摘要:

SEVENTH INTERNATIONAL CONGRESS OF APPLIED CHEMISTRY. ANALYTICAL CHEMISTRY.-SECTION I. The following are the Papers which have been promised up to the present. subject. C‘ontrihd or. Resineuses ... ... ... ... DR. ROEERT ADAK aiid Pentosans and its Practical Applications ... DR. ROBERT ADAK Sur l’unification des Methodes d’analyse des Essences l{esearches on the Quantitative Analysis of Pentoses Laboratory Chemicals ... ... GEO. P. ADAXSOK Nouveaux documents sur le dosage du bore ... Ueber eine quantitative Bestimmung von Fettsauren Nouvelle mhthode d’analyse des huiles e ssentielles Mhthode de dosage rapide du carbone dans les fers, h4M. H. COPAUX aiitl G. BOITEAU in Fetten Oelen und Seifen ... ... ... DR. KARL BRAUN renfermant des alcools Tertiaires ... ... M. VICTOR BOULEZ fontes et aciers ...... .., h4. BRETEAU Analysed Chemicals ... ... ... ... J. T. BAKER A Method for the Determination of Chlorine in the presence of Hydrochloric Acid ... C. E. BOLSER a d ,J. I\-. E:. ... GLATTFELD The Examination of China Wood Oil ... ... E. IT. BOUGHTON Report of Work in Analytical Chemistry in American Universities and Colleges during the years 1906- 1908 ... ... ... ... ... PROF. PHILIP E. BI:()JI-sI~\~(: Analytical Methods of Fuel-Testing (for joint dismsion Application du prockde Rothe a l’analyse des minerais Sur le dosage du Phosphore dans les fers, fontes et Analisi materie tartariche Ricerca del piombo nell Remarques sur l’analyse de quelques mineraux rares A Digest of the Methods of the United States Steel Corporation for the Commercial Sampling and by this Section) ...... ... ... PROF. COXSTAM et produits siderurgiques ... ... ... M. CAMPREDON aciers ... ... ... ... ... PROF. c:. CHEQXEALX acido turtarico e Citric0 ... ... ... DR. RAIRfoNUO CARAMEL1,I PROF. P. c. CHAERIB Analysis of Iron Ores ... ... ... J. M. CAAtP effectudes avec les arGorn6tres.. . ... ... M. DELACHANAL Des Lies et Tartres Prises d’dchantillons ... ... DR. P. CARLES Jrlfluence des tensions superficielles sur les mdsuresSubjcct. Analyse des gaz dissous dans les mktaux ... L’analyse physico-chimique des vins ... ... ... The Analysis of Manufactured India-Rubber Goods Estimation of Sodium Cyanamide and Nitrolime ... Contribzttw. Die Verwendung des Xickel-dicyandiamidins in der Unification des mhthodes analyse des principaux Dosage de petites quantitds de fluor dans les matikres Dosage de l’oxyde cle carbone dans les fers, fontes et aciers ...... ... ... ... 1. Emploi des raies ultimes en analyse chemique ... 2. Analyse spectrales quantitative ... ... Note analitiche su una terramara di Parma quantitativen Analyse ... ... ... dBrives du petrole ... ... ... ... minerales e t organiques ... ... ... ... Technical Coal Analysis ... ... ... The Solution Densities of Dextrose, Laevulose, and Maltose ... ... ... ... ... Mbthode noiivelle et appareil pour determiner le ... Mbthode d’enrichissement des phosphates naturels ... Terpen tinol und Terpentinolersatzmittel ... ... Dhtermination des gaz rares dans les sources thermales Phosphoric Acid Manufacture : Rapid Works Method of Ascertaining Completion of Decomposition of pouvoir calorifique des combustibles gazeux Phosphate Rock by Sulphuric Acid ...... The Analysis of Shellac ... . I . ... 1. Rlhthode d’analyee des ferro-silicium ... ... Analyse des essences de t6rhbenthine ... ... Dosage de l’antimoine ... ... ... New Apparatus for the Absorption of Gases 2. Sur le dhomination duniobium ou colombium ... ... M. DALACHANAL PROF. PAUL DUTOIT WALTER F. A. ERMEN FRANK E. WESTON, B.Sc., and H. RUSSELL ELLIS, B.Sc. DR. H. GROSSMANN M. AT,EERT GUISELIN ARMAND GAUTIER M. GOUTAL M. DF, GRAMONT PROF. LUIGI GABRA and bl. MADERNA EDWARD GUDEMAN M. DE GRAMONT MESSRS. A. R. LING, LEWIS EYNON, and J. H. LANE M. LEMOULT I). LEVAT DR. JULIUS MARCUSSON M. MOUREU A. H. MCDOWELL PARKER C. MCILHTNEY CAPITAINE NICOLARDOT MM.NICOLARDOT and CLEMENT MM. NICOLARDOT and RAULIN E. P. PERMAN CAPlTAlNE NICOLARDOT Emploi industriel de la metallographie microscopique M. REVILLON New Apparatus for the Rapid Electro-analytical Ueber die Beziehungen der Atomgewichtsbestim- 1. Die Bestimmung von Kieselfluor Natrium ... LUDWIG SCHUCHT 3. Die Bestimmung der freien Saure in Super- Also reading under Section VI1.- Separation of Metals ... ... ... DR. HENRY SAND mungcn zur analyt,ischen Chemie ... ... Dr. STAHLER phosphaten ... ... ... ... LUDWIG SCHUCHT Die Entwickelung der chemischen Tatigkeit auf dem Gebiet der Superphosphatfabrikation. 2Subject. Contributor. Review of the Analytical Chemical Work of the Several Bureaus of the United States Department of Agriculture and of the State Experiment Stations since 1903, except that on Foods and Drugs Ana lisi materie Tartariche-Ricerca del piombo nell -acid0 Tartaric0 e Citric0 ...... ... DR. OSCAR TOELEE ... W. W. SKINNER 1. Dosage du zinc dans les blendes et les pyrites ... 2. Dosage ctu Fluor daus les blendes ... ... M. PAUL TRUCHOT M. PAUL TRUCHOT Proposed Discussion ori- Application de 1’6lectrolyse au dosage du zinc dam les minerais de zinc et autres Discussion de la mdthode de Schaffner. Dosag2 du Fluor dans les blendes ... ... ... M. PAUL TRUCHOT A New Form of Laboratory Apparatus ... ... J. W. TURRENTJKE Iit eiizei. yenaeinsnmen Sitnyung 210% Sektion I. and VII. : L 6 Uber die Analyse der Itolplzospl~ate” 1. Internztional Regelung des Keli-Koeffizinten ... DR. MARTIN ULLMAN.Holzfaser ... ... ... ... DR. MARTIN ULLMAN des Weins ... ... ... ... DR. MARTIN ULLMAN 2. Die Methode Konig zur Bestimmung der 3. Ueber Methoden fur die Analyse von Stoffen, dienend zur Bekampfung der. Krankheiten Rapid Analysis of Babbit Metal ... ... PERCY H. WALKEK. and H. A. W HITMAN The Contracts Laboratory of the Bureau of Chemistry Factors which Influence the Creatinine Determination PERCY H. WALKER F. C. COOK On Jaffd’s Colorimetric Method for the Estimation of Creatinine ... ... ... ... ALFRED CHASTON CHAPMAN All communications relating to the work of the Section should be addressed to the 13011. Secretary : ALFRED C. CHAPMAN, 8, DUKE STREET, ALDGATE, E.C. BROMATOLOGY.-SIWTION VIIIc. Systems for the Control of Food Supplies by Analysis, Inspection, or otherwise .:. ... DRS. BORDAS, BUCIHANAN, CARLIN- FANTO EMIIJO, MATTH~OPOULOS and ZALAKOSTAS, MCGILL, VAN RIJN, Roux, WAUTERS, WILEY, and PROF. WYSMAN On the Advantages and Disadvantages of Legally Binding Standards of Composition from the Point of View of the Lawyer ... ... ... F. W. BECK and M. FAYOTALES The Use of Preservatives in Foods ... ... E. J. BEVAN, BONJEAN and HALPHEN, TIIRESH, C. WEBER 3Sulijtd. CoJributoy. ... Brandy ... ... ... ... DR. GIRARD, M. GUILLON, M. Chocolate ... ... ... ... M. ANDR~, DR. GIRARD, Dit. BOK- ROCQUES DAS, M. MENIER, DR. WAUTERS ... Report on the Work of the International Commission on Food Analysis ... ... ... M. ANDRE Les mdthodes d’analyse des denrees alimentaires en gdndral ... ... ... ... ... M. A N D R ~ Les caractkres des eaux pures dans leur rapport avec ceux terrains ...... ... ... M. ANDRB Unification international des mdthodes d’analyse du beurre ... ~ . * ... ... ... M. ANDRI? Unification international des vins ... ... M. ANDRI? ... M. ANDRI~ >, >, des spiritueux ... 7 s 9 9 du lait ... ... M. A N D R ~ Sur l’alimentation de la classe ouvrikre ... ... MM. LANDOUZY and LABBE Sur les Vins Franqais. Bordeaux ... ... M. GAYON ... De l’arsenic dans les boissons et matikres alimentaires M. BRETEAU ... M. MATHIEU 9 9 Y , Bourgogne ... 9 9 1, H6rault ... ... M. Roos Rble du Vins dans l’nlimentntion. Conservation des laits destines aux expertises ... M. GIRARD Qualites Hygihiques et marchandes du lait normal M. NOURRY Sur les limites du plomp dans les dtamages ct uten- Review of American Progress in the Microscopy of Notes on the Quantitative Determinations by means Progress in American Food Chemistry since June, 1906 Composition of Scuppernong, Concord, and Catawba Analysis of Evaporated Milk and Milk Products ... E. GUDEMAN siles culinaires ... ... ... ... MM. PADE and KOTW ABREST Foods ... ... ... ... ... E. M. CHANOT of the Microscope ... ... ... ... E. M. CHANUT Grape- Juices ... ... . . . ... E. C. GORE G. B. DUNBA R All communications relating to the work of the Section should be addressed to the Hon. Secretary : cEcIr, H. CRIBB, 136, SHAFTESBURY AVENUE, W. 4

ISSN:0003-2654    

DOI:10.1039/AN909340X001

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

DECEMBER, 1909. Vol. XXXIV., No. 405 THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE ordinary monthly meeting of the Society was held on Wednesday evening, November 3, in the Chemical Society’s Rooms, Burlington House. In the absence of the President, the chair was occupied by Mr. Cecil H. Cribb, B.Sc., F.I.C., Vice- President. The minutes of the previous ordinary meeting were read and confirmed. Certificates of proposal for election to membership were read for the first time in favour of Messrs. W. Heber Green, D. Sc., Agricultural Chemistry Laboratory, the University, Melbourne, Lecturer and Demonstrator in Chemistry at Melbourne University ; John McCrae, Ph.D., F.I.C., Government Laboratories, P.O. Box 1080, Johannesburg, Government Analyst for the Transvaal ; Malur Srinivasa Rau, M.A., M.D., C.M., B.Sc.(Edin.), D.P.H. (Cantab.), Bangalore, S. India, Chemist and Bacteriologist to the Government of Mysore ; Arthur Whitby, 10, Simmonds Street, Johannesburg, Assayer ; and Allister MacLean Wright, P.O. Box 617, Christchurch, New Zealand, Analytical Chemist to the Christchurch Meat Go., Ltd. Professor Percy F. Frankland, LL.D., F.B.S., was elected an honorary member of the Society ; and Mr. H. H. Ward was elected a member. The following papers were read : The Phosphates in Certain Vinegars and in the Materials used in their Manufacture,” by Thomas Fairley, F.I.C. ; I C Phosphates in Vinegar,” by F. D. Ratcliff; 4 1 On the Determination of Essential Oils and of Moisture in Spices and Aromatic Drugs,” by Richard A. Cripps, F.I.C., and J. A. Brown, F.I.C. ; and a ‘( Note on Holde’s Test, and the Detection of Paraffin Wax, etc., in Lard and other Fats,” by Harry Dunlop.

ISSN:0003-2654    

DOI:10.1039/AN9093400513

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

514 THE ANALYST. THE MARGARINE CLAUSE OF THE FOOD AND DRUGS ACT, 1899. THE Council have rtuthorised the publication of the following Interim Report of Sir Edward Thorpe and a Committee representing the Society of Public Analysts and other Analytical Chemists. The Committee in question consisted of Messrs. R. R. Tatlock, E. J. Bevan, W. W. Fisher, and Otto Hehner. The members of the Committee who conferred in 1900 with bhe Principal of the Government Laboratory as to the method and analytical criteria to be employed in determining whether the quantity of butter fat in margarine exceeds the legal limit, desire, in conjunction with the Principal of the Government Laboratory, to make an addendum to their previous Report to the Council. The table of figures given in the Report, and published in connection with the description of the method, which at a subsequent meeting of the Society was formally adopted as the otficial method, was based upon experiments carried out with mixtures of butter fat and margarine fat into the composition of which cocoanut fat or similar fat did not enter. As, however, the presence of certain fats, such as cocoanut fat, palm-nut fat, and some others, containing greater quantities of volatile acids than the fats formerly used in the manufacture of margarine, may increase the Reichert-Wollny number beyond 4, even when used without any butter fat, and particularly when used in conjunction with butter fat, the presence or absence of such fats must be ascertained before deciding that a Reichert-Wollny number exceeding 4 is evidence of the presence of butter fat in excess of 10 per cent.These fats are now being used to an increasing extent in the manufacture of margarine. They are distinguished, as is well known, by the relatively high quantity of insoluble volatile acids obtained during the determination of the Reichert-Wollny number ; and an indication of the quantity of cocoanut or palm- nut fat present may bs gathered, within limits, by the determination of the insoluble volatile acid number during the carrying out of the prescribed method. The Committee, in conjunction with the Principal of the Government Labora- tory, therefore propose to conduct experiments with mixtures of butter with margarine containing known but varying quantities of cocoanut fat, with a view of recommending to the Council of the Society such modification of the method and table of figures as may be necessary for use in the case of samples of margarine con- taining cocoanut fat. I n the meantime it has been agreed to recommend to the Council that it is desirable that the following words should be added to the Report submitted to the Society on November 7, 1900, viz. : L 6 The limiting figure of 4, obtained by the Reichert-Wollny method described, and the table 6f figures connected therewith, are not applicable to those cases of margarine in which the insoluble volatile acids number exceeds 1.”

ISSN:0003-2654    

DOI:10.1039/AN9093400514

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 515 ON THE PHOSPHATES IN CERTAIN VINEGARS AND IN THE MATERIALS USED IN THEIR MANUFACTURE. BY T. FAIRLEY, F.R.S.E., F.I.C. (Read at the Meeting, November 3, 1909.) SOME years ago certain samples of vinegar taken under the Sale of Food and Drugs Acts were found to differ in several respects from the standards commonly assumed t o be correct, especially as regards the proportion of phosphates, supposed to be one of the most constant quantities belonging to malt vinegar-0.08 per cent. of phosphoric acid (P,O,). Some of these vinegars which had been reported on adversely came to me. In company with the late Mr. Baynes, of Hull, and'at the invitation of the manufac-516 THE ANALYST. turers, I visited the vinegar works, and took samples of the materials used in the process and the products formed.The vinegar in question is the product of an alcoholic and acetous fermentation of an infusion prepared from a mixture of maize and a selected malt ; 1,000 of the mixture contain 850 of maize and 150 of malt. If these units be taken as pounds : 850 pounds of maize contain 150 pounds of malt contain . . . 0.763 ,, 9 , 9 9 . . . 4,828 pounds of phosphoric acid (P,O,). Total ... ... ... 5.591 ,, 9 9 9 , The 1,000 pounds of materials are ground and mixed with water so as to give a mash measuring 590 gallons, and which contains 0,094 per cent., or 5.546 pounds of phosphoric acid (P2OS). The mash is filtered before fermentation, and it is here that the process differs from those commonly followed. A considerable amount of the phosphates remain in the grains, 269 pounds of grains thus accounting for 3.5 pounds of phosphoric acid (P205).The filtered liquid measures about 340 gallons, and is subjected to the vinous and acetous fermentations. I n the vinous fermentation, yeast is added in the proportion of about 12 pounds to this quantity of wort, and about 90 pounds are taken out, so that the net yeast amounts to 78 pounds, containing 0.387 per cent., or 0.3 pounds of phosphoric acid (P205). In the handling of the liquid, and from the rise in temperature, due to the acetous fermentation, a certain proportion of its volume is lost. About 300 gallons of vinegar per 1,000 pounds of materials remain at the end of the process. The use of raw grain (to utilise the excess of diastatic power of the malt) is an alteration which has now been existent in the brewing and vinegar manufacture for many years, and as the vinegar in no way suffers in quality, I think it right to regard such vinegars as the same a3 those formerly brewed from malt only. The following table gives the composition of a number of vinegars : PER CENT. IN 100 C.C. OF VINEGAR. Acetic acid.. . ... ... ... Total solids ... ... ... Ash ... ... ... ... ... Proteins ... ... ... ... Specific gravity at; 15.5' C. ... Phosphoric acid (P20,) ... ... Original solids ... ... ... Average. 4.50 2.51 0.45 0.40 0.058 1016-9 9-26 Maximum. 5.30 4-01 0.96 0.79 0.083 1021 11.96 Minimum. 3.65 1-52 0.14 0.22 0.040 1012 6-99 Vinegar referred to in Paper. 3.67 2.02 0.18 0.24 0.059 1012.8 7.52 I have pleasure in thanking my assistants, Messrs. Lyles and Tattersfield, for their work in making the estimations recorded in this paper.

ISSN:0003-2654    

DOI:10.1039/AN909340515b

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 517 PHOSPHATES IN VINEGAR, BY F. D. RATCLIFF. (Read at the Meeting, November 3, 1909.) THE figures recorded in the preceding paper relate to maize, whereas mine are concerned with maize grits. For the sake of comparison, I have taken the proportions used by Fairley in his experiments, but as a, smaller proportion of malt may be used, figures are quoted for a mash consisting of 10 per cent. of malt and 90 per cent. of maize grits. Experience shows that a gallon of vinegar containing 4.5 per cent. of acetic acid may be made from 1.4 pound of grist; if then 10 gallons are taken as the bulk unit representing 100 c.c., 14 pounds will have been used in its manufacture. Analysis of maize grits shows that this material contains on an average 0.168 per cent. of phosphoric acid (P205).The quantities of malt and grits present in the 14 pounds of grist will be 2.1 and 11.9 pounds respectively, and the amount of phosphoric acid (P205) in this grist, using a malt such as Fairley mentions (Zoc. cit.) will be malt 0.01, grits 0.02, or a total of 0.03 pound. Some of this phosphoric acid (P205) is of course left in the grains; the quantity entering into solution, and which may be found in the finished vinegar when 15 per cent. of malt is used, is 0.018 pound; with 10 per cent. of malt it amounts to 0,015 pound, and this in a vinegar in which nothing but grain has been used. The original solids calculated by Hehner’s method in the vinegar in question amounted to 9.46, and the percentage of phosphoric acid (P205) on this figure works out in the case of 15 per cent.of malt to 0.19, and in that of 10 per cent. of malt to 0.16. Maize having been legalised for use in making whisky, by the final report of the recent Royal Commission (ANALYST, 1909, 425), it would appear only fair to grant the same facilities to the manufacture of so-called ‘‘ pure malt vinegar,” and this being so, even the low percentages of phosphoric acid (P205) mentioned above are not necessarily the minimum for a brewed vinegar, for the malt used in making this vinegar contained more phosphates than that mentioned in Fairley’s paper. DISCUSSION. The CHAIRMAN (Mr. Cribb), in inviting discussion on Messrs. Fairley’s and Ratcliff’s papers, remarked that it would seem to make a considerable difference whether the article was submitted as “ malt vinegar ” or simply as (‘ vinegar.” As regards malt vinegar, the question was now additionally complicated, because there were malt vinegars on the market which had been purposely and admittedly so treated as to remove part of the phosphoric acid, and also part of the proteins.Mr. F. W. RICHARDSON asked whether 0.04 per cent. of phosphoric acid was looked upon by Mr. Fairley as a reasonable standard? If so, he was afraid that518 THE ANALYST, many vinegars would be passed in the manufacture of which considerable quantities of hydrolysed rice and other similar materials had been used. In the recent Local Government Board Report on the subject of vinegar, there was, as far as he recollected, no case mentioned of malt vinegar containing so little phosphoric acid as 0.04 per cent., the average being 0.07 or 0-08 per cent.He presumed that Mr. Fairley, in evaporating the vinegar, had added a little alkali to fix the phosphoric acid. He mentioned this because he had heard of determinations being made without the addition of alkali, the results, of course, being consequently too low. Dr. DYER thought that the differences between Mr. Fairley’s and Mr. Ratcliff’s results were explained by the fact that Mr. Ratcliff had used L d maize grits.” In making “ maize grits,” or (‘ flaked maize,” the germ of the grain was removed, and it was in the germ, or the parts surrounding the germ, that the greater part of the phos- phoric acid was concentrated. He could corroborate Mr. Ratcliff’s figures from experiments of his own with mashes of various mixtures of this kind.He (Dr. Dyer) imagined that there were two accepted meanings for the I ‘ malt vinegar ” term. The view of the extreme purist would be that malt vinegar was vinegar in which everything but the water was derived from malt. The more liberal interpre- tation, and one which for a number of years had been largely accepted, was that malt vinegar was vinegar in which the acid was derived from starch which had been rendered soluble by the diastatic action of malt-ie., vinegar made by means of malt, but not necessarily wholly from malt. Malt vinegar, even according to this liberal interpretation, would differ from vinegar made from sugar or from a mixture of malt and sugar. Mr. E. M. HAWKINS said that, if he had rightly understood Mr.Fairley to say that the wort, before being submitted to vinous fermentation, was filtered quite bright and clear, he would like to ask if the retention of the fine deposit which generally passed through the mash tun-plates involved the removal of so much phos- phoric acid as to throw out all the usually accepted figures. Mr. BLOUNT remarked that some analytical distinction ought to be drawn between phosphoric acid in the form of phosphates and organic phosphorus com- pounds. Mr. R. A. CRIPPS said that he did not think that the proportion of phosphoric acid could be properly taken as an index of the purity either of “*malt ” or of any kind of vinegar. The vinegar formed a better pabulum for the growth of organisms when phosphoric acid was present, and so it was purposely removed.He thought that the original solids might possibly be taken as a basis, but the difficulty was to tell where the original solids came from. Mr. FAIRLEY, in reply, said that the only reason for this paper was that the particular vinegar referred to had been condemned by certain of his friends in Yorkshire, who had taken the proportion of phosphoric acid as their basis of calculation, and that, the manufacturer being willing to afford him every assistance, he had thought that it would be of advantage to explain the reason of the small amount of phosphoric acid present. The question of what was and what was not strictly malt vinegar was only a subsidiary one in this connection, but he thought that if the consumer got an article to all intents and purposes the same in compositionTHE ANALYST.519 and quality as if it was made entirely from malt, he was not in any way prejudiced. Mr. Richardson had spoken of hydroiysed rice, and if the hydrolysis were brought about, not by diastatic action, but by, say, sulphuric acid, a quite different kind of vinegar would be obtained ; but, in cases in which the conversion of the starch was brought about by the same natural process as when malt only was used, the addition of other grains merely served to avoid that waste of the enzymes of the malt which, without any benefit to the vinegar, would occur when malt only was used. He admitted the force of Mr. Blount’s remark as to distinguishing between actual phosphates and organic phosphorus compounds, but he had not made any such distinction here, and he was not sure that the quantities available in ordinary cases would admit of it.The vinegar had been evaporated with a little sodium carbonate, and consequently any organic phosphorus compounds would be converted into phosphates. He did not think the proportion of phosphoric acid alone should be relied upon, but, as he had said, there was no doubt that it had been. Mr. RATCLIFF said that the results obtained seemed to indicate that the proportion of phosphoric acid was given too prominent a position in judging the composition of vinegar. He did not think it was to be expected that any Govern- ment department would handicap manufacturers by insisting on the use of malt alone, even for what was described as ‘‘ malt vinegar,” and he thought, therefore, that analysts should turn their attention to finding other means of distinguishing between different kinds of vinegar. So far as the vinegar referred to in his paper was concerned, there seemed to be no necessity for the removal of phosphates, seeing that, when maize grits were used, the phosphates were mainly removed before the material was mashed.

ISSN:0003-2654    

DOI:10.1039/AN9093400517

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 519 THE DETERMINATION OF ESSENTIAL OIL AND MOISTURE IN SPICES AND AROMATIC DRUGS. BY R. A. CRIPPS, F.I.C., AND J. A. BROWN, F.I.C. (Read at the Meeting, November 3, 1909.) PROBABLY most analysts will have had occasion to notice that the methods commonly used for the determination of essential oils in drugs and spices are not satisfactory. Unless a large amount of material is at service, so that a trial distillation can be made, we venture to suggest that published processes are of very little use ; certainly this is the case when dealing with quantities such as are received under the Food and Drugs Acts. We do not claim to have attained perfection by working in the manner suggested, but in our hands it has at least given far more satisfactory results than any other we have tried, and has enabled us to make analyses of samples taken under the Acts when amounting to less than 10 grms., and could be used with only 5 grms:, and yet a1low.a reserve for repeating any part of the analysis, if desired.Attempts at direct determination of the oil have not met with the success we520 THE ANALYST. desired; hence we have adopted the indirect method by determining (a) moisture, and ( b ) total volatile matter, the difference being the essential oil. (a) Moistum-For this purpose we have adapted the method described by 3. V. Dupr6 (ANALYST, 1906, 31, 213) for determination of water in cordite, which depends upon the action of aqueous vapour upon calcium carbide, and measure- ment of the acetylene produced. Half a grm. of the spice or drug, in fine powder, is introduced into a stout tube, 5 inches long and Q inch internal diameter; dried sand is then added to a depth of about 2 inch, and then calcium carbide, in moderately large pieces, to within 14 inches of the mouth of the tube, which is connected with a CaCI, tube, and this with a nitrometer filled with saturated salt solution.The CaCI, tube is used to prevent any possible return of aqueous vapour from the brine acting upon the calcium carbide. The tube containing spice is immersed in a brine bath to the upper level of the carbide, and, after the apparatus has been adjusted at atmospheric pressure, heat is gradually applied to the bath, which is finally boiled until the volume of gas in the nitrometer ceases to increase during five minutes. The process usually takes about one hour and a half.The brine bath is then removed, and the apparatus allowed to cool to laboratory temperature, which is more quickly attained by immersing the heating tube in cold water. When the volume of the gas ceases to decrease during five to ten minutes, the pressure is adjusted, volume read, and calculated to standard pressure and temperature. The number of C.C. x -001725 (DuprB's factor) gives the weight of water in the quantity of spice taken. I€ several tests are desired at the same time, it is preferable to treat a number of tubes in the brine bath, each being connected with a burette inverted in a deep trough of brine. Care is necessary not to leave the acetylene standing over brine for any great length of time before reading the volume.We have noticed on several occasions a very marked diminution in volume if left overnight-far more than can be due to mere reduction of temperature. Trial experiments were made with known mixtures of various essential oils with starch containing a known amount of moisture-viz., 13.7 per cent. when dried at 100" C. Nine parts of this starch were mixed with 1 part of oil of cloves, pimento, caraway, and nutmeg, respectively. The following results were obtained : Starch ... ... ... ... ,, +Oil of cloves 10 per cent. ,, + Oil of caraway 10 ,, ,, +Oil of pimento 10 ,, ,, + Oil of nutmeg 10 ,, By Drying at 100" c. 13-7 calculated. 12.33 12.33 12.33 12.33 By Calcium Carbide, using Water Bath. 13.45, 13.49 By Calcium Carbide, using Brine Bath.13.55 12-49, 12.18 12.62, 12.35 j 12.42, 12-18 (12.42, 12.40 12.28, 12.42THE ANALYST. 521 To ascertain that the volatile oil does not itself react with calcium carbide, 1 grm. of oil of cloves was treated for moiature, and yielded an amount of acetylene equivalent to 0.9 per cent. of water. This would mean an error of less than 0.2 per cent. on the spice; and, as other aromatic spices and drugs contain far less volatile oil than cloves, this may for all practical purposes be considered a negligible quantity. Possibly this moisture was partly due to the oil being imperfectly dried. Whole Cloves : H,O . . . . . . Essential Oil , . . H,O . . . . . . Essential Oil , . . e o u n d Pimento : Essential Oil . , . Ground Caraway : H,O . . . . . . Essential Oil .. , Wholc Macc : H,O . . . . . . Essential Oil ... H20 . . . . . . Essential Oil ... H,O . . . . . . Essential Oil ... HCO ... Essentiii oil .. H,O . . . . . . Essential Oil ... Ground Cloues : H,O . . . . . Ground MCKC : Whole Fennel : GTOZL~L~ Giiigey : Myrrh : ... ... ... ... .*. ... . . I ... ... ... ... ... ... ... ... ... ... 1. 8.05 16 25 10.04 17.39 11.25 2.75 8.56 2.49 11 -85 6 25 10.42 2.86 11-97 2-13 9.15 3'20 7-41 3'09 2. 8-53 17.77 11.50 15.15 10.14 1 *S6 10'42 3.08 10.45 6.10 9.90 4-00 13.04 2.30 10'22 3'48 5.93 2 -27 3. 8 5 3 l i - 9 0 7 T O 13.60 10.55 1.65 11.10 2.40 11.50 6 *95 9.14 4.21 11.60 4 -00 9'40 3'12 - - NUMBERS OF SAMPLES. 4. 9-52 13'13 8.28 13.52 9.03 3-67 S '60 4.90 11-35 10 80 9.35 7 '15 10.30 3-85 10.98 2.24 - - 5 . - -- 8.44 16.36 10.76 3-04 10.50 2.70 9'04 9-26 - - 11038 1.97 10-95 2.55 - - 6.- - 9 -85 12.75 10.18 3.07 8 *97 2.63 Bombn: 5.75 0.00 10'28 1.42 11.90 1'00 9.50 2.70 - - 7. - - - - 10-65 2-25 9.20 2.05 Bombay 6.03 0.67 7.28 1.97 11-40 1 '20 11-81 3'11 - - 8. 9. 10. No. 10 Pimento.-This was reported as adulterated with '' spent allspice," and a Nos. 3 and 7 Caraway.-These were reported as poor, or of doubtful purity. No. 6 Ground Mace.-This was mainly Bombay or '( wild " mace. No. 7 Ground Mace.-This was reported as 60 per cent. Bombay mace, and a Nos. 6 and 7 Fennel.-These were probably partially exhausted: Nos. 1 and 2 Myrrh.-No. 1 was '' best " quality, No. 2 " seconds." conviction followed. conviction followed. (b) Total Volatile Mattby.-For this determination we at first proceeded in the ordinary way, by heating 1 to 2 grms.in the water-oven until it ceased to lose weight, and the results given above were obtained in this WRY. We, however, found by later experience that this method (which takes six hours, or usually much longer) gives low results on account of a gradual increase in weight, probably due to oxidation;522 THE ANALYST, but we have shown that it is not oxidation of essential oil. This increase varies with different drugs, and, as a matter of course, with the time of exposure; hence no uniform correction can be made. For this reason numerous experiments were made with the object of removing the volatile matter in the shortest time possible. The best results were given by heating the spice contained in a tube in an air-bath a t 135" C.whilst a current of dry air was aspirated. In this way the removal of volatile matter was effected in one hour or less. We have made attempts to absorb the moisture and essential oil by the use of CaCl, and pumice soaked in heavy petroleum respectively, but these have not been successful; hence it is preferable to simply weigh the tube containing the spice both before and after the aspiration treatment. The results so obtained are always higher than by prolonged drying in the oven. The results given in the table on p. 521 have been obtained with various spices and drugs. Obviously the method might be extended to include such drugs as anise and cardamoms, and possibly valerian, serpentary, etc. ; for gum-resins, oleo-resins, and balsams it would appear to be extremely well suited, The ground samples referred to in the table were those received under the Food and Drugs Acts ; the whole spices were usually specially obtained for comparison, and represent samples of widely varying quality.DISCUSSION. The CHAIRMAN (MY. Cribb) remarked that while this was a very iiigenious and apparently satisfactory method, it was open to the objection that the estimation of the essential oil wag made merely by difference. Moreover, he felt a certain amount of doubt as to whether the high temperature might not produce some change in the weight owing to oxidation and other causes, apart from the loss due to moisture and other volatile matters. He should like to hear if the authors had any figures for Macassar mace.Mr. CRIPPS said that the actual temperature in the tube would be somewhat lower than that of the bath. They had made experiments with mixtures of starch and essential oil, and had observed no darkening of the starch, though, of course, that was not quite comparable with what happened in the case of a spice. Rlr. CHAPMAN congratulated the authors on having devised what appeared to be a very useful method, but remarked that it was a little difficult to define an essential oil, particularly from the point of view of the analyst. There were many natural products in which the amount of volatile essential oil obtained by such process as the one described by the authors would diminish on storage, aerj a1 oxidation taking place, accompanied by the conversion of certain volatile hydrocarbons and oxidised constituents into resinous non-volatile substances.He thought, too, that the variations in the numbers given by the authors as the extreme limits for certain spices were so large as to render it 'impossible to detect by that means alone even a considerable amount of adulteration. He suggested that it would be better, instead of drying in a current of air, to use some inert gas, so as to do away with the tendency to oxidise. This would not be a very difficult matter, and it would render the process more exact.THE ANALYST. 523 Mr. SEYLEK. asked whether this method would be likely to be of use in the case of ginger which was under suspicion of being exhausted. Mr. BROWN said that the force of Mr. Chapman's remarks would be admitted; but they did not, of course, regard deficiency in essential oil as being in itself sufficient to condemn a sample.The character of the non-volatile oil was important, and other chemical data were necessary if a correct conclusion was to be arrived at. The microscopical features, of course, were also of considerable assistance, Mr. CRIPPS said that they had not up to the present relied upon the method described of determining the total volatile matter at 135" C., but had used the ordinary oven at 100" C. Their later experience, however, showed that there was a gain in weight during the oven process which was not due to oxidation of essential oil, but probably to oxidation of the fatty oil, or some other constituent of the drug or spice. In the aspiration process the time of heating was quite short.Only the most refractory essential oils required as long as an hour's heating, half an hour being generally sufficient. They had had in view the use of an inert gas- namely, nitrogen-but had not yet had time to try this, They had not made any experiments with Macassar mace, but had obtained figures for West Indian and Penang mace, and, of course, Bombay. In dealing with spices under the Sale of Food and Drugs Act, other factors must, as Mr. Brown had said, be taken into consideration. I n the case of pimento and caraway, for instance, the proportion of matters soluble in ether and water respectively were determined, in order to show whether there had been any addition of extracted seed. I t was, however, quite practicable from a manufacturing point of view to remove volatile oil without using any water. He thought that Mr. Chapman had put a somewhat exaggerated case. Xven with cloves, which contained something like 20 per cent. of essential oil, they found that after heating for six or eight hours in the oven there was not so much as 1 per cent. of difference. Mr. CHAP~\.IAN said that one would not expect oil of cloves to be very much affected, and he was referring more particularly to oils containing unsaturated terpenes. As a matter of fact, in the case of hops almost the whole of the volatile portions of the essential oils might disappear after a sufficient time. Mr. CRIPPS said that from experiments which they had made by absorbing essential oil in an inert powder, and heating it in the oven, it seemed that it was not the essential oil that was oxidised. But, even if this process did not give the proportion of essential oil with absolute exactitude, it did give results which were comparable among themselves, and this, from a practical point of view, was what was required in dealing with a large number of samples.

ISSN:0003-2654    

DOI:10.1039/AN9093400519

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

524 THE ANALYST. HOLDE’S TEST AND THE DETECTION OF PARAFFIN WAX, ETC., IN LARD AND OTHER FATS. BY H. DUNLOP. (Read at the Meeting, November 3, 1909.) THE excellent test due to Holde for the detection of mineral oil in fatty oils can be applied with advantage to the testing of lard for paraffin wax, and is, in the author’s opinion, more delicate and economical both in time and material than that proposed by Shrewsbury (ANALYST, 1909, 348). Although Holde’s test is well known, a short description may not be out of place. From 0.3 to 0.35 grm. (10 drops) of the melted fat is saponified in a test- tube with 5 C.C. of approximately : alcoholic potash, and to the clear hot soap solution water is added in successive quantities of about 1 c.c., the solution being carefully observed after each addition of water.While pure lard gives a clear solution of soap after dilution with 5 C.C. of water, the presence of even 0.5 per cent. of paraffin wax is indicated by the formation of a turbidity, the silky ” appearance of which is characteristic of paraffin wax. A series of tests on prepared mixtures proved that it is possible by this method to detect as little as 0.3 per cent. of parafin wax in lard or margarine fat. Although several cases of adulteration of lard with paraffin wax have been recorded, its employment in the manufacture of margarine appears to have escaped notice. I n 1907 the author had the opportunity of examining a sample of margarine containing 7 per cent. of paraffin wax in the sample, and for the fat of which the following figures were obtaiued : Saponification value, 179.5 ; soluble volatile acids, 2.5 ; insoluble volatile acids, 0.5 ; Zeiss refractometer (at 40’ C.), 49-8; solidifying point, 39” C.It is scarcely necessary to state that the presence of paraffin wax could be easily detected in the mouth. Holde’s test also Berves as a rapid sorting-test in the examination of tallow, which article is now frequently adulterated with ‘‘ fish-oil stearine ” and paraffin wax, samples recently examined containing from 1 to over 20 per cent. of the latter adulterant. Since writing the above, the author has examined two samples of margarine, the fat of which contained 19 par cent. of soft paraffin ” (Vaseline) and 0.4 per cent. of paraffin wax respectively. DISCUSSION. The CHAIRMAN (Mr. Cribb) remarked that the advantage of this method seemed to be its rapidity and the small quantity of material required. It was, however, obviously merely a process for estimating unsaponifiable matter, and would not distinguish between paraffin and any other unsaponifiable substance. Mr. E. R. BOLTON said that he had hoped that the author was going to describe'THE ANALYST. 525 some test capable of detecting the infinitesimal quantities of paraffin which might be added to lard, with the object of interfering with the phytosterol acetate test for vegetable oil.

ISSN:0003-2654    

DOI:10.1039/AN9093400524

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

‘THE ANALYST. 525 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. Method of Increasing the Sensitiveness of the Reactions for Adrenaline and Pyrocatechol. G. Bayer. (Biochem. Zeit., 1909, 20, 178-188.)-The addition of either sulphanilic acid or naphthionic acid to adrenaline or pyrocatechol increases the sensitiveness of the ferric chloride and bichromate tests for these substances between ten and twenty times. The test proposed by Frankel and Allers, in which 2 C.C. of the adrenaline solution are treated with 2 C.C. of sodium periodate solution and 1 C.C. of 10 per cent. phosphoric acid, is also rendered about ten times more sensitive in the presence of the above-mentioned acids. For instance, 1 part of adrenaline in 5,000,000 parts may be detected against 1 part in 500,000 parts in the absence of sulphanilic acid.I t was also found that the iodine reaction described by Abelous, SouliB, and Toujan is rendered more sensitive in the presence of alanine and phenylalanine ; other decomposition products of proteins probably have the same effect. w. P. s. Detection of Certain Animal Fats in Admixture with Other Animal Fats by Means of Polenske’s ‘‘ Difference Method.” L. Laband. (Zezt. Untersuch. Nahr. Genzusm., 1909, 18, 289-299.)-The author finds that the method described by Polenske (ANALYST, 1907, 32, 382; 1908, 33, 476) yields concordant results, and is reliable for the detection of beef fat in lard. In the case of butter, it can only be used in conjunction with the other analytical constants as a means of confirming the purity or adulteration of the sample.w. P. s. Effect of Cold-Storage on Fats. H. Wagner and P. Bohrisch. (zeit. UnterszKh. Nuhr. Genussm., 1909,18,366-367.)-1n order to ascertain what alterations, i f any, take place in the chemical and physical characters of fats when the latter are subjected to low temperatures for some length of time, the authors carried out a number of experiments in which fats, packed in tin boxes, were exposed to temperatures of from - 7’ C. to - 10’ C. for seven weeks ; similar samples were stored for the same length of time at the ordinary temperature, and all the samples were snalysed both at the beginning and at the end of the experimental period. The fats employed comprised margarines, lard, mutton tallow, etc. The results obtained show that only slight changes took place in the physical properties of the fats, the chemical constants generally remaining unchanged.The appearance and taste of the samples kept in cold-store did not alter to a greatereextent than in the case of the samples keptTHE ANALYST. at the ordinary temperature. The only change of note was in the iodine value of the samples ; this was found to increase by 1.3 to 3.3 units in the cold-store samples, and to a less extent in the other samples. The melting and solidifying points of the fats showed slight variations. w. P. s. Volumetrie Estimation of Casein in Cow’s Milk. E. B. Hart. ( J . Biol. Chenz., 1909, 6 , 445-451.)-The method is based upon the fact that casein combines with alkali to form a compound that is neutral to phenolphthalein.The measured quantity (10.5 c.c.) of the milk is mixed in an Erlenmeyer flask with 75 C.C. of water and 1 to 1.5 C.C. of 10 per cent. acetic acid, the flask is then shaken with a rotatory movement, and the precipitated casein collected on a filter. Filtration is accelerated by loosening the adhering precipitate by means of a fine jet of cold water, and both the filter and the residual casein adhering to the sides of the flask are washed quite free from acid at a temperature below 20” C., at least 300 C.C. of water being required for this purpose. The filter-paper and precipitate are trans- ferred to the flask, into which are then introduced about 80 C.C. of water, a few drops of phenolphthalein solution, and 10 C.C. of & potassium hydroxide solution. The flask is closed with a rubber stopper, and shaken vigorously until the whole of the casein has dissolved, after which the stopper is rinsed with water, and the solution titrated with & acid.An addition (usually 0.2 to 0.3 c.c.) is made for the amount of acid consumed in a blank experiment, and the difference between this corrected reading and the 10 C.C. of alkali taken gives the percentage of casein in the milk. The relation- ship between the alkali and the casein was established by preliminary experiments, in which it was found that each 0.1 C.C. of & alkali solution corresponded to 0.0102 to 0.0113 grm. of pure casein prepared by Hammarsten’s method, the average being 0*0108 grm. C. A. M. Composition of C6E1aterium” and the Characters of Elaterin. F.B. Power and C. W. Moore. (Pharnz. J., 1909, 83, 501-504.) - English ‘‘ elaterium,” containing 5.3 per cent. of moisture, and 6.7 per cent. of mineral matters, yielded an inert aqueous extract (6 per cent.) containing a small amount of starch. The dried insoluble portion gave 57 per cent. of matter soluble in hot chloroform and alcohol (used successively), the insoluble portion being quite inert and containing inorganic matters. The combined chloroform and alcohol extracts yielded on extraction : (1) With light petroleum, 15 per cent. of matter containing fatty compounds, and a trace of a substance giving the colour-reactions of the phytosterols; (2) with ether, 73 per cent. of material consisting largely of a nearly colourless crystalline product (“ elaterin ”), melting and decomposing at 217” to 220” C.This yield of elaterin represents 30 per cent. of the (‘ elaterium ” used ; (3) and (4), with chlov-oform and alcohol, small amounts of brown resins. The results of the investigation prove that this “ elaterin ” is not a homogeneous substance, but contains 60 to 80 per cent. of a physiologically inert, colourless crystalline compound, which melts at about 230’ C. with decomposition, and is 1Evo-rotatory (up to [u]. = - 52.9”). This compound is accompanied by small and varying amounts of a crystalline dextro-rotatory substance of the same empiricalTHE ANALYST. 527 composition, but physiologically active. Products (impure) showing [a],, = + 13.9" have been obtained. A. R. T. Estimation of Essential Oils and of Eugenol in Oil of Cloves.R. Reich. (Zeit. Untersuch. Nahr. Genussm., 1909, 18, 401-412.)-The first part of the paper deals with the estimation of total essential oil in spices, etc., a steam-distillation process being described for this purpose, whilst in the second part various methods for the estimation of eugenol in oil of cloves are discussed, and a process preferred by the author is described. instance) are ground up with pumice and placed in the cartridge-case, a (see figure); this is provided with a false perforated bottom, c. The spiral spring, d, is placed above the contents of the case, and the telescopic tube, b, is fitted over a. The cartridge-case is now fixed in the jacket, I I , the small tube at the bottom passing through the cork, f, and the upper tube being connected with a condenser at e .The contents of the cartridge-case are then submitted to steam distillation by boiling the water in the vessel, I , steam being also admitted to the jacket, 11, through the tube, 8 ; the condensed water from the jacket runs away through the pipe, h. I t will be noticed that the jacket is supplied with steam solely by the tube, g. The distillation is continued for about two hours, and from 600 to 800 C.C. of distillate are collected. During the dis- tillation it is necessary to cut off the cold-water supply to the condenser from time to time, so that the oily substances collecting in the condenser may be Es timat ion of Essential 0 ils .-From 10 to 20 grms. of the spice (cloves, for driven over into the receiver.When the distillation is completed, the distillate is saturated with sodium chloride, and the essential oils are shaken out with three successive quantities of about 25 C.C. of pentane. The pentane solution is evaporated under the conditions recommended previously by the author (ANALYST, 1909, 20), and the residue of essential oil is weighed, Pentane does not extract quite as much substance from the salted distillate as does ether, the difference being from 0.3 to 0-6 per cent. This is due to the presence of furfural and other decomposition products which are found in the distillate from cloves ; these substances are soluble in ether, but not in pentane. The use of the latter solvent is, however, to528 THE ANALYST. be preferred, as the residue of essential oil obtained is purer than when ether is employed.Estimatioiz of Eugeszol in Oil of Cloves.-The following method is recommended, as it requires only B small quantity of the oil such as is obtained in the above described process for the estimation of the oil. From 1-0 to 1.5 grrns. of the oil of cloves are mixed with 20 C.C. of 5 per cent. sodium hydroxide, and heated for fifteen minutes in a water-bath under a reflux condenser. After cooling, the misture is shaken with 20 C.C. of pentane, and when the latter has separated to form a clear layer, it is drawn off. The alkaline eugenol solution is diluted with 5 per cent. sodium hydroxide solution to a volume of exactly 30 C.C. ; 15 C.C. of this solution are then transferred to a separating funnel, 5 C.C.of 25 per cent. sulphuric acid, 6 grms. of sodium chloride, and 20 C.C. of pentane are added, and the mixture is shaken thoroughly. When separation has taken place, 15 C.C. of the clear pentane solution are transferred to a flask, and the solvent is evaporated as described previously (~oc. cit.). The method yields from 99.0 to 100.6 per cent. of the actual quantity of eugenol present. The following quantities of essential oil and eugenol were found in various specimens of cloves : Essential Oil. Eugel~ol. Per Cent. Per Cent. Zanzibar cloves (ten samples) ... . . . 18.4-20-1 15.4-166 Commercial ground cloves (ten samples) 17.0-19-3 15 -5-1 6 *3 Amboyna (Molucca) cloves (four samples j 21'3-2201 17.0-17 *G Clove stalks (three samples) ... ... 5.8--G.7 594--4*7 Clove flowers (four samples) .. . ... 2*2--99 I From these figures it is seen that the essential oils contained from 79.0 to 86.1 per cent. of eugenol. w. P. s. Grading of Flours by Reference to their Content of Catalase, P. Liechti. (Chem. Zeit., 1909, 33, 1057.)-For grading flours more sharply than can be done by colour comparison or reference to ash content, the author determines their capacity to split off oxygen from hydrogen peroxide. This is a aieasure of the catalase present, which again, unless the flours are derived from abnormal grain or have been subjected to unusual treatment, is dependent on the amount of germ and bran remaining in the flour, for it is in these parts of the grain that the catalase mainly exists. These numbers show that, for the first four grades of wheaten flour recognised by Swiss millers, the catalytic power on the author's arbitrary scale rises steadily from 1 to 4, whilst that of grades 5 and 6 and of feeding flours has values approximating to 8, 22, and 30 respectively.G. C. J. Estimation of Iodoform in Iodoform Gauze. V. Paolini. (Moszit. Scient., 1909, 648; through Pharm. J., 1909, 83, 537.)-Ten grms. of the sample are cut into small pieces and heated under a reflux condenser for two to three hours on tt water-bath, with 40 grms. of powdered zinc and 60 C.C. of 25 per cent. sulphuric acid. A further addition of 40 to 50 C.C. of the acid is then made, and the heating continuedTHE ANALYST. 529 for some hours. The disappearance of all yellow colour from the gauze denotes the complete decomposition of the iodoform into hydriodic acid.The liquid is made up to 1 litre, and 100 C.C. shaken with an equal volume of chloroform or carbon disulphide after adding a little potassium nitrite solution. The liquid is further shaken with three fresh quantities of chloroform, and the liberated iodine titrated with standard thiosulphate in presence of sodium bicarbonate. The results are accurate, and the method is applicable to iodoform itself. A. R. T. Analysis of Mercuric Iodide Ointment. P. Adam. ( J . Phnrm. Chim., 1909, 30, 300-301.)--A weighed quantity of the ointment is shaken with three to five times its weight of petroleum spirit, the solution of the fat decanted, and the insoluble residue washed several times by decantation and then on the filter until free from fat. It is then dried over sulphuric acid and weighed, and the result checked by dissolving -it in potassium iodide solution, and estimating the mercury as sulphide. The authar’s .experiments show that potassium iodide is nearly insoluble in cold petroleum spirit. Thus, in the case of one sample of ointment, the petroleum spirit solution contained 0.0195 grm, of potassium iodide, whilst 0.348 grm. remained undissolved. Mercuric chloride, if present, would also be dissolved by the petroleum spirit, and in case of doubt it would be necessary to estimate the iodine. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9093400525

出版商:RSC    

年代:1909

数据来源: RSC

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THE ANALYST. 529 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Estimation of Amino Acids in Urine by Titration in the Presence of Formaldehyde. H. Malfatti. (Zeit. Physiol. Clzenz., 1909, 61, 499-507.)-Amino acids may be titrated in the presence of formaldehyde according to the process .described by Ronchese (ANALYST, 1907,32, 303) for the estimation of ammonia. For this purpose the urine is treated with mercuric chloride and sodium carbonate to precipitate the ammonia present, and the amino acids are then titrated in the filtrate from this ammonia-mercury precipitate. From 2 to 4 grms. of mercuric chloride are dissolved in 50 C.C. of the urine under examination, and powdered sodium carbonate is added in small quantities at a time until the solution is alkaline to litmus paper. A large excess of sodium carbonate must be avoided, as it causes 8, loss of amino acids.The precipitate is collected on a filter, the filtrate is treated with a few drops of acetic acid, and the excess of mercuric chloride is precipitated with hydrogen sulphide. After filtration, a definite volume of the filtrate is heated -to remove carbon dioxide and hydrogen sulphide, and is then neubralised by the addition of sodium hydroxide solution, using phenolphthalcln as indicator. An excess of neutral formaldehyde solution is now added, and the solution is titrated with Tz sodium hydroxide solution until the pink coloration reappears. Each C.C. of the Tx alkali solution is equivalent to 0.001 grm. of nitrogen (present as amino acid). Results of experiments with glycocoll show that, whilst the method yields concordant results, the latter are always somewhat low.For instance, from 15 to 16 mgrms. of amino nitrogen are found instead of 17 or 18 mgrms. actually added to a urine in the form of glycocoll. It was also found that amino acids form when urine is kept for some time; one of the urines examined contained no amino acid, but after standing530 THE ANALYST. overnight under toluene yielded 2.8 mgrms., and at the end of fourteen days 8.6 mgrms., of amino nitrogen per 100 C.C. of urine. Whether or not this amino nitrogen was present as glycocoll was not ascertained. w. P. 8. Colour Reaction of Bile Acids with Hydrochloric Acid. 0. Hammarsten. (Zeit. Physiot. Chenz., 1909, 61, 495-498.)-When 0.1 grm. of powdered cholic acid is shaken in a, small stoppered tube with 25 C.C.of 25 per cent. hydrochloric acid, a yellow or yellowish-green coloration is obtained; after the lapse of from four to eight hours this changes to blue-violet, and at the end of twenty-four hours the whole solution exhibits a bright blue-violet coloration. If the solution be now filtered, the blue filtrate within twenty-four hours deposits a yellowish-white precipitate, and when this is removed by filtration, the filtrate deposits a further quantity on standing. This repeated formation of a precipitate is accompanied by a change in the colour of the solution, the blue gradually declining through green and yellowish-green to yellow. The blue-violet coloured solution shows a strong absorption band at the D line of the spectrum, and this band is still seen clearly if the solution be diluted with 25 per cent.hydrochloric acid until the blue colour ie hardly discernible. The production of the blue coloration is dependent on the hydrochloric acid being of the above- mentioned strength and, more or less, on the proportion of cholic acid to hydrochloric acid. The amorphous precipitate produced yields a positive reaction with Petten- kofer’s test, but does not give Mylius’s iodine-cholic acid compound; it is readily soluble in dilute alkali solution, and yields a barium salt which is much less soluble in water than barium cholate. w. P. s. Detection of Bile Acids, Laevulose, Glycuronic Acid, and Pentoses in Urine. (Chem. Zeit., 1909, 33, 1133.)-Jolles (ANALYST, 1908, 33, 430) has proposed a new test for the bile acids which was claimed to possess considerable advantages over Pettenkofer’s test, but the authors, after a careful examination, have shown that Jolles’ test is not only practically useless, but is based on erroneous theoretical grounds.Recently Jolles (Chem. Zeit., 1909, 33, 1043) has made proposals for modifications in methods of clinical analysis relating to Seliwanoffs test for laevulose, Tollens’s test for glycuronic acid, and Bial’s test for pentoses. According to Jolles, the hydrochloric acid used in Bial’s test for pentoses splits up the glycuronic acid, if present, in the short space of about one minute’s boiling, so that Bial’s test is stated not to be reliable ii glycuronic acid be present. On the other hand, Jolles also .states that in Tollens’s test for glycuronic acid the hydrochloric acid (of the same strengthj is not sufficiently powerful to split up the glycuronic acid, and therefore some modification was necessary.The authors have found that Jolles’ test for pentose gives a far less pronounced reaction when 50 C.C. of urine are used than the original Bial’s test gives with 1 to 2 C.C. Mqreover, Jolles’ test requires several hours for its performance, as against one or two minutes with Bial’s test. With regard to the proposed new test for laevulose, the authors conclude that, if properly carried out, Seliwanoff’s test is far more delicate than Jolles’ test. Further, Jolles’ modification of Tollens’s test for glycuronic acid does not F. Wittels and N. Welwart.THE ANALYST.531 admit of an approximate comparison of the quantity of glgcuronic acid in different samples of urine, so that Tohns’s test is always to be preferred. J. F, B. Estimation of Fat in Faxes, A. Chapus. (J. Plzarm. Chim., 1909, 30, 301-304.)-The following rapid method of estimating fat has been in use for the last two years in hospital practice : The faeces are rendered homogeneous by trituration in a mortar, and finally on glass, and two samples of 10 grms. each are taken. A. One of these samples is ground up in a mortar with 20 grms. of freshly ignited sodium sulphate, and the mortar subsequently rinsed out with 5 grms. of the same salt. The dry powder is extracted with anhydrous ether for about one and a half to two hours, and the extract evaporated.The residue is treated with 50 C.C. of 70 per cent. alcohol, and the solution titrated with potassium hydroxide solu- tion. The result, calculated into stearic acid, gives the amount of free fatty acids (a) in the sample. B. The second portion of fmes is rendered distinctly acid with hydrochloric acid, and then treated in the same way as in A, except that the residue left on evaporation of the ether is dried in a tared dish in vacuo over sulphuric acid. If P represent the increase in weight of the dish, b the weight of fatty acids resulting from the decomposition of the soaps, and GN that of the neutral fats, P = GN + a + b. The acid value of the residue, calculated into stearic acid (c), will be the sum of the free fatty acids originally presont and those formed by the decomposition of the soaps in the faeces.The latter will be given by the equation b = c - a, and may be calculated into sodium stearate by multiplying the weight by the factor 1.0774. The neutral fats in the faeces are estimated by difference. C. A. M. The Properties of Urobilin, and its Estimation. D. Charnas. (BzOChe772. &it., 1909, 20, 401-430.)-Urobilin is readily acted on by acids and alkalis, alcohol, chloroform, etc., and by exposure to light, its colour being altered, and spectro- photometric methods for its estimation yield untrustworthy results. Only after urobilin has been converted into urobilogen can these methods be applied, and the following process is described for the estimation : From 500 to 1,000 C.C. of the urine containing urobilin are rendered alkaline by the addition of ammonium carbonate, and allowed to ferment for two days in an incubator.The mixture is then made strongly acid with tartaric acid, filtered, and shaken out with twice its volume of ether. The ethereal layer is washed several times with small quantities of water, and, if the ether eolution be dark-coloured, a little petroleum spirit is added, and the washing with water is repeated. One or 2 C.C. of the ethereal solution are now placed in a stoppered tube, 0.5 C.C. of saturated dimethyl-p-amidobenzaldehyde solution (in ether) is added, together with 2 or 3 drops of alcohol saturated with dry hydrochloric acid gas. The mixture is shaken, diluted with alcohol to a definite volume, and examined in the spectroscope. The intensity of the absorption band (A 550 to 570) is observed, and the reading is then taken several times on varying concentrations. The quantity is calculated from the formula : C=AE, where E is532 THE ANALYSTo the extinction coefficient, and A = 0*000017. C is the weight of urobilogen in grms. in 1 C.C. of the ethereal solution. The urobilogen may also be converted into urobilin by exposing the ethereal solution, diluted with an equal volume of water, to direct sunlight for one day. The urobilin formed dissolves in the water, and the solution, a,fter filtration, ifi saturated with ammonium sulphate. The precipitate i s collected on a filter, air-dried, dissolved in a small quantity of alcohol, the solution is filtered, and the filtrate evaporated iiz vacz&o over phosphorus pentoxide. The residue of urobilin is then weighed. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9093400529

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

532 THE ANALYSTo ORGANIC ANALYSIS. Estimation of Carbon Disulphide in Benzene. I. M. Weiss. ( J . Ind. Eizy. Chem., 1909, 1, 604; Chem. Zeit. Rep., 1909, 33, 489.)-2.5 grms. of the benzene to be examined is mixed with 2.5 C.C. of saturated alcoholic potash, and the mixture allowed to stand for five minutes, after which it is maintained for an hour at a temperature of 60" C. under a reflux condenser. The contents of the flask are then rinsed into a beaker and heated to expel unchanged benzene. The solution of potassium xanthate is oxidised by treatment with bromine water in strongly alkaline solution, and the resulting sulphate determined as usual. G. C. J. Estimation of Arsenic in Organic Compounds. H. F. V. Little, E. Cahen and G. T. Morgan. ( J . Chenz. SOC., 1909, 95, 1477-1482.)-Vith careful mixiug and heating there need be no loss of volatile arsenic compounds in the fusion with sodium peroxide ; but the subsequent precipitation of the arsenic as magnesium ammonium arsenate yields too high results, owing to the presence of the large excess of alkali salt derived from the sodium peroxide.This source of error may be obviated by dissolving the precipitate and re-precipitating it with ammonia, but this process is tedious. The best method of effecting the final estimation was found to be the following modification of Gooch and Browning's volumetric process (Anzer. J. Science, 1901, 11, 66), which is based upon the reaction between hydrogen iodide and arsenic acid, and the titration of the arsenious oxide with standard iodine solution : From 0.2 to 0.3 grm.of the finely powdered substance is cautiously fused in a nickel crucible with 10 to 15 grms. of a mixture in equal parts of sodium peroxide and sodium carbonate. After about fifteen minutes' gentle heating the crucible is heated to dull redness for five minutes. I t s contents are then extracted with water, and washed into a 450 C.C. conical flask, into which is cautiously introduced 25 to 31 C.C. of dilute sulphuric acid (1 : 1). If necessary, the liquid is concentrated to 100 c.c., then treated with 1 grm. of potassium iodide, and further concentrated to 40 C.C. The last traces of iodine are destroyed by the addition of a little sulphurous acid, and the solution diluted considerably and saturated with hydrogen sulphide. The arsenious sulphide is separated, washed with hot water, and dissolved in 20 C.C.of $ sodium hydroxide solution. The solution is filtered, the filtrate returned to the flask, and treated with 30 C.C. of (20 vol.) hydrogen peroxide, the excess of which is destroyed by heating the flask for ten minutes on the water-bath. As soon as frothingTHE ANALYST. 533 is over, a few drops of phenolphthalein solution are introduced, and 11 C.C. of sulphuric acid (1 : l ) , so as to give an excess of 10 C.C. After the addition of 1 grm. of potassium iodide, the liquid, the volume of which should be 100 c.c., is concentrated to 40 c.c., and treated with a few drops of dilute sulphurous acid to destroy the last traces of iodine. I t is now rapidly diluted with water, neutralised with sodium hydroxide solution, and then rendered just acid with sulphuric acid, and the arsenite titrated with standard iodine solution.A substance containing but little oxygen requires proportionately more sodium peroxide for the fusion, and this tends to render the oxidation violent. Compounds containing iodine form sodium iodate in the fusion, and in such cases it is necessary to add to the acidified extract sufficient sulphurous acid to reduce the iodate to iodide, after which the reduction of the arsenate is effected in the usual way. Typical results obtained by this method, and given iu tabular form, show a close agreement with the theoretical figures. C. A. M. The Influence of the Ash in the Valuation of Coal. S. W. Parr and W. F. Wheeler. ( J . Ind. Eng.Chem., 1909, 1, 636 ; Chem. Zeit. Rep., 1909, 33, 551.)-The authors have analysed the ash of fifty samples of coal from the State of Illinois, paying particular attention to the proportions of calcium carbonate. They find that the percentage of this constituent varies according to the manner of heating. A gasometric method was employed for the estimation, using a modifica- tion of the apparatus employed for the estimation of the total carbon in coals and soils. The carbon dioxide expelled by the action of acid was absorbed and measured by difference. The authors state that if a sample of coal be shaken up with a solution of calcium chloride of specific gravity 1.35, it may be separated into a lighter fraction with a low percentage of ash, and a heavier portion with a high percentage of ash.Of the various methods and formulae proposed for the valuation of coal, taking the influence of the ash into account, the authors prefer their own, because it gives the most concordant results for the different fractions separated by gravity. J. 3’. B. Estimation of Graphite. F. Browne. (Chem. News, 1909, 100, 162.)-The author has previously shown that the amount of carbon in graphite can be deter- mined by heating with a specially prepared iron oxide (ANALYST, 1909, 372), and further experiment has confirmed the statement then made-that the iron oxide remains at the end of the determination in the same condition as at the commence- ment, while the oxide is still serviceable after being kept a year. An examination of 4 6 Acheson Graphite, Grade No.1,340,” made in the electric furnace, contained 0.158 per cent. of mineral matter and 0.17 per cent. of moisture, equal to 99.67 per cent. purity. A. R. T. Rapid Method of Estimating the Total Fatty Acids in Soap. H. Dubovitz. (Seifens. Zeit., 1909, 36, 657-658; Chenz. Zeit. Rep., 1909, 33, 515.)-The iodine values of the soap and of the separated fatty acids are determined by Wijs’s method,534 THE ANALYST. an absorption of thirty minutes being allowed, and the results are calculated upon the dry materials. The proportion ?f fatty acids in the dry soap may then be found by means of the equation- where M represents the requirea d u e , and J S and JF the iodine values of the dry soap and fatty acids respectively. C. A. M. The Characterisation of Indicators.M. Handa. (Ber., 1909, 42, 3179- 3182.)-The sensibility of an indicator depends on the concentration of hydrogen or hydroxyl ions necessary to bring about the change in colour. The true neutral point is H. = OH’ = 10-7 grm.-mol. per litre, and the ideal indicator should change at this concentration. The author has devised a method for measuring the sensibility of the various indicators, by taking advantage of the progressive increase in the concentration of hydrogen ions which takes place when an ester is saponified by a small quantity of an alkali. The base employed was barium hydroxide, and the ester methyl formate ; other esters were examined, but their rate of saponification near the ntutral point was too slow. For the estimation, 50 C.C. of boiled water are placed in each of a series of flasks, and 4 drops of 3 barium hydroxide, together with 2 drops of the respective indicators, are added.Then, by a special arrangement, 1 C.C. of freshly-distilled methyl formate is added simultaneously to each flask, and the number of niinutes which elapse before each indicator changes colour are noted. The results for a series of known indicators follow the same order as that found by Fels (Zeit. Elektroclzenz., 1904, 10, 208), and if a curve be plotted with the logarithms of the times observed for abscissae and the logarithms of the concentrations of hydrogen ions corresponding to the changes of each indicator (tabulated by Fels) as ordinates, this curve is found to be a straight line. By interpolation on this curve, the concentration of hydrogen ions corresponding to any observed time may be found for any new indicator.The author has investigated methyl red, proposed by Rupp (ANALYST, 1909, as), and found that it is only slightly less sensitive than litmus; the first change from the alkaline tint takes place at a hydrogen ion concentration of 10 - 6.65, and the characteristic neutral tint at a, concentration of 1 0 - 6 ‘ 4 Cyanin, another new indicator, is decoloriaed at a concentration of hydrogen ions of 10 - 6 3 These indicators are considerably more sensitive and nearer the ideal than p-nitrophenol and methyl orange. J. F. B. Estimation of Nicotine in Concentrated Tobacco Juices. F. Porchet and F. Regis. (Chem. Zeit., 1909, 33, 1128.)--Concentrated tobacco extracts are being used in increasing quantities for combating the parasites of the vine, and the authors have, therefore, made a comparative investigation of three methods for the estimation of the nicotine in such extracts.Schloesing’s method,’ based on the extraction of the alkaloid by means of ether in presence of sodium chloride, gave lower results than the two other methods. Biel’s method, depending on the volatilisation of the nicotine in a current of steam and its separation from theTHE ANALYST, 535 ammonia in the form of its sulphate, gave fairly good results, the maximum difference between duplicate determinations being 1 per cent. Toth's metbod (ANALYST, 1902, 27, 12) is preferred by the authors as the most reliable. The ammonia is absorbed by calcium sulphate, and the nicotine is extracted directly by a mixture of ether and light petroleum.The maximum difference between duplicate determinations by this method amounted to 0-8 per cent. The proportions of nicotine in the various extracts examined ranged from 4 to 10 per cent. According to the nature of the extracts, the results found by Biel's and Toth's methods respectively were not always in concordance, but the latter is more rapid, and sufficiently accurate for technical purposes, J. F. B. Detection of Nitronaphthalene in '' De-bloomed " Oils. F. Schulz. (Chenz. Zeit., l909,33,1093.)-For the detection of nitronaphthalene in (( de-bloomed " mineral oils and in vegetable oils blended with them, the author takes advantage of the fact that the nitro derivative is readily and quantitatively iduced to naphthyl- amine by heating at a temperature of 270" C.with American rosin. In applying the test, 10 grms. of the oil to be examined are heated in a test-tube with 0.5 grm. of rosin to a temperature of 290° to 300' C. The product is allowed to cool to about 80" C., and 4 grms. of 10 per cent. sulphuric acid are added, the two liquids being then thoroughly shaken together. The liquids are allowed to separate by standing the test-tube in a boiling water-bath, and the aqueous layer is drawn off. To test for the presence of naphthylamine in this, a few C.C. of a cold saturated solution of potassium bichroinate are added. If an azure-blue precipitate of hydroxynaphthyl- aniine is formed, it may be further identified by collecting it on a filter, washing it with a dilute solution of an alkali and then with water, and finally dissolving it in alcohol or, after drying, in benzene.The alcoholic solution should have a pink colour, and the benzene solution a cherry-red colour. This test; is sufficiently delicate to detect the presence of 0-05 per cent. of nitronaphthalene in oil. J. F. B. Estimation of Phosphorus in Organic Substances by Means of the Bomb Calorimeter. P. Lemoult. (C'omptes Rend., 1909, 149, 511-513.)-1n estimating phosphorus in organic substances by means of the calorimetric bomb, the interior of the metal vessel is attacked during the process, and the results are low. This is due to part of the phosphorus first oxidised being reduced by the carbon to the elementary state, and then combining with the platinum.This is obviated by using for the combustion porcelain capsules, round which is wrapped a, thin piece of platinum wire, to hold the vessel together, should it break. The interior of the capsule is coated with a layer of fused potassium nitrate, which oxidises any phosphorus (reduced by the carbon) before it attacks the porcelain. Under these conditions no black deposits are formed, and the oxidation is very rapid. The resulting phosphoric acid is dissolved in water, and the phosphorus estimated in the usual way by precipitation as magnesium ammonium phosphate. Results thus obtained in the analysis of triethylphosphine and aniline phosphite were in close agreement with the theoretical values and results given by Carius' method. C.A. M.536 THE ANALYST. Estimation of Rubber as Tetrabromide. C. Harries and H. Rimpel. (Gummi-Zeit., 1909, 23, 1370 ; through Chem. Zeit. Rep., 1909, 33, 556.)-Budde's tetrabromide method, even in its latest modifications, such as that of Pendler and Kuhn (ANALYST, 1908, 33, 60), is found to give results from 8 to 18 per cent. too low, if the numbers yielded by the nitrosite method (ANALYST, 1907, 32, 224) be accepted as representing the truth. The observation that hydrogen bromide was evolved in notable quantities led to an examination of the precipitate, but this proved to have the composition corresponding to the formula C,oH,,Br,. On evaporating the filtrate, however, in cuczio at 20" to 30" C., and drying in V ~ C U O over sulphuric acid and potash, a dark brown solid residue was obtained, which could be purified by precipitation from its solution in carbon disulphide by addition of petroleua spirit.Assuming this material recovsred from the filtrate to be tetrabromide, and calculating it and the precipitated tetrabromide to caoutchouc, various samples appeared to contain more than 100 per cent. of caoutchouc. The authors assume, therefore, that the substance soluble in the mixture of carbon tetrachloride and alcohol is a higher bromine derivative of caoutchouc ; that its formation by substitution iEi the explanation of the evolution oE hydrogen bromide which they observed; and that its solubility is the cause of the low results given by the tetrabromide method. The percentage of bromine in this new bromine derivative does not appear to have been determined.G. C. J. Methods for the Estimation of Salicylates. A. Seidell. (J. Amel: Clzewz. SOC., 1909, 31, 1168-1177.)-The bromate method of Freyer, and the iodine method of Messinger and Wortrnann (cj. ANALYST, 1900, 25, 20), are shown to be of uncertain reliability for the estimation of salicylic acid in salicylates. A new reaction by which dibromosalicylic acid is formed almost quantitatively by the action of bromine upon salicylates in concentrated hydrochloric acid solution is described, and methods based upon this reaction and which yield fairly definite results are suggested. The details of the method as first devised are as follows : A weighed quantity of the salicylate (about 0.2 grm.) is placed in a glass-stoppered bottle, dissolved in a few C.C.of water, and about 50 C.C. of concentrated hydrochloric acid are added. The solution is then titrated with bromine solution (in hydrochloric acid), the mixture being shaken and warmed gently after each addition of bromine until tbe yellow colour of the excess of bromine persists for five minutes after the addition of the last two drops, the temperature having reached 80" to 100' C. in the meantime. A number of titrations made in this manner upon crystallised sodium salicylate yielded nearly theoretical results (from 98.7 to 101.8 per cent. of the quantity taken) when calculated on the basis of 4 atoms of bromine per 1 molecule of salicylate. It was also found that from 97.0 to 99.5 per cent. of the quantity of salicylic acid taken for an estimation could be found by adding the salicylate solution to an excess of the bromine solution and titrating the excess with stannous chloride solution.The latter solution was standardised by titration against the bromine solution, which in turn was standardised on 2; thiosulphate solution in the presence of potassium iodide. Experiments were also carried out with other methods for the determination of salicylic acid; these included acetylisation, a gravimetric bromine process, and precipitation as silver salicylate, but the results were useless. w. P. s.THE ANALYST. 537 Silver Cyanamide. H. R. Ellis. (Chem. News, 1909, 100, 154-155.)-1n the methods described by Weston and Ellis for the analysis of ‘‘ sodium cyanamide ” and “ nitrolim ” (AKALYST, 1909,366), it was assumed that silver cyanamide possessed the formula Ag,CN, ; in order to make certain about this an investigation was undertaken, the results of which are given below.The silver cyanamide was obtained by treating ail ammoniacal solution of ‘ I nitrolim ” with an excess of silver nitrate. The precipitate was separated, the silver cyanamide contained in it was dissolved in nitric acid and reprecipitated by the addition of ammonia,, these operations being repeated until no residue remained which was insoluble in cold dilute nitric acid. The silver cyanamide thus obtained was dried over sulphuric acid for two months. I t consisted of an amorphous yellow powder, which exploded violently when heated rapidly. I t was, however, possible to estimate the quantity of silver present in the compound by heating it cautiously in a tube closed with a plug of asbestos ; different estimations yielded from 84-18 to S4.78 per cent.of silver. The silver was also estimated by titration with ammonium thiocyanate, $3.3 per cent. of silver being found. These results are sufficient to show that the compound has the formula Ag,CN,, and not AgHCN,, as the former requires 84.36 per cent. of silver, and the latter 72.5 per cent. Silver cyanamide decomposes on heating with the formation of nitrogen a’nd cyanogen, according to the equation : 2Ag,CN, = 4Ag + 2CN + N, ; 1 grm. should therefore yield 43.64 C.C. of nitrogen and 43.64 C.C. of cyanogen at normal temperature and pressure. I n an experiment, 41.6 C.C. of nitrogen and 31.79 C.C.of cyauogen were obtained, the low result in the case of the cyanogen being due to the formation of paracyanogen. w. P. s. Polarimetric Estimation of Starch dissolved in Trichloraeetic Acid. P. Biourge. (Bull. de Brass, 1909, 22 ; Clbem. Zeit. Rep , 1909, 33, 446.)-Starch is dissolved in trichloracetic acid in a closed bottle, and digested for twenty-five minutes under a pressure of 1 atmosphere. The solution is then Gltered through the smallest possible quantity of loosely packed glass wool, clarified with alumina and polarised. If the specific rotstory power of starch be taken as [a]u= 1 9 7 O , the results are sufficiently accurate for rapid technical analyses. If other carbohydrates are present, the dissolved starch should be precipitated with barium hydroxide and alcohol.The barium precipitate may then either be dissolved according to Lintner’s method, or the excess of barium hydroxide may be titrated by Asboth’s method. If cupric reducing sugars have to be estimated in the filtrate, any possible traces of chloroform should first be removed, since the latter reduces Fehling’s solution powerfully . J. F. 13. Rapid Method of Starch Hydrolysis. G. A. Olson. (J. Ind. and Eng. Chem., 1909, 1, 445 ; Chenz. Zed Rep., 1909, 33, 446.)-The author describes a rapid method for the hydrolysis of starch, the results of which are slightly higher than those obtained by Sachsse7s method, but are still sufficiently accurate. The process can be carried out in about four minutes : One grm. of the finely-powdered sample is mixed in a, Kjeldahl flask of 500 C.C.capacity with 10 C.C. of water. After the addition of 6 C.C. of concentrated sulphuric acid (sp. gr. 1.84) the mixture is held53s THE ANALYST. over a flame and rotated until it becomes transparent. I t is then diluted with 10 to 15 C.C. of water and heated to boiling; the solution is cooled neutralised with sodium hydroxide, and made up to 250 C.C. in a measuring flask. The dextrose is then estimated in an aliquot portion. J. F. B. Colour Reactions of Sugars due to the Formation of Methyloxyfurfural. J. Ville and E. Derrien. (Bull. SOC. Chim., 1909 [iv.], 5, 895-901.)-The author shows by the results of spectroscopic examination that Pettenkofer’s test for bile acids (purple coloration with sulphuric acid and cane sugar), and SQliwanoff‘s reaction (red coloration given by fructose with resorcinol and hydrochloric acid), are not due to the formation of furfural, as has frequently been asserted, but t o the formation of methyl-4-oxy-2-furfural.Similarly, the reaction of Boas for the detection of hydrochloric acid in the gastric juice by means of resorcinol and cane sugar must also be attributed to the presence of methyloxyfurfural, derived mainly from the fructose part of the molecule. In the authors’ opinion, methyloxyfurfural plays as important a part in the colour reactions of ketohexoses as does furfural in the reactions of pentoses or methylfurfural in the reactions of rhaimose (cf. ANALYST, 1908, 33, 450). C. A. M. Analysis of Vibernum Dentatum. C. R. Blake. (Chenz. Nezos, 1909, 100, 210-211.)-The Yibernunz dentatum, or arrow-wood berries, examined were gathered near Sylvan Beach, New York; the berries grow on bushes from 5 to 6 feet high, are dark blue in colour, and oblong in shape.Each berry weighs about 0.03 grm. On analysis the berries yielded 35.7 per cent. of sugars, probably lzvulose and dextrose ; 0.93 per cent. of nitrogen ; and 2-16 per cent. of ash, which contained small quantities of manganese and chromium. Considerable quantities of tannin were present, and malic acid was also detected. On extraction with ether the berries yielded two distinct oils, one colourless, and the other dark-green-coloured. The former was volatile, whilst the green oil was heavy and somewhat viscous. w. P. s. Estimation of Wool in Presence of Cotton.B. Ruszkowski and E. Schmidt. (Chem. Zeit., 1909, 33, 949-950.)-The method usually prescribed for the estimation of wool in presence of cotton consists in dissolving the animal fibre in boiling sodium hydroxide, and weighing the residual cotton. A correction must then be made for the loss of weight suffered by the cotton under the conditions adopted-usually from 3.5 to 4 per cent. This method is fairly satisfactory when no finishing materials are present, but if the cloth contain these, they must first be removed by boiling with dilute hydrochloric acid. This makes the method far less accurate, since the sample must be dried and weighed again, and the cotton becomes more or less brittle. Further, since cotton and wool absorb different quantities of hygroscopic moisture, all weighings must be made in the air-dry condition, and the estimation takes a considerable time. The authors have found that an accurate result is obtained more rapidly by calculating the percentage of wool in the mixture from the percentage of nitrogen determined by Kjeldahl’s method. As a basis forTHE ANALYST. 539 this calculation they have estimated the percentage of nitrogen in fifteen samples of plain and coloured wools (presumably in the air-dry condition) after the extraction of the fat. The results ranged from 13.81 to 14.23 per cent., giving a mean of 14 per cent. of nitrogen. In carrying out the analysis of a textile, it is only neces- sary to remove the fat and estimate the nitrogen by Kjeldahl’s method. It is not necessary to remove the finishing materials, since the proportions of nitrogen in these and in the cotton itself are negligible. J. F. B.

ISSN:0003-2654    

DOI:10.1039/AN9093400532

出版商:RSC    

年代:1909

数据来源: RSC