can be stopped when the iodine value reaches a desired number, the possibility becomes evident of the preparation of a fat with any required analytical figures.Appearance . . . ... ... Butyro-refractometer (corrected Fatty acids : Iodine value ... ... Titer . . . ... ... ... Neutralisation value (mgrms. to 40" C.) ... ... ... KOH) ... ... ... Original Oil. Clear liquid 57.7 110 34.7" c. 197 Hardened Oils. Solid particles, floating in oil - 94 37.0" C. 196 Soft greasy solid 55 42.5O C.196 Brittle solid 47.7 28 57.2' C. 192 The analyst is chiefly interested in the question of how these new fats are to be detected. It is doubtful if their most characteristic feature, the relatively high per- centage of stearic glycerides which they contain, will be of much service. Until the manufacturer accomplishes the difficult process of completely removing the nickel, the detection of traces of this metal will be the simplest and most reliable test for hardened oils.Although the catalyst is very finely divided, the manufacturer can obtain a perfectly clear fat by careful filtration, and hence it is the nickel contained in the nickel soaps formed by the free fatty acids present that one has to detect. The following method is suggested : 50 grms.of the fat is heated in a, flask with 20 C.C. hydrochloric acid, with continued vigorous shaking. The mixture is allowed to separate whilst hot, and part of the acid solution is evaporated to dryness, dissolved in a drop of water, and placed on a white tile. One drop of ammonium sulphide is added to this, and also to a drop of water for comparison. I have only tried this test on a few hardened oils, and in some cases with negative results.Dimethyl- glyoxime is a much more delicate test, but unfortunately Prall has found (Bomer, Zeitsch. Untersuch. Nahr. Genussrn., 1912,24, 104 ; and ANALYST, 1912, 37, 452) that certain pure untreated oils give a red coloration. Hence further investigation is needed. One of the most characteristic tests for fish oils-the bromide estimation-is quantitatively useless for these oils after hardening, as the percentage of ether- insoluble brominated glycerides is greatly reduced thereby.Not only are the analytical figures for the oils altered by this absorption of hydrogen, but also the tiraces of substances which often serve as a useful test for the particular oil in which they occur-e.g., in Halphen's reaction (Bomer, Eoc.cit.). It is a remarkable and valuable observation that phytosterol and cholesterol are not changed in this process (Bomer, Eoc. cit.).104 KNAPP : NOTE ON “HARDENED” OILS Character of Product. The three fats exhibited were obtained from a clear cottonseed oil. They were hardened by hydrogen with the help of different catalysts, and gave the following figures : Butyro-Refraction (corrected to 40” C.).Catalyst . Nickel ... ... Platinum . . . ... Palladium ... Percentage of Catalyst in Oil. 1 *oo 0.10 0.06 Hard Hard Brittle 45.7 47.8 45.5 Melting-Point : O c. 49 46 52 The keeping properties of these hardened oils are remarkably good. The above have been prepared for nearly a year and a half, have often been exposed to damp air, and show no signs of rancidity.The free acidity (0.70 per cent. as oleic acid) has not appreciably changed. Hardened oils give soaps which are good in colour, but lacking in lathering properties. I t is unlikely that any objection will be raised to their admixture with other fats for soap-making. Their use in the preparation of edible fats is more open to question, and in the interests of public health certain investigations ought first to be made to show (1) that no harmful substances are produced by the chemical changes in the fatty glycerides and unsaponifiable matter ; (2) that a high percentage of tristearin does not render the fat indigestible ; (3) that traces of nickel, from 1 to 10 parts per million, are not harmful. There is perhaps little to be feared from objectionable substances in the hydrogen used, as the majority of such substances would poison the catalyst. e*fi*+Bidt

ISSN:0003-2654    

DOI:10.1039/AN9133800102

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

104 KNAPP : NOTE ON “HARDENED” OILS THE DETECTION OF ADULTERATION IN LINSEED OIL. BY G. D. ELSDON, B.Sc., A.I.C., AND HERBERT HAWLEY, M.Sc., A.I.C. REPLY TO DISCUSSION, (SEE ‘( ANALYST,” JANUARY, 1913, P. 3.) WE would point out that this method is not recommended so much as an additional test for some particular adulterant, but rather as a general test to which all linseed oils should conform, those oils not conforming being subsequently examined for the actual adulterant, oils passing the test being considered genuine without further exam inat ion.The curve given in the figure is, as will be seen on reading the text, that for the maximum permissible extract obtained from linseed oils under the standard conditions given; the points for pure linseed oils will then, of course, all lie on or below this line. The use of thinner paper might be an advantage, but we have found that con- tinued extraction for many hours of the dried papers has given practically the same figure as that obtained by three hours’ extraction. The hexa-bromide method is a t present being investigated by one of our colleagues.

ISSN:0003-2654    

DOI:10.1039/AN9133800104

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

FOOD AND DRUGS ANALYSIS 105 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. Oil of Manketti Nuts. C. Grimme. (Chem. Rev. Fett Ind., 1913, 20, 1-3.)- Manketti nuts are the seeds of the fruit of Ricinodendron Rautenii (Schinz), a tree growing in various parts of German South-West Africa. The nuts examined con- tained 62.9 per cent. of kernels, which yielded 51.5 per cent.of oil, corresponding to 5.15 per cent. of the whole fruit. The oil was light yellow and viscous, and had a pleasant odour and taste. It gave the following analytical results : Sp. gr. at 15' C. ... ... ... Solidification-point ... Refractive index at 15' C. ... Acid value ... ... ... ... Saponification value ... Reichert-Meissl value ... ... Polenske value ... ... ... Iodine value (Wijs) ...Insoluble fatty acids ... Unsaponifiable matter ... Glycerol ... ... ... ... Melting-point ... ... Mean molecular weight ... ... ... ... ... ... ... ... ... Neutralisation value ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... Oil. 0.9286 1,4805 0.94 194-80 1.24 0.56 94-8 % 0-85 % 10-6 -8' to - 10" C. 134.8 - - - Fatty Acids. - 35' to 36' C. 1.4694 at 50' C.- - - - 137.6 - - - 41' C. 196.5 285-6 The oil had good drying properties, and would be suitable for the manufacture Physiological tests are required to ascertain whether it of varnishes, paints, etc. can be used for food purposes. C. A. M. Estimation of Quinine by Titration with Picric Acid. E. Richter. (Apoth. Zeit., 1912, 949-950, 960-961 ; through Chem. Zentralbl., 1913, I., 194,)- The extraction of quinine from cincbona bark is more readily effected in an acid medium than by the use of alkali as prescribed in the German Pharmacopoeia.The following method is shown to give reliable results : 3.75 grms. of the finely powdered bark are dried at 100" C., and heated for fifteen minutes in a 200 C.C. flask on the water-bath with 2.5 C.C. of 20 per cent.hydrochloric acid and 20 C.C. of water. When cold, the mixture is shaken with 25 grms. of chloroform and 60 grms. of ether, and after the addition of 10 C.C. of 10 per cent. sodium hydroxide the shaking is continued for fifteen minutes. An addition of 1 grm. of gum tragacanth is then made, and the shaking resumed until the layer of ether and chloroform becomes clear, after which 0.5 grm.of magnesium oxide is introduced, and 60 grms. of the solution ( = 2 4 grms. of bark) are filtered into a separating funnel. The clear filtrate is shaken twice with106 ABSTRACTS OF CHEMICAL PAPERS 20.2 C.C. and twice with 10 C.C. of & hydrochloric acid, and the mixture of chloroform and ether then washed with three successive portions of 10 C.C. of water.The united acid extracts and washings are made up to 250 c.c., after evaporation of any dissolved ether on the water-bath, and 100 C.C. of the solution (=I grm. of bark) shaken with 20 C.C. of water and 30 C.C. of picric acid solution until clear, after which the liquid is filtered and 50 C.C. of the filtrate titrated with & potassium hydroxide solution, with phenolphthalein as indicator.Each C.C. of & picric acid will precipitate 00007725 grm. of quinine + cinchonine or 0.0081 grm. of quinine. If a represents the number of C.C. of & alkali used in the titration of the 50 C.C. of filtrate, the percentage of alkaloid in the bark is obtained by the formula : 70 - 3~ x 0.7725. C. A. M. Distilled Wool Fat. J. Mareusson and A. von Skopnik, (Zeitsch.angew Chem., 1912, 25, 2577-2580.)-The products which are obtained when the fatty acids of wool fat are submitted to distillation with superheated steam at a temperature of 300" to 450" C. are known commercially under the names " wool-fat olein" (the liquid portion), ( ( wool-fat ointment," and " wool-fat stearine." Wool-fat olein con- tains from 40 to 60 per cent. of unsaponifiable substances consisting of higher alcohols and unsaturated hydrocarbons ; the fatty acids present are liquid.The wool-fat (' ointment" consists of a mixture of solid and liquid fatty acids, together with from 16 to 33 per cent. of unsaponifiable substances. The solid fatty acids amount to about 50 per cent. of the total acids, have a melting-point of from 44" to 47" C., an iodine value of 9.9 to 15.1, and a molecular weight of 258 to 267 ; the liquid fatty acids have an iodine value of 43 to 48, and a molecular weight of 270 to 302, Wool-fat stearine contains from 32 to 42 per cent. of unsaponifiable substances, the remainder consisting of fatty acids having a melting-point of 58" to 67" C., an iodine; value of 9-5 to 10.2, and a molecular weight of 318 to 382. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9133800105

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

106 ABSTRACTS OF CHEMICAL PAPERS BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Estimation of Arsenic in Blood and Urine. F. Lehmann. (Arch. Pharnz., 1913, 251, 1-4.)-A method of estimating arsenic described previously by the author and E. Rupp (ANALYST, 1912, 37, 415) may be applied to blood and urine. Blood-Fifty grms. of the blood are treated in a Kjeldahl flask with 2.5 grms. of powdered potassium permanganate.After the lapse of ten minutes, 60 C.C. of concentrated sulphuric acid are added, and then 10 grms. of powdered potassium permanganate in small portions at a time. If the reaction becomes too violent, the flask is cooled under a stream of water. The contents of the flask are shaken for fifteen minutes, 30 C.C. of hydrogen peroxide solution are then added, and, after 7-5 grms.of anhydrous ferrous sulphate, 50 grms. of sodium chloride and 5 grms. of olive oil have been introduced, the mixture is distilled as described, the arsenic be-ng collected in sodium bicarbonate solution and titrated with r& iodine solution. Urine.-Five hundred C.C. of the urine are mixed with 2.5 grms. of potassium permanganate and evaporated to dryness. Frothing may be prevented by the ,BACTERIOLOGICAL, PHYSIOLOGICAL, ETC.107 addition of 0.5 grm. of paraffin wax. Five grms. of powdered permanganate and 20 C.C. of dilute sulphuric acid are mixed with the saline residue, and 20 C.C. of concentrated sulphuric acid are then added. When the evolution of gas has ceased, the mixture is heated with 30 C.C. of 3 per cent. hydrogen peroxide solution, and the arsenic is then distilled and titrated under the conditions given.W. P. S. Estimation of Purine Bases in Blood. R. Bass and W. Wiechowski, ( Wien. med. W-ochenschr., 1912, 25, 1863-1864 ; through Chem. Zentralbl., 1913, I., 331.)-The proposed method is based on the fact that uric acid and purine bases are not precipitated from very dilute solutions by means of phosphotungstic acid, pro- vided that a minimum quantity of the latter is used for the precipitation of other substances present.The blood is treated with hirudin (an extract prepared from leeches' heads) to prevent it clotting, then diluted with three times its volume of water, and the mixture is heated to 80" C. on a water-bath, when partial coagulation takes place. After the addition of from 3 to 4 C.C.of 12 per cent. acetic acid for every 100 C.C. of blood taken, the heating is continued for a short time and the mixture is filtered. The filtrate is treated with 1 per cent. of its weight of concen- trated hydrochloric acid, and small definite volumes of the liquid are mixed with varying amounts of 1 per cent. phosphotungstic acid solution in order to ascertain the quantity of this reagent which is necessary for precipitation without introducing an excess; the treated solutions are filtered, and the filtrates tested with albumin and 5 per cent. quinine hydrochloride solution.The test coqtaining the largest amount of phosphotungstic acid without yielding a precipitate with the quinine- albumin reagent indicates the quantity of phosphotungstic acid to be added to the main volume of the blood-filtrate.When this has been done, the mixture is filtered, the filtrate is evaporated to 50 c.c., then rendered ammoniacal, and the phosphate is precipitated with magnesia mixture. The filtrate from the phosphate precipitate is treated with silver nitrate solution until a, distinct precipitate of silver chloride is obtained; this is collected on a filter, washed with dilute ammoniacal silver nitrate solution, then decomposed with hydrogen sulphide, and the filtrate from the silver sulphide is acidified with hydrochloric acid and evaporated.Uric acid usually crystallises out, and may be collected and weighed; in cases where but little uric acid and a large quantity of purine bases are present, the two crystallise together, and the uric acid may be subsequently separated from the bases as ammonium urate.Uric acid is a normal constituent of human blood ; its quantity amounts to 1 to 2 mgrms. per 100 C.C. of blood, but varies considerably with different individuals. Ox blood also invariably contains uric acid, but this is not the case with horse blood. Purine bases are a constant constituent of human and animal blood, the larger quantity being found in human blood ; the quantity of purine bases present is usually from four to ten times that of the uric acid.w. P. s. Composition of Colostrum and of Colostrum Fat. A. Burr, F. M. Berberich, and A. Berg. (Chem. Zeit., 1913, 37, 69-71, 97-lOl.)-Analyses are recorded of colostrum obtained from twenty different cows, the results found being as follows : Sp.gr. at 15' C., 1.0330 to 1.0679 ; total solids, 11.83 to 31.11 per cent. ; fat, 1-30 to108 ABSTRACTS OF CHEMICAL PAPERS 9.00 per cent. ; solids-not-fat, 10.08 to 22-11 per cent. ; total proteins (nitrogen x 6*25), 5.14 to 19-25 per cent. ; casein (nitrogen x 6*37), 3.34 to 5.48 per cent. ; ash, 0.82 to 1.37 per cent.In the case of nine of the samples the quantity of fat present amounted to less than 20 per cent. of the weight of the total solids, whilst in two cases the total solids contained 33.8 and 36.3 per cent. of fat, respectively. The Gerber method was found to be the best for the estimation of the fat; the Rose-Gottlieb method yielded low results, especially when the colostrum was rich in fat and total solids, and the Wollny refractometric method was unreliable.Results of analyses of the sera obtained from the samples of colostrum are also given; the sp. gr. of the sera varied from 1.0286 to 1.0727, and corresponded with the quantity of total solids present. The total solids ranged from 6.57 to 22-31 per cent. ; the fat from 0.01 to 0.07 per cent. ; and the ash from 0.87 to 1.31 per cent.As a rule the quantity of soluble nitrogenous compounds in the sera was slightly larger than in the corresponding colos trum. The authors also separated the fats from the different samples of colostrum, and submitted them to examination. The fat appears to differ considerably in its compo- sition from that of butter fat, the results obtained being-Refractometer reading at 40" C., 44.3 to 48.8; melting-point, 32" to 41" C.; Reichert-Meissl value, 11-5 to 29.1 ; Polenske value, 1.35 to 3.83 ; saponification value, 203.1 to 231.4 ; iodine value, 21.9 to 44.4.The fat contained 0.80 per cent. of cholesterol and 0.025 per cent. of lecithin. w. P. s. Influence of Centrifugal Action on the Distribution of Cell Elements in Milk. R.S. Breed. (Arch. Hyg., 1912,75,383-392 ; through Clzem. Zentralbl., 1913. I, 321.)-Although it is possible to obtain apparently all the cel: elements in the sedi- ment when milk is subjected to centrifugal action in a machine rotating at 9,000 revolutions per minute, the separation of the cells is subject to the influence of other factors which cannot be clearly defined, and the number of cells found in the sedi- ment bears no constant relation to the total number present in the milk.On this account, a correct estimate of the total number of cells in a sampleof milk cannot be deduced from an examination of the centrifugal sediment, and methods in which the cells are estimated in this manner are of doubtful value. w. P. s. Determination of Respiratory Quotients.L. Maquenne and E . Demoussy. (Comptes rend., 1912, 155, 881-886, 1055-1060.)-The determination of the real ratio of a in respiratory exchanges in exceedingly difficult, because the absorption and emission of the gases are not truly simultaneous. This is due to the different solubilities of oxygen and carbon dioxide, further complicated by a condition of supersaturation of the latter.To obtain correct results, it would be necessary either to extract before and after the experiment the whole of the dissolved and occluded gases, or else to leave the system at the end exactly in the same condition &B at the start. Most experimenters have adopted the principle of confined air, which, although useful, can only give the apparent quotient, sometimes far removed from the real; and this difference will depend on the density of the charge- co 0 2BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 109 i.e., the ratio of the volume of leaves or other tissue under investigation to the volume of the enclosed space.In such experiments it is obvious that the tempera- ture must remain constant, as the solubility of the carbon dioxide is directly affected thereby.Two experimental principles are available for the determination of the apparent respiratory quotient, viz. : (1) By connecting two tubes together, one con- taining the leaves, and the other filled with mercury; it suffices then to reverse the system at the end of the period to obtain a sample of the gas surrounding the leaves ; (2) by connecting the respiration tube by means of a stopcock with a smaller tube which has been completely evacuated, rapidly opening the cock, and thus taking an instantaneous sample of the gases.From an analysis of these gases the apparent quotient p can be calculated, and if S= the density of charge, and c the coefficient of absorption of the carbon dioxide, then the real quotient m is obtained from the formula p= m by determining p for two different values of 6 it is possible to calculate the solubility c of carbon dioxide in the plant juice, which is approxi- mately double the solubility in water a t the same temperature.The accuracy of such a method depends on the rapidity of the gaseous exchanges, and the results 3x8 liable to be too low, particularly with thick, fleshy tissues. The authors now describe a new method, termed the ‘ 4 displacement method,” which consists in passing a current of air through a tube charged with the leaves at a constant slow rate of speed, such that the gas issuing shall contain at least 2.5 to 3 per cent.of carbon dioxide. After a certain time, the juices becoming saturated with carbon dioxide, an equilibrium is established, and the composition of the issuing gases remains constant as long as the intensity of respiration and quotient g2 are constant ; analysie then immediately yields the real respiratory quotient.The motive portion of the apparatus (see figure) consists of a sort of tantalus flask, A, fed by a fine jet of water issuing from 1 - 6 1-6+C6’ 0 2110 ABSTRACTS OF CHEMICAL PAPERS a capillary tube under absolutely constant pressure, The impulses derived from this apparatus are transmitted to a small mercury pump, P, which aspirates 2 to 4 C.C.of air at each oscillation, according to the adjustment, and pumps the air into the respiration tube T, containing the leaves, at the same time displacing the respiratory gases. The tube T is immersed in a water-bath at constant temperature, and the respiratory gases are collected by displacement in the tube C, care being taken to avoid variations in pressure; or else an instantaneous sample may be taken from the tube T itself in the manner indicated above.If it be assumed that the arriving air mixes immediately with the gases already present in the tube, the principle of the method will be readily understood, The time required for the establishment of the equilibrium depends on the capacity of the pump and the density of the charge ; if the pump discharges a volume of air equal to the volume of the tube T in one hour, and the density of charge is 0.1, about four hours must elapse before a sample can be drawn for ana,lysis.With organs which respire very actively, the action of the pump may be accelerated, and the operation completed in two hours ; but with tissues respiring slowly, as with the leaves of fat-yielding plants, the current of air must be slowed down, so that the analysis cannot be made until after twenty-five to thirty hours.When the intensity of respiration remains constant for a sufficient length of time, this method gives results only very slightly lower than the real quotient; in the case of leaves in which the reserve material is very rapidly exhausted, the long duration of the experiment is a drawback and the quotient is too low. Comparing the displacement method with the vacuum method, it is noted that in the case of leaves with thin parenchyma, where gaseous exchanges take place easily and rapidly, either method may be used, since both give results in good concordance.I n the case of fleshy leaves, stems, wood, or germinated seeds, where equilibrium with the outer air takes place with difficulty, the displacement method is the only one which affords a result closely approximating to the real quotient, the vacuum method yielding numbers which are much too low. J. F. B. Estimation of Acetone in Urine.0. Sammet. (Zeitsch. physiol. Chem., 1913, 83, 212, 225.)-Results of a critical investigation of various methods for the estimation of acetone are recorded, particular attention being paid to the application of the methods to the estimation of acetone in urine. The first method examined was that proposed by Graaf (Pharm. Weekblad, 1907, 44, 555), in which the urine is distilled and the acetone in the distillate precipitated by means of p-nitrophenyl- hydrazine in acetic acid solution ; the precipitate is collected, dried at 1 0 5 O C., and weighed.The precipitate has the formula (CJH,),.C:N.NH.C,H,(NO,), and 198 parts of it by weight correspond with 58 parts of acetone. This method was found to yield from 95.5 to 96.2 per cent. of the quantity of acetone actually present when the amount of acetone varied from 0.1 to 0.2 grm.per 100 C.C. of urine. Messinger’s method also yielded satisfactory results (cf. ANALYST, 1908,33,98). When this method is applied to urine, the latter should be treated with tartaric acid and distilled; calcium carbonate is then added to the distillate, and the mixture is again distilled.The second distillate is rendered alkaline with potassium hydroxide solution, an exoess of -& iodine solution is added, and, after shaking, the mixture is acidified withBACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 111 hydrochloric acid and the excess of iodine titrated with thiosulphate solution. Each C.C. of TG iodine solution is equivalent to 0*000967 grm. of acetone. The yield obtained by the method was about 96 per cent.of the quantity of acetone present. Oppenheimer has used a method, described originally by Denigds (cf. ANALYST, 1899, 24, 92), for the estimation of acetone in urine; but the results obtained are about 10 per cent. too high when Oppenheimer’s factor (0.055) is used for converting the weight of the precipitate into acetone; better results are obtained when the factor 0-0495 is employed.The volumetric method of estimating the mercury in the precipitate (ANALYST, 1896, 21, 303) is untrustworthy. The author has also carried out a number of experiments in which it was sought to estimate the amount of acetone from the volume of the precipitate obtained i n Denigds’s method ; the precipitate was subjected to centrifugal action in a graduated tube until it no longer decreased in volume, and it was found that the total volume of the precipitate multiplied by 0.0912 gave the weight of acetone. This is only the case when the volume of the precipitate does not exceed 0-4 c.c., and even then the w. P. s. results are not strictly correct. Comparison of the Farup and Schumacher-Jung Methods for the Estimation of Mercury in Urine. (Arch. Pharm., 1913, 251, 4-7.)-Experiments carried out by the author show that Farup’s method (in which the mercury is precipitated as metal by means of zinc-dust and subsequently with stannous chloride, then collected on a gilded asbestos filter, and weighed) and Schumacher-Jung’s method (ANALYST, 1902, 27, 368) yield practically identical results. w. P. s. W. Beckers.

ISSN:0003-2654    

DOI:10.1039/AN9133800106

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 111 ORGANIC ANALYSIS. Berlin (Prussian) Blue Reaction (Detection of Ferrocyanides and Cyanides). D. Vorlander. (Bey., 1913, 46, 181-192.)-1t is shown that the reaction between ferric salts and ferrocyanide requires a considerable time for its completion, and that it is retarded by high acid or saline concentrations. When testing for ferrocyanide in very dilute solutions, ferrous sulphate is a far more sensitive reagent than ferric chloride.The pale colour of the ferrous solution allows the use of a large excess, which tends to carry the reaction to completion, and there is usually enough dissolved oxygen in the water to convert the ferrous ferro- cyanide to ferric ferrocyanide, so that, with only traces of ferrocyanide present, the maximum intensity of colour is obtained instantaneously.G. C. J. Estimation of Caoutchouc in Rubber Wares, particularly Insulated Wires. P. Goldberg. (Chem. h i t . , 1913, 37, 85-86.)-The direct estimation of caoutchouc in vulcanised rubber does not yield very satisfactory results, and, recognis- ing this, the Verband Deutcher Elektrotechniker has adopted an indirect method for estimating the caoutchouc in wire insulations.The method approved is one adapted by Hinrichsen and Manasse, according to which 1 grm. of the material, after extrac- tion with acetone and drying at 50" to 60" C., is boiled with 25 C.C. of petroleum112 ABSTRACTS OF CHEMICAL PAPERS (fraction 230° to 260" C.) until the caoutchouc is dissolved, after which the solution is diluted with benzene, and the insoluble matter is washed by decantation or centri- fuging and finally weighed.This residue will include not only the mineral matters, but also any organic fillers, such as lampblack, cellulose, etc., and the sum of these together with the acetone extract (free sulphur and paraffin hydrocarbons) gives the total loading, which, deducted from 100, gives the vulcanised caoutchouc. From this, 3 per cent.is deducted for the combined sulphur in order to arrive at the pure caoutchouc. The objection to this method lies in the fact that caoutchouc-like bodies may remain undissolved in the residue, which may also be contaminated with charred products owing to the high temperature employed. In either case the percentage of true caoutchonc would be lowered, and differences up to 3 per cent.are often recorded. An estimation of the mineral loading matters by incineration in the ordinary way is scarcely possible, owing to the profound modification of many of the loadings used, under the action of the high temperature, the oxidising influence of the air, and the reducing influence of the carbon. Most of these inconveniences may, however, be avoided by performing the incineration in an atmosphere of nitrogen.A temperature of 400' C. is quite sufficient to decompose and drive off the caoutchouc in the form of volatile compounds, and under these conditions oxidation, reduction, separation of carbon or oxidation of a sulphide, need not be feared. The author describes the following procedure : 1 grm.of the material, extracted with acetone and dried at 50' to 60" C., is placed in a tared porcelain boat which is inserted in a glass tube 50 cm. long, open at both ends. One end is connected with a supply of dried nitrogen, and as soon as the air has been expelled a small flame is applied. The caoutchouc melts, decomposes, and distils, and the resulting vapours are drawn off by connecting the other end of the tube with a water air-pump.The operation is complete in about twenty minutes, and the boat is weighed, the caoutchouc being calculated as indicated above. Mixtures were made containing all the usual mineral loadings employed in vulcanised wares, and the estimations of caoutchouc in no case differed by more than 0.3 per cent. of the calculated percentages.Exceptions are- readily decomposable carbonates, such as magnesium carbonate, and red sulphides, such as golden antimony and vermilion. These cases must be dealt with specially : the carbonates by the insertion of potash bulbs to collect the carbon dioxide expelled; the golden antimony, which remains in the ash as the trisulphide, by an estimation of antimony in the residue and calculation as pentasulphide ; and the vermilion, which volatilises as such, by a separate estimation.J. F. B. Quantitative Separation of Mixtures of Certain Acid Coal-Tar Dyes. W. E. Mathewson. (J. Ind. Eng. Chem., 1913, 5, 26-29.)-The method proposed depends on the extraction of one of two dyes from an aqueous solution by means of an immiscible solvent, and the following procedure, or some simple modification of it, has been employed: The solution, containing from 0.2 to 0.4 grm.of the dyes, is treated with sufficient water and hydrochloric acid of known strength to bring its volume to about 50 c.c., and its acid concentration to that point at which the difference in percentage of colour extracted for the two dyes is near its maximum. The solution is then shaken out with the immiscible solvent, being passed successivelyORGANIC ANALYSIS 113 through three or four separating funnels, each containing about 50 C.C.of the solvent. The portions of the solvent are washed with 50 C.C. of acid of the same concentration as the original solution, and this washing operation is twice repeated. The dye relatively more soluble in water is estimated in the combined washings and extracted solution.The second dye is removed from the solvent by shaking with water or very dilute sodium hydroxide solutiou, or, more quickly, with dilute sodium hydroxide solution, after the addition of a quantity of gasoline or similar substance in which the dye is insoluble. In many cases it will be found to be necessary to increase the number of successive extractions.I n the following mixtures, each containing two dyes, from 97 to 102 per cent. of the quantities actually present were obtained ; the solvent used and the acidity of the solution are also given : Naphthol Yellow S and Light Green S Yellowish, solvent, amyl alcohol; acidity, 20 C.C. of 5 N. hydrochloric acid to 30 C.C. of solution. Ponceau 3 R and Naphthol Yellow S, solvent, amyl acetate; acidity, 20 C.C.of concentrated hydrochloric acid to 20 C.C. of solution. Amaranth and Orange I, solvent, amyl alcohol ; acidity, 2 C.C. of 5 N. hydrochloric acid to 30 C.C. of solution. Light Green S F Yellowish and Ponceau 3 R, solvent, amyl alcohol; acidity, 20 C.C. of concentrated hydrochloric acid to 30 C.C. of solution.Ponceau 3 R and Indigo Carmine, solvent, amyl alcohol; acidity, 2 C.C. of 5 N. hydrochloric acid to 28 C.C. of solution. Light Green S F Yellowish and Indigo Carmine, solvent, dichlorhydrin; acidity, 2 c,c. of 5 N. hydrochloric acid to 23 C.C. of solution. Naphthol Yellow S and Amaranth, solvent, amyl acetate; acidity, 10 C.C. of concentrated hydrochloric acid to 10 C.C. of solution.w. P. s. Comparative Investigation of Methods for the Estimation of Dyes. H. Salvaterra. (Monatsh. fur Chem., 1913, 34, 255.)-Knecht’s method (J. SOC. Dyers and Colorists, 1903, 165, and 1905, 111 and 292) consists in titrating the dye, which acts as its own indicator, with standard titanium chloride solution. In Pelet’s method (‘‘ Die Theorie des Fiirbeprozesses,” Dresden, 1910, p.49 et seq.) a basic dye is precipitated with a standard solution of an acid one, the end-point being shown by the disappearance of one or both of the coloured rings produced by dotting on filter- paper. These two methods were applied to a number of carefully purified dyes. Both gave good results. The method of Knecht, which involves titration in an atmosphere of carbon dioxide, is less convenient to carry out than that of Pelet; but this, on the other hand, requires the provision of a large number of standard solutions.For dyed silk the Knecht method alone is capable of giving satisfactory results. Both methods are applicable to baths which have been used for dyeing but the colorimetric method is quite useless for this purpose. 0. E. M. Quantitative Study of the Absorption of Ultra-Violet Rays by the Fatty Acids and their Isomeric Esters.J. Bielecki and V. Henri. (Comptes rend., 1912, 155, 1617-1620.)-1n order to study the influence of molecular constitution on the absorption of ultra-violet rays by substances of the aliphatic series, the authors have investigated comparatively various isomeric bodies--e.g., free fatty acids and esters having the same empirical formulae, also various isomeric esters.Observations were made in aqueous and alcoholic solutions, the molecular114 ABSTRACTS OF CHEMICAL PAPERS absorption coefficients being tabulated for the various wave-lengths for each pair of isomerides examined. The results showed that the absorption spectrum in the case of the acids differs from that of the esters isomeric with them.This difference exists independently of the solvent; it is as distinct in aqueous as in alcoholic solutions. The absorption of the ultra-violet rays by acids and esters is not deter- mined by the empirical formula. As the molecule becornes more complex by the addition of CH, groups, the absorption increases. The absorption depends on the actual constitution of the molecule, and is not only different for isomeric acids and esters, but also for esters isomeric with one another.J. E. B. Fractional Precipitation of Fatty Acid Mixtures (Detection of Rape Oil). H. Kreis and E. Roth. (Chem. Zeit., 1913, 37, 58.)-The presence of rape oil, and possibly of cocoanut oil, in another oil may be detected by fractionally precipitating the mixed fatty acids of the oil with lead acetate and examining the fatty acids separated from the lead precipitate.A portion of the mixed fatty acids is dissolved in alcohol and treated with about one-tenth the quantity of lead acetate required for complete precipitation. The lead salts of the fatty acids thus pre- cipitated are separated, decomposed with hydrochloric acid, and the melting-point, refractometer value, and molecular weight, of the liberated fatty acids are determined.The results given by the fatty acids obtained in this manner from various oils are shown in the following table : Fatty Acids froni- Olive oil ... ... Earthnut oil ... Sesame oil ... Cottonseed oil ... Rape oil ... ... Butter fat ... Cocoanut oil .,. Tallow . . . ... Lard ...... (Erucic acid) . . . ... ... ... ... ... ..- ... ... ... ... Melting-Point : O c. About 53.0 ,, 56.8 ,, 52.5 ,, 58.4 ,, 30.0 ,, 61.0 ,, 58.0 ,, 53.5 ,, 37.5 33-34" c. Refrac ton1 et.er Value a t 60" C. 1'7.0 19-5 17-5 15.0 32.0 17.0 11.0 17-0 17.5 Molecular Weight. The precipitate obtained in the case of rape oil fatty acids evidently consists principally of erucic acid, but the high molecular weight of the fatty acids indicates that a quantity of lignoceric acid is also present (cf.J. SOC. Chem. Ind., 1898, 17, 1009). w. P. s. Detection of Histidine. K. Inouye. (Zeitsch. physwl. Chem., 1913, 83, 79- 82,)-When an aqueous solution of histidine is treated with an excess of sodium carbonate, and diazobenzenesulphonic acid is added to the mixture, a cherry-red coloration is produced; 1 part of histidine in 100,000 parts of solution will give the coloration.The reaction may be employed for the detection of histidine when thisORGANIC ANALYSIS 115 is combined in a protein molecule, but the value of the reaction is influenced by the fact that tyrosine also gives a coloration under similar conditions. The interfering reaction of tyrosine may, however, be prevented by shaking the protein solution, after the addition of sodium carbonate, with a few drops of benzoyl chloride until the odour of the latter disappears, and then adding the diazobenzenesulphonic acid ; a large excess of benzoyl chloride must be avoided or removed by continued shaking, or the histidine reaction will also be affected to some extent.Before testing a protein for the presence of histidine it must be hydrolysed, preferably by heating for six hours with hydrochloric acid; the hydrolysis may also be brought about by the action of trypsin, but in this case a control experiment must be made to ascertain whether the trypsin is free from histidine. The solution of the hydrolysed protein is evaporated to a syrupy consistence, dissolved in water, warmed after the addition of lead oxide, and then cooled.The mixture is next rendered alkaline with sodium carbonate, filtered, and a portion tested with the reagent. If a red coloration is obtained, another portion of the solution is shaken with benzoyl chloride, and again tested to insure that the reaction is due to histidine and not to tyrosine.Both histidine and tyrosine may be detected in Witte's peptone by means of the test; sturine yields only histidine and no tyrosine, whilst orzynine (a protamine obtained from the testes of the tunny-fish) contains only tyrosine. w. P. s. Modification of the Official Method of Determining Humus. 0. C. Smith. (J. Ind. and Eng. Chenz., 1913, 5, 35-37.)-The official method states that 4 per cent.ammonia solution should be shaken with the soil for the first twenty- four hours, and then allowed to stand twelve hours and settle. The clearest part is then drawn off, filtered, and the determination made without further treatment. This filtering does no good, and it is rarely that sufficient clear solution is obtainable. I t is better not to allow the sediment to settle, but to shake well and pour all the soil possible on to the filter, when, after about five or six hours as a rule, and some- times less, a perfectly bright filtrate is obtainable.The first turbid runnings may be discarded or returned to the filter, a Schleicher and Schiill folded filter about 30 cm. in diameter, with hardened points, being found most suitable. Duplicate experiments usually agree within 0.1 per cent.H. F. E. H. Behaviour of Nitroglycerine when Heated. W. 0. Snelling and C. G. Storm. (Technical Paper 12, Department of the Interior, Bureau of Mines, Washington.) -The experiments were carried out in a heavy steel cabinet with a thick plate-glass window. Usually about 2 C.C. of nitroglycerine were heated in a small test-tube in a paraffin-bath ; the temperature was measured by means of a constantan-copper couple in the nitroglycerine.Resdts were as follows : Nitroglycerine begins to decompose at 50" to 60" C. At 70' C. commercial nitroglycerine reacts with potassium iodide starch paper in fifteen to thirty minutes. At 135" C. the nitroglycerine is coloured strongly red by oxides of nitrogen, produced by decomposition.The boiling- point varies one or two degrees with the sample, but is about 145" C. at normal pressure ; ebullition is due partly to decomposition, and partly to volatilisation of the nitroglycerine. The heat produced by decomposition is sufficie@ rapidly to raise the116 ABSTRACTS OF CHEMICAL PAPERS temperature in the absence of cooling. At about 218" C., the temperature varying within about 5 degrees, according to the sample, explosion takes place.Nitro- glycerine may be distilled at temperatures between 145" and 210° C.; the distillate consists of nitroglycerine, nitric acid, water, and other decomposition products, and the residue probably contains chiefly glycerol, with dinitroglycerine, mononitro- glycerine, and other decomposition products. 0. E. M. Examination of Tung Oil. W. Hoepfner and H. Burmeister. (Chem. Zeit., 1913, 37, 18-19, 39.)-From the examination of a large number of samples, the authors conclude that the iodine value (Hubl) of commercial tung oil ranges from 156 to 171, the average being 164.6, whilst the average refractive index at 20 O C. in Abbe's apparatus is 1.5175. These two values considered, in conjunction with the results of Bacon's test (ANALYST, 1912, 37, 546) give information as to the purity of a, sample. In using Bacon's test it was found best to modify the time of heating to twelve minutes at 310" C. If under these conditions the oil becomes so solid that it can be powdered in a mortar, there can be no doubt about its being pure. On the other hand, a mixture containing as little as 5 per cent. of soya, bean or teaseed oil remains viscid or fluid at the end of the heating. As a further test that the solid polymerised product is free from foreign oils, the fatty acids may be separated and their values determined (cf. ANALYST, 1912, 37, 410). C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9133800111

出版商:RSC    

年代:1913

数据来源: RSC