摘要:

THE ANALYST. A-UGUST, 1904. OBITUARY NOTICE. A L F R E D H E N R Y A L L E N , IN the quiet and beautiful little country churchyard of Fulwood, on the rugged hills surrounding the town of Sheffield, which he loved, and where he laboured so long, we laid to rest on Saturday, July 16, our good and excellent friend, Alfred Henry Allen. The large concourse of mourners, representing the municipality and numerous Sheffield institutions, national and local scientific societies, charitable and literary bodies, spoke eloquently for the esteem in which he had been hald, and obvious was the sorrow of the mourners. Next to his family, there is no body of men in the country who will feel his loss so deeply as his colleagues forming the Society of Public Analysts, of which he was the most distinguished president and member.He was one of the founders of the Society ; his name appears in almost every number of The ANALYST, on the Editorial Committee of which he was an active member from its inception to the time of his death; few meetings were held which he did not attend, and whenever he was present he freely gave of his inexhaustible store of knowledge. Whether he sat in the presidential chair or on the benches, or came to the social gatherings after the meetings, there wae no man who filled his place better than Allen. To comparative strangers he may at times have appeared brueque and forbidding, but no franker and dearer friend was there to friends than he. When there was occasion for joyfulness he was amongst the most boisterous, and none poseessed the social talent, be it in speech or in song, more happily than he.For ten long years he carried on his incessant work under the cloud of the illness to which he at last succumbed. He fought it with all the knowledge at his com- mand, knowing that the malady in the end would conquer. Yet just these ten years of his life were his most active; paper followed paper, volume followed volume, the work being broken only occasionally by recuperative journeys to the South. Yet onoe more he rose from what seemed his death-bed, and began to think of wmk, when his death occurred almost suddenly on Thursday, July 14. Four months ago the end appeared to have oome.234 THE ANALYST. A. H. Allen was born on January 17,1846, and was the son of Mr. George Allen, an architect, of Southwark.Often, in later years, when travelling on the railway lines which dissect the south of London, he was wont proudly to point out a neighbouring church steeple erected by his father. He learnt his chemistry first at the College of Chemistry and Agriculture, Kennington, under John Nesbit, and afterwards at the Royal School of Mines, under A. W. Hofmann. He studied metallurgy and assaying under Percy, and geology and mineralogy at the classes of University College. His first professional appointment was as assietant to Dr. A. H. Hassall, where he, like Muter and the present writer (at different times), first came into contact with the problem of the analysis of food. Hassall, a medical man, with some skil1,in micros- copy, was confronted with innumerable chemical questions concerning food and drink which required chemical skill and knowledge for their solution.Scientific literature on food analysis was then almost non-existent, and Hassall’s assistants ha? to construct their methodsof analysis as they went along. What seemed a hardship was in reality a blessing. The bent of thought then given to Allen influenced the whole of his career to the very time of his death. After a short assistantship with Haessll, Allen went to Sheffield as assistant to a Dr. James Allan, who practised as an analytical chemist. The short connection was severed by Dr. Allan’s death, before Allen had been made a partner in the business, as had been his employer’s intention. Allen continued the practice on his own account, and for thirty-one years Surrey Street was the centre of his incessant activity.He was soon afterwards appointed Lecturer on Chemistry and Physics a t the Sheffield School of Medioine, also on Chemistry at Wesley College ; and, in ac- cordance with the spirit of the timee, he followed an active career as a popular lecturer on subjects like The Philosophy of the Microscope,” L6 The Air we Breathe,” ‘ I Fuel,” “ Optical Illusions,” ‘‘ Artificial Light,” ‘‘ Photography,” etc. He was a most facile speaker and an excellent experimentalist. In 1873 he wae appointed Public Analyst to the Corporation of Sheffield. He therefore ww one of the few Public Analysts who held office before the Sale of Food and Drugs Act came into existence. He eventually also became Publio Analyst for the West Riding of Yorkshire, the Boroughs of Chesterfield, Barnsley, Batley, Doncaster, and Rotherham, and for many years was one of the analyeta for Derbyshire.From the foundation of the Society of Public Analyets in 1874 he took the greatest possible interest in the work of the Society. Innumerable questions of analytical procedure, of professional ethics, of the status of the Public Analyst and his relations to the Public Authorities, arose, to which Allen, with never-flagging energy and interest, devoted himself. One has only to glance at the collective index of the first twenty volumes of the ANALYST to wonder at the wide range of subjects on which he wrote. Those of us who listened to his papers, or read them in the ANALYST or in the Journal of the Society of Chemical Industry, know well that he never touched a subject without adding something to our knowledge. Of immense practical experience, he could see better than moat men where processes could be simplified or improved, or how, by artful devioes, they could be rendered more work- able and accurate.Amongst the very long list of his papers there are few where he A Box of Matches,” ‘‘ Boiling Water,”THE ANALYST. 235 waa entirely original ; hence, Allen’s name is not so much associated with processes or apparatue as are the names of some others muoh less fertile than was he. For that reason, doubtless, the Fellowship of the Royal Society did not come to him ; but who can doubt that the sum total of his additions to knowledge is not far greater than that of many others who are thus honoured? To enter here upon even a cursory discussion of the classes of subjects which at one time or another occupied his attention and on which he wrote is almost impossible. His papers, and, before all, his magnum opus, are in daily use in every analytical laboratory over the whole world.As long as the question of the composi- tion of milk occupied our attention he contributed to i t ; when water analysis emerged out of endless discussion into the settled form which it now has taken he greatly helped ; when the composition of butter was in question, of petroleum spirit, of creosote-when any subtle drug presented difficulties to the analyst, he was sure to come to the fore. All this activity led to tLCommercial Organic Analysie,” the first volume of which appeared in 1879, and the last, so far, in 1901.4 6 While the libraries of chemists are replete with manuals and treatises on inorganic analysis, and the number of these works is being increased almost monthly, books on organic analyeis are chiefly conspicuous by their absence. I t is a lamentable fact that while our young chemists are taught to execute ultimate organic analysis, and to ring the changes on bodies of the aromatic series, the course of instruction in many of our leading laboratories does not even include qualitative tests for such every-day substances as alcohol, chloroform, glycerin, carbolic acid, and quinine. As a natural consequence of this neglect, the methods for the proximate analysis of organic mixtures and for the assay of commercial organic products are in a far more backward state than is justified by the inherent difficulties of this branch of analysis.” This Allen said in his first preface in 1879.In the fourteen years, from 1885 to 1898, the second edition, now swelling to six volumes, cost him incessant labour. Every paragraph he read in any scientific journal was marked, numbered, and indexed. With a method which could not be excelled, every item of knowledge was docketed by him and (‘ made note of.” The result was of benefit not only to analysts in the English-speaking world, but to manufacturers as well. Organic analysis emerged from his hands as an orderly and manageable science. No thanks which can be given, no gratitude which can be expressed on that score, can adequately honour his memory.For the development of his idea he laboured and virtually died. The taek of keeping up the continually required new editions overwhelmed him and ruined his health. At the present time a third edition, revised by Allen, Dr. H. Leffmann, Mr. Tankard, and Dr. Matthews, has partly appeared, or is still in course of prepara- tion, but it will be long before an analyst arises who is possessed of the grasp of the subject that Allen had. Of some of his earlier work on 6 1 The Presence of Nitrogen in Steel,” read before the British Association, he was proud, but of greater practical importance were his contributions to the chemistry of fats and oils, into which complicated subject he succeeded in bringing something like order and system.His paper on the “ Examina- I n 1882 the second volume appeared.236 THE ANALYST. tion of Spirituous Liquors for Secondary Constituents,” which he wrote, in conjunc- tion with Mr. W. Chattaway, in 1891, and that ‘‘ On the Chemistry of Whisky,’’ are only now being appreciated when analysts have to refer to them. To the town of Sheffield, and to users of peaty waters generally, he rendered a most important service. By explaining the cause of the action of such waters on leaden service pipes, and his simple scheme of neutralizing the acidity of such waters by chalk, he at once freed these towns from great danger. Since 1874, when he gave evidence before the Select Committee on Adulteration of Food, he appeared as a witness before every Parliamentary Committee that dealt; with food or drink, and in this respect had more to do with the formation of Parlia- mentary opinion than any other chemist.As a, witness, he was tenacious of his points, rather combative and peppery, but he always had cases and facts at his fingers) ends. He gave much thought to maintaining and raising the status of the profession of analytical chemist and especially of the Public Analyst. Of this several papers from his pen in the ANALYST, and his addresses as President of the Society of Public Analysts in 1887 and 1888, his constant activity in the Council of that Society and in that of the Institute of Chemistry (of which he was one of the founders), give overwhelming evidence. The position of Public Analyst was to him much more than the mere official function for analysing food and drink.He desired the widening of the Food Acts upon articles other than food and drink, but of common household use, upon which fraud and substitution is, at least, as commonly practised as in food. The Public Analyst was to him the protector of the public in all matters chemical. The rise of the analytical profession in public esteem and its differentiation from tutorial chemistry, which was accomplished in his time, afforded him much gratification. To a man like Allen, even his very illness was the cause of research and investigation. As early as June, 1894, he wrote a paper on the “Examination of Urine for Small Quantities of Sugar,” and in 1895 he published a work on the “Chemistry of Urine.” His studies of the influence of his diet on the amount of sugar secreted doubtless prolonged his life for years.The jolly hours which many of us spent with him, either before or after our scientific meetings, will not readily be forgot ten. His remarkable talent for versifica- tion, his none too tuneful songs, his good-tempered sarcasm, often helped to oil the wheels of the scientific machinery. H e had built up in Sheffield a very large analytical practice, where he was assisted by very many men who now occupy prominent positions in our profession. He never failed to couple their names with his own when they assisted him in any important matter of investigation. For some years he attempted to carry on practice both in Sheffield and in London, but the wear and tear of the continual travelling between the two places caused him, not too soon, to abandon that experiment.He never quite realized that his name was such that it was utterly immaterial whether he worked in Sheffield or in London; he often, if not mostly, undervalued the services which he rendered to his clients or to the public. We, his colleagues in the analytical profession, on the other hand, cannot over- value what he has done for us and our branch of science. Wberever analyticalTHE ANALYST. 237 chemistry is practised at the present time, and for many years to come, the name of Alfred Henry Allen will be a household word, and his work will assist and help us though he be gone. OTTO HEHXEH. il2LgIlst 3, 1904. LIST O F PAPEHS WRITTEN BY A. H. ALLEN. Papers read before the British Association for the Aduamenwlt of Scieme.On the Detection of the Adulteration of Tea, 1873. On a Method of effecting the Solution of Difficultly Soluble Substances, 1875. Reports (Three) of the Committee on the Methods employed in the Estimation of Potash and Phosphoric Acid and on the Mode of stating the Results (A. H. Allen, secretary), 1875, 1876, and 1877. A Lecture-experiment in Illustration of the Hollway Process of Smelting Sulphide Ores, 1879. On the Presence of Nitrogen in Steel, 1879. On Petroleum Spirit or ‘( Benzoline,” 1879. On the Specific Rotatory Power of Cane and Invert Sugar, 1880. Further Notes on Petroleum Spirit and Analogous Liquids, 1880. On the So-called ‘( Normal” Solutions of Volumetric Analysis, 1880. On the Separation of Hydrocarbon Oil from Fat Oil, 1881.An Apparatus for determining the Viscosity of Oils, 1885. On the Action of Water on Lead, 1885. On the Utilization of Blast-furnace Creosote, 1887. On the Reaction of Glycerides with Alcoholic Alkalies, 1891. Papers read before the Secticns of the Socrety of Chemicul Ijidustry. On the Chemistry and Analytical Examination of the Fixed Oils, 1883, ii., 49. Note on the Stability of Hypobromite Solution, and its U s . for the Titration of New and Little-known Applications of the Nitrometer, 1885, iv., 178. Further Notes on the Methods of Examining and Chemistry of Fixed Oils, Supplementary Notes on the Methods of Examining Fixed Oils, 1886, v., 282. On the Treatment of Soap-makers’ Leys for Recovery of Glycerin, 1887, vi., 87. Crude Carbolic Acid and its Substitutes, 1887, vi., 671. The Analytical Examination of Water for Technical Purposes, 1888, vii., 795.Notes on Commercial Cresylic Acid and Allied Products, 1890, ix., 141. The Chemistry of Whisky and Allied Products, 1891, x., 305. Supplementary Notes on the Chemistry of Whisky, 1891, x., 519. Oils, etc., 1884, iii., 65. 1886, v., 65. Papers read a t the Neetiitgs of the Iron and Steel Institute. Preliminary Experiments to determine the Existence of Nitrogen in Steel. Further Experiments on the Existence of Nitrogen in Iron and Steel, 1880, i., 181. Journal, 1879, 480.238 THE ANALYST. Papers read before th Society of Public Analysts ((( The Analyst ’,). On the Adulterations and Impurities of Tartaric and Citria Acids, Prooeedinge of tbe On the Determination of Quinine, 1876, i., 17.The Solution of Difficultly Soluble Substances, 1876, i., 139. On the Analysis of Plating and Gilding Solutions, 1877, ii., 178. Some Points in the Analysis of Water and the Interpretation of the Results, Note on the Determination of Alcohol in Ether and Chloroform, 1877, ii., 97. Note on the Detection of Strychnine, 1877, ii., 111. The Assay of Carbolic Acid Powders, 1878, iii., 285. A Curious Case of Poisonipg by Mouldy Bread, 1878, iii., 355. On the Distinctive Tests for Carbolic Acid, Cresylic Acid, and Creosote, 1878, Experiments on the Determination of the Free Acids of Vinegar (with R. Bodrner), Notes on the Analytical Examination of Tinctures, 1879, iv., 101. Note on the Quality of the Paper employed by the Daily Press, 1879, iv., 161.A Suggestion respecting the Expression of the Results of Butter Aesays by Note on the Examination of Coffee, 1880, v., 1. An Improvement in the Mode of Estimating Nitrates by Crum’s Method, 1880, Notes on the Analysis of Cream of Tartar, 1880, v., 114. Relative Proportions of Olefines in Shale and Petroleum Products, 1881, vi., 17’7. On Maumenb’s Test for Oils, 1881, vi., 102. Note on the Isolation of Strychnine, 1881, vi., 141. Notes on the Action of Water on Lead, 1882, vii., 169. Notes on Commercial Albumen, 1882, vii., 209. On Milk Analysis, 1883, viii., 256. Notes on the Estimation of Lead in Aerated Waters, 1884, ix., 194. Beichert’s Method for examining Butter-fat, 1885, s., 103. Note on the Optical Estimation of Milk-sugar, 1885, x., 72.The Assay of Carbolic Soap, 1886, xi., 103. Saponification Equivalents of Fixed Oils, 1886, xi., 145. Commercial Shark Oil, 1886, xi., 122. On the Determination of the Glycerin produced by the Saponification of Fatty Oils, 1886, xi., 52. Suggestions for the more ready employment of Adam’s Method of detcrmining Fat in Milk (with W. Chattaway), 1886, xi., 71. Note on the Fat of Porpoise Milk, 1886, xi., 290. Specific Gravity and other Properties of Waxes and Allied Bodies, 1886, xi., 223. Preservation of Milk Samples for Reference, 1886, xi., 203. An Improved Nethod of detecting Quassia and certain other Hop Substitutes in Society of Public Analysts, 1876, p. 151. 1877, ii., 61. iii., 319. 1878, iii., 268. Dr. Koettstorfer’s Method, 1879, iv., 162. v., 181.Beer, 1887, xi, 107.THE) ANALYST. 239 Note on Reichert’s Distillation Process, 1887, xii., 11. Note on the Composition of some Preparations sold as Hop Substitutes (with On the Detection of Cptton-seed Oil in Lard, 1888, xiii., 161. Adulteration of Lard with Cocoanut Oil, 1888, xiii., 189. Laboratory Notes : Alumina in Wheat, etc. ; Detection of Sulphur in Oils ; Pre- Use of the word Presidential Addresses to the Society of Public -4nalysts, 1888-1889, xiii., xiv. A Critical Examination of Dr. Voelcker’s Published Statements on the Composition The Detection of Saccharin in Beer, 1885, xiii., 105. On some Abnormal Samples of Butter, 1889, xiv., 5. Abnormal Danish Butters (a reply to Mr. Estcourt), 1889, xiv., 72. Possible Future Extension of the Duties of Public Analysts, 1890, xv., 2.Detection of Hop Substitutes in Beer (with W. Chattsway), 1890, xv., 181. Suggestions for the Assay of Aconite and its Preparations, 1891, xvi., 185. On the Constitution of Butter-fat, 1891, xvi., 161. Examination of Spirituous Liquids for Secondary Constituents (with W. Chattaway), Notes on Acetin (with D. Homfray), 1891, xvi., 167; 201. Neutrality Note on Tabarie’s Method of determining Alcohol, 1892, xvii., 5. Proportion of Water in Butter, 1892, xvii., 104. Vinegar (with C. G. Moor), 1893, xviii., 180; 240. Detection of Exhausted Ginger (with C. G. Moor), 1894, xix., 124. The Vinegar Question, 1894, xix., 8, 26. Note on G. S. Cox’s Paper on Cider Vinegar, 1894, xix., 91. The Elxamination of Urine for Small Quantities of Sugar, 1894, xix., 178.On Extraneous Mineral Matter contained in Commercial Ginger, 1894, xix., 217. Change in the Cornposition of Butter by long keeping (with C. G. Moor), 1894, xix , Notes on Commercial Condensed Milk, 1896, xxi., 274. Note on the Concentration of Condensed Milks, 1896, xxi., 281. Composition and Analysis of Commercial Cream of Tartar, 1896, xxi., 174, 209. Preparation of Pure Eydrofluoric Acid, 1896, xxi., 87. Note on the Titration of Quinine, 1896, xxi., 85. Note on the Presence of Heavy Metals in Cheese (with F. H. Cox), 1896, xxi., 85. Improved Method of determining Proteid and Gelatinoid Substances (with Detection of Arsenic in Beer, 1901, xxvi., 10. Is the British Pharmacopeia the Legal Standard for the Preparations described A Contribution to a Knowledge of the Chemistry of Cider, 1902, xxvii., 183.W. Chattaway), 1887, xii., 112. cipitation of Hop-bitter by Lead ,4cetate, 1888, xiii., 41. Normal ” in Volumetric ,Analysis, 1888, xiii., 181. of Milk, 1888, xiii., 256. 1891, xvi., 102. A Paper read before the Chemists’ Assistants’ Association, 1892, xvii., 186; 215. 128. A. B. Searle), 1897, xxii., 258. therein? 1901, xxvi., 86.a40 THE ANALYST. Certain Reactions of the Alkaloids of Ipecacuanha (with G. E. Scott-Smith), 1902, The Analysis of Prepat ations containing Opium (with G. E. Scott-Smith), 1902, Existing Defects and Possible Improvements in the Laws relating to Adulteration, Papers read before th Chemical Society. On Meta-Stannic Acid, and the Detection and Eetimation of Tin, Journ. Chem. Soc., An Improved Method of determining Urea by the Hypobromite Process, Proc.Chm. xxvii., 345. xxvii., 350. 1903, xxviii., 264. 1872, xxv., 274. Soc., 1896, xxxi., 33. Papers publishd in the < ( Chmical iVcws.” On the Employment of Potassium Ferricyanide as a Test for Cobalt, Nickel, and Suggestions for the Improvement of the Method employed for Qualitative Analysis, Note on the Solubility of Gold, and the Stability of Auric Nitrate and Sulphate, 1872, Estimation of Silicon and Graphite in Pig-irons, 1874, xxix., 91. Chemistry applied to the Detection of Adulteration, 1874, xxix., 129, 140, 167, 189, 221 ; 1874, xxx., 2, 116 ; 1875, xxxii., 77. The Action of Water on Lead, 1882, xlvi., 145. Constitution of Butter-fat (controversy with J. A. Wanklyn), 1891, lxiv., 223, 249, 263.On the Reaction of Glycerides with Alcoholic Alkalies, 1891, lxiv., 179. The Saponification of Beef-fat, 1891, Ixiv., 223, 282. The Volumetric Determination of the Alkaloids, 1892, lxvi., 259. Note on the Assay of Electro-Plating and Gilding Solutions, 1897, lxxvi., 199. On the Synthesis of Albumin, 1898, lxviii., 97. The Detection of Arsenic, 1900, lxxxii., 305. Manganese, 1871, xxiii., 290. 1871, xxiii., 301. xxv., 85. Papers rend before the British Pharmaceutical Conferciice. Report on the Permanganate of Potassium of Pharmacy, Pharm. Year-Book for On the Examination of Tea for the Detection of Adulteration, 1873, p. 540. On the Horsley-Stoddart Method of estimating the Fat of Milk, 1575, p. 583. The Distinctive Tests for Carbolic Acid, Cresylic Acid, and Creosote, 18‘78, p. 5‘75.Notes on Petroleum Spirit or ‘( Benzoline,” 18‘79, p. 478. Further Notes on Petroleum Spirit and Analogous Liquids, 1880, p. 523. Further Notes on Shale and Petroleum Products, 1881, p. 490. The Determination of Ethyl Nitrite, and the Change undergone by the Spirit of Trie Assay of Amy1 Nitrite, 1885, p. 469. Notes on Crude Carbolic Acid and its Substitutes, 1887, p. 566. 1871, p. 564. Nitrous Ether on keeping, 1885, p. 463.THE ANALYST. 241 Vermin-killers containing Strychnine, 1889, p. 434. Suggestions for the Assay of Aconite and its Preparations, 1891, p. 451. Experiments on the Alkaloid of Tea, 1892, p. 415. White Wine Vinegar, 1896, p. 321. Condensed Milk, 1896, p. 326. Papers read before the Society of Dyers and Colourists.On the Assay of Commercial Picric Acid, Jozmz. Soc. Dyers, etc., 1888, iv., 84. On some of the Constituents of Natural Waters, with Observations on Lead Experiences of a Public Analyst, about 1900. Corrosion, 1889, v. 54. Papers published in the Pharmaceutical Journal.” The Determination of Ethyl Nitrite in the Spirit of Nitrous Ether and Kindred Methyl Orange and other Indicators, 1889, May, 903, 1028. Note on the Constitution of Certain Antipyretics and Allied Bodies, 1890, July, 62. Alkaloids of the Veratrums (from advance sheets of “ Commercial Organic Analysis ”) , A Proposed New Method of examining Pepsin, 1897, ii., 561. Notes on Pepsin Assaying (from advance sheets of ‘‘ Commercial Organic Analysis ”). On the Synthesis of Albumin, 1898, ii., 243.Preparations, 1885, February, 673-768. 1895, ii., 242, and 1896, i., 146. 1898, i., 416. 3liscellaneous Papem, e tc. Neutrality : Proceedings of the Chemist’s Assistants’ A4ssociation, London (reprinted in the ANALYST), 1891, ii., 56. The Assay of Commercial Cyanide oE Potassium (pamphlet), 1884, Shefield. The Chemistry of Whisky, Journal of the Fedcmted Institute of Brewing, 1897, Lead Poisoning (a monograph on the subject of poisoning by lead compounds, with J. and A. Churchill, The Examination of Urine for Small Quantities of Sugar, Lancet, 1894, July 28, 213. Notes on the Analytical Examination of Urine (with A. R. Tankard), Lamet, 1904, cxi., 24. special reference to the action of drinking-water on lead). about 1885. June 18.242 THE ANALYST. Editions of ( ( Commercial Organic Analysis.” FIRST EDITION. VOl. I. VOl. 11. SECOND EDITION. VOl. I. VOl. 11. Vol. III., Part I. Vol. III., Part 11. Vol. III., Part 111. VOl. IV. THIRD EDITION (printed in America) VOl. I. Vol. II., Part I. Vol. II., Part 11. Vol. II., Part 111. Vol. III., Part I. Date. 1879. 1882. 1885. 1886. 1889. 1892. Also reprinted 1899, and with Ad- denda in 1902. 1896. Also reprinted with Addenda in 1902. 1898. 1898. 1899. 1900. In the Press. 1901. ~ ~ Chief Contents. Cyanides ; Alcohols, etc. ; Scids ; Hydrocarbons ; Oils and Fats ; Sugars Phenols and Acid derivatives. and Starches ; Alkaloids ; Dyes. Alcohols, Ethers, etc.; Sugars, Starches; Fixed Oils and Fats ; Glycerin, etc. Aromatic Acids ; Tannins ; Dyes. Amines ; Hydrezines ; Tar Bases ; Vegetable Acids. Vegetable Alkaloids. Lesser Alkaloids ; Bitters ; Animal Acids and Bases; Cyanogen and Derivatives. Proteids (Milk, etc.) ; Albuminoids (in- cluding meat extracts, blood, etc.). Revised (partially) and additions by Dr. H. Leffmann. Revised by author and Dr. H. Leff- mann. Revised by author and Dr. H. Leff- mann. Essential Oils and Resins and Turpentine omitted in this edition. Aromatic Acids and Essential Oils, etc. Written by the Author and A. R. Tankard. Left incomplete at Mr. Allen’s death. Being now edited by A. R. Tankard. Revised and edited by Dr. J. Merritt Metthews. Aromatic Acids omitted. Chemistry of Urine. 1895.

ISSN:0003-2654    

DOI:10.1039/AN9042900233

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

THE ANALYST. 243 PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. NOTE ON THE SUGARS OF CONCENTRATED MALT EXTRACT. BY ARTHUR R. LING, F.I.C., AND THEODORE RENDLE. IN the course of an investigation on commercial malt extract we have analysed a number of samples prepared, under conditions which have been communicated to US by the manufacturers, from malts of known origin. We believe the results we have obtained, more especially with respect to the carbohydrate composition of the extracts, are of sufficient interest to warrant us in submitting them to the Society. Thus, we found that the malt extracts contained a considerable proportion of dex- trose, which we were able to estimate gravimetrically, with a fair amount of accuracy, as glucoeazone, employing the method recently described by Davis and Ling ( J o z L ~ ~ .Chem. SOC. Trans., 1904, lxxxiv., 24). Having also examined a few of the well-known brands of malt extract on the market, and in every case obtained similar results, we have arrived at the conclusion that dextrose is an invariable constituent. I t is remarkable how very little work has been published on the composition of concentrated malt extract. We believe, however, that most chemists would have regarded the presence of dextrose in this product as evidence of adulteration. Among the few papers on the subject we have been able to find is one published in 1896 by P. Korn (B. d . Deutsch. p'harnz. Ges., vi., 349), and from an abstract of this paper in the Wochenschrift fiir Brauerei we find that he gives the following mean carbohydrate cornposition of nine samples of malt extract which he examined : Maltose ...... ... ... between 41.43 and 60.43. Dextrose ... ... ... . . . ,, 0.47 ,, 6.24. Cane- sugar ... ... ... ,, 0.33 ,, 3.69. Dextrin ... ... . . . ,, 11.70 ,, 22.70. As will be seen, the amounts of dextrose found by us are much higher than those recorded by Korn. Indeed, the highest percentage of dextrose which Horn finds is only about half our lowest percentage. The methods adopted by Horn were to mix the extract with ignited sand and absolute alcohol, and to extract the mass with absolute alcohol. I n this way it is contended that the sugars pass into solution in the alcohol, whilst the dextrin remains behind with the sand, and is estimated by lixiviating the dried mass with water and determining the total solids in the aqueous solution.This value, corrected for ash, is taken as the percentage of dextrin. The maltose, dextrose, and cane-sugar are esti- mated after distilling the alcohol from the alcoholic extract, the residue being taken up with water and its cupric reducing power (towards Ost's solution) determined before and after hydrolysis with hydrochloric acid and with invertase respectively. I n an attempt to make something like a complete analysis of certain samples of malt extract, we found that it was not possible to determine the sugars in terms of apparent maltose and dextrin by the copper method in conjunction with the polari- meter. This will be seen by the results obtained with Samples I. and II., whicha44 THE ANALYST.samples we shall deal with more funy further on. These gave 58.9 and 60-5 per cent. of apparent mdtose-Le., cupric-reducing power towards Fehling's solution expressed in terms of maltose-whilst the rotatory powers of the 10 per cent. solu- tions in a 200 millimetre tube for sodium light were 14.2" and 13.9" respectively. The above amounts of maltose, however, require rotations of 16.2" and 16.7' respectively. It is therefore evident that the malt extracts contained either a l ~ v o - rotatory compound or a sugar having a much smaller dextro-rotatory power than maltose. We are aware that malt extract contains asparagine and other similar compounds, but we do not think the amount of these is sufficient to account for the above differences, the more so as we assured ourselves that the extracts in question contained carbohydrates of higher rotatory power than maltose-e.g., dextrins (malto- dextrins).This €ed us, therefore, to examine the behaviour of the malt extracts towards phenylhydrazine, and, as a, result of this, we had no difficulty in isolating glucosazone in a practically pure state, when twice crystallised from alcohol it melted at 204". The ratios of the carbohydrates in the malt extracts being somewhat different from those in the starch conversions of Davis and Ling, we therefore determined the yield of glucosazone in artificial mixtures of dextrose, maltose, and dextrins (malto- dextrin - a was employed), and we found that with approximately equal quantities of these three carbohydrates the yield of glucosazone under the conditions described by Davis and Ling was 0-0731 gramme from 0.1 gramme of dextrose.In the following analyses the dextrose was determined as glucosazone, the maltose being calculated from the reducing power, less that due to the amount of dextrose found, whilst the dextrin was calculated from the rotatory power after deducting that due to the dextrose and maltose. We have ignored the small amount of cane-sugar which, according to Korn, is present. Specific gravity : 15.5" C. 4 5 - 5 0 c. } Maltose (apparent) Dextrose - Dextrin (apparent) U'n f e r m en t a b 1 e matter (expressed as dextrin) - Ash - Water Diastatic power (Lintner) - Specific rotatory power [uID - I. -- .395-7( % 31.1 17.2 9.8 4.5 1 -4i 24*3( 30-8 91.8' 11. .395*lf % 30.9 18-2 8.6 3.5 1.4! 24.6' 27.2 90.5' 111. - % 24.8 22.0 10.0 8.9 1.58 27 *36 32.3 84.2" IV.- % 27.4 19.1 9.8 5.8 1.64 24.84 25.6 86.8" V. - % 23.0 19 -4 13.5 4.1 1.68 24.82 32.2 88.0" VI. - % 25-9 16.5 12.3 - 1.21 25.20 28.0 89.6 VII 1408.43 % 34.2 12.5 9.9 1.34 24.38 39.2 94.5" VIII. 1377.82 % 25.2 20.0 6-7 - 1-64 29.52 46.5 81.1" IS. -. - % 33.0 16.9 7.8 - 1.33 24-20 61.7 90.7"THE ANALYST. 245 Of these extracts, Samples I. to VI. were prepared under known conditions from low-dried English malt. We are not at liberty to state what were the precise mashing conditions adopted in the preparation of these samples; but the first two were not raised in the tun at any time during the mashing process to a temperature above 145" F., whilst Nos. 11. to VI. were mashed a few degrees lower.The values given under " unfermentable matter expressed as dextrin " were obtained as follows : 25 grammes of the extract were dissolved in water (150 c.c.), and the solution boiled to destroy the diastase. After cooling, the solution was pitched with yeast at 70" F., and allowed to ferment at that temperature. When fermentation was complete, a little moist alumina was added and the liquid made up to 250 C.C. It was then shaken and filtered through a dry filter, the rotation of the clear filtrate being observed and calculated as dextrin. The yeast used in the above experiments was a Yorkshire stone square yeast. I t is interesting to note that the values for apparent dextrin, calculated from the rotatory power, less that due to dex- trose and apparent maltose, differ from the values for dextrin calculated from the rotatory power of the unfernientable residue.Not only this, but the two sets of values do not exhibit a constant difference. This is, however, by no means surpriyiug when we bear in mind the fact that the dextrins (maltodextrins) are all reducing com- pounds, and that their fermentability probably differs inverDely as their reducing power. The nature of these dextrins or maltodextrins, other things being equal, will vary according to the diastatic power of the malt. The malt used for the first two samples had a diastatic power of 60.6 04 Lintner's scale. In seeking for an explanation of the production of glucose, there is the possi- bility that it may be due to the presence of the enzyme maltase in the malt.This enzyme is seldoin found even in low-dried malt, and an extract of the malt from which the first two samples were prepared was incapable of hydrolyzing maltose, so that it was not present. The glucose might also be formed as a result of restricting the diastase in the manner shown by Ling and Davis (Journ. Fed. Imt. of Brewing, 1902, viii., 475, and Jozcrn. Chem. SOC., Zoc. cit.). We find, however, that when the malt in question is mashed in the ordinary laboratory manner, but at a temperature of 145" F. for two hours, the amount of glucose in the wort is only 0.39 per cent., cal- culated on the malt. Now, there is certainly iiiore dextrose (or invert sugar) existing ready formed in the walt than this; but we have some data showing that during mashing this ready-formed dextrose disappears, laboratory worts from ordinary brewer's malt giving, as a rule, no glucosazone whatever.This is what we might expect from the recent observations of Davis and Ling (Zoc. cit.). One of us has shown (British Association Report, 1903, and Jozwn. Fed. Inst. Brewing, 1903, ix., 450) that when any of the products of the incomplete hydrolysis of starch by diastase are isolated, and submitted to the further action of the enzyme, even at a temperature of 131' F., glucose is invariably formed. Now, in the prepara- tion of malt extract there are two distinct stages: first the mashing process, and secondly the evaporation. The hydrolysis of the starch is never carried to its final point in the mash-tun, and after the mashing process, the reaction is temporarily stopped.It commences again, however, during the evaporation, which in the case346 THE ANALYST. of the first six extracts was conducted at a temperature of 115°F. I t is probable that any reaction which occurs during this stage would be quite distinct from that which takes place in the mash-tun, not only on account of the lower temperature and the different concentration, which gradually increases up to the point at which further diastatic action is impossible, but also because the diastase is not acting on starch during this second stage, but on the hydrolytic products of starch formed during the first stage. Under these circumstances, we might expect glucose to be formed, although we must leave the exact explanation of this to future experiment.DISCUSSION The PRESIDENT (Mr. Fairley) having invited discussion, Mr. JULIAN L. BAKER said that this paper was especially interesting, because malt extracts of the kind referred to were now beginning to command attention in some of the fermentation industries, notably in the manufacture of alcohol, and also in bread-making. One of the most striking statements the authors had made was the large amount of dextrose which was present in these evaporated malt extracts, and which, they pertinently pointed out, might well be regarded, in the hands of anyone unaccustomed to deal with such extracts, as an indication of adulteration with glucose syrup.' Mr< Ling's further investigations concerning the reasons for the presence of this amount of dextrose would be awaited with much interest.I t was to be remembered that the extracts were prepared under special conditions. In the first place, the barleys used were inferior small-grain foreign barleys-Californian, Smyrna, Indian, and so forth-which were in themselves highly diastatic as barleys. They were malted under entirely different conditions from the malt which the brewer used, being grown freely and dried off-they could hardly be said to be cured-at a very low temperature, somewhere about 100" to 120" F., whereas brewer's malt would be finished off at about 190" to 200°F. Thus none of the diastase was crippled by the curing process. The mash was made at a low temperature, filtered in a press and evaporated, and there was a pause in the process (during filtration) between the mashing and the evaporation, which, as the authors pointed out, would mark the second stage in the diastatic action.He did not think that analogies could very well be drawn between the action of brewer's malt extract and these highly diastatic ones, because, under the conditions obtaining in the preparation of the latter, it seemed quite possible that the starch hydrolysis would proceed somewhat differently. One other point was that these malt extracts were highly concentrated syrups from a large amount of malt, and he should like to know how much of the dextrose present the authors would put down as being ready-formed in the iiialt before mashing. Dr. SCHIDROWITZ said that the fact of the presence of sucli a considerable amount of dextrose was in his opinion possibly to be put down to the general conditions of enzymic action.He understood the authors to say that in low-dried malts-ordinary brewer's malts, he presumed-they had never found any maltose-splitting enzyme. These malt extracts, however, were evaporated at a temperature very iavourable to enzymic action, and the degree of concentration was constantly changing. As a solution became more concentrated there was a tendency towards a reversion of the enzymic actior, and he thought it just conceivable t-hat the amount of dextrose foundTHE ANALYST. 247 in the final product might not be a maximum, but that at an intermediate stage a considerably larger quantity might be present, there being a certain amount of rever- sion as the extract became more concentrated. Of course, this mas purely hypothesis ; but possibly Mr, Ling had made some experiments in this direction, and if so, his opinions would be of interest. The PRESIDENT said he had been wondering whether it would be worth while making synthetic experiments, under as definite conditions as possible, with carbo- hydrates of known composition, so as to study this problem in its simplest form. In complicated mixtures of varying concentration, such as those now under considera- tion, all sorts of change, and even reverse action, might occur, and he thought that possibly such a matter could be best attacked in detail by studying the carbohydrates themselves, or known mixtures of them.Mr. SEYLER inquired how the authors had determined the cupric oxide reducing power, which was a matter of some importance in the case of complex mixtures of this kind. The methods generally used seemed to be very largely conventional.For his own part, he was in the habit of relying chiefly on the tables of Soxhlet, Wein, and Allihn. These, however, although they answered very well for pure solutions of dextrose and maltose, were not applicable to mixtures, owing to the different condi- tions under which each was obtained. Mr. LING, referring to the President’s remarks, said that corresponding determi- nations had already been made in pure starch conversions, in the course of the investigation which he had recently communicated to the Chemical Society, in con- junction with Mr. Davis. I n determining the dextrose as glucosazone, it was most essential always to start with freshly-distilled phenylhydrazine ; otherwise the results fluctuated very much.For the gravimetric determination of the cupric oxide reducing power he preferred the method of Brown, Morris, and Millar. I n the case of these malt extracts, however, the cupric oxide reducing power had been determined volumetrically. Many chemists stated that the volumetric process lacked sufficient accuracy, but, after many years’ experience, he had modified the process, so that in repeated experiments he was able to get almost as great uniformity as with a gravi- metric process. His solutions were all standardized with the pure carbohydrates. In cases where no disturbing element occurred the volumetric results were identical with those yielded by the process of Brown, Morris, and Millar. That reversion during evaporation occurred he thought was very likely ; in fact, in the experiments made by Mr. Davis and himself it was noticed how much the results fluctuated from day to day, especially the percentage of glucose. The nature of the body produced from glucose was not known. He had suggested at the British Association that i t was Lintner’s isomaltose. He believed that the body which yielded the osazone with a melting-point of Ma0, and which Lintner regarded as one of the products of starch hydrolysis, was a secondary product. He had a number of data on that point, which he hoped to publish sooner or later. He agreed with Mr. Baker that no anabgy could be drawn between low-dried and high-dried malts.

ISSN:0003-2654    

DOI:10.1039/AN9042900243

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

248 THE ANALYST. THE ANALYSIS OF CONDENSED MILK. BY J. BRISTOWE P. HARRISON, F.I.C. STRICTLY speaking, this paper should have been entitled ( ( The Analysis of Sweetened Condensed Milk,” for as the examination of unsweetened condensed milks is only a matter of dilution and the employment of the ordinary methods of milk analysis, there is little more to say about the analysis of milks of this class. The usual determinations in the complete analysis of sweetened condensed milks are : Total solids, ash, fat, proteids, cane and milk sugar. The contents of a tin having been turned out into a basin or other suitable vessel, the sample is thoroughly mixed by means of a glass rod. About 75 grammes are weighad out into a beaker, enough water added to bring the whole into solution, and then raised to the boiling-point with continual stirring, to prevent burning. The whole is then cooled and made up to 250 C.C.in a graduated flask. The boiling is absolutely essential to destroy birotation of the milk-sugar, which, as I shall describe later, is estimated polarimetrically. We have now sufficient of a 30 per cent. solution to effect a complete analysis, and, as the concentration of condensed milk is usually about three times that of ordinary milk, the solution will roughly approximate in composition to cow’s milk containing a certain amount of added sugar. A determination of the specific gravity at 60” F. of this solution should now be made either by means of a Sprengel tube or specific gravity bottle, and the factor found which will be necessary in calculating the percentage of each constituent.If x =number of gramines of condensed milk diluted to 250 c.c., y= the weight of solution used in the determination of any constituent, the percentage of any constituent in the original milk is found by multiplying the weight of that constituent obtained on y grammcs of the solution by the factor : 250 x 100 specific gravity $9 Total Solids and ,4s?z.-The most satisfactory method of estimating the total solids is by drying on asbestos, whereby constancy can be obtained in five or six hours. The bowl of an ordinary platinum milk dish is packed fairly closely with pieces of teased-out asbestos not greater than 3 inches in length. The whole is then strongly ignited (preferably in a muffle) for about five minutes, and weighed. Five grammes of the diluted milk are weighed on to the asbestos, dried for two hours on the steam bath, and finally for three or four hours in the water oven.If the drying is done in an ordinary platinum milk dish without asbestos, constancy can only be obtained after twenty to twenty-four hours. By using the flat porcelain dishes now largely employed for the estimation of total solids the drying can be accomplished in eight or nine hours. The ash is obtained by igniting the residue a t a dull red heat in the muffle. Fat.-Five grammes are placed on an extracted coil, and the fat estimated by Adams’ method. Pearmain and Moor (ANALYST, ss., 270) have pointed out that this is the most reliable way of estimating the fat in condensed milk, and my experi- ments go to confirm their statement.Ritthausen’s method of extracting the precipiTHE ANALYST. 249 tated fat and proteids with ether has also been recommended, but the following results obtained in collaboration with Mr. J. A. Goodson show that this method leaves much to be desired, which is the more remarkable seeing that it is completely applicable in the case of fresh milk. J. B. and P. H. J. A, G. J. B. and P. H. Precipitate -‘- obtained by Acetic Acid Copper Sulphate :kg1 Acetic Acid. Precipitate. Precipitate. Time of extraction ... l+ hours. 24- to 5 hours. 5 hours. 33 hours. Percentage of fat ... 7.79 9.05 to 9.57 9.75 10.47 The Gerber process can be applied with considerable accuracy in the fat estima- tion, the results being usually a trifle high.The fat, however, does not separate at once, but requires two or even three ‘‘ whirlings ” before the full amount is obtained. The Gerber bottles are graduated, so that each large division on the stem represents 1 per cent. by weight of fat on 11 C.C. milk of average specific gravity 1.032. Supposing 77.12 grammes condensed milk diluted to 250 C.C. had a specific gravity of 1.069, and that I1 C.C. of this solution yielded 3.5 large divisions of fat, the necessary calculation would be : Protcids.-Five grammes of the solution are weighed out into a flask and the nitrogen determined by the Kjeldahl process. Multiplying the percentage of nitrogc n by 6-38, we obtain the proteids. rn IHE ESTIMATION OF CANE AND MILK SUGAR. Milk-sugar in condensed milk is generally estimated either by Fehling’s method or some modification of it.Cane-sugar is often determined by difference ; that is, by subtracting the sum of the other ingredients from the total solids. Bstimations by difference are always obviously unsatisfactory, because an assumption has to be made that the difference is due only to one constituent, whereas it may be accounted for by two or more substances. Under certain circumstances, however, the cane- sugar has to be determined exactly, and several processes more or less satisfactory have been devised to this end. These may be said to depend on three different principles, viz. : 1. The determination of the difference in reducing power before and after 2. The determination of the difference in specific rotatory power before and after inversion.3. The determination of the specific rotatory power given by the two sugars, and subtracting that due to the milk-sugar as calculated from the reducing power withont inversion. Each of these principles has its own peculiar advantages, but the determination of the difference in specific rotatory power before and after inversion seemed to me the best, both in point of time and accuracy. I n this respect Kjeldahl’s idea of inversion by the action of invertase is highly recommendable. The method is rather inversion.250 THE ANALYST. elaborate, however, and involves keeping the solution for several hours at a definite temperature. Something much quicker and simpler seemed to me desirable, and the more rapid inversion of the cane-sugar by means of an acid suggested itself.The acid used, however, must be such as to secure complete inversion of the cane- sugar without affecting the milk-sugar. Stokes and Bodmer had shown that citric acid was a suitable agent for this purpose in the estimation of cane-sugar in presence of milk-sugar by means of the Fehling method, and I determined to find how far such an agent was applicable for use with the polarimeter. Experiments 017 the 1mw-s ion of Caizc-s.z~gai- b2 Citric Acid Having proved that a solution containing a normal weight of cane-sugar (16.29 grammes per 100 C.C. for the Laurent instrument) was completely inverted by heating with 3 per cent. citric acid for twenty minutes in a boiling water-bath, I then found that the same result could be accomplished with 2 per cent.As there was no particular object in further reducing the quantity of citric acid used, I decided to make experiments with 2 per cent. in order to ascertain the inversion figure for a normal solution. The exact manner of carrying out the inversion was as follows : One gramine of finely-powdered citric acid was weighed out into a clean, dry conical flask of about 100 C.C. capacity. Fifty C.C. of t'he normal sugar solution were then introduced, and the whole weighed on a balance turning to 0.02 gramme. The acid solution was placed in a briskly boiling water-bath, and kept there for exactly twenty minutes. The flask and its contents were then cooled, reweighed, the amount of water lost by evaporation replaced, a eorrection being also made for the volume occupied by the citric acid.The whole was then thoroughly mixed, filtered, and examined in the polarirneter. Expcrinzcn t 1 ( tzoeiz t y inim tes ' hecc t iizg ) . Solution examined before inversion ... + 99.57 sugar scale degrees. Average reading 00 opposite sides of scale after inversion , , ... ... - 30.12 sugar scale degrees. Temperature of reading 23-5" C. = - 32.25 - 1.15(3-5 x 0.5) = - 32.00 at 20' C. - 30.12 x 100 99-57 Exijeriment 2 (tweiztp min2btes' heating). Temperature of reading 21.5" C. = - 31-31 - 0-75(1.5 x 0.5) = - 32.06 at 20" C. Average reading after inversion . . . - 31.18 sugar scale degrees. - 31*18 99-57 Experiment 3 (thirty minutes' heating). Temperature of reading 23.0" C. Average reading after inversiou . , . - 30.40 sugar scale degrees.- 30'4 loo = - 30.53 - 1-5(3 x 0-5) = - 32.03 at 20" C. 99.57THE ANALYST, 251 These results give a mean value of -32.03 at 20" C., and further show that there is no object in heating for longer than twenty minutes. My next concern was to find the best method of removing the proteids and fat. For the sake of uniformity I tried the action of citric acid on fresh inilk after the manner of Stokes and Bodmer. For polarimetric purposes this method was not successful, for the proteids were not completely removed, and it was also very difficult to obtain a clear solution. Removal of these substances by acid mercuric nitrate and the subsequent inversion of the cane-sugar by citric acid seemed feasible enough, provided no action took place in the cold between the mercuric nitrate and the sucrose.I therefore decided to put this idea to the test on milk containing a known amount of cane-sugar. Estimation of Cane-sugar and Milk-sugar in Fresh Milk containing 10 Grammes added Cane-sugar per 100 C.C. On analysis the milk alone gave the following figures : Specific gravity, 1.032. Fat, 4.05 per cent. Milk-sugar, 4.6 per cent. The volume of the mixture after adding cane-sugar was 106.3 C.C. The proteids and fat were precipitated in 100 C.C. of the mixture by adding 3 C.C. of acid mercuric nitrate, prepared according to Wiley's formula (dissolving mercury in twice its weight of nitric acid of specific gravity 1.42, and adding, after solution, an equal bulk of water). The filtered solution was examined polarimetrically immediately sufficient to fill a 200-millimetre tube had been collected.One gramme citric acid was added to 50 C.C. of the solution, and the inversion carried out as before. The cane and milk sugar are calculated as follows : Dividing the difference between the two readings before and after inversion by The reading was 16" 50' = 16.83'. The inverted solution then read 50' at 1 9 O C. the inversion value for citric acid at 19" C., as found above, we have : . 16*oo -~ =12-07 due to cane sugar. 1.3255 Deducting this from the reading due to both sugars, then 16.83 12.07 ___ 4.76 =reading due to milk-sugar, Dividing by 1.33 (the factor for a 200-millimetre tube) gives the amount of cane-sugar per 100 C.C. ; and increasing this value by one-tenth, we get the amount in the total volume of sugar solution (110 c.c.).938- per cent. cane-sugar.252 THE ANALYST. Similarly, dividing the reading due to milk-sugar by 1.106, adding one-tenth, and dividing by the specific gravity of the original milk, we have : 4-76 =4.3 1.106 0.43 4 3 3 ,/ 1.032 = 4.60 per cent. milk-sugar. This and subsequent experiments prove that cane-sugar is not appreciably affected in the cold by acid mercuric nitrate under the conditions named, a point men- tioned by J. C. Shenstone (ANALYST, xiii., 223) in a paper on the same subject. I n taking the reading before inversion, I would urge the necessity of examining polari- metrically immediately after the removal of the fat and proteids, and may state that " local emess " of the acid reagent, through improper mixing, gave rise to a consider- able error on one occasion.Several experiments were then carried out on fresh milk containing added cane- sugar, with the idea of shortening the time of inversion. I t was found that this could be reduced by at least ten minutes. On repeating the inversion by citric acid on a normal sugar solution, however, I found that the time could not be materially shortened, and could only draw the conclusion that, in the cme of milk containing added sugar, the excess of acid mercuric nitrate after removing the proteids and fat was aiding the citric acid in its action. The idea of leaving out the citric acid alto- gether, if possible, and using iiiercuric nitrate alone, suggested itself as simplifying mattem, and experiment proved that not only was this the case, but that the inver- sion was complete in seven minutes.T ~ L C I ~ i ~ e ~ s i o i i 0.f Cane-s ugnr h j Acid X e rcii ric X i t m t e . The inversion values with 1 C.C. acid mercuric nitrate on 50 C.C. normal sugar solution in seven minutes were obtained, corresponding to those found by the action of 2 per cent. citric acid. The values found in three experiments were: -32*7i, - 32.55, and - 32.53 at 20" C. The presence of milk-sugar had apparently no appreciable effect on the value, for on substituting a solution containing 13 graninies of cane-sugar (99.7 per cent.) and 5 grainines milk-sugar (100 per cent.) per 100 c.c.-which approxiniates to the condi- tions obtaining in a 30 per cent. solution of condensed milk-I obtained values of -32.S0, - 39.70, -32.84, acd - 32.60.The mean of all these values is -33.68, which is practically identical with the well-known Herzfeld fwtor-viz., - 32*6C;-- and I therefore decided to use his figure in subsequent experiments. Using this d u e and calculating the amounts of cane and milk sugar per 100 C.C. from the figures obtained in four experiinents, they appear thus : Cam-sugar. Jlill;-sugar. Experiment I. .. ... . . . ... 12.98 4.9'3 ,, 111. ... ... ... ... 12.99 4.98 ,, IT. ... . . . ... ... 12.97 5.00 ,, IT.-. . . ... ... ... 12-96 5.01 Another experiment on the action of 1 C.C. acid mercuric nitrate on 50 C.C. of the solution containing the mixed sugars, in which the heating was prolonged to twentyTHE ANALYST. 253 minutes instead of seven, showed that the inversion waB apparently incomplete, which meant either destruction of the lamdose or inversion of the milk-sugar. This shows that the Herzfeld factor can be only employed when the experimental conditions already detailed are strictly adhered to.Action of Acid Merczcric Nitrate on n Solution of Milk-sugar. A 5 per cent. hydrated milk-sugar solution was prepared, which gave an angle of 5-25'. After heating 50 C.C. of this solution with 1 C.C. acid mercuric nitrate for seven minutes the reading was 5.25". Another experiment after twenty minutes' heating gave 5.23". Therefore, under the conditions necessary for the complete inversion of cane-sugar acid mercuric nitrate has no action on milk-sugar. E'stimcction of Lldt7ecl Cane-szLga.1. in Fmsh Milk bg Iwnersion zuith Acid Jlcrcuric Two test experiments were made up of milk containing certain quantities of Expeyimeizt I.-I was told that the volume of sugar solution, after removal of the The figures obtained on polarimetric examination were : Xztmte.added cane-sugar per 100 c.c., the amounts of which were unknown to me. proteids and fat and addition of 10 C.C. water to hasten filtration, was 114.5 C.C. Before inversion + 20.05". After ,, - 0.20" at 21.5" C. These on calculation gave : Cane-sugar . iliilk-sugar. 13.21 grammes 4.71 per cent. Actual amount added 13.17 ,, Difference +0.04 ,, _- Exp7"ivient 11.-Volume of sugar solution, 103.6 C.C. On examination the figures were : Before inversion + 21 57". After ,, = 0.28' at 20.0" C. On working these out I obtained : Cane-sugar.Xilk-sugar. 12.83 grammes 4.63 per cent. Actual amount added 13-67 ,, Dif'ference ~ 0 . 1 6 ,, The question arose as to whether there was sufficient excess of acid mercuric nitrate contained in the filtrate, after removal of the proteids and fat by the addition of 3 c.c., to completely invert the cane-sugar by heating to boiling for seven minutes, and experiment proved that this was the case. As the result of the foregoing experi- ments, I have adopted the following method for the inversion of cane-sugar by acid mercuric nitrate, which is, of course, equally applicable in the case of condensed milk : Fifty C.C. or more of khe filtrate are introduced into a clean dry flask of about 100 C.C. capacity, and the whole weighed on a balance turning to 0.02 gramme.The254 THE ANALYST. acid solution is then placed in a briskly-boiling water-bath, and kept there for exactly seven minutes. The flask and its contents are then cooled, reweighed, the amount of water lost by evaporation replaced, and the whole thoroughly mixed, filtered, and examined polarim e t rically. Estimation of Cam- and Milk-Sxgar in Condensed Milk. 78.48 grammes of the milk were weighed out and diluted to 250 C.C. ; the proteids and fat were then removed from 100 C.C. of this solution by the addition of 3 C.C. acid mercuric nitrate. The percentages of proteids and fat found in the original milk were 9.43 and 11.52 respectively ; 100 C.C. of the solution contained 31.39 grammes of milk, and the total volume occupied by the fat and proteids was obtained thus : Volume due to fat 31.39 x 0.115 x 1.08 = 3.90 C.C. ,, ,, proteids 31.39 x 0.094 x 0*86x' = 2.54 C.C.Total = 6-44 C.C. ___- The volume of sugar solution was therefore 103 - 6.44 = 96.56 C.C. The solution examined before and after inversion gave : Before inversion + 21.33O After 1 9 - 0.55 at 23" C. Subtracting the two readings and dividing by the inversion value (Herzfeld) for 23" C., we have : 21*88 = 16.68 due to cane-sugar. 1-3116 Deducting this from the reading due to both sugars, then, 21.33 16.68 4.65 =reading due to milk-sugar. Dividing the figure for cane-sugar by 1.33 (the factor for a 200-millimetre tube) gives the amount per 100 c.c., which, expressed as percentage on the original milk, appears- 16'68 -- - 12-54 x 0*9656 ___ - - 38.59 per cent.cane-sugar. 1.33 0.3139 Similarly, dividing the reading due to milk-sugar by 1.106, and applying the same factor, we have- 0.9656 4'65 = 4.20 x -----= 12.92 per cent. milk-sugar. 1.106 0.3139 Assuming the percentage of proteids in condensed milk to be 10, and applying the Gerber process for the estimation of the fat, the estimation of the cane- and milk-sugar can be accomplished in a comparatively short time. For all practical purposes this can be done within a possible error of 1 0 . 2 on the percentage of the cane-sugar contained, an error of 0-5 per cent. of fat accounting for less than half this possible error, whilst an error of 1 per cent. on the proteids would make no greater difference than &0.1 in the percentage of cane-sugar. * 0'84 is the more correct factor.THE ANALYST.255 On this assumption the usual calculation can be very much simplified, as in Richmond and Boseley's method for the estimation of milk-sugar (ANALYST, xxii., 99), by adding to every 100 C.C. of the solution : 1. A number of C.C. of water calculated by adding to 10.6 a figure equal to 2. Three C.C. of acid mercuric nitrate. the volume of fat and proteids minus 3. The reading due to milk-sugar, as calculated in the usual way, will give percentages of milk-sugar direct in the solution, and this, of course, has to be brought to per- centages on the condensed milk. Dividing the cane-sugar reading by 1-2, we get the percentage of cane-sugar in the solution, and this is also calculated as percentages on the condensed milk. The percentage of fat in a condensed milk was found to be 9.5, and a solution was made up containing 30-95 grammes per 100 C.C.Calculating the combined volume of the fat and proteids : Volume due to fat . . . 30.95 x 0.095 x 1-08 = 3.17 Volume due to proteids 30.95 x 0.1 x 0.86 = 2.66 5.83 + 10.6 = 16.43. Therefore 13.45 C.C. of water and 3 C.C. acid mercuric nitrate were added. The following results were obtained polarimetrically : Before inversion . . . ... ... +18*70° After inversion ... ... ... - 0.33 at 25" C. 19-03 due to both sugars. The percentage of cane-sugar was therefore "'03 = 14.62 / 1-2 x 0-3095 = 39-38, 1-16 the percentage of milk-sugar being 18-70 14-62 4.08 / 0.3095 = 13.18. The following analyses give the composition of three well-known brands of sweetened condensed milk : I.Water . . . ... 25-48 Fat ... 11-52 Proteidi ... 9-43 Cane-sugar . . . 38.57 38.68 38.59 38.45 11. 111. (Machine Skimmed). 25.04 25.97 9-58 0.75 10.00 10.99 39.40 ! 39'43 44.72 i 39-38 Milk-sugar . . . 12.89- (12.90 12.92 (13.09 Fehling) 13.06{ 12.94 13.18 14-07 (14.45 Fehling) 112.86 Ash ... .. . 1.93 99.82 2.10 2.39 99.18 98.89256 THE ANALYST. I am in agreement with Shenstone in questioning whether invert sugar exists in sweetened condensed milk in more than mere traces. The process of condensing elnployed in the manufacture of the best-known brands is not conducive to the formation of invert sugar. The method of estimating the cane- and milk-sugar polarimetrically before and after inversion, however, takes no account of the presence of invert sugar. The existence of 1 per cent.of this would not influence the per- centage of cane-sugar, but would cause the milk-sugar to be estimated 0.4 per cent. too low, the total sugars showing a deficiency of 1.4 per cent. as determined by this method. The percentage of invert sugar can, of course, be determined by com- bining the polarirneter readings before and after inversion with a determination of the cupric reducing power of the sample, but the experimental errors made in obtaining these values would render the figure obtained of little value. The Fehling values of the milk-sugar given in the analyses of the condensed milks Nos. I. and 111. were obtained by precipitating the proteids by copper sulphate in neutral solution, and estimating the cupric reducing power of the filtrate, using as a blank a solution containing amounts of cane- and milk-sugar approximating as nearly as possible to those in the solution of condensed milk.The difference between the value of No. 111. found in this way and that obtained polarinietrically is possibly due to the presence of invert sugar. DISCUSSION. The PRESIDENT (Mr. Fairley) said that ililessrs. F. TV. Richardson and A. JafG, in a paper which they read in January before the Yorkshire section of the Society of Chemical Industry, had described a scheme for the estimation of cane-sugar and lactose in milk, etc., and he had drawn attention at the time to the special advan- tages of methods which did not need the destruction of any great amount of the substance worked upon.That might be repeated here, though he was afraid that the inversion processes employed by Mr. Harrison might involve some loss of substance. Mr. RICHMOXD said that a large number of careful experiments had been made by Mr. Harrison in order to work out the best conditions for the inversion and estimation of the cane-sugar. The times of heating calculated to give the most reliable results had in particular been ascertained by a large number of trials, and these times must not be departed from. The figures 13.01, aud 1445 for the inilk- sugar in samples Nos. 1 and 3, as determined by Fehling’s solution according to O’Sallivan’s method, iyl each case were a little higher than that shown by optical methods. The fact that the analyses all added up to less than 100 seemed to indicate some small inversion of the cane-sugar, which would raise the apparent milk-sugar by Fehling’s solution, and would be altogether in accordance with the results.The inversion of cane-sugar by citric acid was probably not complete, and the ‘‘ Herzfeld value ” of 132.66 really only indicated the point of equilibrium in the presence of 10 per cent, of hydrochloric acid. Probably also, with both citric acid and acid mercuric nitrate the stage at which the quantity of cane-sugar, dextrose, and laevulose is in equilibrium is not complete inversion. Possibly the equilibriumTHE ANALYST. 257 would reach the same point with the free nitric acid from the acid mercuric nitrate as with the hydrochloric acid. Mr. A. R. LING said he presumed the object aimed a t was to choose an acid which would invert the cane-sugar to a maximum and the milk-sugar to a minimum, but he very much doubted whether even the citric acid fulfilled both these con- ditions. Since very few yeasts hydrolysed milk-sugar, it would be interesting if Mr. Harrison would try the physiological method of determining that sugar in presence of a fermentable sugar, employing ordinary Xucchuromyccs C C T ~ Y I J ~ ~ Z to ferment away the latter, as it would, at any rate, afford a means of corroborating his very interesting results.Mr. MOOR congratulated the author on the successful result of what must have been a very great deal of work. He (the speaker) was glad to find that the Adanis method had proved satisfactory, because it seemed to be the only one that could be easily used.The Werner-Schmid method had the disadvantage that a great deal of black matter was formed, while with the Gerber, Leffmann-Beam, and other forms of centrifugal apparatus there was a great quantity of fluff formed which interfered with the reading; so that the Adams process appeared to be the only satisfactory one. He had no doubt that the sugars were much more accurately estimated by the optical method described than by that of Pavy, but surely the Pavy process was very much more simple to use, and if one employed that method it was not necessary, as far as his experience went, to remove the proteids. If one worked with a 10 per cent. solution, 10 C.C. of that diluted to 100 C.C. with about equal parts of ammonia and water could be run into the Pavy solution, and in a short time a fairly accurate estimation of the milk-sugar was obtained.The proportion of cane-sugar could then be obtained with fair accuracy by deducting the other constituents from the total solids. He was interested to note that one of the samples of which the analytical results were given contained only 1.93 per cent, of ash, as he had been taken to task because out of a large number of figures which he had obtained for ash in condensed milk some fell below 2 per cent., and it was thought that there was some mistake. The ash of ordinary milk condensed in the proportion of 3 : 1 would be 3 x 0.75, but it would very often be found that the ash of condensed milk, owing to coagulation, was not equally distributed through the bulk, so that the milk in one tin might contain more ash than that in another.He would much like to hear whether anyone present had heard of any new preservative for condensed milk. He had recently met with some samples which would keep almost indefinitely, but he had been quite unable t o find any preservatives at all in them, though he had tested for all the ordinary substances used for the purpose. Mr. CHAPMAN said it seemed to him that what was really needed was not SO much a scientifically exact method as a simple and rapid one, that should be sufficiently accurate for the purpose of the examination of samples taken under the Sale of Food and Drugs Acts. He had made a number of experiments at various times for the purpose of ascertaining whether the method of Stokes and Bodmer could be relied on, having added to milks containing estimated quantities of lactose known quantities of cane-sugar, and he had always obtained results which were quite satisfactory.He must confess that as the result of his experience he did not258 THE ANALYST. find himself able to attach that importance which Mr. Moor attached to the method of Pavy. He presumed that in Mr. Harrison's determinations the milk-sugar was calculated as monohydrated milk-sugar. If it were calculated as the anhydrous sugar it would make an appreciable difference on a 5 per cent. solution. Mr. HEHNER agreed that the Adams method, judiciously employed, was the only really reliable one for the determination of fat in condensed milk. He thought, however, that the inodz~s oprandz of Mr.Harrison might be usefully modified by extracting a larger quantity on two or three coils, and if there was any suspicion that the extraction was not complete, owing to the presence of the large amocnt of cane-sugar, steeping the extracted coils in water to dissolve out the sugar, and then, after drying, extracting with ether once more. h small further quantity of fat, as a rule, would be obtained in this way. Centrifugal methods seemed incapable of yielding sufhiently accurate results. Mr. Harrison had mentioned an instance in which 3.5 divisions corresponded to 11.7 per cent. of fat, 1 division, therefore, corre- sponding to 3.4 per cent. of fat. This would altogether place such a method outside of the range of accurate methods for this purpose. He would also suggest that inversion by means of acid mercuric nitrate in an aqueous solution was on a different footing from inversion by the same agent in the case of milk.The mercury precipitated the casein and other albuminoids, and it seemed probable that the inversion was not the result of the action of the acid mercuric nitrate as such, but was virtually brought about by the action of dilute nitric acid. He thought it was too much to expect that the analyses should sum up to 100. There were other substances in milk beyond those which were usually determined. The ash, for instance, was present, not as ash, but was the residue of something the exact nature of which had not been determined. Many years ago he had investigated Pavy's method, and he found that, although under constant conditions it was capable of yielding comparable results, yet it was so largely affected by any variation in the conditions of working that it could hardly be classed among exact methods.Mr. CHAPMAN remarked that Mr. Richmond had alluded to the very important influence (frequently overlooked in the treatises on the subject) which the inverting agent exercised on the optical activity of the invert sugar produced. I n almost all cases a definite number was taken for this, but, as a, matter of fact, it depended upon whether hydrochloric acid was used and was present at the moment of observation, or whether citric acid or any other inverting agent was used. This was not merely an academic matter, the variations being sometimes sufficient to affect the results appreciably.Mr. HARRISON, in reply, said that he was very much indebted to Mr. Richmond for valuable assistance in this work, and also for his kindness in allowing it to be carried out in the laboratory of the Aylesbury Dairy Company. With regard to Mr. Ling's remarks, he was quite of opinion that, theoretically, the process of fermentation by means of yeast was an admirable one, and remarked that some years ago he had tried the process of inversion by yeast by keeping the sugar solution to which yeast had been added for five hours at 55" F., but had only succeeded in getting about 80 to 90 per cent. of the cane-sugar inverted. Although he had found that the Gerber process gave results somewhat too high, which was, of course, onlyTHE ANALYST. 259 an approximate method, his experience did not confirm that of Mr. Moor as to the presence of fluffy matter about the meniscus. One very great objection to Pavy’s method was the necessity of conducting the ammonia fumes out of the laboratory. The determination of ash referred to in the paper had been made by heating in a muffle, which, in his experience, was the only way in which this determination could reliably be made. The ash in condensed milk should be in much the same ratio to the proteids and milk sugar as in ordinary milk, and the results now given were not far divergent from this. He was quite aware that the reaction which took place when inversion was carried out by acid mercuric nitrate was rather complex, but the method had certain practical merits, the principal of which was that it enabled the estimations of cane-sugar and milk-sugar to be made in about a couple of hours, wherees processes in which yeast or inverta,se was used required a much longer time. With relation to Mr. Hehner’s excellent suggestion as to a second extraction of the Adams’ coils after dissolving out the sugar with water, it was pointed out that the thereby increased results of the Adams process would cause those of the Gerber process to be in closer agreement, as these he had generally found to be about 0-2 per cent. higher. In reply to Mr. Chapman’s question, moizohycZ~ated milk sugar was used iu the test experiments.

ISSN:0003-2654    

DOI:10.1039/AN9042900248

出版商:RSC    

年代:1904

数据来源: RSC

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THE ANALYST. 259 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. The Composition of Lard and Beef-fat Crystals. H. Kreis and A. Hafner. (Zeit. Uyztersuch. Nahr. Genussmittel, 1904, vii., 641-669.)-The difference in the form of the lard and beef-fat crystals deposited in the Belfield test was attributed by Hehner and Mitchell (ANALYST, xxi., 328) to the presence of a larger proportion of stearic acid in the latter. The authors, however, find that the difference is due to the lard crystals consisting of the mixed glyceride heptadecyl-distearin, while beef and mutton fat crystals consist of palmitic distearin (ANALYST, xxviii., 359). They have not observed the gradual change of lard crystals on recrystallization into bunches of needles practically indistinguishable from beef-fat crystals, which was noticed by Hehner and Mitchell. In their experiments, 2.4 kilos of lard were dissolved in 4 litres of ether, and the solution cooled at 10" C.to 12" C. The deposit, which weighed 216 grammes, melted at 44.5" C. and 59.8" C. It was recrystallized nine times, until eventually the melting-point became constant at 50.5" C. and 65.2" C. In similar experiments with beef and mutton fat, the first deposits melted at 43" and 54" C. and 44.5" C. and 56" C., and the recrystallized deposits at 50" C. and 60" C. and 50.5" C. and 61.6" C. respectively. These deposits were freed from traces of olein by treatment with Hubl's solution, and were then found to have the same composition and characteristics as the mixed glycerides already described (Zoc.cit.). Determina-260 THE ANALYST. tions of the stearic acid present in the fatty acids gave the following results : Beef- fat crystals, 70.1 per cent. ; mutton-fat crystals, 70.4 per cent. ; and lard crystals 68.6 per cent. Pure heptadecylic acid (C17H3402), isolated from the lard crystals, melted at 55.5" C. I t was more soluble than palmitic or stearic acid in 95 per cent. alcohol, 100 C.C. of which dissolved 0.971 gramme at 0" C. The magnesium salt was readily soluble in alcohol, while the lead salt, which was a white, non-crystalline powder, dissolved easily in hot alcohol, but was only sparingly soluble in cold alcohol. The silver salt formed a flocculent precipitate, which was more soluble than the lead salt in alcohol. The mixed glyceride, ,/3-heptadecylo-distearin [C,H,(C,,H,,O,)(C,;II,,O,) (ClS%OJI, was prepared synthetically by heating the pure acid from lard with a-distearin for twenty hours at 200" C.under reduced pressure (ANALYST, xxviii., 152). I t melted at 51%" C. and 66.0" C., and after crystallization at 66" C. When crystallized from ether, it formed microscopic, well-defined, chisel-shaped crystals, identical in every respect with the recrystallized lard crystals. C. A. 31. The Use of Aluminium Acetate as a Preservative in Sausage. Ed. Mac - Kay Chace. (Joiux A i i w . cllic712. Soc., xxvi., 662.) - The author has recently examined some samples of canned sausage of German origin to which aluminium acetate had been added as a preservative. Two brands were found to contain 60 to 70, and 175 to 200 milligrammes of aluminium respectively per 1-pound tin, the greater part being present in the sausages themselves, Prom the sausages the aluminium could not be removed by either boiling water or dilute hydrochloric acid.On digestion at 40" C. for twelve hours with a solution contain- ing 0.33 per cent. of hydrochloric acid and 0.1 per cent. of pepsin, the greater part of the aluminium passed into solution, so that probably a considerable proportion of the aluminium would be dissolved in the stomach and retard digestion. A. G. L. DiEerentiation of the Various Hinds of Cinrnmon. J. Hanu6. (Zed. Unter- such. Nahr. Gc?zzLssmitteZ, 1904, vii., fX9-G72.)-The author's method of determining cinnamic aldehyde (ANALYST, xxviii., 361 ; xxix., 222) affords a means of distin- guishing between different kinds of cinnamon.Thus, four samples of Ceylon cinnamon yielded 1-74 to 2.19 per cent. of aldehyde-average, 1.89 per cent. Cassia cinnamon gave 2.25 to 3-Sl per cent.-average, 2-71 per cent. ; and flowers of the same cinnamon 3.70 to 6.0 per cent.-average, 4.57 per cent. Two samples of cinnamon chips gave 1.23 and 1.42 per cent. Other barks allied to cinnamon were also examined, with the following results : Czn7~~~~~0rn~im Tcin~clta (East Indian cinnamon), 1.80 per cent. ; wild Ceylon-Canehl, twig bark, 0.12 per cent., and stem bark, 1.31 per cent.; Java Massoy cinnamon (Cin?camornzwt Kiamis Nees) gave no precipitate ; whilst only a slight precipitate wasTHE ANALYST. 261 given by the distillate of Cinnamomum Ceylanici Nees (Tigablas). Hence, cinnamic aldehyde is not present in all varieties of cinnamon.The author suggests that ground cinnamon intended for food should contain at least 1.5 per cent. of cinnamic aldehyde. I n his opinion, all samples containing less than that proportion are adulterated or prepared from refuse (chips). He describes experiments to show that there is no loss of aldehyde during the distillation, and that the aldehyde is in all probability present in the cinnamon in the free state, and not in the form of a glucoside. C. A. 111. Analysis of Drugs. A. Panchaud. (Schweix. Wochenschr. fiir Chem m d Plzarm., 1903, xli. ct seq. ; through Pharnz. Jaw. 1904, lxxii., 716-718.) - The committee engaged in preparing a new edition of the Swiss Pharmacopceia com- missioned the author to undertake experiments on the methods at present in use in the assay of drugs, and also to examine new methods intended to replace the old.The results of these experiments are given in four principal sections: (1) Critical observations on Keller’s method; (2) a proposed new method ; ( 3 ) assay of extracts ; (4) details of the assay of numerous drugs by the new method. Keller’s method was selected as a basis on account of its simplicity and general utility. I t consists in treating the powdered drug with ether or ether-chloroform, liberating the alkaloids with ammonia, and then adding water so that the ethereal layer may be separated. The latter is then shaken with 0.5 per cent. hydrochloric acid, the alkaloid transferred to ether-chloroform, evaporated and weighed.In some cases it was found preferable to use ether instead of ether-chloroform, and to employ a less quantity of solvent than Keller recommends. With all the drugs examined, Panchaud was able to obtain clear solutions without the addition of water. The new method proposed consists in shaking the drug with the solvent and ammonia, drawing off a known volume of the clear liquid, and evaporating. The residue is taken up with 10 C.C. of water, a crystal of hmnatoxylin is added and then q , hydrochloric acid until the colour changes from violet to reddish-brown. Thirty C.C. of water are now added and the titration continued until the colour changes to lemon-yellow. In the analysis of dry extracts, the author reduces them to a fine powder with sand and applies the above method. Soft extracts are dissolved in dilute alcohol, and liquid extracts are dried upon sand and powdered.Tinctures may be con- centrated to one-sixth their volume before analysing. Details are given of the analysis of many drugs by the new method. w. P. s. The Detection of Acetanilide. A. Gregoire and J. Hendrick. (Bzcll. soc. Chim. BeZg., xviii., 94-96.)-1t is stated that acetanilide (antifebrin) is frequently given to animals to nullify the effects of the tuberculin test, and the author has devised the following simple method for the detection of the fraud. The urine is acidified with phosphoric acid and shaken with ether, and the ethereal extract evaporated in the preaence of a small quantity of water to prevent oxidation. The262 THE ANALYST. residual aqueous solution is mixed with a fourth of its volume of concentrated hydrochloric acid and boiled for a short time. I t is then cooled and treated with 1 C.C. of water saturated with phenol, followed by several drops of a solution of calcium chloride, the liquid being shaken after the addition of each drop. If the urine contained paramidophenol (formed in the body from acetanilide) there is a bright red coloration, changing to blue on the addition of ammonia. This reaction is capable of detecting 1 part of pure paramidophenol in 10,000,000, or 1 part in 100,000 in the case of impure solutions such as are obtained by the extraction of urine. Paramidophenol appears in the urine very soon after acetanilide has been taken, and in an hour a strong reaction is given, which begins to decrease in intensity after eight hours, and disappears after twenty-four hours. c. A. b!.

ISSN:0003-2654    

DOI:10.1039/AN9042900259

出版商:RSC    

年代:1904

数据来源: RSC

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262 THE ANALYST. ORGANIC ANALYSIS. The Estimation of Methyl Alcohol in Formaldehyde. R. Gnehm and F. Kaufler. (Zed. f. n;rzge?r. Clzem., 1904, xxi., 6'73.)-The formaldehyde is condensed with the sodium salt of sulphanilic acid, the methyl alcohol is distilled over, and the quantity is estimated by taking the specific gravity of the distillate. In order to reduce the sodium sulphanilate t3 a sufficiently fine state of division, 90 gramines of the salt are added by degrees to 35 C.C. of boiling water, and when solution is complete, the liquid is rapidly cooled. Of the formaldehyde solution to be examined, 20 C.C. are then added ; the flask is corked and left for three or four hours at the ordinary temperature, or one and a half to two hours at 35" to 40" C. A still-head containing glass beads is then fitted to the flask, and 30 to 35 C.C.are distilled over ; the distillate is made up to 50 c.c., and its specific gravity determined. The quantity of methyl alcohol may be calculated by means of the empirical formula : d = 1 - 0.00189 ;U 4- 0.00002 j~', which is based upon the determination of Dittmar and Fawsitt (Trans. Roy. SOC. Edin., xxxiii., 509). d is the density at 15" C. compared with wat;er at the same temperature, both being weighed in air, and 21 the number of grammes of methyl alcohol contained in the alcohol-water mixture. I n the distillates the authors have found small quantities of reducing substances having a specific gravity greater than that of water ; these consequently make the results too low. The error does not, however, exceed 0.5 to 0.6 grainme per 100 C.C.A. 31. Note on the Indophenine Reaction. F. W. Bauer. (Bci-ichtc, 1904, xxxvii., 1,244 ; through Chenz. Zeit. Rep., 1904, xxviii., 134,)-On shaking benzene containing thiopbene with concentrated sulphuric acid and isatine, the sulphuric acid is coloured blue. This coloration, known as the indophenine test, only appears when the sulphuric acid used contains a trace of an oxidizing substance, such as ferricTHE ANALYST. 263 chloride or nitric acid. obtained. is thus not entirely consistent with the fact that an oxidizing agent must also be With "chemically pure" acid a faint green coloration is The usual equation given to explain the formation of indophenine- C,H,NO, + C,H,S = C,,H,NOS + H,O- present. W. P. s.The Rapid Determination of Fat by Means of Carbon Tetrachloride. A. P. Bryant. (Joz~rn. Amer. Gizenz. Xoc., xxvi., 368.)-The author recommends the use of carbon tetrachloride for the extraction of fat from foods and feeding-stuffs. The extraction only requires two hours, and the solvent is uninflammable and of comparatively high boiling-point, besides being inexpensive. The only objection appears to lie in the fact that the last traces of carbon tetrachloride are difficult to remove completely from the fat. I t is recommended to heat for two hours at 100" C., and then to raise the temperature for a short time to 120" C. Actual tests A. G. L. have shown that this can be done without oxidizing the fat. Analysis of Linseed Oil. G. Fendler. (Berichtc, 1904, xiv., 294; through Chein.&?it. Rep., 1904, xxviii., 134.)-A number of experiments were carried out by the author in order to ascertain what is the amount of unsaponifiable matter naturally present in pure linseed oil, and to what extent, if any, this quantity is influenced by treating the oil in various ways. The results show that the quantity of unsaponifiable matter in a, normal oil does not exceed 2 per cent. Oxidation, blowing, or boiling the oil does not increase this figure. Linseed oil obtained by pressing does not contain more unsaponifiable matter than extracted oil. I n all cases a second saponification was found to be necessary, otherwise the results were too high. The best means of detecting small quantities of mineral oil in linseed oil consists in a determination of the iodine value of the unsaponifiable matter, the consistency of the latter and its solubility in hot 90 per cent.alcohol being also taken into account. The unsaponifiable matter of linseed oil is usually solid, and is soluble in hot alcohol, whilst mineral oil is liquid and insoluble in such alcohol. TIV. P. s. The Detection of Mineral Oil in Distilled Grease Oleines. Augustus H. Gill and Stephen N. Mason. ( J o z L ~ . d77zer. Clzem. SOC., xxvi., 665.)-The authors have investigated several tests for the detection of mineral oils in recovered distilled grease oleines. They isolated the hydrocarbons due to the breaking up of the fatty acids from several samples of distilled oleines by saponification with camtic potash, extraction of the unsaponifiable matter with benzol, and treatment with boiling acetic anhydride to remove cholesterol and other higher alcohols, and compared these hydrocarbons with several mineral oils likely to be used as adulterants.They find that the total bromine numbers (54.7 to 57-2), and especially the addition numbers (14.2 to 16*8), are much higher for the oleine hydrocarbons than for the mineral oils (total, 16.9 to 21.3; addition, 5.6 to 8.4). The distilled grease hydrocarbons264 THE ANALYST. show an optical rotation of 16" to 18", as against a maximum rotation of la or 2" for the mineral oils. The indices of refraction of the latter (1.4662 to 14750) are also lower than those of the oleine hydrocarbons (1.4948 to 1.4991). The fluorescence of mineral oils is in general blue, whilst that of the oleine hydrocarbons is generally green.By applying the above tests, an opinion may be arrived at as to the presence and approximate amount of mineral oils in the oleines. A. G. L. The Constituents of Chaulmoogra Seeds. Frederick B. Power and Frank H. Gornall. (Proc. Clzenz. SOC., xx., 135.) - On expression, the seeds yielded 30.9 per cent. of a fatty oil, which had the following constants: Melting-point, 22' to 23" C. ; specific gravity, 0-951 at 25", and 0.940 at 45' ; [uIr,l5', = + 52"; acid value, 23.9 ; saponification value, 213 ; iodine value, 103.2. On hydrolysis, the oil yielded glycerol, a very small amount of phytosterol, and a mixture of fatty acids consisting chiefly of several homologous acids belonging to the series C,H,,-,O,, con- taining a closed ring and one ethylenic linkage; the mixed fatty acids gave the constants : Melting-point, 44" to 45O ; [aII,, = + 52.6" in chloroform ; acid value, 215 ; iodine value, 103-2.The highest homologue (' chaulmoogric acid " present was obtained in glistening leaflets, of melting-point 68" ; boiling-point, 247" to 248" under 20-millimetre pressure ; and [a],, = + 56" ; it combines with only two atoms of bromine or iodine. The ( ( press cake " yielded, besides formic and acetic acids and a very small amount of volatile esters, an appre- ciable amount of a neutral oily substance, C1SH3202, isomeric with chaulmoogric acid, of boiling-point 314" to 215" under 18-millimetre pressure ; specific gravity, 0.9066 (16"/16") ; and [aID, = + 42.4". Palmitic acid was also shown to be present.A. G. L. On the Losses of Sulphur in Charring and Incinerating Plant Substances ; and on the Accurate Determination of Sulphur in Organic Substances. William Edward Barlow. (Joz~nz. Anzer. CJze?n. Soc., xxvi., 341.)-The author discusses the value of the various methods for determining sulphur in organic corn- pounds at considerable length, and concludes that the only accurate method consists in burning the substance in a current of oxygen, and absorbing the products of com- bustion by means of heated sodium carbonate. This process, however, must be carried out under certain conditions, all of which are satisfied by the author's method (vide ANALYST, this vol., p. 124), in which the apparatus shown in the figure is used. A. G.L.THE ANALYST. 265 Quantitative Determination of Sulphur in Organic Substances. M. E. Pozzi-Escot. (Rev. gdndr. chim. pure et appliq., 1904, vii., 240 ; through Chem. h i t . Rep., xxviii., l'iO.)-The substance is oxidized by means of chlorochromic acid, 1 gramme of the substance being agitated for several minutes in a 500 C.C. flask with 10 to 15 grammes of chromic acid and 20 to 25 C.C. of concentrated hydrochloric acid. After standing for twenty to thirty minutes the whole is heated to boiling for ten minutes, using a reflux condenser. Some unreduced chromic acid should still be present at the end of this time, X solution of chlorochromic acid itself in glacial acetic acid, to which some hydrochloric acid is added, may also be used. I n either case, the excess of chromic acid is reduced by cautiously adding alcohol, and the solution is diluted with 500 C.C.of water and precipitated with barium chloride. A. G. L. Estimation of Sulphur in Oils, Bituminous Substances, Coals, and the Like. Edmund Graeffe. (Zeit. f. aizgew Clicm., 1904, xix., 616.) The substances are burnt in oxygen in a large glass flask at about atmospheric pressure, and the sulphur is entirely converted into sulphuric acid by means of sodium peroxide. The flask has a capacity of 6 to 7 litres, and is fitted with a rubber cork, 8, through which pass a dropping funnel and two copper-wires, 1:5 to 2 millinietres in diameter. At the lower end of the shorter wire they are both covered with platinum foil, pre- ferably soldered to the copper, and are united by a thin platinum wire, 0.1 to 0.3 millimetre in diameter.To the lower end of the longer wire a platinum cone and wire are fixed, as shown in F. The under surface of the rubber cork is a protected by means of the asbestos disc, B. The temperature of the glass bottle is equalized by means of the wire cage, C, which also serves to prevent pieces flying about in case the bottle shouId burst. The platinum cone is weighed together with some cotton, on which is placed about 0.5 C.C. of the oil, and .the cone is then again weighed and hung on the lower end of the copper-wire. One end of a piece of thread is wrapped round the platinum wire, and the other introduced into the cone. The bottle having been filled with oxygen, the stopper is tightly fixed. The dropping funnel is filled with 50 C.C.of a solution of sodium peroxide in ice-cold water. The ignition is started by means of an electric current, and at the same time the rubber stopper is held down with the hand or wired down. The excess of pressure generated is reduced either by cooling under the tap or by allowing gas to escape gradually through the funnel. The contents of the funnel are then allowed to run into the bottle, the rubber stopper is266 THE ANALYST. removed and an ordinary cork substituted, the bottle being allowed to stand about an hour for mist to settle. The contents of the bottle are then washed out, filtered, acidulated, and precipitated with barium chloride in the usual way. If there be no electric current available, the arrangement shown at D is used, and a thread is led right up to the stopper.This is lit with an ordinary match, the stopper is immedi- ately replaced, and the estimation is carried out as above. When volatile oils are to be tested they are weighed in small glass tubes, which are closed with a stopper of paraffin wax. A. 11. Determination of Sulphur in Caoutchouc. Paul Alexander. ( GWILUL~ Ztg., xviii. , 729 ; through Chcnz. Zcit. Rep., xxviii., 180.)-The author defends Carius’s method against the statements made by W. Esch (ClLem. Zeit., sxviii., SOO), and reviews the barium chromate method of Pennock and Morton (JOZL~IL. JIILCI.. Chenz. XOC., xxv., 1265) and Pontio’s manganese peroxide and soda method (Eev. gc:itdi-. clzim. p w e et appliq., vii., 13). W. Esch (GZLYTUIL~ Ztg., xviii., 752 ; through C‘lLem. Zeit. Rep., xxviii., 130) points out that P. Alexander’s use of Henrique’s formula for the calculation of the caoutchouc from the sulphur content is incorrect, as this formula really only holds good for certain simple cases. Further, he states that, in using Carius’s method, instead of fusing only the residue insoluble in nitric acid with sodium carbonate, it is better to evaporate the total contents of the tube to dryness and fuse the whole residue, as the presence of lead may otherwise cause errors in the subsequent precipitation of the sulphuric acid. A. G. L. The Estimation of Carbon by means of Phosphoric Acid. Gilbert T. Morgan. (Proc. Chena SOC., xx., 167.)-Phosphoric acid is substituted for sulphuric or hydrochloric acid in the determination of carbonates and in the chromic acid method of combustion, the use of a non-volatile acid obviating the danger of acid fumes being carried into the absorption apparatus. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9042900262

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

266 THE ANALYST. INORGANIC ANALYSIS. Volhard’s Method for the Estimation of Silver. C. Hoitsema. (%tit. f. aiigew. Clzem., 190.1, xvii., 846.)-T. K. Rose has proposed to improve Volhard’s sulpho- cyanide method and increase the sensitiveness of the end-point by filtering the liquid before the titration is finished, and completing it in the filtrate (TYCLUS. CJzcm. Xoc., 1900, 232). The author finds that the sensitiveness is indeed greatly improved, but that serious error is introduced through the fact that considerable quantities of silver nitrate are retained in the precipitate of silver sulphocyanide by absorption. If ammonium sulphocyanide be present in excess it is similarly retained, though not to quite such a large extent. I t is not practicable to wash the precipitate free from soluble salts because of its pasty nature and its tendency to decompose in the light.A. M.THE ANALYST. 267 A Volumetric Method for the Determination of Mercury Fulminate. Henry W. Brownsdon. (Chem. News, lxxxix., 303.)-The method depends on the fact that, when mercuric fulminate is decomposed by means of an excesfi of sodium thiosulphate, the resulting solution gives an alkaline reaction. By titrating the solution with a TG sulphuric acid solution, a measure of the amount of fulminate used is obtained. The sulphuric acid solution is standardized against pure mercuric fulminate. This is prepared by dissolving the ordinary commercial salt (I molecule) in potassium cyanide solution (1 molecule), precipitating the mercuric fulminate by means of dilute nitric acid, washing till quite free from acid, and drying at 80" to 90" C. From 0.04 to 0.05 gramme of this salt is weighed out into a 100 C.C.flask containing 50 C.C. of water; 1 gramme of sodium thiosulphate is then added, the flask well shaken until the fulminate has dissolved, and the liquid made up to the 100 C.C. mark. Portions of 25 C.C. each are then withdrawn and titrated with the acid, using methyl orange as indicator. The mean of three separate estimations should be taken. In applying the method to detonating compositions, a quantity of the com- position, containing not more than 0.05 gramme of mercuric fulminate, should be used for a determination, as otherwise the alkali formed may act on the antimony sulphide also present, leading to low results.The procedure is the same as with the pure salt, except that the liquid is filtered before titrating ; should the first portion of the filtrate be turbid, it is run through the same filter again until clear. The liquid should also be titrated as soon as possible after the addition of the sodium thiosulphate, since otherwise secondary reactions may set in. The method gives excellent results. A. G. L. A Rapid and Convenient Method for the Quantitative Electrolytic Precipitation of Copper. Theodore W. Richards and Harold Bisbee. (Joz~r?~. Amer. Clzem. Soc., xxvi., 530.)-Since the electrolytic deposition of a metal increases in rapidity with the concentration of the solution to be electrolysed and with the area of the electrodes, the authors propose the use of a very concentrated electrolyte spread in a thin film between two concentric platinum dishes or crucibles, separated by a tripod-like device of thin glass.As the concentration of the electrolyte diminishes in the course of the electrolysis, the current strength must also be diminished, either by inserting resistance into the circuit, or else, automatically, by employing a secondary cell as the source of current. I n the latter case a storage cell of 1.9 volts was employed, the effective electromotive force being the difference between this value and that of the copper-oxygen couple; and because this difference diminishes with the diminishing concentration of the copper solution, the current strength, and hence the current density, will also diminish. Proceeding in this way, it was found possible to deposit 0.3416 gramme of copper completely in a weighable form from 5 C.C.of liquid in one and a half hours, the current used being 0.5 ampere at the start and 0.03 ampere at the end of the operation. To prevent spirting, it was found advisable to cover the electrolyte with 1 C.C. of pure kerosene. A. G. L.268 THE ANALYST. The Electrolytic Estimation of Minute Quantities of Arsenic. Henry J. S. Sand and John E. Hackford. (Proc. Chem. Xoc., xx., 123.)-The authors recommend using lead elmtrodes for the estimation of small quantities of arsenic. Lead cathodes are especially suitable for the reduction, owing to their high supertension. Errors due to the presence of foreign metals in the solution can be rectified by adding lead acetate or zinc sulphate before electrolysing, except when mercury is present.Using lead or zinc cathodes, the smallest quantity of arsenic which can be detected in alkaline solutions is about thirty times as great as in acid solutions. Platinum cathodes are altogether unsuitable. A. G. L. The Separation of Arsenic b y Distillation in Hydrogen Chloride. Gilbert T. Morgan. (Proc. Chcm. Soc., xx., 167.)-The author uses a modification of Piloty and Stock's apparatus (BET., 1897, xxx., 1649), in which the vapours produced by the distillation of the mixed sulphides of arsenic and antimony in a current of hydrogen chloride do not come into contact with organic, matter until they have passed through a cooled aqueous solution of hydrogen sulphide. When arsenic in both states of oxidation is present in the mixture, that in the pentavalent condition does not distil unless hydrogen sulphide is mixed with the hydrogen chloride.A. G. L. The Sepsration of Iron from Nickel and Cobalt by Lead Oxide. (Field's method.) (Chem. NCZUS, lxxxix., 480.)-The author has examined the accuracy of Field's method of separating nickel and cobalt' from iron. As used by him, the method consists in evaporating a solution of the nitrates of these metals nearly to dryness on the water-bath, diluting the residue with water, heating tlie liquid to boiling, and adding an excess of lead oxide, at least six times the weight of the iron present being used. The precipitate is washed with hot water containing a little lead nitrate. In the filtrate the lead is removed by means of sulphuric acid, with or without expulsion of the nitric acid, and nickel or cobalt determined by electrolysis. The separation was found to be rapid and fairly sharp, about 99 per cent.of the nickel, and rather nore of the cobalt, being found in the filtrate. Apparently, the precipitation of the iron is complete. T. H. Laby. A. G. L. The Determination of Xolybdenum in Steel and in Steel-making Alloys. Frederick Van Dyke Cruser and Edmund H. Miller. (Jozmz. Amel.. Clzcm. Soc., ssvi., 6$5.)-The authors have investigated several methods for the determination and separation of molybdenum in steel. They come to the conclusion that the quickest and most accurate method is to separate the molybdenum from the bulk of the iron by means of hydrogen sulphide under pressure.This is done by passing a very rapid stream of hydrogen sulphide through the dilute sulphuric acid solution, and then heating the liquid in a closed bottle to 100" C. for one or two hours. The precipitate is next dissolved in a mixture of sulphuric, hydrochloric, and nitric acids, .and all acids save sulphuric are expelled by evaporation. An excess of ammonia isTHE ANALYST. 269 added to precipitate the small quantity of iron carried down by the molybdenum, and the acidified filtrate is run through a reductor and titrated with permanganate. The molybdenum may also be determined in the filtrate as lead molybdate, but this method requires more time, the results obtained being as accurate as in the titration method. Vanadium, uranium, and chromium do not interfere with this method of ,geparetion. If tungsten is present, some tartaric acid should be added before passing hydrogen sulphide through the solution.The separation of molybdenum from iron by sodium or ammonium hydroxide gives high results owing to the formation of a ferric molybdate, which dissolves to a slight extent in the excess of alkali used. Sodium gives better results than ammonium hydroxide. If the excess of the latter is expelled by boiling before filtering, the values obtained are worthless, owing to the precipitation of ferric molybdate. Vanadium, uranium, and tungsten are not separated from molybdenum by either sodium or ammonium hydroxide. Chromium does not interfere with the separation. A. G. L. The Use of Nitrosonaphthol in Quantitative Analysis, especially for the Separation of Iron and Zirconium.(Zeit. f. nizgezu. Chenz., 1904, xx., 641, and xxi., 676.)-The use of nitroso-5-naphthol has already been proposed by the author and Ilinski for the separation of nickel from cobalt (ANALYST, x., 189) and iron from aluminium (ANALYST, x., 232), and by the author alone for the separation of copper from cadmium, magnesium, manganese, zinc, mercury, and lead, also of iron from manganese, zinc, nickel, and chromium (Ber., xx., 283). The separation of iron from beryllium has been dealt with by Schleier (Chem. Zeit., 1892, 420), and Atkinson and Smith (Joz~rn. dmer. Clzcnz. SOC., svii., 698). Burgass has shown its suitability for the separation of copper, iron, and cobalt from antimony and arsenic (Zeit.f. ayezu. Chem., 1896, 596); and, finally, Knorre has now worked out a method for separating iron and zirconium by means of nitrosonaphthol. To the solution containing zirconium and iron tartaric acid is added, and then a slight excess of ammonia. If the quantity of tartaric acid be sufficient, complete solution should now take place, even if there were some cloudiness before the addition of the ammonia. The liquid is diluted 200 C.C. and slightly acidulated with hydro- chloric acid; 10 to 20 C.C. of acetic acid are added, the liquid boiled, and precipitated with a hot solution of nitrosonaphthol in acetic acid. When quite cold the ferric nitrosonaphthol iR filtered off, washed and ignited, and weighed as ferric oxide. Zirconium can be estimated in the filtrate by evaporating to dryness and igniting to destroy tartaric acid, but it is more convenient to determine iron and zirconium together in a separate portion by precipitation with ammonia, and obtain the per- centage of zirconium by difference.G. v. Knorre. A, M. Some Methods for the Detection of Cobalt and Nickel. Stanley R. Bene- diet. (Journ. Amer. Chem. SOC., xxvi., 695.)-The following test is proposed for the detection of nickel in the presence of an excess of cobalt, as little as 2 per cent. of nickel being recognisable with comparatively little trouble : The solution of the two270 THE ANALYST. metals is treated with an excess of sodium peroxide and heated to boiling. This treatment oxidizes the cobalt, but not the nickel. The precipitate is washed and repeatedly treated on the filter with a cold saturated solution of oxalic acid, which dissolves both hydroxides, the cobalt forming a complex cobaltioxalate. A few drops of potassium ferricyanide are added to the liquid to oxidize the nickel, and then a small excess of sodium hydroxide is added.If nickel is present, a black precipitate or colour is produced, the cobalt not being precipitated. For the detection of both cobalt and nickel the author uses the following simple method: To the solution of the two metals an excess of 5N sodium hydroxide is added, and the colour of the precipitate is noted. With cobalt a dark blue precipitate is obtained, which changes in a few seconds to a bright pink. The presence of small quantities of nickel delays this change in colour somewhat. If much nickel is present the change may not take place for half an hour or more, and only a dirty grey colour is produced; whilst, if no cobalt is present, the precipitate is pale green.Very small quantities of cobalt give a bluish tinge to this colour. By making comparative tests with solutions of the pure salts, less than 1 per cent. of either metal may be detected in this way in presence of the other. A. G. L. Separation of Chromium and Vanadium. P. Nicolardot. (Compt. Xc7zc1us7 March 28, 1904 : through ClLem. ATezcs, 1904, lxxxis., 182, ISS.)-Two methods are described. I n the first the chromium is distilled off as chromyl chloride, and in the second the vanadium is precipitated together with ferric oxide by evaporating in the presence of nitric acid, all chromium remaining in solution.First Jfethocl.-A mixture of chlorides, chroniates, and anhydrous alkali vana- dates is treated with sulphuric acid containing a little anhydride in a dry bulb. At first the heat evolved is sufficient to cause the action to proceed, but the evolution of chromyl chloride is assisted by attaching the apparatus to an air-pump, and heating the bulb towards the end of the reaction. The last traces of chromyl chloride are removed by a current of dry air. To retain a little vanadium, which is carried over mechanically owing to the energy of the reaction, a small wash-bottle containing concentrated sulphuric acid is placed between the bulb and air-pump, the chromyl chloride being absorbed by sodium hydroxide solution contained in a second wash- bottle placed immediately before the air-pump.I n the case of ores or compounds containing chromium and vanadium, a pre- liminary fusion with a mixture of sodium carbonate (1 part) and chlorate (4 parts), or with a large excess of chlorate alone, is necessary. Small quantit'ies of iron and manganese, if present, are separated by the ordinary methods. The alkaline salts are then concentrated, dried, melted, and the molten mass is completely washed until the washings are colourless. If no iron be present, the mixture can be directly melted in the bulb mentioned above, and the process proceeded with. The bulb should not be heated above 60" C., and the current of dry air must be drawn through the apparatus until no more red fumes are evolved.To prove that all chromium has been removed, the residue is treated with hot sodium carbonate solution, and then with ammonia. If a Precipitate of chromium hydroxide be obtained, the processTHE ANALYST. 271 must be repeated. To determine the vanadium in the residue, a little alcohol is added, and the mixture heated until all the alcohol has been driven off. The solution is then titrated with permanganate. The presence of molybdenum does not influence the titration. Second Method-If the compound containing the chromium and vanadium also contain a large quantity of iron, it may be attacked with hydrochloric acid, the solution obtained oxidized with nitric acid or chloric acid, and then evaporated on the water-bath in the presence of an excess of hydrochloric acid.The greater quantity of the acid is thus driven out, and a precipitate of ferric oxide obtained which retains the metalloids, the metals remaining in solution. The soluble chromic acid is separated, except traces which remain in the ferric oxide precipitated. These traces are extracted by treating the ferruginous deposit with hot water containing a few drops of alcohol. After boiling the mixture, ammonium sulphate is added, when all the chromium is dissolved. The vanadium is separated from the iron precipitate by first washing with ammonia and then fusing with alkaline salts to remove the last traces, These two methods may als3 be used for the separation of chromium from other metalloids or metals. w. P. s. The vanadium is now determined volumetrically.The Quantitative Analysis of Chromite. L. Duparc. (Ann. de Chirn. anal., 1904, ix., 201-203.)-The following method is stated to obviate the difficulties usually experienced in the analysis of chromite, which has the formula Cr,O,,FeO, but invariably contains silica, iron in the ferric state, alumina, and magnesia. The mineral cannot be attacked by acids, and is best fused with sodium carbonate in a platinum crucible. For this purpose it should be reduced to an extremely fine powder, of which not more than 0.3 gramme should be taken. A t least eight hours’ heating is necessary for complete disintegration of even this quantity. The crucible is then immersed in cold water and left for several hours, and the resulting liquid, containing ferric oxide in suspension, heated on the water-bath with successive small additions of hydrochloric acid until the iron oxide has dissolved.The silica is then rendered insoluble and separated in the usual manner, and the chromium, iron, and aluminium precipitated from the filtrate by means of ammonia. The filtrate from these hydroxides contains the magnesium and calcium, which are determined in the usual manner. For the separation of the chromium, iron, and aluminium, the calcined oxides are finely powdered and fused with sodium carbonate. The mass is treated with water and insoluble ferric oxide filtered off, dissolved in hot hydrochloric acid, and reprecipitated with ammonia. The filtrate containing sodium chromate and aluminate is neutralized with nitric acid, avoiding the slightest excess, and the aluminium precipitated with ammonia, of which an excess is also avoided.Finally, the chromium is precipitated as lead chromate or as hydroxide, after reduction with hydrochloric acid. C. A. M.2 72 THE ANALYST. The Analysis of Ferrosilicons. H. Cantoni. (Ann. de Cliim. anal., 1904, ix., 203, 204.)-The compound FeSi resists the action of dilute acids, but is attacked by alkaline solutions with the liberation of hydrogen and formation of a silicate. The compound Fe,Si is not attacked by nitric acid, but is soluble in hydrochloric acid. Industrial sili- cates containing 10 to 20 per cent. of silicon are known, whilst Chalmot has described products containing 40 to 50 per cent. These consist of mixtures of two definite compounds, Fe,Si, and FeSi,, insoluble in acids.The author has been able to separate the compounds FeSi and Fe,Si from ferrosilicons rich in silicon (60 to 80 per cent.) by the successive and prolonged action of hydrochloric and sulphuric acids (5 per cent.), and concludes that these do not contain the compounds described by Chalmot. He recommends the following rapid method of disintegration as a general method : The finely-powdered ferrosilicon is mixed with sodium peroxide and fused in a copper crucible, the fusion being complete in a few minutes. The crucible is then suddenly cooled so as to detach the mass, which is then treated with distilled water. The silica is separated in the usual way by evaporation with hydrochloric acid, the copper from the crucible removed by a current of hydrogen sulphide, and the iron, manganese, etc., determined in the filtrate.From 7 to 8 grammes of sodium peroxide are required for the fusion of 0.5 to 0.6 gramme of ferrosilicon. A copper crucible is attacked much less than a nickel one. Alkaline solutions only attack when hot and concentrated. C. A. M. Determination of Sulphur in Calcium Carbide. Hj. Lidholm. ( h i t . f. angezo. Chcm., 1904, xvii., 558.)-Sulphur occurs in commercial carbide principally as calcium and aluminium sulphides, the latter being the more objectionable impurity, as it evolves sulphuretted hydrogen more readily. The sulphur is estimated by fusing the carbide with potassium sodium carbonate (ammonium chloride being added to render the mass more fusible), and is subsequently evolved as sulphuretted hydrogen.This may be oxidized with bromine or hydrogen peroxide and precipitated as barium sulphate, or absorbed in the manner described below. About 3 grammes of the pulverized carbide are weighed out and mixed with five times as much sodium potassium carbonate and two parts of ammonium chloride, and the mixture is heated in a closed crucible over a powerful spirit-lamp, being kept in a state of fusion for about five minutes. The crucible and its contents are allowed to cool, and then introduced into a flask provided with an inverted condenser and a, dropping funnel. The evolved gases are led from the top of the condenser to a series of absorption vessels. The last traces of gas are driven out by boiling and leading a current of carbon dioxide through the apparatus. The absorbent liquid used by the author consists of 5 gramrnes of cadmium acetate, 20 grammes of zinc acetate, and 200 C.C.of acetic acid, made up with water to 1 litre. When the whole of the gas has been driven over, the precipitated sulphides of cadmium and zinc are converted into copper sulphide by adding 10 C.C. of a solution Water is added, and afterwards hydrochloric acid gradually.THE ANALYST. 273 made by dissolving 120 grammes of copper sulphate and 120 C.C. of concentrated sulphuric acid in 1 litre of water. The copper sulphide is filtered off, washed, and ignited. A. If. The Determination of Free Sulphur in ‘‘ Golden Sulphide of Antimony ” for the Manufacture of Rubber. W. Esch and Fritz Balla. (Chenz. Zed., XXViii., 595.)-The authors have made experiments to test the correctness of Weber’s asser- tion that antimony pentasulphide is more or less decomposed into the trisulphide and free sulphur by extracting it with boiling carbon disulphide.. They find that the pure solvent has no action, although impure carbon disulphide appears to decompose the pentasulphide to some extent. They also find that for the determination of the free sulphur in the antimony sulphide the use of carbon disulphide is preferable to that of acetone or benzene. A. G. L. The Titration of Hydrogen Fluoride and Silico-fluoride. J. Katz. (Chcm. Zcit., xxviii., 356, 387.)-In bitrating aqueous solutions of hydrogen fluoride and silico-fluoride with standard potassium or barium hydroxide solution, using phenol- phthalein as indicator, the author found that a permanent red colour is obtained only when, after the neutralization of the hydrogen fluoride, a further quantity of alkali, corresponding to 6 molecules of KOH (or 3 of Ba(OH)2) for every 1 molecule of H,SiF,, has been added. When alcoholic solutions are titrated with potassium hydroxide, on the other hand, 1 molecule of H2SiF, requires even less than 2 molecules of KOH, since the precipitated potassium silico-fluoride carries down with it some hydrogen fluoride.Empirically, the author has determined the quantity of hydrogen fluoride carried down, which varies with the ratio of the two acids to each other, and uses the following procedure for the analysis of commercial hydrogen fluoride, which generally contains some silico-fluoride : The acid is diluted so as to contain 3 to 6 per cent.of HF ; 10 grammes are then heated to boiling a,nd titrated with 2N potassium, or, better, sodium hydroxide. The titration may also be carried out in the cold, in paraffined vessels, if calcium chloride is added, which hastens the decomposition of the hydrogen silico-fluoride owing to the insolubility of the calcium fluoride formed. Another portion of PO grammes of the diluted acid is then titrated with 2N potassium hydroxide, after the addition of 100 C.C. of 60 per cent. alcohol, phenolphthalein being used in both cases as indicator. The difference between the alkali used in the two titrations is a measure of the quantity of hydrogen silico- fluoride present. According as to whether this difference amounts to less than 5, from 5 to 10, from 10 to 20, or more than 20 per cent.of the total quantity of alkali used, it is multiplied by the factors 0*0576, 0.0580 to 0.0595, 0*0600 to 0.0610, and 0.0617 to find the quantity of hydrogen silico-fluoride present in the 10 grarnmes of acid taken. The quantity of hydrogen fluoride corresponding to this is obtained by multiplication with 0.833 ; to find the amount of hydrogen fluoride present as such, this value is deducted from that for the total hydrogen fluoride, which is found by multiplying the number of C.C. used in the first titration by 0.004. (This value should evidently be 0*040.-A. G. L.)274 THE ANALYST. The method appears to be sufficiently accurate for technical purposes, especially in view of the fact that the difference between the two titrations rarely amounts to more than 6 per cent.of the whole. A. G. L. The Detection of Chlorides in the Presence of Bromides. Chapman Jones. (Chem. News, lxxxix., 229.)-The silver salts of the halogens are allowed to remain in contact with cold ammonium bicarbonate solution for a few minutes, with occa- sional agitation. On acidifying the liquid with nitric acid, a distinct turbidity is produced if silver chloride was present, whilst the bromide gives at the most a very faint turbidity. To test whether this last is due to a trace of chloride present or only to the bromide, the turbid liquid is divided into two parts ; to one a slight excess of bicarbonate solution is added, to the other an equal quantity of water. If the turbidity is due to silver chloride, the ammonium bicarbonate will dissolve it in a few seconds; if it is caused by bromide, it will remain unaffected for several minutes at least.In this way small quantities of chloride can be identified in the presence of much bromide. The The part diluted with water serves for comparison. ammonium bicarbonate solution should not be too old. :I, G. L. The Volumetric Determination of Chlorates, Bromates, and Iodates. L. D6bourdeaux. ( A m . de CTzim. anal., 1904, ix., 167, 168.)-This method is analogous to that devised by the author for the determination of nitric nitrogen (ANALYST, xxix., IOO), and is based on the fact that oxalic acid in a solution con- taining 12 per cent, of sulphurjc acid is destroyed by chloric, bromic, or iodic acids, though the reactions are not quantitative unless an intermediate oxidizing agent is present, such as manganese sulphate. Thus the oxalic acid solution used for the nitric acid determination (loc.cit.) is quantitatively decomposed in accordance with the equations : HC10, + 3C,H20,.2H,0 = 6C0, + 9H20 + HC1. 2HI0, + 5C,H20,.2H,0 = IOCO, + 16H,O + I,. HBrO, + 3C,H20,.2H20 = GCO, + 9H20 + HBr. . The precautions as to the proportion of sulphuric acid and manganese sulphate and mode of heating found necessary for nitrates also hold good for these determina- tions. The residual oxalic acid is titrated with standard permanganate solution, the halogens being first precipitated by the addition of silver nitrate, since otherwise their hydracids would be acted upon by the potassium permanganate.The method can also be adapted to the determination of hypochlorites, hypobromites, and hypo- iodites, these compounds being first converted into chlorates, etc., by boiling the liquid with a few drops of sodium hydroxide solution. Picrates and perchlorates have no action upon the oxalic acid in the reagent, C. A. M. The Estimation of Cyanates. Thomas Ewan. (Joz~rn. Soc. Chenz. Ind., November 15, 1904.)-In this communication an account is given of an examination into the usual methods for the determination of cyanates in samples of potassium orTHE ANALYST. 275 sodium cyanide. These methods depend on : (I) The insolubility of the silver salt ; (2) the decomposition of an aqueous solution of cyanic acid into COB and NH,.First method: As silver cyanate is soluble in water (at 12.) to the extent of 0-006 per cent ., small quantities cannot be accurately determined. Separation by means of dilute nitric acid is also unsatisfactory, as silver cyanate is but slowly soluble in cold 5 per cent. nitric acid, whilst hot acid dissolves the cyanide. The loss by this method was material, and in the presence of substances giving silver salts results were not even approximate. A slight excess of sulphuric or hydrochloric acid is added to a solution of 1 gramme of the sample in 50 C.C. of water in a distilling flask. The distillate (30 C.C. to 40 c.c.) is collected in dilute caustic soda and baryta solution, and the apparatus is swept out by a slow current of air free from GO,. The barium carbonate is filtered off, and titrated with & HC1.(A preliminary examination for carbonate is made by precipitating a cold solution with barium chloride.) The ammonia may be distilled off after addition of caustic soda, and collected in & HC1. Figures are given which show that a considerable degree of accuracy is obtainable by this method, though it is pointed out that, if carbamate were present, it would behave like the cyanate. The other method is sufficiently accurate for most purposes. H. A. T. - _ The Mechanical Analysis of Soils, and the Composition of the Fractions resulting therefrom. Alfred Daniel Hall. (Proc. Chem. Soc., xx., 152.)-The author has investigated the effect on the mechanical analysis of soils of the pre- liminary treatment with dilute acid followed by ammonia. For the separation into fractions, Osborne’s method of sedimentation was adopted, the soil being separated into two fractions by sieving and into five by sedimentation. He found that the raw soil rarely yielded as much of the finest fraction as was given by the same soil after washing with acid, the difference being greatest with soils rich in humus, the reason probably being that the humates, which act as a weak binding material, are decomposed by this treatment. Soluble salts, which might interfere, are also removed. The method consequently reveals the original character of the soil, irrespective of its manuring. A. G. L. T A New Magnesia Cupel. (Chem. News, lxxxix., 304.)-The Morgan Crucible Company now make magnesia cupels having a cup-shaped depression in the bottom, SO that the middle portion is not in' contact with the muffle floor. The advantage claimed is that the litharge absorbed diffuses evenly into the cupel and does not corrode the muffle, in spite of the comparatively slow diffusion of litharge in magnesia cupels, and the consequent tendency to run straight through the cupel. It is also claimed that cupellation is more rapid with this form than with the older cupels. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9042900266

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

276 THE ANALYST. INSTITUTE OF CHEMISTRY O F GREAT BRITAIN AND IRELAND. PASS LIST OF THE JULY EXAMINATIONS. OF twenty-three candidates who entered for the Intermediate Examination, the following fifteen passed : Leslie Hamilton Berry, Thomas William Cheke, Winifred Cox, B.Sc., Reginald Mead Filmer, Charles Gordon Gates, Harry Hurst, Vincent Herbert Kirkham, B. Sc., Jessie Mary Isabel Landon, B.Sc., Archibald William Mairet, Edwin Archibald Maskelyne, William Rest Mummery, Joseph Race, jun., Robert Robison, Robert Thatcher Rolfe, and Samuel Summerson. I n the Final Examination for the Associateship (A.I.C.), of eight who entered in Mineral Chemistry the following five passed : David Allan, John Alexander Campbell, David Cowan Crichton, John Gatecliff, jun., B. Sc., and Charles James ; one Candidate passed in Metallurgical Chemistry : Thomas Baker, M.Sc.; one Candidate passed in Physical Chemistry: Sydney Herbert Smith, Assoc.R.C.Sc. Of the five who entered in Organic Chemistry the following three passed : Robert William Clarke, Bernard Furley Davis, and Edgar Charles Martin, B.Sc. ; and of ten who entered in the Branch of the Analysis of Food and Drugs, and of Water, including Examination in Therapeutics, Pharmacology, and Microscopy, the following five passed : Walter Kay Cheshire, B. Sc., Harold Deane, B.Sc., Leonhardt Erich Hinkel, Ernest Gabriel Jones, B.Sc., and Francis Langston Watt, Assoc.R.C.Sc. Two Candidates were examined for the Fellowship (F.I.C.) and both passed: David Runciman Boyd, B.Sc., Ph.D., and James McLeod.The Examiners in Chemistry were Mr. Walter William Fisher and Professor George Gerald Henderson. Dr. Arthur P. Luff con- ducted the Examination in Therapeutics, Pharmacology, and Microscopy. It has been resolved by the Council that after October 1, 1905, any Fellow or Associate of the Institute desiring to obtain the Certificate in Therapeutics, Pharma- cology, and Microscopy will be required to pass the whole of the Final Examination in Branch (e), the Analysis of Food and Drugs, and of Water, which includes the Examination in Therapeutics, Pharmacology, and Microscopy. The fee for such Candidates will be $5 5s. Any Examination in Therapeutics, Pharmacology, and Microscopy held prior to October J, 1905, will be open to any Fellow or Associate of the Institute who can produce evidence satisfactory to the Council that he has been continuously and systematically engaged, for at least one year prior to the date of his application for admission to the Examination, in the Analysis of Food and Drugs, in the Laboratory of a Fellow of the Institute engaged in such practice. An Examination in Biological Chemistry is to be held at the Laboratories of the For particulars see notice in Institute, commencing on Tuesday, October 25, 1904. our advertisement columns.

ISSN:0003-2654    

DOI:10.1039/AN9042900276

出版商:RSC    

年代:1904

数据来源: RSC