摘要:

APRIL, 1905. Vol. XXX., No. 349. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. THE annual meeting of the Society was held on Wednesday evening, March 1, in the Chemical Society’s Rooms, Burlington House. The President, Mr. Thomas Fairley, occupied the chair. Messrs. J. H. B. Jenkins and Arthur Tighe were appointed scrutators of the ballot-papers for the election of Officers and Council. The HON. TREASURER (Mr. E. W. Voelcker, A.R.S.M.) presented his annual report, with the accounts of the Society for the year 1904. On the motion of Mr. DIBDIN, seconded by Mr. BLOUNT, the Hon. Treasurey’s report was unanimously adopted, and a vote of thanks accorded to the Hon. Treasurer for his services during the year. The HON. TREASURER, having acknowledged the vote of thanks, proposed a vote of thanks to the auditors, Mr.W. P. Skertchly and Mr. C. G. Moor, M.A. Mr. RICHARDS seconded this, and the vote was unanimously passed. On the motion of Dr. VOELCKER, a vote of thanks was unanimously passed to the Mr. BEVAN acknowledged the vote of thanks. The PRESIDENT moved, and it was unanimously agreed, that a vote of thanks be accorded 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 Ron. Secretaries for their services during the year. year. The PRESIDENT delivered his annual Address. Dr. DYER proposed that a very hearty vote of thanks be accorded to President for his Address, and that his permission be requested to publish Address in the ANALYST.Mr. FISHER seconded the resolution, which was carried unanimously. The PRESIDENT briefly responded. the the The scrutators having reported to the President the result of their examination of the ballot-papers, The PRESIDENT announced that the Officers and Council for the ensuing year had been elected as follows : President.--E. J. Bevan. Past-Presidents (limited by the Society’s Constitution to ten in number).-M. A. Admns, F.R.C.S. ; A. DuprB, Ph.D., F.R.S. ; Bernard Dyer, D.Sc. ; Thomas Fairley ; W. W. Fisher, M.A. ; Otto Hehner ; Alfred Hill, M.D. ; J. Muter, Ph.D. ; Sir Thomas Stevenson, M.D., F.R.C.P. ; J. Augustus Voelcker, M.A., B.Sc., Ph.D.110 THE ANALYST. Vice-Presidents.-L. Archbutt, B. Kitto, W. J. Dibdin. Hon. Treasurer.-E. W. Voelcker, A.R. S.M. Ron. Secretaries.-Alfred C. Chapman and P. A. Ellis Richards. Other Members of Council.-Julian L. Baker; R. Bodmer; R. Hellon, Ph.D., A.R.S.M. ; G. T. Holloway, A.R.C.S. ; J. H. B. Jenkins; E. W. T. Jones; S. Rideal, D. Sc. ; Alfred Smetham ; J. E. Stead, F.R.S. ; R. T. Thomson ; L. T. Thorne, Ph.D. ; John White . Mr. Fairley then vacated the chair in favour of the newly-elected President, Mr. Bevan. Mr. BEVAN expressed his acknowledgment, and the proceedings then terminated. The monthly ordinary meeting of the Society was held on Wednesday evening, March 1, in the Chemical Society’s Rooms, Burlington Eouse, immediately after the annual meeting. The President, Mr. E. J. Bevan, occupied the chair. The minutes of the previous ordinary meeting were read and confirmed. Certificates of proposal for election to membership in favour of Messrs.E. Rinks amd S. E. Melling were read for the second time; and certificates in favour of the following candidates were read for the first time: Edward Richards Bolton, 16, Flanchfort Road, Ravenscourt Park, W., chief chemist to the East Indian Products Co., Ltd., at Albert Mills, Hammersmith; John Thomas Dunn, D.Sc. (Dunelm), F.I.C., 10, Dean Street, Newcastle-on-Tyne, joint Public Analyst for the Cities of Durham and Newcastle-on-Tyne, and for the Boroughs of Gateshead, Sunderland, South Shields, Berwick-on-Tweed, and Tynemouth ; Edward Kenneth Hanson, M.A. (Cantab.), A.I.C., Mapledene, Hadley Wood, Barnet, Analyst and Lecturer on Physical Chemistry at University College, Reading ; Frederick Thomas Harry, 106, Sandmere Road, Clapham, S.W., assistant to Mr, Alfred C. Chapman; the Ron. Francis Robert Henley, M.A. (Oxon.), A.I.C., 6, Melville Street, Edinburgh, chemist at Messrs. Jeffrey’s Brewery, Roxburn, Edinburgh. The following papers were read : (‘ The Estimation of Oxygen in Copper,” by S. Dickson; and l 4 Some Conditions affecting the Ether Value of Brandies,” by Philip Schidrowitz, Ph.D., and Frederick Kaye, A.R.C. Sc.

ISSN:0003-2654    

DOI:10.1039/AN9053000109

出版商:RSC    

年代:1905

数据来源: RSC

摘要:

110 THE ANALYST. ANNUAL A.DDRESS OF THE RETIRING PRESIDENT. Delivered at the Amma1 Meeting, February 1, 1905. LAST year I was in the fortunate position of being able to say that we had not lost any members by death during my term of office. Now at its close I regret to have to report the death of six ordinary members and one honorary member, Dr. A. W. Williamson. During the year we have elected fourteen new ordinary members, and our numbers now stand at : Honorary members . . . ... ... ... ... 8 Ordinary members . . . ... ... ... .. 301THE ANALYST. 111 Our loss by death is the greater as it includes Mr. Allen and Mr. Chattaway, both members of the publication committee. Mr. Allen was one of the founders of our Society, and has held its chief official positions. That he was one of the most active workers in the ranks of our profession is well shown in the able and sympa- thetic review of his work by Mr.Hehner, a tribute more eloquent of Mr. Allen’s untiring energy than anything that I can say. It is indeed difficult to overestimate how much practising analysts throughout the world owe to him for his work in testing and collating processes and methods of organic analysis. Mr. W. Chattaway, who has passed away in middle life, was at one time associated with Mr. Allen, and was an active worker in several directions. He held qualifications as a pharmaceutical chemist, and had special knowledge in the chemistry of drugs. I n recent years he occupied the position as Head of the Laboratory of the Apothecaries’ Hall. His amiable qualities endeared him to his friends, and his services will be much missed in many directions.He held the appointments of Public Analyst for the Boroughs of Hammersmith and Colchester. Dr. A. P. Aitken, an old member of our Society, was Chemist to the Highland and Agricultural Society of Scotland, Professor of Chemistry at the Royal (Dick) Veterinary College, Edinburgh, and Public h a l y s t for several of the counties in Scotland. He received his training at the Universities of Edinburgh and Heidel- burgh, and was the author of numerous papers published in the HighZand and Agricultural Society’s Joumal, and occasionally in the ANALYST. Mr. T. A. Pooley was educated first in France, and afterwards at King’s and University Colleges, London. For a time he edited one of the brewing journals, and afterwards frequently contributed papers to them.He held the positions of Public Analyst for the County of Essex and the Borough of West Ham, and has contributed papers at various times to the ANALYST. Mr. H. S. Carpenter formerly practised as an analyst in London, and con- tributed a number of papers to the earlier volumes of the Journal. For some years before his death he had retired from the ranks of our profession. Mr. Edgar B. Kenrick held the position of Professor at St. Johds College, Winnipeg, Canada. His contributions to the ANALYST related to the detection of cocoanut oil and of cotton-seed oil in lard. The financial position of our Society is approximately the same as at this time last year. Owing to a number of special reasons our expenses have been heavier in each department, as shown in the statement carefully compiled by the Hon.Treasurer, to whom our best thanks are due. I t is our duty to try to improve the position of our Society, and to increase the value of its Journal. Thus, we have spent $31 more on the ANALYST in 1904 than in 1903. Our ideal is to make this paper the best of its kind in the world, and an increased expenditure should be regarded as well-spent money, even if we only attain partial success in this direction, I t has been decided at the close of the present year to increase the price of the Journal to non-members, and due notice of this change will be given to subscribers. Your Council have carefully considered the matter of the Incorporation of the Society under the Limited Liability Companies’ Act, and they have taken the necessary steps towards preparing the documents required for registration under that Act.The draft scheme will, it is hoped, be shortly submitted to the members, and112 THE ANALYST. considered at a special meeting called in accordance with the rules of our Society and the requirements of the Act. The Journal and funds belonging to the Society are now held for us by trustees. We are grateful to, and in no way dissatisfied with, those who have taken this responsibility, but it is felt that the position and aims of the Society can be better secured and maintained by incorporation under the clause permitting “ associations not for profit ’’ to register without using the adjective ‘( limited.” The following papers have been presented to the Society during the year : “ Note on Chinese Tallow-seed Oil.” “ Note on the Estimation of Mechanical Wood-pulp in Paper.” “ Note on the Analysis of Jam.” (‘ The Microscopic Examination of American Cotton-seed Cake.” (‘ The Composition of Milk.” “ The Estimation of Morphine in Opium.” “ The Iodine Absorption as a Factor in the Examination of Otto of Roses.” By F.Hudson-Cox and W. H. Simmons. ‘‘ Analyses of Potable Spirits used by the Native Population in India.” By Harold H. Mann. ‘‘ A Rapid Accurate Method for the Volumetric Estimation of Carbon Dioxide.” By Thomas Macara. ‘I The Microscopic Examination of Metals,” illustrated by Lantern Slides. By J. H. B. Jenkins and D. G. Riddick. “ Cod-liver Oil and other Fish Oils.” “ Note on Mushroom Ketchup.” “ Note on some Constants obtained in the Examination of Margarine.” “ Note on the Estimation of Sugars in Concentrated Malt Extract.” (‘ A ‘ Beer-Beater ’ for Use in Original Gravity Determinations.” (‘ Roasted Beetroot.” ‘‘ The Analysis of Sweetened Condensed Milk.” “ A Collection of Readings with the Zeiss Oleo-Butyrometer.” By the late W.Chattaway and C. G. Moor, M.A. &‘ Note on the Estimation of Sugars and Starch in Vegetable Substances.” By John S. Ford. “ Improved Continuous-Observation Polarimeter Tube.” By John S. Ford. “ Further Note on Mushroom Ketchup.” (‘ The Detection and Estimation of Spa11 Quantities of Maltose in the Presence ‘‘ The Use of Palladium-Hydrogen as a Reducing Agent in Quantitative By L.Myddleton Nash. By C. F. Cross and E. J. Bevan. By Raymond Ross. By A. L. Winton. By H. Droop Richmond. By Philip Schidrowitz, Ph.D. By J. F. Liverseege. By J. F. Liverseege. Edward Russell, B.Sc., and V. H. Kirkham, B.Sc. Arthur R. Ling and Theodore Rendle. Ford, F.R.S.E. By By By John S. By E. G. Clayton. By J. B. P. Harrison. By J. F. Liverseege. of Dextrose.” Analysis.” By Alfred C. Chapman. By Julian L. Baker and W. D. Dick. Some Abnormal Milk Results.” By Sidney Harvey.THE ANALYST. 113 ’‘ Electric Furnaces for Laboratory Use.” “Note on Commercial Amy1 Alcohol.” By Bertram Blount. By EL Droop Richmond and J. A. Goodson, The following exhibits were shown at the meetings : ‘( An Improved Form of Tin for the Collection of Samples under the Sale of “ A Double Surface Condenser.” Food and Drugs Act.” By the late W.Chattaway. By Herbert E. Burgess. The following reprints were inserted in the Journal : ‘‘ The Determination of Boric Acid in Cider, Fruits, etc.” By the late Alfred H. Allen and Arnold R. Tankard (read at the British Pharmaceutical Conference, 1904). (( Results of Experiments on the Effect of Boric Acid and Borax administered with Food )’ (from Circular No. 15, issued by the United States Department of Agriculture). Judgment of the High Court of Justice, King’s Bench Division, in the case Hzdl v. Horsnell, relating to Copper in Preserved Peas (from the Times of November 7, 1904). The list of papers for the year is good, but their number, I regret to say, has remained somewhat stationary for several years past.We are still much below the proportion of one paper from each member every five years. I know well the difficulty there is to find time in a busy laboratory for many kinds of original work, and I willingly admit my own shortcomings in this respect. At the same time, I earnestly press each member to do his best to increase his contributions to the Journal. I n contributing st paper giving an account of honest work an author may benefit his fellows, but he benefits himself most of all. I n this matter the splendid example set by Mr. Allen is surely one we should all try to follow, even if we must, many of us, come far short of his generous limit. The best way of showing our gratitude and appreciation of the work of those who have gone before us is to do something to add to what they have done for their fellow-members.The paper by Messrs. Jenkins and Riddick on “ The Microscopic Examination of Metals” is one which we stre proud to have had read before our Society, and, with its beautiful illustrations, forms a fitting commencement to what we hope may prove to be an enhanced and improved volume of the Journal. Another paper of great scientific interest was given by our hard-working Secretary, Mr. Chapman, on I ‘ The Use of Palladium-Hydrogen in Analysis.” This and the paper by Messrs. Baker and Dick relating to the estimation of sugars are the first-fruits of the investigation scheme initiated by the Council, and form a most excellent beginning. I am happy to say the scheme has been taken up very kindly by the professors and teachers at the leading colleges in London, and we may hope for a series of useful papers or notes on analytical problems and methods of analysis, the work to be carried on under the supervision of the professor by selected students.During the past year more than half the papers presented have been related to the analysis of food and drugs.114 THE ANALYST. I n addition to these original papers and reprints, abstracts of the following papers have been given in the Journal : Food and drugs analysis ... ... ... ... ... 127 Toxicological and bacteriological analysis . . ... 6 Organic analysis ... ... ... ... ... ... 112 Inorganic analysis ... ... ... ... ... ... 156 Apparatus ... ... ... ... ... ... ... 31 _- Total number of abstracts ... ... ... 432 I am sure every member and every reader of the Journal will join with me in testifying our thanks to the Publication Committee and our gratitude to the Editor, for their labours during the year, not forgetting the most useful work done by the abstractors.The question of the purity of the food and drink of the people continues to attract more and more public attention-a welcome change from the apathy with which such matters were formerly regarded. We still wait, however, for the enforcement of the recommendations of the Committee on the Use of Preservatives in Food. Recently the United States Department of Agriculture has published the first part of an elaborate report on “The Influence of Food Preservatives and Artificial Colours on Digestion and Health,” drawn up by Dr. Wiley, the Chief of the Bureau of Chemistry.An abridgment of this report has already appeared in the ANALYST, but I may here repeat the final sentence of the report : “It appears, therefore, that both boric acid and borax, when continuously administered in small doses for a long period, or when given in large quantities for a short period, create disturbance of appetite, of digestion, and of health.” If this be the case as regards boric acid and borax, possibly among the least detrimental of these preservatives, what shall we say of salicylic acids and sali- cylates, already forbidden by some of the Continental nations in articles for home consumption in their own countries ? The processes of digestion require certain changes to take place in the food easily and without resistance, whereas the function of preservatives is to resist all such changes. I n view of the uncertainty now pre- vailing, some of our local authorities have-I think not without reason-decided that no prosecutions shall be instituted in regard to preserves and similar foods where sugar is saved by the addition of small quantities of salicylic acid.We may hope that Dr. Wiley and his department may continue their valuable investigations, and that some day our authorities may decide that the health of our people is much more important than any extension of food manufacture founded on the use of preservatives. One of the chief recommendations of the Select Committee, which sat in 1896, on Food Products Adulteration was that a Board or Court of Reference, preferably a standing Departmental Committee, be constituted, with advisory powers in matters relating to standards and analysis of food and drugs.This recommendation was further strongly supported by the Royal Commission on Arsenical Poisoning which sat 1901-1903, and the proposal has throughout been advocated by the Council of this Society. With the exception of the limits for milk and butter issued by the Board of Agriculture, the following words are still as true as when they were givenTHE ANALYST. 115 out by your Council in 1897 : “ At the present time each individual Public Analyst is left to decide what does or does not constitute adulteration, what is or is not to be regarded as injurious to health, and what limits and standards are to be adopted in judging of the genuineness or otherwise of samples submitted to him.Disputed questions of the greatest scientific intricacy are now fought out, more or less imperfectly, in open court at the expense of vendors or public authorities, and, as a consequence, questions which might have been settled, to the benefit of the com- munity, many years ago are still undecided, after more than twenty years’ working of the Food and Drugs Acts.” Quite recently an example has arisen showing the uncertainty which exists. One of the recommendations agreed to by the Select Committee in 1896 was that the British Pharmacopceia should “ be legally constituted the standard for drugs, and that deviations from such standard should be permitted only upon the production of a prescription of a duly qualified medical practitioner.” It is true that this recommendation was not incorporated in the Act of 1899, but, considering the authorities responsible for the Pharmacopceia, analysts have, I think, rightly used it as a standard.A sample of cod-liver oil was condemned by a Public Analyst as not conforming to the Pharmacopceia tests, On reference to the Government Laboratory, the chemists there stated: “The sample does not conform to the tests specified in the British Pharmacopceia, 1898, for the examination of cod-liver oil.” On further examination and analysis by the best authorities on this subject, it was given in evidence that the British Pharmacopaia tests were worthless as tests for the purity of cod-liver oil, and were devised at a time when the oil was made from putrid livers, and had been copied into siiccessive editions of the Pharmacopceia.Does not this case prove the urgent necessity for a properly constituted authority to supervise all such matters? I n the Transactions of the Highland and Agricultural Society of Scotland for 1904 are three papers bearing on the milk question : ‘‘ The Influence of Food on Milk.” “ Milk Records.” By John Speir. ‘‘ Milk Investigations at Garforth, 1903.” I n the first of these papers the author pleads for the upholding of the milk standards introduced by the Board of Agriculture, in the interests of the dairy industry itself. He describes a large number of experiments with individual cows fed alter- nately with poor and with rich rations. By Allan Barnes Graham, junior.B y Charles Crowther, M.A., Ph.D. The average percentages ol fat in the milk were : With Poor Rations. With Rich Rations. 1 2 3 1 2 3 2.92 2-95 3-02 3-36 3-37’ 3-20 Except at pasture, the quantity of water given to the cows is noted. The writer’s view is that it is mainly by regulating the quantity of water consumed by the cow that we can alter the quality of the milk. To get a large yield of rich milk, use food rich in oil and albuminoids. The milk varies according as the cows are fed-in fact, the milk can be watered through the mouths of the cows. Mr. Speir’s paper on milk records gives the results of constant testing of the116 THE ANALYST, milk of 1,342 cows, chiefly of the Ayrshire breed, located on farms in Ayrshire, Dumfriesshire, and Wigtonshire.Full details are given of the effect of age and varying conditions on the milk yield. The records extended over periods of three months and six months, and the proportion of cows who ever gave morning milk under the 3 per cent. standard was less than 1 per cent. The average of all the cows for twenty-six weeks was 3.65 per cent. of fat in the milk, These two papers can, I think, be well set against the low results chronicled from the farm at Garforth. I venture to suggest that in the latter there is something requiring explanation ; it may be in some detail of the housing, feeding, or milking, or in the health or selection of the cattle at this experimental farm. Other milks in the same district do not show the same low results. The consumption of millrin the city of Leeds is very great, and its centre is seven miles from Garforth.The following are the averages for the past two years of testing many hundreds of samples of milk, including in the average the adulterated samples : 1903. 1904. Average percentage of fat in the milk ... 3-53 3.68 Percentage of adulterated samples . . . ... 20.3 23-8 These adulterated samples were not only lower than the limits specified by the Board of Agriculture, but in each case the ash and the nitrogen of the milk were carefully determined and were found deficient. The report of the Departmental Committee appointed a year ago to inquire into the Working in Great Britain of the Fertilizers and Feeding Stuffs Act, 1893, has now been issued. The Committee recommend that powers be given to local authorities to use public funds for the purposes of the Act, to appoint official samplers to take samples on behalf of purchasers, or to take test samples on behalf of the local authority.The procedure recommended is similar to that under the Sale of Food and Drugs Act, but where articles differ from the guarantee, copies of the certificates are to be sent to the Board of Agriculture, whose approval is necessary before instituting a prosecu- tion. Purchasers, or associations of purchasers, may submit samples for analysis, taken with or without the formalities required under the Act, but in the latter case the analyst shall have power to charge an enhanced fee. Sellers are required to state This, I presume, means the actual proportions or percentages of constituents.If so, one exception is made, I think, without sufficient reason, in regard to the oil and albuminoids present in foods consisting of a particular seed, either whole or ground, but not otherwise altered. That the Board of Agriculture take steps to secure uniformity of procedure in khe analysis of fertilizers and feeding stuffs, and issue a statement of limits for each constituent of the principal fertilizers and feeding stuffs. The district agricultural analysts must specially endorse their certificates when there is such a difference between the analysis and the guarantee as either to render inquiry desirable or to give a pyirna facie case for a prosecution. Consistently with securing the services of competent men, the analyst is to reside in the district for which he acts, so as to afford opportunity for farmers and - the actual constituents present in fertilizers and feeding stuffs.”THE ANALYST.117 others to consult him. I n my experience as analyst to an agricultural society before this Act came in force, and as an analyst under the Act, there are very few personal consultations ever required, and advice is more frequently given by letter than personally. Unless in the future the amount of work arising under the Act is in- creased beyond any comparison with what it has been up to the present time, I think it will be difficult to find competent men to devote themselves entirely to work under this Act, and, as a rule, the men who now hold these appointments locally derive their chief income from other sources.I n determining the value of basic slag, the proportion soluble in 2 per cent. citric acid is to be noted, I n regard to agricultural analyses, I have found farmers sometimes averse to stating the price at which they bought the articles. With samples taken under the Act the price must be stated, and I think this is most desirable in all cases, whether samples be taken under the Act or not. I have rnet with some extraordinary cases where the analysis and guarantee were quite in agreement, but the price charged was twice or three times the market value. The vendor in these cases traded on the ignorance of his customers, and simply laughed at the threat of proceedings being taken. I t is, I think, very evident that the Board of Agriculture through its staff are most anxious to do all they can in the interests of the farmers and as regards farming produce of all the citizens of the country.- It might tend to promote this end if copies of every publication issued by the Board were sent to each agricultural or public analyst, even when these publications do not bear directly on matters relating to analysis.Many of us have to acknowledge the courtesy of the Govern- ment Departments in sometimes sending us copies of reports relating to the work in which we are engaged. This society is really a co-worker with these departments, and any trouble or expense incurred in a more liberal circulation of reports or papers would in due time be well repaid. The Supplement to the Thirty-Second Annual Report of the Local Government Board, drawn up by Dr.Power, the medical officer of the Board, contains reports of a number of investigations of great interest to those engaged in the sanitary examination of air and water. I n Appendix A, No. 11, report by Dr. Bulstrode, “On the Water-Supply of Bridgend, Glamorganshire, and the Relation thereto of the Prevalence of Enteric Fever. ” Report by Dr. Gordon, ‘‘ On a Bacterial Test for Estimating the Pollution of Air in Rooms and Inhabited Places.” Reports by Dr. Houston, “ On the Chemical and Bacteriological Examination of the Tunbridge Wells Deep Wells Waters,” and, ‘‘ On the Nature and Relative Amounts of the Bacteria in the Contents of the Lower Bowel of the Healthy Human Subject.” Speaking of these last-mentioned investigations, Dr.Houston finds that of the Bacillus coli group-the predominant organisms present-90 per cent. of the total microbes of that group are so markedly positive in their attributes as to preclude their being regarded as other than typical B. coli. The atypical B. coli, commonly found in sewages, effluents, etc., is rare in the contents of the lower bowel of the healthy human subject.118 THE ANALYST. I n a former report Dr. Houston had investigated the shallow wells of Chichester, and in this he speaks of the deep wells of Tunbridge Wells, which were found to be both chemically and bacteriologically of a high degree of purity. I n a few instances coli-like microbes, were found isolated from a relatively large volume of water, which, however, could not, when duly tested, be confounded with the typical 23.coli from the intestine. It is, however, a notable circumstance that the coli group of organisms is represented at all in water drawn from several hundred feet below the surface. Comparing the Chichester shallow wells with the Tunbridge Wells deep wells, 45 per cent. of the former yielded typical B. coli, whereas in no single instance was this organism found in the Tunbridge Wells waters. Hitherto it has been assumed that bacteria-in the air are disseminated mainly in the dry state. Dr. Mervyn Gordon's experiments afford examples of transference, which may be of frequent occurrence in the act of speaking, where the bacteria remain in the moist condition. They give a test capable of being used as an index of the pollution of air comparable with the tests for BaciZZus coli as an index of the pollution of water.As the result of the examination of the saliva of a number of healthy persons, he found that streptococci of various kinds are extremely abundant in human saliva, and in particular Streptococcus brevis is commonly present to the amount of at least ten millions per cubic centimotre of the secretion. Among other tests he found that this streptococcus gives a definite colour reaction with Rothberger's neutral-red broth when incubated under anaerobic conditions at 37" C., changing the red colour to a canary yellow with slight, fluorescence. H e proved that minute quantities of saliva produce the same effect. Dr. Gordon then applied this test to the air of a large room, first by placing Petri dishes charged with neutral-red broth set about the empty room, and afterwards by placing similarly another set of Petri dishes charged as before, set about the room during loud speaking by a person standing at one end of tbe room.He repeated these experiments with a series of different speakers. He thus was able to show, first, the absence of all streptococci before the speaking began, and afterwards to prove that droplets of saliva were diffused generally throughout the air of the room, even as far as 40 feet away from the speaker in front and 12 feet from him behind. I n view of the fact that phthisical patients do cough up invisible droplets of mucus or saliva containing the material cause of their malady, Dr. Gordon's experiments afford a most valuable means of gauging the possible contamination of the air by the human subject.Dr. Gordon has also examined the air in different places in London and its vicinity by methods founded on these observations. The water-supply at Bridgend, Glarnorganshire, had for several years been tested both chemically and bacteriologically with uciformly satisfactory results, but in December, 1900, the bacteriological examination began to show doubtful characters, and more detailed and frequent examinations confirmed these doubts, though the chemical examination remained satisfactory. The water was tested both by the local analyst and by Dr. Thorpe at the Government Laboratory. This water-supply is obtained from springs rising in a carboniferous limestone rock containing many fissures, and the collecting basin or area is liable, in times of heavy rain and in certain states of the tide in the tidal river adjacent, to occasional connection with polluted waters, and the practical outcome is to show that thoughTHE ANALYST. 119 the pollution may be small in amount, yet it may be dangerous in its quality or character, and that in such cases of unexplained illness the chemical analysis should be supplemented by a bacteriological examination. Had time permitted, there are many other points of interest on which I might have spoken, but the preceding imperfect survey may, I hope, be useful to members. And now the time has come when I close my term of office, and give up this chair to a worthy successor. He has already done yeoman service for many years as your Secretary, and though he has not been able to retire on the emoluments of that important office, yet I am sure all of us willingly accord to him heartfelt gratitude, and welcome his accession to the office of President. On my own behalf, I thank you all for the honour and the confidence you placed in me two years ago, and especially do I wish to thank the Secretaries, the Editor, and the Members of the Council, for their unvarying kindness to me. I hope that the future may be ever bright for the Society of Public Analysts, and that the past record of good and useful work done by its members may be greatly surpassed in the years to come. Mr. Bevan needs no introduction from me. I wish him as pleasant a tenure of office as I have had.

ISSN:0003-2654    

DOI:10.1039/AN9053000110

出版商:RSC    

年代:1905

数据来源: RSC

摘要:

THE ANALYST. 119 THE INVERSION OF CANE-SUGAR IN PRESENCE OF MILK CONSTITUENTS. BY THE HON. FRANCIS WATTS, C.&$.G., D.Sc., F.I.C., AND H. A. TEMPANY, B.Sc., A.I.C. (Read at the Meeting, Februarg 1, 1905.) IT was observed by one of us, while making analyses of condensed milks containing cane-sugar, that the method of Stokes and Bodmer gave results which were appreciably too low. The following description of the principles involved is taken from Allen’s ‘‘ Commercial Organic Analysis,” vol. i., p. 343, 1898 edition: ‘L Coagulation of the milk by citric acid, dilution to ten times its original volume, filtration and titration of a portion of the filtrate with Pavy’s ammoniacal copper solution. To 100 C.C. of the same filtrate 2 grammes of citric acid are added, the liquid boiled for ten minutes, cooled, neutralized, made up to 200 c.c., and titrated as before.The difference between the reducing powers of the solution before and after inversion is due to the invert sugar derived from the cane-sugar present, the milk-sugar not being inverted by boiling with citric acid.” It was observed that by following the process above detailed the complete inversion of the cane-sugar was not effected in presence of the constituents of milk. That this incomplete inversion was not due to insufficiency of citric acid was shown by a series of experiments in which 5 per cent. solutions of sucrose were boiled with 2, 1, and 4 per cent. of citric acid for ten minutes, and found to be fully inverted at the end of that time; it was therefore concluded that some constituent of milk exercised a retarding influence on the progress of the reaction.This method was described in the ANALYST, vol. x.120 Lactose Per Cent. THE ANALYST. Time of withdrawing solution in minutes. To investigate this point a series of experiments was instituted whereby the progress of the inverting action of citric acid could be followed on two similar solutions of cane-suqar, one containing milk constituents, the other not. The two solutions were prepared as follows : Two portions of 100 C.C. each of a soliltion containing approximately 25 per cent. of sucrose were measured out, and to each of these 12 grammes of citric acid were added ; to one solution 200 C.C. of whey, from which the curd had been precipitated by addition of a small quantity of citric acid, were added, and the two solutions then made up of 400 C.C.For further reference the solution containing milk constituents is termed A, and that not containing milk constituents B. The lactose in solution A was first determined by neutralizing the acidity of 25 C.C. by means of sodium hydrate, making up to 50 c.c., and determining by Fehling's solution. The two solutions were then transferred t o two flasks fitted with reflux con- densers and with tubes whereby portions of liquid could be withdrawn without interfering with the progress of the reaction. The two flasks were simultaneously heated up to the temperature of experiment, and from time to time portions of the contents withdrawn by means of the tubes provided. The portions withdrawn were rapidly cooled down to 30" C., 10 C.C.taken! neutralized with sodium hydrate, and made up to 100 C.C. with distilled water at 30" C.:+ The reducing sugars present were then determined by means of Pehling's solution. I n the first series the two flasks were heated to 85" C. by immersing both in one large water-bath maintained at that temperature. Two series of experiments were performed. The following results were obtained : CONSTITUENTS. ONLY. II Time from commencement of experiment a t which solution \\-as withdrawn. Invert Sugar Per Cent. 3.74 5.36 6-32 6.59 6.74 6-90 6.98 II Invert Sugar Per Cent. 5.87 6.68 6.98 7.26 7.26 7.26 7-26 I t will be observed that in the case of solution A the inversion was not quite complete in the time of experiment. A second series of experiments was performed at the boiling-points of the solutions, the liquid in the flasks being kept at a gentle ebullition over a small flame.* 30" C. is the average laboratory temperature in the Leeward Islands, where these experiments were performed.THE ANALYST. 121 The following results were obtained : SOLUTIOS A, CONTAINIXG CANE-SUGAK AKD MILK CONSTITUENTS. Time from commencement of experiment a t which solution was withdrawn. 10 minutes 25 7 , 40 9 , 55 9 , 70 9 , Invert Sugar Per Cent. 5.03 6.38 6-38 6-46 6-53 6.67 6.53 6-60 Lactose Per Cent. SOLUTION B, CONTAINING CANE-SUGAR ONLY. Time of witlidrawiiig solution in minutes. 10 minutes 25 7 3 40 ? > 55 $ 7 70 Y > 85 7 , 100 I , 115 ,, Invert Sugar Per Cent. 6.50 6.59 6.50 6.59 6.59 6.59 6.59 6.59 TO ascertain definitely that citric acid is without action on lactose, as stated by Stokes and Bodmer, an experiment was performed in which 200 C.C.of whey were acidified with 12 grammes citric acid, made up to 400 C.C. with distilled water, and boiled as in the previous experiments, portions being withdrawn at e p a 1 intervals of time and the lactose estimated. Time of withdrawal of solutioii in minutes. 0 minutes 30 7 , 60 7 , 90 7 Y , Y Lactose Per Cent. 2.57 2-57 2.57 2-62 2.57 This experiment shows conclusively that, as stated by Stokes and Bodmer, citric acid is entirely without inverting action on lactose even after heating for a very considerable length of time. From the results above detailed it is obvious that the presence of some con- stituent of milk exerts a marked retarding influence on the inversion of cane-sugar by citric acid, and that boiling for ten minutes, as advised by Stokes and Bodmer, is insufficient to insure complete inversion.To obtain satisfactory results the boiling should be continued for forty minutes. On the electrolytic dissociation hypothesis the velocity of inversion of cane- sugar by acids depends on the active mass of the hydrogen ions present, reduction of the number of free hydrogen ions occasioning retardation of the reaction. This reduction, one would anticipate, would be occasioned by some dissociated substance in solution, which, interfering with the solubility product of citric acid, would cause reduction of the number of free hydrogen ions, and thus retardation of the reaction.One would expect that the effect was not due to the presence of the lactose in122 THE ANALYST, Time of withdrawal in minutes. solution, and that this is the case is shown by an experiment in which two similar solutions of cane-sugar, to one of which approximately 5 per cent. of lactose had been added, were boiled with 3 per cent. citric acid, portions being withdrawn and the reducing sugars determined from time to time as in the previous experiments. Invert Sugar Per Cent. SOLUTION A. CANE-SUGAR AND LACTOSE. Time of withdrawal in minutes. Invert Sugar Per Cent. 10 minutes 20 3 , 35 ,, 60 ,> 6-55 6.55 6.55 - Lactose Per Cent. 5.20 - SOLUTION B. CAKE-SUGAK. 6.25 6-65 6-55 6.60 These results show, as one would anticipate, that lactose is entirely without influence on the rate of inversion of cane-sugar.The practical bearing of these experiments appears to be that, in following the method of Stokes and Bodmer, ten minutes’ boiling is insufficient to effect the complete inversion of all the cane-sugar present, and a longer time should be allowed for its completion. Forty minutes’ boiling would appear sufficient to effect the in- version of all the cane-sugar present, if the milk under examination has been diluted down till it contains between 5 and 10 per cent. of cane-sugar. I n the foregoing experiments the determinations were made by titrating the solutions against 10 C.C. of Violette’s modification of Fehling’s solution diluted with its own bulk of distilled water. This method gives results sufficiently accurate for the purposes of comparison required in this inquiry ; for analytical purposes, where high accuracy is desired, it is preferable to use the gravimetric method as laid down by Brown and Morris. GOYEREMEKT LABORATORY, LEEWARD ISLANDS, B.W.I. DISCUSSION. The CHAIRMAN (Mr. Blount) said that, as far as he had been able to follow the paper without having read it beforehand, the authors seemed doubtful as to what effect would be produced on the activity of the citric acid by a substance like lactose. Clearly, however, on the dissociation hypothesis, lactose, which was not an electro- lyte in aqueous solution, could have no influence at all. The rapidity of inversion must depend on the activity of the citric acid, That, in turn, must depend on the degree of dissociation, which, again, depends on the degree of dilution and the nature of the solvent.This small criticism, however, did not invalidate the authors’ general argument. Dr. THORNE said that he might perhaps add to the paper a few words of explana- tion. The authors had sent it to him with the request that it might be published asTHE ANALYST. 123 he deemed most suitable, and it seemed to him to be undoubtedly a paper which should be laid before that Society. H e had taken an opportunity of first reading through the paper himself, and he thought, that, when it came to be printed, it would be found not to justify the Chairman's criticism. The authors' experiments with lactose were merely for the purpose of obtaining definite proof of what, as the Chairman had indicated, was a priori to be expeebed.The main question was that of the determination, in preserved milk, of quantities of cane-sugar which were small relatively to those of milk products. The method of Stokes and Bodmer seemed under such circumstances to give too low results, and the authors had endeavoured to ascertain whether better results could be obtained by increasing the time of inversion. Their experiments indicated that in the milk constituents there was something, the nature of which they had not yet been able to determine, which had a retarding influence on the inversion of the cane-sugar by citric acid. When the cane-sugar mas relatively small in quantity, the retardation was sufficient to impair the accuracy of the method, and it was necessary to increase the time of inversion to forty minutes in order to obtain satisfactory results.Mr. BAKER expressed surprise that the authors had not tried the use of invertase as an inverting agent for the cane-sugar. I t had no influence on the lactose, even at the inverting temperature of 50" to 55" C., and its use would, as it seemed to him, get over all the difficulties the authors had mentioned. Dr. SCHIDROWITZ thought that anyone looking at the matter from a purely chemical point of view would at once dismiss the idea that lactose could, under the conditions of this process, have any influence on the inversion of cane-sugar. It aEorded an excellent illustration of the disadvantages of the system, or, rather, fashion, which had sprung up of regarding all chemical phenomena from the purely ionic standpoint. Mr. J. B. P. HARRISON said that in a recent paper before the Society (ANALYST, 1904, xxix., 248) he had described a polarimetric method for the determination of cane-sugar in sweetened condensed milk. The specific rotatory power was deter- mined before and after inversion in an aqueous solution of the condensed milk from which the fat and proteids had been removed by precipitation with acid mercuric nitrate. An excess of this reagent was used, and the inversion was brought about by the action of the excess on boiling a portion of the filtrate for seven minutes.

ISSN:0003-2654    

DOI:10.1039/AN9053000119

出版商:RSC    

年代:1905

数据来源: RSC

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124 THE ANALYST. THE COLORIMETRIC ESTIMATION OF SALICYLIC ACID IN FOODSTUFFS. BY FRED T. HARRY AND W. R. MUMMERY. (Read at the Meeting, February 1, 1905.) THE work was carried on with a view to obviating the difficulties experienced in obtaining a good colour with Fe,Cl,, when using the present methods employed for estimating small quantities of salicylic acid in foodstuffs containing tannin bodies. The test is based upon the fact that lead tannate is insoluble in caustic alkalies, while lead salicylate is readily soluble, and resolves itself into the separation of the lead salts of both acids by means of potash or soda. The process which gave the best results with preserved fruits, fruit pulps, or jams is the following : Fifty grsmmes of the crushed sample to be tested are placed in an ordinary flask which has previously been marked at 300 C.C. ; a small quantity of water is added, then 15 to 20 C.C.of a saturated solution of basic lead acetate, and the whole made alkaline by the addition of about 25 C.C. of roughly normal soda. The alkali first throws down the excess of lead, afterwards dissolving the hydroxide and a quantity of alburninoids, etc., which are reprecipitated on adding acid, giving a clear colourless filtrate ; to effect this, 15 to 20 C.C. roughly normal HCl are added. The above procedure was found necessary in order to obtain complete solution of the lead salicylate, which is not reprecipitated by the acid. The contents of the flask are then made up to the 300-C.C. mark, well shaken, and filtered cold through Rhenish fiaper, 200 C.C.of the filtrate being collected. The filtrate is acidified with HCl, refiltered if necessary, and extracted three times with ether ; HC1 has been used in preference to H,SO,, as lead chloride is easily filtered off and washed, and if present in small quantiiies only, does not interfere with the ex traction. The ether is distilled off, the salicylic acid dissolved in a small quantity of dilute alcohol, made up to 100 c.c., and estimated colorimetrically with Fe,CI, in the usual way. The result multiplied by three will bring the amount to percentage. The presence of alcohol in the liquid to be extracted prevents complete solution of the salicylic acid in ether ; in cases where large quantities of alcohol are present this must be driven off before proceeding with the test.To effect this, the sample must be made alkaline and boiled gently; afterwards the process is continued as before. I t is advisable to neutralize the alkali before adding lead acetate, or too great an excess of the former may result. Different samples require different treatment (with regard to the quantity of lead acetate and alkali used), in order to insure the maximum rapidity of filtration combined with the smallest quantity of lead hydroxide dissolved; there is one point at which this takes place, a point which can readily be judged by practice. If the contents of the flask are made too alkaline, filtration is rapid, but a large excess of lead and albuminous bodies come through into the filtrate, making a second filtration necessary ; on the other hand, if too acid, filtration is also rapid, but theTHE ANALYST.125 complete solution of the lead salicylate is then doubtful. After the addition of the lead acetate and alkali the contents of the flask may be raised to boiling with safety; this will materially assist filtration, but has the disadvantage of allowing a large amount of lead to go through into the filtrate, We do not recommend this unless absolutely necessary; in any case, the filtration should bo conducted in the cold. For beers the process used was the following : 100 C.C. of beer are placed in a, flask marked at 200 c.c., made alkaline with 5 C.C. roughly normal NaOH, and all the alcohol driven off; this should be done at a temperature just below the boiling-point, as vigorous boiling appears to result in loss even when the solution is alkaline.After cooling, 5 C.C. of roughly normal HC1 are added, and then at least 20 C.C. basic lead acetate; the whole is then made alkaline with about 20 C.C. normal NaOH, and made up to the mark, At this stage the whole may be raised to boiling and allowed to cool before filtering, but this may be omitted if thought advisable. One hundred C.C. of the filtrate are collected and acidified as before ; in this case a precipitate of lead chloride is thrown down, which is filtered off, and the filtrate extracted with ether as before. The process which gave the best results with wine was the same as with beer- taking 50 C.C. of the wine, making up to 100 c.c., and filtering off 50 C.C. As with beer, it was necessary to add a large excess of lead acetate, and to have the whole fairly alkaline, in order to exclude all tannin bodies from the filtrate.If any tannin colours present themselves in the process of matching, they are probably due to using an insufficient quantity of lead acetate. The lead acetate used was a saturated solution made in the usual manner by boiling with lit harge. The tendency which beers and wines have to emulsify when shaken with ether is entirely obviated by this process, it being impossible to produce an emulsion with the filtrate even with the most vigorous shaking. With regard to the actual colorimetric readings, these were observed in ordinary 50-C.C. Nessler tubes, using a very weak solution of ferric chloride, which should be made up fresh when required.The standard salicylic acid solution used was 0.01 per cent., which could be kept without change for a very long time. In a paper read before this Society on November 5, 1902, Mr. Harvey recom- mended the use of ferric alum instead of ferric chloride, claiming that it gives with salicylic acid a deeper and more permanent colour. We have tried several samples of ferric alum, and are unable to confirm Mr. Harvey’s results. On allowing two tubes to stand over night, one containing ferric alum and the other ferric chloride, we found that the former had become quite turbid and the iron had separated out, while the latter, although not the same tint as at first, was just as clear. The use of sulphuric acid in the ferric alum solution as recommended is also a, drawback, since using one drop in excess will prevent the colour with salicylic acid appearing at all. We find our process gives excellent colours with black beers and wines con- taining large quantities of tannin, and works perfectly satisfactorily, even after the addition of about 0.5 gramme tannic acid in solution.326 THE ANALYST, The subjoined table will show the degree of accuracy which may be expected : Sample.Apple pulp ... ... 9 , 9 , ,? 3 , 7 9 ... ... ... .-. ... ... ... ... ... ... Blackberry jam ... Blackberry jam ... Black currant jam ... Preserved apricot ... Bitter beer ... ... Apple pulp ... ... ? 9 ¶ 9 ... ... ... 1.. Preserved apricots ... ... . . I ... ... ... .., ... ... ... ... ... ... ... ... ... ... ... ... ...... ... ... ... ... ... ... ... ... ... ... Salicylic Acid added in Grains per Pound or per Pint. 0.23 0.45 0-45 0.45 1.06 1.50 0.40 0.70 0.56 3-80 3 -80 1.14 1-14 1.14 1 -50 Salicylic Acid found in Grains per Pound or per Pint. 0.22 0.36 0.43 0.32 0.93 1-36 0.30 0.54 0.42 3.77 3.77 0.91 0.92 0.91 1.40 Error. 0.01 0.09 0 -02 0.13 0.13 0.14 0.10 0.16 0.14 0.03 0.03 0.23 0.22 0.23 0.10 The working error of the method applied to beers, etc., appears to be slightly larger than in the case of fruit pulps, jams, etc., but this is no doubt due to the boiling required at the commencement of the operation and the subsequent filtra- tion. Again, any method that depends on an extraction with ether and a colorimetric matching must of necessity possess an inherent minus error.In the case of jams, etc., the average error is about 0.09 to 0.1 grain per pound, while in the case of beers, etc., it is about 0.22 grain per pint. We may, perhaps, point out that we have in all cases worked with quantities representing about 1 grain per pint, or 1 grain per pound in the case of solids, partly because in the estimation of larger quantities the percentage error due to the inter- ference of tannin bodies is very much smaller, and such cases consequently present no difficulty. We have also been influenced by the consideration that the above- mentioned quantity is the limit recommended by the Preservatives Committee. In conclusion, we should like to take this opportunity of thanking Mr. Chapman for his kindness in not only allowing us the use of his laboratory, but also for the personal assistance he has given us in carrying out this work.DISCUSSION. The CHAIRMAN (Mr. Blount) having invited discussion, Mr. BEVAN said that the difficulty of getting the salicylic acid in a state of purity was well known to those who were in the habit of estimating it, either directly or by titration or colorimetrically, and they were therefore much indebted to the authors for showing how that difficulty might be overcome. The authors had mentioned, in the case of beer, an error of 0.23 in 1.14, or something like 25 per cent. He should like to hear whether, supposing the quantity of salicylic acid present to be 11.4, the error would be 2.3. If so, it would be a rather serious error.THE ANALYST, 187 Dr. SCHIDROWITZ said that in his experience there was an exaggerated view as to the frequency of the occurrence of salicylic acid in beer.He should like to know whether the authors had ever met with a sample of beer which did contain salicylic3 acid; he himself never had. Mr. BEVAN : In the case of lager beer, certainly. Dr. SCHIDILOWITZ said that some little time ago attention had been strongly directed to the use of salicylic acid in imported beer, and he had taken the trouble to obtain samples of nearly every kind of lager beer in London, but had not been able to detect salicylic acid in any of them. If, however, beer or wine containing salicylic acid was kept for some time, the salicylic acid undoubtedly disappeared gradually. Mr. CHAPMAN said that the paper to which they had listened that evening had had its origin in the fact that in his laboratory it had been found absolutely im- possible to detect salicylic acid in one or two samples of fruit pulp in which it was known to be pressnt in small amounts.Some fruits contain relatively large quantities of tannin and other bodies capable of producing a dark coloration with ferric chloride, and this in some cases entirely masks the fainter colour due to the salicylic acid. It was with the object of surmounting this difficulty that the authors had tried the method now described, and had found it to be very satisfactory. The method worked well with beer, but, as in the case of most analytical processes, some experience of it was essential for its successful application. A very interesting point in connection with the method was that the solutions to be extracted showed no tendency whatever to emulsify.This was, of course, highly important, inasmuch as the formation of emulsions is one of the most fruitful sources of error in processes involving extraction by the employment of immiscible solvents. Mr. A. E. PARKES said that he had not quite followed the way in which the authors treated the ether extract. If the solvent were distilled off, the amount of salicylic acid obtained would be lower than when the ether was extracted with alkaline water or allowed to evaporate spontaneously. Mr. LING inquired whether a clean crystalline residue was obtained after the first extraction, or whether it was necessary to extract again. In the ordinary process one had to make two extractions, one with ordinary ether and one with petroleum spirit, in order to obtain anything like a clean residue. Mr. EARRY, in reply, said that they had only tried the method with small quantities of salicylic acid, but were certainly of opinion that with larger quantities the error would not be larger in proportion. There was no great dificulty in estimating large quantities of salicylic acid in beer, as the tannin was but small in quantity and did not interfere ; in fact, they doubted whether it would be necessary to use this method at all. With regard to the treatment of the ether extract, they distilled off the ether in an ordinary Soxhlet apparatus, and then made up with dilute alcohol, the estimation being proceeded with as described. In some cases the residue might not be quite dry, but where a fairly dry extract was obtained it was quite crystalline and generally colourless. In some beers it might be slightly yellow, but this was not noticeable when it was in solution.

ISSN:0003-2654    

DOI:10.1039/AN9053000124

出版商:RSC    

年代:1905

数据来源: RSC

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128 THE ANALYST. ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. The Influence of Various “Fining” Materials on the Composition of Wine. K. Windiseh and T. Roettgen. (Zeit. Untersuuch. Nahr. Genussmittel, 1905, ix., 129-133.)-The authors have previously described the action of casein, milk, and charcoal on wine (ANALYST, 1904, 370), and now give the results of their experiments with isinglass, gelatin, white of egg, and ‘( Spanish earth,” the latter being a disintegration product of felspar. Except in the case of white of egg, which was found to increase the total solids and mineral matter in red wine, none of these fining materials had any influence on the acidity, total solids, or mineral matter in red or white wine. As was to be expected, gelatin and white of egg decreased the amount of tannin in the wines, as did also the Spanish earth.” The nitrogenous matters in the wines remained unaltered in quantity in all the experiments.The general conclusion arrived at is that the composition of wine is but little influenced or changed by any of these fining materials. I t might be mentioned that some samples of ‘‘ Spanish earth ” contain considerable quantities of calcium carbonate, and are quite unsuitable for clarifying wine, as they neutralize the acidity of the 1st ter . w. P. s. Fat Extraction from Milk. Th. Thomsen. (Tidskrift f o r Landoecolzomi, February, 1905, 101,)-The usual methods of extracting fat from milk after drying on paper, gypsum, etc., have, as is well known, failed in giving correct results in the cases of skimmed milk, butter-milk, or milk which has undergone violent agitation.I n such cases the Gottlieb-Rose method (ANALYST, 1898, xxiii., 259, and 1904, xxix., 112) gives higher results. It has been supposed by several analysts that the low results obtained in the former method were due to the retention of a portion of fat, viz., the very minute globules, which had become incorporated with the fat solids, and to ascertain if this was the cause the author has made the following investigations, He found that by treating the sample of milk with pepsin and hydrochloric acid before drying, the thorough peptonization caused the milk solids to dry in a loose form, which insured a complete extraction. In this way he obtained absolute agreement between the results obtained by extraction and by shaking out in the Gottlieb method.H. F. The Influence of Formalin on the Estimation of Total Solids in Milk. H. Haft. (Chem. Zeit., 1905, xxix., 54.)-Some experiments were performed in order to test whether the addition of formalin to milk made any appreciable difference in the weight of total solids, and, if so, what the exact difference was. The author gives figures which show, both for full and for separated milk, that an addition of any amount of formalin below 0.6 C.C. per 100 C.C. of milk has no effect on the total solids, even after twenty-five days. As the amount of formalin usually added for the purpose of preserving milk is said to be 4 drops per 100 c.c.,THE ANALYST. 129 this amount can have no effect on the analysis of the milk as regards total solids.The addition of 0.6 C.C. makes a difference of about 0.1 per cent. in the total solids, and increasing amounts of formalin have a corresponding influence on the figures. E. K. H. The Adulteration of Beeswax. R. Cohn. (Zeit. f. Of. Chenz., 1904, x., 404.)-The author disagrees with the usual methods for obtaining the saponifica- tion number of substances saponifiable with difliculty, such as beeswax, and especially with the limited time allowed for saponification. From a series of 200 experiments he considers that the saponification number for this substance may occasionally rise as high as 108, though usually it is about 100. These values could, however, rarely be obtained by treating for only one hour, as usually recom- mended, certain samples of pure wax requiring six hours.To this cause must be attributed the fact that many samples of pure wax are reported to be adulterated. The method suggested is the following : 2 to 3 grammes of the wax are dissolved in 25 C.C. of 96 per cent. alcohol, 25 C.C. KOH (in 95 per cent. alcohol) added, and boiled for three hours under a reflux condenser. The excess of KOH is titrated with HC1 and using phenolphthalein as indicator, the acid being added until the red colour no longer reappears on boiling. Saponification with NaOH is very much slower, and this the author attributes to the different solubilities of the potassium and sodium compounds formed. The maximum values obtained averaged 102, the minimum 96, whilst the greater nuniber of the experiments averaged 100.This (100) is therefore suggested as the standard saponification number, and is the factor employed in the calculation of three typical analyses, details of which are given. H. A. T. Oil of Eucalyptus Polybractea. John C. Umney and C. T. Bennett- (Pham. Joum., 1905, lxxiv., 143.)-This species of eucalyptus is that known as the " Blue Malee," and is very closely allied to E. dumosa. An authentic specimen of the oil from E. polybractea has recently been examined by the authors, with the following results : Specific gravity, 0.529 ; optically inactive ; cineol, as determined by Schimmel's process, 79 to 80 per cent. About 78 per cent. of the oil distilled between 173" and 176" C. The oil is quite free from any irritating odour of aldehydes, and contains only very small amounts of aromadendral and cumic aldehyde.I n this respect the oil differs from those from thesame source examined by R. T. Baker (" Research on the Eucalypts," p. 116), who states that the oil resembles that from E. cineorifolia, which contains aromadendral in quantity. If the authors' sample of the oil from E. polybractea bo a normal distillate, it is of great medicinal value, and in this respect is not even second to the official oil from E. globzdus. The species grows luxuriantly, and the oil should be obtainable in large quantities. A. R. T. Adulteration of Eucalyptus Oil with Castor Oil. C. T. Bennett. (Clze??zist and Druggist, 1905, 33.)-Extensive adulteration of commercial eucalyptus oils with castor oil, to the amount of 12 to 20 per cent., has recently been observed.The adulterated oils, which complied with the tests of the British Pharmacopceia, had the130 THE ANALYST. following characters: Specific gravity, 0.917 to 0.919; optical rotation, 0” to + 2’; cineol, 38 to 45 per cent. Suspicion was aroused owing to the low cineol content and comparatively high specific gravity. On fractional distillation, 80 per cent. of the oil distilled over, leaving a viscid, non-volatile portion in the flask. This fraction had a specific gravity of 0-957 and a refractive index of 1.4b10. It absorbed a large proportion of caustic potash on saponification, and glycerin was present in the liquid. The adulterant was soluble in 90 per cent. alcohol and in petroleum spirit, but when excess of the latter solvent was added, separation took place.These reactions are characteristic of castor oil. On destructive distillation, a sample of castor oil yielded a fraction having precisely similar characters to the product obtained from the adul- terant in the same way (specific gravity, 0.866 ; 0.869 ; refractive index, 1.4345 ; 1.4360). This limpid and pungent liquid contained in each case aldehydes and acrolein. An admixture of 5 to 10 per cent. of castor oil in eucalyptus oils of good quality may easily be overlooked unless special tests are applied. A. R. T. A Contribution to the Knowledge of Arachis. W. Moser. ( C ? M ~ . Zeitl Rep., 1905, xxix., 6.)--“ Earth-nut ” or ( ( ground-nut ” cakes, made from Arachis hypopa freed from oil, are largely used as food for cattle.The author describes the preparation and properties of an alkaloid isolated by him from the earth- nut, in addition to the bases cholin and betain previously found therein by E. Schutze. The author suggests the name (‘ Arachin ” for this new substance. Its poisonous action was investigated by subcutaneous administration to animals, but the tests were inconclusive, and further experiments are necessary. AS the author always obtained this ‘ I arachin ” in the numerous samples of earth-nut meal investigated, he comes to the conclusion that it exists already formed in the fresh seeds, and is not formed as a decomposition product of the proteids during storage. E. K. H. The Detection of Gum Arabic in Gum Tragaeanth. E. Payet. (Aizn. de Chim. anal., 1095, x., 63.)-A distinctive test is based on the fact that gum arabic contains an oxydase while gum tragacanth does not. A solution of the gum (1 : 30) made in the cold is shaken with an equal volume of a 1 per cent. aqueous solution of guaiacol and 1 drop of hydrogen peroxide solution. If gum arabic be present the liquid rapidly turns brown, but remains absolutely colourless if the gum tragacanth was pure. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9053000128

出版商:RSC    

年代:1905

数据来源: RSC

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130 THE ANALYST. ORGANIC ANALYSIS. Determination of Glycerol in Soap. E. Martin. (No?zitew Scieirzt., [4], xvii., 797; through Pharm. Journ., 1904, lxxiii., 958.)-Ten grammes of the soap are dissolved in 50 C.C. of hot water, the fatty acids liberated from the solution by the addition of a slight excess of diluted sulphuric acid, and the solution kept hot until the acids are completely melted. The liquid is filtered through a wetted filter paper, and the fatty acids washed on the filter with boiling water. Excess of basic lead acetate solution is added to the filtrate, the liquid filtered after half an hour, and the precipitate washed. The excess of lead in the solution is then precipitated by theTHE ANALYST. 131 addition of a little sulphuric acid, and the liquid made up without filtration to 250 C.C.When the precipitate has subsided, 25 C.C. of the clear solution ( = I gramme of soap) are examined by Hehner's dichromate method for the determination of glycerol in the usual way, whereby the glycerol is quantitatively oxidized to carbon dioxide. This gives the free glycerol. If the combined glycerol be also required, as in the case of superfatted soaps, a further determination of the glycerol after saponification must be made. The difference between the total glycerol thus found and the free glycerol gives the proportion of combined glycerol in the sample. A. R. T. A New Sugar from Mountain Ash Berries. G. Bertrand. (BUZZ., SOC. Chim., 1905, xxxiii., 166-168.) When the juice of these berries, or, better still, the mother- liquid from the crystallization of sorbitol, is fermented with sorbose bacteria, there remains in the liquid a substance that can be isolated as a benzoic acetal, and which Vincent and Meunier regarded as an octitol.The author, however, has been able to separate this substance in crystalline form, and shows that it is a hexitol of the formula, C,H,,O,. The new sugar crystallizes in anhydrous rhombic plates, which are extremely soluble and deli- quescent, and melt at 73.5" C. It is l~evorotatory, an aqueous 10 per cent. solution at 20" C. giving [u],, = - 3" 53. I t s molecular weight determined by the freezing- point method was 174.2. I t combines with benzaldehyde in the presence of sulphuric acid to form a mixture of two acetals, one of which melts below 190" C., and is readily soluble in boiling alcohol, while the other melts about 242" C., and is much less soluble in alcohol.He gives it the provisional name of sorbierite. It does not reduce Fehling's solution. C. A. 35. Artificial Colouring Matter in Ceresin. Utz. (Oest. Chern. Zcit., 1904, vii., 509.)-From the examination of a number of samples of commercial ceresin, the author finds that the yellow varieties are invariably coloured with coal-tar dyes. He considers such admixtures to be distinctly injurious. H. A. T. Note on Halphen's Reaction for Cotton-seed Oil. K. Fischer and H. Peyau. (Zed. Untersuch. Nahr. Genussmittel, 1905, ix., 81-90.)-The authors agree with previous observers that cotton-seed oil, when heated to a temperature of 250" C., no longer gives a coloration with Halphen's reagent (see ANALYST, 1899, 214; 1900, 270; 1903, 79).When heated to this temperature, however, the oil becomes quite unedible. Further experiments showed that, by treating the oil with zinc and sulphnric acid, no weakening of the reaction is produced. Bleaching by chlorine, while rendering the oil unfit for food, completely destroys its sensibility to Halphen's reagent, Treatment with sulphurous acid, followed by washing with alcohol to remove acid products formed, yields an oil which gives no coloration with this test, and which cannot, in other respects, be distinguished from natural cotton-seed oil. The presence of small quantities of cotton-seed oil so treated in other oils can, therefore, only be detected by means of the phytosterol- acetate test (ANALYST, 1902, 94).w. P. s.132 Specific gravity.. . . . . Iodine value . . . ... Maumenii test ... ... THE ANALYST. 0.9256 0.9253 0.9255 0.924 to 0.9235 145-3 145.8 145.9 138 to 139.9 101" c. 100" c. 1 0 1 O c. 100" to 99" c. The Detection of Foreign Oils in Walnut Oil. J. Bellier. (A~zn. de Chim. maZ., 1905, x., 52, 53.)-In many districts of Prance walnut oil is preferred to olive oil for food purposes, and as its price is often more expensive than that oil, it is very liable to adulteration. Most of the ordinary oils can be detected by the usual methods, but a mixture of equal parts of walnut and poppy oils is hardly to be dis- tinguished from the pure oil. One difference between the two oils is the freezing- point, walnut oil solidifying at - 27.5" C., and poppy oil at - 18" C., but a test based on this difference is not easy to apply.The author has therefore devised a test based on the difference in solubility of the respective solid fatty acids in alcohol (about 70 per cent.) containing potassium acetate. The solutions required are (1) 25 C.C. of glacial acetic acid with 75 C.C. of water; and (2) 16 grammes of pure potassium hydroxide in 100 c.c of 91 to 93 per cent. alcohol, The amount of solution (1) required to neutralize 5 C.C. of solution (3) should be determined. Usually it is about 2-5 C.C. I n testing the oil, 1 C.C. is mixed with 5 C.C. of the alkali solution (a), and a parallel test made with walnut oil of known purity. The tubes are heated below the boiling-point until the oils have dissolved, and are then closed and placed for thirty minutes in a water-bath at about 70" C., after which the quantity of the acetic acid solution (1) corresponding to the 5 C.C.of alkali solution is introduced, and the tubes again closed and kept in water at 17" to 19" C., with frequent agitation. Under these conditions walnut oil requires a long time to produce even a scanty precipitate at the bottom of the tube, whereas poppy oil speedily yields an abundant one, which remains distributed throughout the liquid in the tube. Other oils give an immediate abundant precipitate, the contents of the tube becoming nearly solid. I n this way it is possible to detect a very small percentage of olive, sesamii, cotton-seed, arachis, linseed, or rape oils in walnut oil.In the case of poppy oil the results are uncertain with less than 10 per cent., but with 15 to 20 per cent. there can be no doubt. The following values were obtained in the analysis of walnut, poppy, and edible linseed oils : WALNUT OILS. Pressed. ~ Pz:td. ~ P H d . Poppy oil, Levant. Cold Edible Lin- seed Oil. 0-930 159.8 130" C. C. A. M. Note on Bergamot Oil and other Oils of the Citrus Series. Herbert E. Burgess and Theodore H. Page. (Proc. Chem. Xoc., 1904, xx., 181.)-Amongst the minor constituents of oil of bergamot, acetic acid, pinene, camphene, limonene, and octylene have been detected. The pungency of the first fractions of bergamotTHE ANALYST. 133 oil is due to acetic acid, which occurs in smaller quantities in lemon oil, and which is no doubt present in other oils of this class.The octylene present in oil of bergamot is identical with that present in lemon oil, since, on oxidation with permanganate, butyric acid is formed in each case. Thus octylene is probably a normal constituent of all citrus oils. A second phenyl- urethane has been isolated from the terpineol-containing fraction of distilled oil of limes. This compound is more soluble than that obtained from ordinary terpineol, crystallizes in tufts of needles, and yields on hydrolysis an oily body having a strong odour of oil of limes. A. R. T. Characteristies of Certain African Copals. C. Coffignier. (BzdZ. Xoc. Chim., 1905, xxxiii., 169-176.)--KisseZ CupaZ.-This consisted of small, yellowish-red, vitreous fragments, without odour, and very free from impurities.It became soft at about 65" C., and melted at 110" C. I t dissolved in sulphuric acid of 66" B., (S.G. 1.843) yielding a dark-brown solution and a chocolate froth on shaking. On treatment with boiling alcohol it left 57.4 per cent. of a hard, brilliant residue, while 42.6 per cent. of friable yellow residue was obtained on extraction with ether. It gave the following values : Specific gravity, 1.066 ; acid value, 70.4 ; and saponification value, 117.8. Cameruon Cop?.-This was in rounded, irregular lumps of a pale-yellow or reddish-yellow colour, and with an odour recalling that of pepper. I t had a brilliant fracture, and was very hard. When heated it softened about 100" C., and melted at 150" C. Sulphuric acid dissolved it at once, giving an orange-yellow solution, becoming red after twenty-four hours.On shaking the liquid a deep yellow froth was obtained. A friable residue (66.7 per cent.) was obtained with boiling alcohol, while ether left a yellowish-white residue of 55.8 per cent. Analytical values: Specific gravity, 1.052 ; acid value, 159.7 ; and saponification value, 70.0 (?170*0). Accra CopaL-Irregular pieces of yellowish-white colour, vitreous or opaque, with a strong pepper-like odour. On heating it softened at 75" C., and melted at about 120" C. Sulphuric acid dissolved it, giving a reddish-brown solution, which frothed red on shaking. Alcohol left 47.8 per cent. of a pale-yellow, friable residue, while ether left 44 per cent. of a similar residue. Analytical values : Specific' gravity, 1.033 ; acid value, 97.8 ; and saponification value, 140.0.C. A. M. The Detection and Determination of Bituminous Substances in Gutta- percha. Pontio. (Ann. de Chim. anal., 1905, x., 57, 58.)-Gutta-percha is stated to be frequently adulterated with bituminous substances, and the following method is recommended for their determination. Bitumen is composed mainly of a mixture of liquid petrolene, C20H32, and of asphaltene, C,,H,,O,, with some sulphur compounds. It is soluble in petroleum spirit, toluene, benzene, chloroform, and carbon bisulphide, and is partially soluble in ether (38 per cent.) and alcohol to the extent of 7 per cent., the resinous substance dissolving in alcohol being also soluble in ether. On the other hand, gutta-percha is completely soluble in boiling ether, and thus, on extracting a mixture of gutta-percha and bitumen with that solvent, 62 per cent.of the latter will be left in the insoluble residue. I n examining a commercial sample it is first digested with absolute alcohol for the134 THE ANALYST. determination of the resinous constituents, and is then extracted for twelve hours with boiling ether, after which the residue is dried and weighed. This residue is then treated with boiling carbon bisulphide or toluene, which will dissolve the 62 per cent. of bituminous constituents if present, and the residue from this extraction will consist of natural impurities in the gutta-percha. C. A. M. The Quantitative Determination of Betaine. V. Stanek. (Zeit. Zu,ckerind in Bohmen, xxviii., 578-583 ; Biochem.Centralbl., 1905, iii., 471.)-Betaine is pre- cipitated by a solution of iodine in potassium iodide, yielding brownish-red crystals, rapidly changing to green, which are readily soluble in alcohol, hydriodic acid, and an aqueous solution of potassium iodide, but dissolve with difficulty in water. The compound, which has the formula, C,R,,NO2.HI.I,, melts at 58" to 61n C., with evolution of iodine, and is decomposed by boiling water into iodine and hydrated betaine iodide. The best reagent for the quantitative precipitation of betaine consists of a solution of 100 grammes of potassium iodide and 153 grammes of iodine in 200 C.C. of water. The solution of betaine, the strength of which should be from 1 to 4 per cent., is treated with a little sodium chloride or sulphuric acid, to reduce the solubility of the betaine hexaiodide, and an excess of the reagent introduced.After standing for three hours, the precipitate is collected in a Gooch crucible, and washed with water. It is then transferred to a Kjeldahl flask, where it is decomposed with sulphuric acid, and the liberated iodine collected in a flask containing alcohol. The residual liquid in the flask is boiled until colourless, after the addition of mercury, the nitrogen determined in the usual manner, and the amount of betaine calculated from the result. I n this way betaine can be quantitatively determined in the presence of glycocoll, asparagine, tyrosine, and ammonium salts. C. A. M. New Reaction for Enzymes. Winckel. (Phnrm. Post, xxxvii., 598 ; through Pharm.Journ., 1904, lxxiii., 957.)-The enzymes emulsin, myrosin, rennet, diastase, trypsin, invertin and ptyalin all give a violet colour when treated with vanillin and hydrochloric acid, and this reaction is suggested as a method for the detection of enzymes. The coloration is readily obtained by treating sections of fatty and oily seeds containing enzymes with the above-named reagents. A. R. T. A Method for the Rapid Ultimate Analysis of Certain Organic Com- pounds. John Norman Collie. (Proc. Chem. SOL, 1904, XX., 174.)-The combustion of the substance is carried out in the presence of a known volume of oxygen, and any change in the volume of the gas subsequently noted. The carbon dioxide produced is then determined by absorption in the usual manner and, from these data, the percentage of carbon and hydrogen in the compound may be calculated.The method is applicable only to those substances which are not appreciably volatile in ti vacuum, and which contain only carbon and hydrogen, or these two elements combined with oxygen. The method is capable of being used in cases where only small amounts of substance are available, and it is very accurate, since the determinations depend upon the measurements of volumes of gases. An analysis can be made in about one hour. A. R. T.THE ANALYST. 135 Simplified Ultimate Organic Analysis : Quick Method. Communication from the State Chemical Laboratory in Hamburg. M. Dennstedt. (ClLem. .%it., 1905, xxix., 52.)-The author has attempted to simplify the process of estimat- ing the elements in organic compounds so that constant attention is unnecessary, and thus save time for other work, rather than to shorten the time taken by the single analysis.The process used is a modified form of that already described by the author (“ Anleitung zur vereinfachten Elementaranalyse,” Otto Meissner’s Verlag, Hamburg), and is not, therefore, detailed in the present communication, a knowledge of its contents being pre-supposed. The principle involved is that the substance should be largely volatilized in oxygen and carried over platinized quartz, where the com- bustion proper takes place. Difficulty was encountered in getting this combustion to take place evenly, as the inflammable gases produced by volatilization formed an explosive mixture with the oxygen.To remedy this, the substance to be burnt was placed in an inner tube, and only a limited supply of oxygen allowed to pass over it, the main bulk of oxygen passing between the tubes, and only meeting the inflammable gas at the platinized quartz. Various devices were tried and rejected, for details of which reference must be made to the original paper, but the following account of the final process is of interest : A combustion tube prepared and dried as usual is used : about the middle is a piece of platinized quartz, in front of which, in the case of sulphur or halogen- containing substances, are four small or two large boats filled with pieces of quartz coated with lead peroxide-the latter prepared by covering pieces of quartz of the size of a pea with a coating of a thin paste of lead peroxide and water, and drying in an air-bath at 100’ C.The front end of the tube is connected to the requisite absorption apparatus, and the platinized quartz heated to redness. The substance is weighed in a boat, if solid, in a bulb, if liquid, and placed in the inner tube, the front end of which is open, and the back end either entirely closed for very volatile substances, or more usually drawn out to a fine capillary. A piece of previously ignited quartz is put next the boat (or bulb), and then three small pieces of platinum quartz. This tube is pushed down the combustion tube till the open end is close up to the platinized quartz, A well-fitting cork with a tube for passing in oxygen is then inserted in the combustion tube. The heating is next started from the rear forwards, whilst a stream of oxygen is passed in.The rate of heating and of the oxygen must be regulated, so that a small flame is just maintained on the platinized quartz. If the volatilization is too great, carbon, or unburnt substance is carried beyond the platinized quartz, and so not burnt. After the disappearance of the flame, which marks the end of the combustion proper (this takes from fifteen to twenty minutes usually), any carbon deposited on the boat and inner tube is burnt off by raising the temperature through the full power of the burners. I n order to see the flame above-mentioned, one of the top tiles is provided with a mica window.136 THE ANALYST. One analysis can be quickly followed by another, as the tube will have cooled sufficiently for the introduction of the second substance in the time taken to change the absorption apparatus. I n this quick process it is necessary to renew the first soda-lime tube com- paratively soon, but warning is given by the second tube increasing unduly in weight. The author has successfully used this form of apparatus for the analysis of a great variety of substances, including such diverse things as carbon disulphide, which it bas been found impossible to analyse by the usual combustion methods, ether, alcohol, acetanilide , phenanthrene, oils, caoutchouc and factis, these last two sub- stances, which are exceedingly difficult to manipulate by the older methods, give no trouble with the author’s method. E. K. H.

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DOI:10.1039/AN9053000130

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年代:1905

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136 THE ANALYST. INORGANIC ANALYSIS. Testing Zine Oxide used for the Estimation of Manganese by Potassium Permanganate. L. L. de Koninek. (Chem. Zeit. Rep., 1905, xxix., 5.)-The process depends on the fact that, if the oxide contains metal or sulphide, these will reduce ferric salts to the ferrous condition. The ferrous salt formed will at once decolorize potassium permanganate solution, whereas the original metal or sulphide acts either not at all or only slightly on permanganate. Two to 3 grammes of the zinc oxide are carefully rubbed down in a mortar with 20 to 30 C.C. water, in which has been dissolved 0-5 to 1.0 gramme of pure iron alum. 6 N sulphuric acid is then added gradually, with constant shaking, until the solution is complete. A single drop of permanganate solution should be sufficient to give a distinct rose colour.Excess must be carefully avoided. E. K. H. Note on the Determination of Chromium in Steel. F. Ibbotson and R. Howden. (Chewz. News, 1905, c., &)-The following method permits the estima- tion of the chromium to be determined on the portion of the sample taken for the manganese determination : To the liquid in which the permanganate has been titrated 50 C.C. of nitric acid (specific gravity 1.20) and 10 grammes of sodium bismuthate are added, and the mixture is heated slowly to boiling. As soon as it clear red solu- tion is obtained, a little manganous sulphate is added to reduce the permanganic acid formed, and boiling is continued for one or two minutes. The small amount of manganese dioxide precipitated, which retains only a trace of the chromium, is filtered off, and the chromic acid determined in the filtrate, diluted if necessary, as usual with ferrous sulphate and potassium permanganate.A. G. L. The Determination of Chromium in Steel. F. Ibbotson and R. Howden. (Chenz. News, 1904, xc., 320.)-The method depends on the oxidation of the chromium to chromic acid in a, nitric acid solution by means of ammonium persulphate in the presence of a small quantity of silver nitrate. Steels soluble in nitric acid (specific gravity 1-20> are dissolved in as small an amount of acid as possible. After expelling nitrous fumes and diluting copiously, 2 or 3 grarnmes of ammonium persulphate and 0.01 gramme of silver nitrate are added. The solution is heated until the evolution of gas commences, and allowed to stand for a few minutes until oxidation of theTHE ANALYST+ 137 chromium and manganese is complete.If much manganese is present, it is pre- cipitated as dioxide, which must be filtered off, but generally this does not take place. The solution is cooled, and the chromium precipitated as lead chromate by adding ammonium acetate and lead acetate. This precipitate is filtered off, washed, and dissolved in nitric acid, after which chromium is determined as usual. For the original oxidation the solution should not contain too much acid; if it is nearly neutral, the addition of silver nitrate is unnecessary. For steels not soluble in nitric acid, 0.5 gramme of drillings is boiled briskly with 10 C.C. of sulphuric acid (1 : 4).When decomposition is nearly complete, 2 C.C. of nitric acid (specific gravity 1.41) are added, nitrous fumes are expelled, and the liquid is diluted up to 100 C.C. with warm water, any separated tungstic acid being disregarded; 20 C.C. of nitric acid (specific gravity 1.20) and 20 C.C. of 0.2 per cent. silver nitrate solution are then added, followed by 2 or 3 grammes of amnioniuin persulphate. The liquid is heated with vigorous shaking until the evolution of gas ceases, when it is boiled for a few seconds, cooled, and diluted. An excess of standard ferrous sulphate solution is then added, and the determination completed with dichromate solution. Excellent results are obtained unless manganese is present, any manganese being reckoned as chromium. Steels containing large quantities of chromium and tungsten are decomposed with hydrofluoric and nitric acids, the solution being then evaporated with a little sulphuric acid and treated as above.An alloy containing over 30 per cent. of tungsten and 11.34 per cent. of chromium yielded 11-35 per cent. by this method, 0.25 gramme of the sample being used. A. G. L. Colorimetrie Determination of Phosphorus in Iron and Steel. T. E. Hewitt. (PYOC. Engimew' Society of W. Pennsylvania, xx., 1904, 432.)-The colour obtained on passing hydrogen sulphide into an alkaline phosphomolybdate solution is employed for the colorimetric determination of phosphorus, and also of molybdenum. For the determination of phosphorus, 2 grammes of pig-iron or steel are dissolved in 40 C.C. of nitric acid (specific gravity, 1*20), and the solution evaporated to dryness.The residue is baked until all acid fumes are driven off, and, when cool, 30 C.C. of strong hydrochloric acid are added, and the mixture heated rapidly until insoluble basic ferric chloride first appears on the bottom of the vessel. Ten C.C. of strong nitric acid are next added, followed by 50 C.C. of cold water when the violent action has ceased. The solution is filtered and the siliceous residue on the paper washed with 2 per cent, nitric acid solution. To the filtrate strong ammonia is added until a permanent precipitate is produced, when strong nitric acid is added in slight excess. The solution, which should now have a clear amber colour, is heated to 85" C., and 50 C.C. of ammonium molybdate solution quickly added and the liquid thoroughly shaken for five minutes.(This molybdate solution is prepared by dissolving 225 grammes of molybdic acid in a mixture of 600 C.C. of water and 400 C.C. of strong ammonia, and adding the solution to 24 litres of nitric acid of 1-20 specific gravity. The liquid is filtered after being kept in a warm place overnight.) When the precipitate has subsided, it is filtered, and washed with 2 per cent. nitric acid solution. The yellow precipitate is now Grst '( churned up " with very hot water, and a known amount of approximately decinorrnal caustic soda added until a clear solution138 THE ANALYST+ results in the filter. When this solution has run through the filter into a 100-C.C. flask, the operation is repeated until all the precipitate is dissolved.Half of the total volume of caustic soda used is now added in excess to the solution of the precipitate, and the liquid made up to 100 C.C. A larger excess of alkali should be avoided. An aliquot portion of this solution is then diluted with water to about 30 C.C. in a Nessler tube, and hydrogen sulphide passed into the liquid for five minutes, when saturation should be complete. The tube is placed in boiling water for five minutes, and the contents diluted to 50 C.C. The yellow colour obtained is compared with a standard prepared in a similar manner. A standard phospho- molybdate solution of suitable strength is obtained by adding sufficient decinormal caustic soda to 0.2737 gramme of the yellow precipitate (prepared by precipitating sodium phosphate solution with the ammonium molybdate reagent, washing the precipitate with 2 per cent.nitric acid, and drying) to dissolve it, and then half the amount of caustic soda again in excess, and making the solution up to 500 C.C. with water. The colour tints are judged by looking through the column of liquid. A number of test analyses are appended, showing that the method is capable of considerable accuracy. A. R. T. Ten C.C. of this solution contains 0~000009122 gramme of phosphorus. The Gravimetric Estimation of Calcium. Utz. (Oest. Clzmn. Zeit., 1904, vii., 5lO.)-The author finds that Brueck (Zeits. f. angew. Chern., 1904, xvii., 945) is wrong in his statement that calcium cannot be quantitatively precipitated from an acetic acid solution, as well as from an ammoniacal solution.A series of experi- ments have shown that the character of the solution has no influence on the precipitation by means of ammonium oxalate. An important point observed was that precipitation from an acid solution gave a more crystalline precipitate, thus facilitating filtration. H. A. T. Methods for the Detection of Acetates, Cyanides, and Lithium. Stanley R. Benedict. (Amer. Chem. Jozmz., xxxii., 480.)--Acetates.-The method depends on the facts that silver acetate is soluble in water and that the degree of ionization of acetic acid is greatly reduced by the presence of an acetate. The solution is freed from all metals except those of the alkali group, and made just alkaline with sodium carbonate. An excess of silver nitrate is then added and the precipitate filtered off, leaving the solution perfectly neutral.The filtrate is next saturated with hydrogen sulphide and mixed with a solution prepared by adding two or three drops of normal acetic acid to 2 C.C. normal cobalt nitrate solution and saturating with hydrogen sulphide, any slight precipitate of cobalt sulphide formed being disregarded. If an acetate was present in the original solution, a heavy precipitate of cobalt sulphide will be produced when the two solutions are mixed. The test is capable of detecting acetate in & solution ; it is applicable in the presence of all strong acids and of all weak acids having insoluble silver salts. Cyanides.-To test for cyanides in presence of thiocyanates and ferrocyanides, the solution is made alkaline with sodium hydroxide, and then about 0.5 C.C. of & mercurous nitrate solution is allowed to flow slowly down the side of the test-tube, a ring of black mercurous oxide being thus produced.On gently shakingTHE ANALYST. 139 the tube, a portion of the precipitate will dissolve, while the remainder will become light gray in colour, owing to the formation of metallic mercury, if a cyanide is present. The test will detect cyanide in 5 C.C. of a solution containing 1 part CN in 1,000,000 parts of solution. Lithiicrn. -Advan tage is taken of the slight solubility of lithium phosphate in hot or cold dilute alcohol, sodium phosphate, on the other hand, being diEcultly soluble only in cold dilute alcohol. To the solution to be tested a little ammonia and one-tenth its volume of sodium phosphate solution are added, and then enough ethyl alcohol to produce a fairly heavy permanent precipitate. On heating the liquid to boiling, any lithium phosphate present will remain insoluble, whilst the sodium phosphate will dissolve; if the quantity of lithium present is very small, the solution will first become clear, and the lithium phosphate will only form after some boiling.Potassium does not interfere with the reaction. For very delicate work a blank test may be made. A. G. L. Examination of Different Methods of Standardizing Potassium Perman- ganate Solution. H. Cantoni and M. Basadonna. (Am2. de Chim. anal., 1904, ix., 365-371.)-Details of experiments are given from which the conclusion is drawn that, in general, the different methods employed for this purpose are not very exact.The easily-applied method of standardizing on piano-wire is not to be recommended, owing to the impossibility of obtaining wire of sufficient purity, Thus, four separate samples gave results differing by 0.00002393 gramme of active oxygen per C.C. of per- manganate solution. The impurities, consisting of carbon, manganese, copper, etc., usually amount to about 0-45 per cent. Where very accurate work is not essential, the authors advocate taking a long piece of the wire, and cutting it into very small particles, so as to obtain a homogeneous sample, which should, however, be analysed by a gravimetric process. Where an absolutely exact result is required, the per- manganate should be standardized on pure iron obtained electrolytically. The oxalic acid method yields concordant results, but these are generally too high, owing to the adventitious water that the crystals can retain. The use of anhydrous oxalic acid, recommended by Hampe, is not advantageous, as it is very hygroscopic and difficult to weigh. Ferrous ammonium sulphate gives more discordant results than either piano-wire or oxalic acid, this being due to the di6culty of obtaining the salt perfectly free from the isomorphous sulphates of potassium, magnesium, etc. Volhard’s method of running the potassium perinanganate solution into a mixture of potassium iodide and pure hydrochloric acid, and titrating the liberated iodine with standard thiosulphate solution, is that which gives results in closest agreement with standardization on electrolytic iron, and is the one recommended by the authors where the electrolytic process cannot be used. c. A. 111.

ISSN:0003-2654    

DOI:10.1039/AN9053000136

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年代:1905

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140 THE ANALYST, INSTITUTE OF CHEMISTRY OF GREAT BRITAIN AND IRELAND. THE Twenty iseventh Annual General Meeting of the Institute of Chemistry was held at 30, Bloomsbury Square, on Wednesday, March 1, Mr. David Howard, President, in the chair. The accounts for 1904 having been submitted by Mr. A. GORDON SALAMON, Hon. Treasurer, and duly received, Professor FRANK CLOWES moved the adoption of the annual report of the Council, at the same time commenting on the progress of the Institute. The register now contains the names of 973 Fellows and 163 Associates, making in all 1,136 members. The number of candidates for the examinations had increased to such an extent that it was found necessary to hold both intermediate and final He referred to the increase of 38 members during the past year.THE ANALYST.141 examinations three times a year. After commenting on other matters in the report, Professor Clowes remarked on the growth of the library. Concluding, he said that the Institute was doing excellent work, and its qualifications and examinations were receiving more and more recognition. H e was of the opinion that the time had come when the diploma of F.I.C. or A.I.C. should be insisted on, as evidence of competency, in connection with professional chemical appointments. Mr, H. J. HELM, I.S.O., formally seconded the report. Dr. G. T. MOODY said that he was disappointed to find no mention in the He alluded The PRESIDENT said that the question had been under the consideration of the The report was then formally received and adopted.Sir Thomas Stevenson, Professor J. Millar Thomson, Professor William A. Tilden, and Dr. John A. Voelcker were elected Censors; and Messrs. C. H. Cribb, R. E. Alison, and W. T. Burgess were appointed Hon. Auditors. Before commenting on the matters which had engaged the attention of the Council during the past year, he referred to the loss the Institute had sustained by the death of several distinguished Fellows. He specially mentioned Mr. Alfred H. Allen, an earnest worker for applied chemistry, who had taken an active interest in the Institute since its foundation, and Mr. William Chattaway, who had for several years assisted in the examination work of the Institute. He remarked on the steady growth of the Institute, saying that he thought there was still a wide field for those possessing the highest chemical know- ledge and skill, and that those who had to call in the aid of such knowledge and skill were becoming more and more alive to the importance of employing only the properly trained and competent. He was of opinion that the training prescribed by the Institute and the high standard of the examinations had resulted in a decided improvement in the status of professional chemists.He emphasized the importance of requiring all candidates to produce evidence of a high standard of general educa- tion. The professional chemist should be a professional man as well as a chemist, and must, therefore, possess that general culture which is essential if he is to deal with his work in a professional spirit. He warmly supported the view, hitherto held by the Council, that Latin should be retained as a compulsory subject in the preliminary examinations.Referring to the position of the Institute in connection with the Sale of Food and Drugs Acts, he mentioned that 94 per cent. of the Public Analytical appoint- ments were held by Fellows of the Institute. He drew the attention of the members to the memorial presented by the Association of Public Analysts of Scotland to the Local Government Board (Edinburgh). They had been obliged to draw the atten- tion of the Board to the fact that a number of authorities in Scotland were in the habit of submitting test samples to persons whose qualifications had not been approved by the Board, which practice was not calculated to secure the proper administration of the Acts.The Government of India and the India, Office had considered communica- tions made to them by the Institute with reference to the practice of professional report of the question as to the subjects of preliminary examination. particularly to the retention of Latinhas a compulsory subject. Council, and he felt sure that it would be raised again. The PRESIDENT then delivered his address.142 THE ANALYST. chemistry in India. The President drew the attention of the Fellows to a resolu- tion recently passed by the Government, in which the qualifications F.I.C. and A.I.C. were formally recognised for public analytical appointments in India. The Coancil had undertaken to consider under what conditions officers of the Indian Medical Service could be admitted to the examinations of the Institute.The President then proceeded to deal with other matters mentioned in the report, and alluded to the action of the Board of Agriculture in encouraging provincial technical and agricultural colleges to undertake professional chemical work gratuitously, or at purely nominal fees. I n conclusion, he reminded the members that if they might congratulate them- selves on the present position of the Institute, they should not lose sight of the fact that much of its success was due to those who had worked for it in its early history. They had realized that, much as chemists had done for the world in the past, still greater things must be done by them in the future, and an organization such as the Institute should tend to draw them together to work for the common good.On the motion of Professor J. MILLAR THOMSON, seconded by Dr. JOHN A. VOELCKER, a cordial vote of thanks was accorded to the President for his address. The officers and members of Council for the ensuing year were duly elected as follows: President : David Howard. Vice-Preside?zts .- Edward John Bevan ; Edward Divers, M.D., D.Sc., F.R.S. ; Percy Faraday Frankland, LL.D., Ph.D., F.R.S. ; Edmund Albert Letts, D.Sc. ; Edmund James Mills, D.Sc., F.R.S. ; John Millar Thomson, LL.D., E.R.S. Hon. Treusurer .- Alfred Gordon Salamon, A.R.S.M. Members of Council! .- Bertram Blount ; Charles Edward Cassal, Lieut.-Colonel ; Alfred Chaston Chapman ; Arthur Crozier Claudet, A.R.S.M. ; John Norman Collie, Ph.D., F.R.S. ; James Kear Colwell ; James Johnstone Dobbie, M.A., D.Sc. ; Bernard Dyer, D.Sc. ; Martin Onslow Forster, D.Sc., Ph.D. ; Richard John Friswell ; William Gowland, A.R.S.M. ; Arthur George Green ; Oscar Guttmann ; Henry James Helm, I.S.O. ; James Hendrick, B.Sc. ; Egbert Grant Hooper ; Herbert Jackson ; William Walker James Nicol, M.A., D.Sc. ; William Jackson Pope, F.R.S. ; Alexander Scott, &!LA., D.Sc., F.R.S. ; William Ashwell Shenstone, F.R.S. ; Alfred Smetham ; Arthur Smithells, B.Sc., F.R.S. ; David Alexander Sutherland ; Edward William Voelcker, A.R.S.M.; William Palmer Wynne, D.Sc., F.R.S. ; Sydney Young, D.Sc., F.R.S.

ISSN:0003-2654    

DOI:10.1039/AN905300140b

出版商:RSC    

年代:1905

数据来源: RSC

摘要:

THE ANALYST. 143 REVIEWS. THE CHEMICAL SYNTHESIS OF VITAL PRODUCTS AND THE INTER-RELATIONS BETWEEN By RAPHAEL MELDOLA, F.R.S., V.P.C.S., F.I.C., etc. All students of chemistry owe a debt of gratitude to Professor Meldola for having undertaken the coinpilation of this very interesting and suggestive contribution to chemical literature. The work under review deals not only with those “vital products ” which are actually formed in the organism as the result of cell activity, and which may therefore be said to be of truly ‘( vital ” origin, but includes all those ‘‘ atomic complexes ” into which such vital products are capable of being resolved (assuming, of course, that these complexes have been prepared synthetically in the laboratory), as well as all substances isolated from animals or plants, even when there is reason to believe that they have not existed as such in the organism, but have been formed as the result of secondary changes occurring during the process of extraction.The reasons given for thus extending the scope of the work are of a weighty character, and are fully set forth in the preface. In the introductory chapters the author deals at some length with the question of the existence of a special vital force. H e says, “The testimony of pure chemistry cannot, as it at present stands, be legitimately interpreted into a direct negation of vitalism in any form. This negation may, and probably will, be made possible in the future when our chemical methods have been made to approximate more closely to the vital methods,” and goes on to remark: (( When we can transform sugar into alcohol in the laboratory at ordinary temperatures by the action of a synthesized nitrogenous organic compound, when we can convert glucose into citric acid in the same way that Citromyces can effect this transformation ; when we can build up heptane, or cymene, or styrene, or when we can produce the naphthalene or anthracene complex in the laboratory by the interaction of organic compounds at ordinary temperatures, then may the chemist proclaim with confidence that there is no longer any mystery in vital chemistry.” Whilst a consideration of the vast mass of accumulated facts contained in the body of this work may well engender pride in our marvellous achievements in the domain of synthetical chemistry, the author seeks to guard us against undue conceit by reminding us of the vast number of transformations which are constantly being carried out in Nature’s laboratory, and which we are at present apparently as far as ever from reproducing artificially, and reminds us that the science of biochemistry is yet to come.In two prefatory chapters the author dis- cusses organic chemistry and chemical synthesis from the biocentric standpoint, and explains the reasons which have induced him to treat his subject-matter throughoiit on biochemical lines. He says, (( The ordinary chemical equation representing the genetic relationship of one vital compound to another is apt to delude those who are not experts in chemistry into the belief that it is all-sufficient, and that it explains ’ the biochemical process ; as a matter of fact the sign connecting the two sides of the equation stands for the whole unexplored region of biochemical transnautation.” The above will sufficiently indicate the position taken by Professor Meldola in relation to his subject as set forth in the highly interesting chapters which serve as a preface to this work.The text embraces a very large number of naturally occurring compounds, ORGANIC COMPOUNDS. (Vol. I. London : Edward Arnold. 1904. Price 21s. net.)144 THE ANALYST. and contains detailed information in connection with their natural sources and the various synthetical processes by which they have been prepared. Full references to the original papers are in all cases given, and the general arrangement (a matter of no little importance in a work of this description) is admirably clear.The volume is well printed, is provided with an excellent index, and appears to be remarkably free from typographical errors. Attention may perhaps be called to a few slips which the writer has observed, so that they may be corrected in future editions : HoZn on p. 45 should obviously be HoZm, Ekenstein and Nonnose, on the same page should of course be Eckenstein and Nonose respectively, and Saatx on pp. 245 and 247 is usually spelt Saax. I n paragraph ( ( E ” on p. 250 the letter (‘ d ” should prefix the word “fructose.” The fact that the above trifling errors, in addition to the few mentioned in the list of errata and corrigenda, should be the only ones which the reviewer has been able to detect in the course of a somewhat careful perusal of the book is a testimony to the great care which must have been exercised in its produc- tion.The author might, perhaps, have distinguished somewhat more clearly between the designation Saccharomyces and Schixosacc~~arornyces. I n some sections these expressions are used quite correctly, but in others it is not clear whether the letter ( ( S ” stands as an abbreviation for the one or the other. I t is interesting to note that hydroquinone, which is specially referred to in one of the introductory chapters, has, since the publication of this work, been found to occur in considerable quantities in the leaf-buds of the pear-tree, The present volume deals with the literature of the subject to the end of the year 1902, and contains an appendix in which such additional syntheses are included as were accomplished while the main text was passing through the press.This work is one which cannot fail to be of the highest value, not only to the teacher and to the scientific investigator, but also to the chemical technologist, and the appearance of the second volume, which is promised by the author, will be looked forward to with the greatest interest. A. C. C. CHEMISTRY IN DAILY LIFE. By Dr. LASSAR-COHN. Translated by M. M. PATTISON This the third edition of Pattison Rluir’s translation of Lassar-Cohn’s famous lectures contains some few additions by the author, designed to render the book more perfect and to bring it up to date. These will further enhance the value of this well-known and deservedly esteemed popular scientific work. MUIR, M.A. Third Edition. (London : Grevel and Co. 1905.) W. J. S. OBITUARY NOTICE. PROFESSOR S T E I N . WE regret to learn that Professor V. Stein, of Copenhagen, died suddenly on February 1, at the age of fifty-nine years. He had a great reputation for work in technical and agricultural analysis, not only in Denmark, but also in Sweden and Germany. H e will be best remembered by our readers from his collaboration in 1888 with the late Mr. A. H. Allen on the question of the low Reichert-Wollny figures given by some Danish butters, the results of which were published in the ANALYST, 1889, xiv., 5.

ISSN:0003-2654    

DOI:10.1039/AN9053000143

出版商:RSC    

年代:1905

数据来源: RSC