ISSN:0003-2654    

DOI:10.1039/AN95075FX017

出版商:RSC    

年代:1950

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN95075BX019

出版商:RSC    

年代:1950

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN95075FP031

出版商:RSC    

年代:1950

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN95075BP035

出版商:RSC    

年代:1950

数据来源: RSC

摘要:

MAY, 1950 THE ANALYST Vol. IS, No. 890 PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS NEW MEMBERS, ELECTED FEBRUARY lsT, 1950 John Peter Bowen, A.R.I.C. ; Ronald James Fay; Ernest Barford Fielding, B.Sc. (Lond.) ; Allen James Goodall, B.Sc. (Lond.), A.R.I.C. ; Ronald Charles Jackson ; John Price Riley, BSc., Ph.D. (Liv.), A.R.I.C. ; Thomas Edward Rymer, F.R.I.C. ; George Sykes, M.Sc., F.R.I.C.; James Fairweather Walker, B.Sc. (St. And.), A.R.I.C.; Frank Williams, B.Pharm. (Wales), Ph.C., M.P.S. ANNUAL GENERAL MEETING THE Annual General Meeting of the Society was held at 4.30 p.m. on Friday, March 17th, 1950, in the meeting room of the Royal Society, Burlington House, London, W.l. The Chair was taken by the President, Mr. George Taylor, O.B.E., F.R.I.C.The financial statement for 1949 was presented by the Honorary Treasurer and approved, and the Auditors for 1950 were appointed. The Report of the Council for the year ending March, 1950 (see pp. 230-239) was presented by the Honorary Secretary and adopted. The Scrutineers, Dr. S. G. Burgess and Mr. D. M. Freeland, reported that the following had been elected Officers for the coming year. President-George Taylor, O.B.E., F. R.1 .C. Past Presidents serving on the Council-Lewis Eynon, E. B. Hughes, G. Roche Lynch, Vice-Presidents-D. C. Garratt, J. G. A. Griffiths, J. R. Nicholls. Honorary Treasurer- J. H. Hamence. Honorary Secreta ry-K . A. Wi 11 iams . Other Members of Council-The Scrutineers further reported that 346 valid ballot papers had been received and that votes had been cast in the election of Ordinary Members of Council as follows-A. L.Bacharach, 257; D. W. Kent-Jones, 228; J. Haslam, 182; H. H. Bagnall, 179; E. Voelcker, 170; A. A. Smales, 144; R. H. Jones, 143; D. D. Moir, 126; F. R. Williams, 123; H. J. Evans and S. G. E. Stevens, 120; A. N. Leather, 117. The President declared the following to have been elected Ordinary Members of Council for the ensuing two years-A. L. Bacharach, D. W. Kent-Jones, J. Haslam, H. H. Bagnall, E. Voelcker, A. A. Smales. R. C. Chirnside, E. T. Illing, J. King, C. J. Regan and N. Strafford, having been elected members of the Council in 1949, will, by the Society’s Articles of Association, remain Ordinary Members of the Council for 1950. J. G. Sherratt (Chairman of the North of England Section), J.Sword (Chairman of the Scottish Section), R. Belcher (Chairman of the Microchemistry Group), B. S. Cooper (Chairman of the Physical Methods Group) and N. T. Gridgeman (Chairman of the Biological Methods Group) will be ex-oficio members of the Council for the forthcoming year. After the business outlined above had been completed, the meeting was opened to visitors, and Sir’E. John Russell, O.B.E., D.Sc., F.R.S., delivered the first Bernard Dyer Memorial Lecture (see pp. 240-251). 229 G. W. Monier-Williams,230 ANNUAL REPORT OF COUNCIL [Vol. 75 NEW MEMBERS, ELECTED MARCH 1 7 ~ ~ , 1950 Miss Joan Abigail, B.Sc. (Lond.) ; John Andrews, B.Sc. (Lond.), F.R.I.C. ; Cecil Walter Ballad, B.Sc. (Lond.), Ph.C., F.R.I.C.; Jitertdra Nath Barman, B.A., MSc.(Calcutta), A.R.I.C. ; Ronald Charles Curtis, B.Sc. (Bristol) ; William Melville Eno; Brian Montague Gibbs, B.Sc. (Lond.), A.R.I.C. ; Tennyson Harris, Ph.C., A.R.I.C. ; Joseph Ephraim Ho-Yen, B.Sc. (Lond.), A.R.I.C. ; . Kenneth Armitage IKyde, B.Sc. (Leeds), A.R.I.C. ; Jack Philip Jefferies, B.Sc. ; Henry Austen Jenkins, A.R.I.C. ; Frank Pace Johnson, BSc. (Lond.), A.R.I.C. ; Edwin Charles Jones, B.Sc. (Lond.) , A.R.I.C. ; Frank James McMurray ; Albert Ronald Moss, B.Sc., Ph.D. (Lond.); Ernest Richard Pike, M.P.S., F.R.I.C.; John Barnabas Price, B.Sc. (Birm.) ; John Norman Robson, B.Sc. (Lond.), A.R.I.C. ; Rudolf Rothwell; Rosemary Pemberton Russell, B.Sc. (Edin.) ; Isidore Schreiber, B.A. (Cantab.) ; Hedley Raymond Stafford, A.R.I.C. ; Gordon Roy Sutcliffe, F.R.I.C. ; Ronald George Toms, B.Sc. (Lond.) ; Frank Arthur Walker, F.R.I.C.; Ernest Roy Sealey Winter, B.Sc., Ph.D. (Lond.), A.R.C.S., D.I.C., A.R.I.C. DEATHS WE regret to record the deaths of Norman Parr Booth. Alfred James de Hailes. John Arthur Heald. Y. V. Srikanteswara Iyer. Robert Tatlock Thomson.

ISSN:0003-2654    

DOI:10.1039/AN9507500229

出版商:RSC    

年代:1950

数据来源: RSC

摘要:

230 ANNUAL REPORT OF COUNCIL [Vol. 75 Annual Report of Council: March, 1950 THE roll of the Society numbers 1547, an increase of 51 over the membership of a year ago. HoNouRs-During the year the C.B.E. has been awarded to Dr. J. R. Nicholls, the O.B.E. to Mr. H. T. Cranfield, and the M.B.E. to Mr. R. L. Collett. Dr. J. H. T. Ellingham has been elected to an Honorary Fellowship of the Imperial College of Science and Technology. The Council offers its congratulations to the recipients of these honours. HONORARY MEMBER-The Council is very pleased to record that Sir E. John Russell, O.B.E., D.Sc., F.R.S., has been elected an Honorary Member of the Society. DEATHS-The Council regrets to have to record the death of the following members- C. T. Bennett J. Hendrick W. P. Skertchley W.Rhys Davies Y. V. S. Iyer H. F. Stephenson N. N. Dutta C. H. Robinson R. T. Thomson J. W. Hawley Sir Robert Robertson A. J. de Hailes Sir Robert Pickard Bennett was educated at Wyggeston High School, Leicester, and qualified as a chemist and druggist in 1898 and as a Ph.C. a year later. He entered the service of Wright, Layman & Umney Ltd. in 1898 and remained associated with them as chief analyst until his death. He graduated B.Sc. of the University of London in 1905 and became a Fellow of the Institute of Chemistry in 1909; he joined the Society in 1910. He was an expert on the chemistry of essential oils, and served on the sub-committees responsible for these and related substances in the British Pharmacopoeia and the British Pharmaceutical Codex.Rhys. Davies received his scientific training at Bradford City Technical College and at the University of Leeds. He started an analytical and consulting practice in Bradford in 1902 in which he dealt mainly with the problems of the wool industry and later extended his interests to the technology of textiles, oils, fats and waxes. He became a Fellow of the Institute in 1927 and joined the Society in 1!329. de Hailes worked in the laboratories of G. W. Wigner and Dr. Redwood, and mean- while studied physics and chemistry at the Pharmaceutical Society, King’s College (under Professor Hartley), City of London College and the Birkbeck Institution. He set up in private practice in 1885. About 1894 he became assistant to Theophilus Redwood; later he went into partnership with him, and too:k over the practice when Redwood died.He joined the Society in 1889.May, 19501 ANNUAL REPORT OF COUNCIL 231 Hawley was apprenticed in 1904 to Readman & Gemmell, consulting chemists in Edin- burgh. In 1912 he joined the Glasgow Corporation Chemical Laboratory as assistant to F. W. Harris. In the war of 1914-18 he was commissioned in the Highland Light Infantry and saw service in France. He returned to his work at Glasgow and in 1926 was appointed Public Analyst and Official Agricultural Analyst for Dumfriesshire and later for Kircudbright and Wigtownshire. He served as a member of the Council of the Institute of Chemistry and was a Vice-president of the Society in 194142. He was a founder member and a Chairman of the Scottish Section of the Society.Hendrick joined the Society in 1897 after becoming lecturer in agricultural chemistry in the University of Aberdeen and chemist to the Highland and Agricultural Society of Scotland. He was Public Analyst and Official Agricultural Analyst to a number of local authorities, but resigned these positions in 1912 to become the first Strathcona-Fordyce Professor of Agriculture in the University. On his retirement he received the title of Emeritus Professor, and in the next year the University of Aberdeen honoured him with the degree of LL.D. Robinson, a B.A. of Toronto University and a Fellow of the Canadian Institute of Chemistry, was Dominion Agricultural Chemist for Canada. He joined the Society in 1940. Robertson received his scientific training at the University of St.Andrew’s, becoming M.A. in 1889 and B.Sc. in 1890. He received his doctorate in 1897 and was subsequently made H0n.LL.D. He was for two years assistant to R. R. Tatlock in Glasgow, and in 1892 went to the Royal Gunpowder Factory, Waltham Abbey. In 1907 he became superintending chemist in the Chemical Research Department, Woolwich, where he rose to be Director of Explosives Research. He was appointed Government Chemist in 1921, retiring from that post in 1936. Next year he was appointed Director of the Salters’ Institute of Industrial Chemistry. He was elected F.R.S. in 1917, and received the Davy Medal of the Society in 1944. He was President of the Faraday Society, 1923-24, and was created K.B.E. in 1918. He was a Vice-president and Censor of the Institute of Chemistry and an Honorary Member of the Society.Pickard studied under Tilden and Frankland at Mason College, Birmingham, and graduated B.Sc. of the University of London in 1895. Next year he went to Munich to work under A. von Bayer and Thiele and gained the degree of Ph.D. summa czcm Zaude. In 1900 he was awarded the degree of DSc. by the University of London. A year earlier he had been appointed head of the chemical department of Blackburn Municipal Technical College, and in 1905 became its Principal. In 1917 he was elected a Fellow of the Royal Society. He became Principal of the Battersea Polytechnic in 1920 and in 1927 succeeded A. W. Crossley as Director of the British Cotton Industry Research Association. From 1920 to 1927 he was Director of the British Leather Manufacturers Research Association and he remained consultant to that body until the time of his death.He was elected an Honorary Liveryman of the Leathersellers Company in recognition of his interest in the industry. He was Vice-Chancellor of the University of London, 1937-39, and was elected Chairman of Convocation in 1948. He was President of the Royal Institute of Chemistry, 1936-39, and an Honorary Member of the Society. Skertchley was born at Ambaston, Derby, in 1872, and educated a t St. Andrew’s Church School and London University. He became assistant to Otto Hehner in 1892, joining the Society in the same year, He was elected a Fellow of the Institute of Chemistry in 1899. For many years he was an abstractor for The Analyst. He assisted Percy Spielman with Richter’s Organic Chemistry.In 1917 he went to British Celanese Ltd., becoming chief analyst in 1920, and held this position until he retired in 1949. He was President of Borrowash Bowls Club for many years. Stephenson was awarded the Associateship of the Royal College of Science in 1889, in which year he became chief assistant to Professor Groves, chemist to the Thames Conservancy. He subsequently succeeded to the office of chemist to the Conservancy and the P.L.A., retiring in 1945. For many years he was analyst to the Rotherhithe Gas Works and to the Acton Urban District Council. Thomson founded, in 1888, with his uncle the late R. R. Tatlock, the firm of Tatlock and Thomson, analytical and consulting chemists, Glasgow. He was the originator of the method for the determination of boric acid by titration in presence of glycerol.He held the appointments of public analyst and official agricultural analyst for many of the Scottish counties. He joined the Society in 1893, and died in his 95th year. He served on the Council of the Society in 1902-03. He was knighted in 1937. He joined the Society in 1910.232 ANNUAL REPORT OF COUNCIL p o l . 75 ORDINARY MEETINGS-Five Ordinary Meetings of the Society were held during the year “A Technique for Paper Chromatography iising Volatile Solvents, with Special Reference to the Estimation of Penicillin in a Mixture.” By P. B. Baker, M.P.S., F. Dobson and A. J. P. Martin, M.A., Ph.D. “Penicillin, some Applications of a Chromatographic Technique in Production Control.” By J.W. Albans, B.Sc., A.R.I.C. “Report of the Analysts’ Sub-committee of the Ministry of Health Conference on the Differential Assay of Penicillin.” “The Colorimetric Determination of Streptomycin B (Mannisido-streptomycin).” By W. B. Emery, BSc., F.R.I.C., and A. D. Walker, B.Sc., A.R.I.C. “The Chemical Determination of Nicotinic Acid in Food Products.” By P. 0. Dennis, B.Sc., A.R.I.C., and H. G. Rees, B.!Sc., A.R.C.S., F.R.I.C. “The Reduction of Antimonial Tin Solutions with Metallic Nickel and Cobalt.” By H. Holness, M.Sc., F.R.I.C. “The Calculation of the Botanical Composition of Wheat Flours and Off als from the Chemical Analysis.” “A Photo-electric Method of Determining; the Colour of Flour, as Affected by Grade, by Measurements of Reflecting Power.” By D.W. Kent-Jones, B.Sc., Ph.D., F.R.I.C., and W. Martin, B.Sc. “Experiments in the Photo-electric Recording of Flour Grade by Measurements of the Reflecting Power.” By D. W. Kent-Jones, B.Sc., Ph.D., F.R.I.C., A. J. Amos, B.Sc., Ph.D., F.R.I.C., and W. Martin, BSc. The rheeting held in November dealt with “Some Recent Advances in Water Examination,” the following contributions being made- “Introductory Remarks.” “Recent Developments in the Coli-Aerogenes Test.” By C. B. Taylor, D.Sc. “The Determination of Turbidity.” “The Determination of Residual Chlorine.” By G. U. Houghton, M.Sc., F.R.I.C. “The Determination of Ammonia by Direct Nesslerisation.” By J. E. Houlihan, B.Sc., The February meeting was organised by the Physical Methods Group of the Society The following papers were “A Review of Some Developments in the 1Jse of the Karl Fischer Reagent.” By A.G. Jones, B.Sc., F.R.I.C. “A Radio Frequency Moisture Meter for Routine Control.” By A. T. S. Babb, B.Sc., A.R.I.C. “Moisture Determination of Granulated, Pulverised or Milled Food Materials such as Sugar Products.” By R. W. Money, M.Sc., F.R.I.C. “The Determination of Moisture in Tobacco.” By C. F. M. Fryd, B.Sc., A.R.C.S., A.R.I.C., and P. R. Kiff, B.Sc. An open discussion followed. JOINT MEETINGS-A Joint Meeting was held on October 18th, 1949, with the Agriculture Group of the Society of Chemical Industry and the Fertiliser Society. The subject of the meeting was “Fertiliser Analysis, with Special Reference t o Available Phosphoric Acid.” Contributions were made by Dr.E. M. Crowther, F.R.I.C., Mr. George Taylor, O.B.E., F.R.I.C., Mr. W. C. Hanson and Dr. J. H. Hamence, M.Sc., F.R.I.C. The December meeting of the Society was as usual a Joint Meeting with the Food Group of the Society of Chemical Industry. The subject was “Properties of Pectin and its Use in the Food Industry.” “Chemical Composition and Properties of l?ectin.” By J. K. N. Jones, D.Sc., A.R.I.C. “Laboratory Assessment of Pectin Quality with Special Reference to Jelly Grading.” “Distribution, Sources and Manufacture of Pectin.” By V. L. S. Charley, B.Sc., Ph.D. “Industrial Uses of Pectin.’’ By R. W. Money, M.Sc., F.R.I.C. and the following papers were communicated-- Read by C. R. Bond, M.Sc., F.R.I.C. By J. Straub, Chem.Ing. By J. H. Hamence, M.Sc., Ph.D., F.R.I.C.By Roy C. Hoather, B.Sc., Ph.D., F.R.I.C. A.R.I.C. and dealt with “Modern Methods of Moisture Determination.” presented- The following contributions were made- By Miss M. Olliver, M.Sc., F.R.I.C.May, 19501 ANNUAL REPORT OF COUNCIL 233 BERNARD DYER MEMORIAL LECTURE-The first Bernard Dyer Memorial Lecture was given at the Annual General Meeting, 1950, by Sir E. John Russell, O.B.E., D.Sc., F.R.S. The Council of the Society has decided to present Sir John and future memorial lecturers with a commemoration medal. NORTH OF ENGLAND SECTION-Four meetings have been held during the year at which the following contributions have been made- “Chairman’s Address.” “Tests of the British Pharmacopoeia, 1948.” By J. R. Walmsley, A.M.C.T., F.R.I.C., “The Application of Science to the Detection of Crime.” By J.B. Firth, MSc., D.Sc., “The Standardisation of Hortvet Thermometers.” By R. W. Sutton, B.Sc., F.R.I.C., “Notes on Molasses in Grass Meals and Pellets.” In addition there have been a number of discussions on matters of professional and scientific interest. Mr. W. Collingwood Williams, former Lancashire County Analyst, has generously provided the Section with a Chairman’s badge, and the indebtedness of the Society to him is most gratefully acknowledged. SCOTTISH sEcTIoN-In addition to the Annual General Meeting, three ordinary meetings were held during the year. One of the meetings took the form of an Exhibition of Films, presented by Dr. Dryerre. The subjects of the films included “The Making of Sheet Glass,” “Radar Goes to Sea,” “Microscopy of Opaque Objects,” “Refining of Oil,” “Protection of Fruit,” “Transfer of Power” and “Taken for Granted” (Middlesex C.C.sewage disposal plant). At the other two meetings lectures with practical demonstrations were presented, viz.- “Adsorption Chromatography.” “Some Micro Tests.” Although 4 members of the Section were transferred to other Sections and 2 members By C. H. Manley, M.A., F.R.I.C. Ph.C. M.I.Chem.E., F.R.I.C. and J. Markland, B.Sc., F.R.I.C. By F. Robertson Dodd, F.R.I.C. By Dr. Neil Campbell. By Dr. A. B. Crawford. resigned, the membership shows an increase of 14 and now totals 88. MICROCHEMISTRY GRoup-Three meetings have been held during 1949 : in London, Belfast and Nottingham, respectively. The Belfast meeting was held jointly with the Belfast and District Section of the Royal Institute of Chemistry and the Nottingham meeting with the East Midlands Section of the Royal Institute of Chemistry. The following papers have been read- “The Rapid Micro-analytical Determination of Carbon and Hydrogen in Organic Com- “Some Microchemical Problems associated with Plant and Animal Nutrition.” By “The Micro-determination of Oxygen in Organic Compounds.” By W.T. Chambers, “Microchemical Balance Design.” “Maintenance and Precision of Micro-balances.’’ “The Ultra Micro-balance.” There was also an open discussion on B.I.O.S. Final Report No. 1606, prepared by R. Belcher and D. F. Phillips, “Progress in Microchemistry in Germany.” An exhibition of all types of micro-balance manufactured in Great Britain was held at Nottingham. Three meetings will be held during 1950.The Annual General Meeting at London in January, the Spring Meeting at Teddington in May, and the Autumn Meeting at Birmingham in September. The number of Group members is now 309, an increase of 51 since the last report. The Group is now represented on the Analytical Methods Committee of the Society. In future all new Group members are to receive a letter of welcome describing the functions The possibility of compiling a card index showing in some pounds.” Stewart McConaghy. B.Sc., Ph.D., A.R.I.C. By A. F. Colson, B.Sc., Ph.D., F.R.I.C. By G. F. Hodsman, B.Sc., Ph.D., A.Inst.Pet. By D. W. Wilson, M.Sc., F.R.I.C. By C. L. Wilson, M.Sc., Ph.D., F.R.I.C. and activities of the Group.234 ANNUAL REPORT OF COUNCIL [Vol.75 detail the special interests of each member has been thoroughly investigated, and it is hoped to have this in operation early in 1950. The Council of the Society has again been approached regarding the Memorandum on the Teaching of Microchemistry which had been submitted through them to the Royal Institute of Chemistry. Although no reply has been received from the R.I.C. on this matter, the whole question of training in analysis is under review by the Council on broad lines in conjunction with the Royal Society, and an assurance has been given that Council will consider the Group Committee’s representations in the light of their own problems. A small Sub-committee has been formed to consider Micro-analytical Reagents in conjunction with British Drug Houses Ltd.Its terms of reference are to eliminate redundant items from the present list of reagents. The Nottingham Symposium on Micro-balances will, by arrangement, be published in extended form by the Royal Institute of Chemistry as a monograph. It has been decided that there should be a second meeting in the London area in 1950, in addition to the Annual General Meeting, and preliminary arrangemeuts have been made to hold this at Teddington, jointly with the London and South-Eastern Counties Section of the Royal Institute of Chemistry. PHYSICAL METHODS GROUP-The Physical Methods Group has held four meetings in London and one each in Nottingham and Sheffield during the past year. One of the London meetings and the Sheffield meeting had been organised by the Polarographic Discussion Panel. The Sheffield meeting was held jointly with the Sheffield Section of the Royal Institute of Chemistry and the Sheffield University Chemical Society.All the meetings were well attended. The Polarographic Discussion Panel, which now has 68 members, organised two Group meetings. Dr. Cule Davies was the Chairman of the Panel and for the greater part of the year Dr. J. E. Page acted as Honorary Secretary. The following papers were read and discussed at meetings of the Group- Annual General Meeting, London, November 30th, 1948. “The Measurement of Colour.” By R. Donaldson, M.A. Rheology Meeting, London, January 25th, 1949. “Industrial Applications of Rheology.” By G. W. Scott Blair, D.Sc., Ph.D., F.R.I.C.“The Application of Rheological Methods in the Milling and Baking Industries.” By A. J. Amos, B.Sc., Ph.D., F.R.I.C. “The Use of Rheological Tests in the Pharmaceutical and Cosmetical Industries.” By R. H. Marriott, D.Sc., F.R.I.C. “Rheological Methods and their Uses in the Paint Industry.” By P. S. Williams, B.Sc., A.R.C.S. “Recent Modifications in the Spekker Photo-electric Absorptiometer and Fluorimeter. ” “Some Experiments with the Spekker Photo-electric Absorptiometer and Fluorimeter.” “Buffer Solutions and the Concept of Polai-ographic Buffer Capacity.” “Paper Strip Extraction and Polarography.” “The Polarographic Behaviour of Aromatic Nitro-Compounds.” “The Technique of Moving Boundary Electrophoresis.” “Electrophoresis in the Analysis of Serum Proteins.” “The Effect of Antrypol on the Electrophoretic Pattern of Sera.” “Ionophoresis of Amino Acids and Peptides.” Polarography Meeting, Sheffield, October 7th, 1949.“The Use of Polarographic Methods for the Analysis of Fine Chemicals.” Photo-electric Absorptiometer Meeting, London, February 22nd, 1949. By R. A. C. Isbell, A.1nst.P. By F. Wokes, B.Sc., Ph.D., F.R.I.C., and G. Slaughter. B.A., A.1nst.P. Polarography Meeting, London, March llth, 1949. By P. Welford, By J. G. Waller, B.Sc., By J. A. Lewis. A.R.I.C. Electrophoresis Meeting, Nottingham, April lst, 1949. By R. A. Kekwick, D.Sc. By N. H. Martin, M.A., M.B., By A. E. Ambler, M.R.C.P., F.R.I.C. B.Sc., and J. Madinaveitia, Ph.D. By A. J. P. Martin, M.A., Ph.D. By G. H. Osborne, A.R.I.C.May, 19501 ANNUAL REPORT OF COUNCIL 235 “Applications of Mercury Drop Control to Differential and Derivative Polarography.” By L.Airey, B.Sc., A.R.I.C., and A. A. Smales, B.Sc., A.R.I.C. “Diffusion Current Measurement with the Tinsley Polarograph.” By W. Furness, B.Sc., F.R.I.C. The number of Group members is now 326. This represents a record increase of 76 since the last Annual Report. Dr. Page, who had been Honorary Secretary of the Group since May, 1946, has resigned from this post, and Mr. R. A. C. Isbell has succeeded him. The thanks of the Group and of the Council are extended to Dr. Page for the very excellent work he has done as Honorary Secretary. BIOLOGICAL METHODS GROUP-AS in previous years, the Group has held four meetings for the reading and discussion of papers. On December 17th, 1948, the Annual .General Meeting was followed by an ordinary meeting at which the following papers were presented- “The Assay of Aneurine by the Plate Method.” By A.Jones and S. Morris, DSc. “The Extraction of Growth Factors from Natural Products prior to Microbiological A Joint Meeting with the Agriculture Group of the Society of Chemical Industry was held on February 15th, 1949, on the “Evaluation of Selective Weedkillers.” The following papers were read- “Introduction to the Evaluation of Selective Weedkillers.” By M. A. H. Tincker, “Laboratory Methods and Trials leading up to the Field Use of Selective Weedkillers.” “The Evaluation of Selective Phytocidal Action in Field Trials.” By E. K. Woodford, “The Determination of Selective Weedkillers in Soils, etc.” By J.H. Hamence, MSc., Three papers were read at a meeting on May 26th, as follows- “Use of a Rotating Drum in Assessing the Activities of Paralysant, Convulsant and By H. 0. J. Collier, B.A., Ph.D., E. C. Fieller, M.A., and “The Microbiological Assay of Growth Factors after Paper Chromatography.” By “A Method for Determining the Potency of Heparin.” By R. F. Long, B.Sc., A.R.C.S. A meeting on “Hormone Assay” was held jointly with the Society for Endocrinology After the Assay.” By J. S. Harrison, M.Sc. M.A., D.Sc., F.L.S. By W. G. Templeman, M.Sc., Ph.D., F.R.I.C. Ph.D. Ph.D., F.R.I.C. Anaesthetic Drugs.” R. A. Hall. J. S. Harrison, M.Sc. on October 20th, 1949, under the chairmanship of Professor J. Gaddum, F.R.S. Chairman’s Introduction, the following papers were presented- By H.0. Schild. “General Approach to Biological Assay.” “The Measurement of Thyroidal Activity.” “The Assay of Insulin.” By K. L. Smith. “The Assay of Gonadotrophins.” “The Assay of Posterior Pituitary Lobe Extracts.” “Clinical Methods of Assaying Oestrogens.” By P. M. F. Bishop, B.M., B.Ch., M.R.C.S., In order that the Group may continue to provide a forum for the discussion of a wide range of topics of interest to bio-assayists there is a real need for members to support its activities by submitting research papers and encouraging their colleagues to do so. It is hoped therefore that members will overcome their natural reticence and come forward with communications suitable for ordinary meetings of the Group. Membership of the Group continues to increase, and now stands at 169; 34 new members have been added during the year and there have been no deaths or resignations.ANALYTICAL METHODS CoMMIrrEE-Sub-Committees continue to be very active and considerable work has been done. Progress reports indicate that material for publication should be ready for presentation in the near future. A Report from the Committee on the Evaluation of Flake Tragacanth (Analyst, 1949, By G. F. Somers, Ph.D., Ph.C. By J. A. Loraine, M.B., Ph.D., M.R.C.P. By G . A. Stewart, B.Sc. L.R.C.P., B.A., D.M.236 ANNUAL REPORT OF COUNCIL [Vol. 75 p. 2) and a note on the Determination of Riboflavine by Chemical Means (Analyst, 1949, p. 528) have been published. A new Sub-committee has been formed to investigate the Determination of Egg Yolk Solids in Salad Cream and a Sub-committee is to explore and report on the best procedure for securing the production in this country oi an efficient fluorimeter suitable for analytical purposes.The Bibliography of Standard Methods of Analysis, prepared by a Sub-committee of the Analytical Methods Committee, has been completed and is in the hands of the printers. PUBLIC ANALYSTS AND OFFICIAL AGRICULTURAL ANALYSTS COMMITTEE-The Committee have met on four occasions during the past year. Many matters of domestic interest to Public Analysts have been discussed and infclrmation circulated to members. Questions of fees and service conditions have also been considered. Awongst the various activities in relation to other bodies, the Milk (Special Designation) Bill was considered and representations were made thereon to the Ministry of Health.Representations have been made to the Ministry of Food on various matters. Advice on problems connected with food has been given to the County Councils Association. Two members of the Committee have been appointed particularly to assist the County Councils Association in this matter. Representations have also been made to the Royal Institute of Chemistry in respect of certain circulars issued by a Provincial Supervisor of the Ministry of Agriculture and Fisheries. Members of the Committee have attended on a number of occasions at the Ministry of Fuel and Power, and have participated in discussions arising on the testing of commercial petrol under the Motor Spirit Regulations.LIAISON COMMITTEE-During the year thie following appointments have been made- Dr. G. W. Ferguson and Mr. W. M. Seaber, additional members of the Essential Oils Miss I. H. Hadfield and Dr. G. H. Wyatt, Filtration Apparatus Committee. Mr. S. Dixon, Standards of Cleanliness for Hessian Committee. Dr. J. G. A. Griffiths, Committee on Chemical Symbols and Abbreviations. Mr. W. H. Simmons, Committee on Soaps for Domestic Use. Mr. E. S. Hawkins, Committee for Stand.ardisation of the Orsat Apparatus. Dr. K. A. Williams and Mr. J. King, Oils, Fats, Greases and Soaps Industry Standards Dr. W. Mitchell, Committee on Tragacanth. Mr. W. H. Simmons, Ministry of Healthi, Advisory Committee on Detergents. Dr. J. G. A. Griffiths was re-appointed to represent the Society on the Joint Library Committee of the Chemical Society. Mr.C. H. Manley was appointed as representative of the Society on the County Advisory Committee (West Riding North) of the Yorkshire Council for Further Education. Dr. W. F. Elvidge reported that the Regional Advisory Council for Further Education in the East Midlands, on which he represents the Society, was extremely active during the year and was performing a very useful service. Many other reports were received from the representatives of the Society, and the Council takes this opportunity of thanking all its representatives for the work they have carried out on the various Committees on behalf of the Society. HONORARY TREASURER’S REPORT-For the last two years the Society’s accounts have shown a substantial loss on the year’s working, and for the first time in the history of the Society it has been found necessary to increase the membership subscription. This increase in subscription has been occasioned mainly by the heavy increase in the cost of producing The Analyst, and also by the increased expenditure which has been necessitated by the considerable advance in recent years of the Scciety’s activities.The decision of the Council to increase the subscription to two guineas is based upon the report of the Sub-committee which was set up to consider the finances and the future developments of the Society, and it is hoped that it will cover not only the imreased cost of The Analyst and the working B.S. I. Committees- Committee. Committee. 0 ther Committees-May, 19501 ANNUAL REPORT OF COUNCIL 237 expenses of the Society, but will also leave a small balance which can be utilised for future developments. THE ANALYST-Considerable difficulties were experienced early in 1949 in publishing The Analyst within a reasonable time of its proper publication date; and a very determined effort was initiated to ameliorate the situation.This has had a great deal of success, but a little more time must elapse before we can ensure publication on the 16th of each month. The Council of the Society approved far-reaching changes which have operated from the beginning of 1950. Of these the most noticeable is the disappearance of the abstracts section. As was indicated in the editorial article prefaced to the January issue of the journal, it is no longer justifiable to devote the necessary labour, expense and printing space to the production of working abstracts which cannot perform for modern methods of analysis what the same system achieved for the classic techniques. In place of our old system, members and subscribers will be supplied with Abstracts C, less detailed in nature, but covering a far wider field than The Analyst has ever before reviewed.The thanks of the Council have been conveyed to all the abstractors and to Mr. L. S. Theobald for the great work they have done in the preparation of Analyst abstracts in the past, and also to the members of the panel of the Publication Committee who have advised during the last few years on the suitability of original papers for abstracting in The Analyst. The Council has subscribed to the Royal Society’s Fair Copying Declaration so that photo-copies of original papers which have appeared in The Analyst may become obtainable from libraries.In accordance with the wishes of the Royal Society we have adopted the system of placing a synopsis of each paper at its head. THE NAME OF THE SocIETY-The Council has given earnest consideration to the replies made by members to the questionnaire circulated last year on this subject. It was clear from these that a majority was in favour of a change of the name of the Society. We were advised however that such a change would require a Special Resolution passed a t an Extra- ordinary General Meeting by a three-fourths majority. Until then the idea of a change of the name had been thought necessarily to involve some modification of the objects of the Society by either the deletion or the alteration of Clauses 3 (c) and 3 (D) of the Memorandum of Association.The Council decided by a large majority that such deletion or alteration was not desirable, and that whatever the name they would continue to look after the pro- fessional interests of members. It was believed that uncertainty on this issue had influenced the answers of some members to the questionnaire, and the Honorary Secretary was instructed to call an Extraordinary General Meeting at which the Council would recommend changing the name to “The Society for Analytical Chemistry” so that the true verdict of the members could be obtained. This meeting was duly held in September last; including proxy votes, 253 votes were cast in favour of the change and 164 against.The majority in favour of a change was thus not high enough for the Resolution to be passed as a Special Resolution, and the name of the Society remains unchanged. considering the Memorandum and Articles of Association recommended to the Council that alterations should be made in the procedure for electing new members of the Society, in the composition of the Council and in the procedure for the nomination of ordinary members of the Council and for their election. These recommendations were adopted by the Council, which, in turn, recommended them to Extraordinary General Meetings, where they were adopted by large majorities. It is intended that the amendments should be incorporated in a reprint of the Memorandum and Articles to be sent to all members.ORGANISATION-A Special Committee was appointed during the year to consider the future organisation of The Analyst and of the office of the Society. So far as The Analyst was concerned it recommended that, starting with the January, 1950, issue, abstracts should no longer be published in the journal, but that arrangements should be made for the supply of Abstracts C to all members. Conversations with the Bureau of Abstracts, made with the approval of the Council, led to such an arrangement being agreed upon and extended to cover the supply of these abstracts to all subscribers to The Analyst as well. On the suggestion of the Bureau, the Council has nominated a representative to sit as a Director on the Bureau and it has also nominated two representatives to sit on the Abstracts C Committee.MEMORANDUM AND ARTICLES OF ASSOCIATION-The Special Committee which had been238 ANNUAL REPORT OF COUNCIL [Vol. 75 The Council adopted a recommendation that an Assistant Editor should be appointed to assist Mr. Lane, and that Mr. Okell should be asked to continue his services on the Editorial staff. Mr. Attrill has been appointed as Assistant Editor, and Mr. Okell has been Acting Editor since Mr. Lane was ordered complete rest for a time. The recommendation was also adopted that Miss Wilson be appointed Secretary from the beginning of 1950, the appointment to appear in The Analyst. The Special Coimmittee made recommendations which were amended only to a very small extent by the Finance Committee, whose final form of them was adopted by the Council.These recommendations included the increase in subscription noted above and the increase in the cost of The Analyst to outside subscribers. The Honorary Treasurer’s budget, which he had made for the convenience of the Special Committee, was reviewed and accepted by the Council. The funds of the Analytical Investigation Scheme (amounting to some fT240) were made available by the Council in grants to Sub-committees of the Analytical Methods Committee for out-of-pocket expenses in connection with their work, and the name of the scheme was changed to the “Analytical Investigation Fund.” Council further decided to apply a sum of money handed to the Society by the late Dr.C. A. Mitchell, and now known as the Miss Elliott Fund, to purchase some article such as a piece of furniture which might serve as a memorial to Miss Elliott. It was decided that no general payments should be made to members of Committees and Sub-committees (apart from those of the Groups) to cover travelling expenses, though special cases might be dealt with on their merits. Tentative negotiations were started by the Special Committee, with the approval of the Council, for obtaining new office accommodation. PLACE OF ORDINARY MEETINGS OF THE SOCIETY-During the spring of 1949 the Society continued to meet in a number of different places in London, but an invitation was received in the summer from the Chemical Society for us to avail ourselves again of their Rooms in Burlington House.This was gratefully accepted by the Council, and meetings have been held there since October, as in the past. CHEMICAL CouNcIL-The Council of the Society gave sympathetic consideration to a letter received from the Chemical Council whic:h laid emphasis on the importance of obtaining the publication of short articles on chemical topics in the more prominent weekly papers as well as in some of the more important daily papers. The President retired from representing the Society on the Chemical Council in December, 1949, and Dr. J. H. Hamence was appointed in his place. The Council again made a grant to the Society towards the cost of The Analyst, for which the Council of the Society expresses its gratitude. An endeavour is being made by the Chemical Council to ensure that all societies represented on it draft their accounts in the same manner, so that they may easily be collated. It appears that our own accounts are already in the desired form.INTERNATIONAL CONGRESS ON ANALYTICAL CHEMISTRY-The Executive Committee set up last year to organise an International Congress in 1952, and referred to in the last Annual Report, has made considerable progress during the year. An approach has been made to the Council of the International Union of Pure and Applied Chemistry for its patronage. This was accorded at the meeting of the Union in Amsterdam in September, where six autonomous sections of the International Union were formed, one of which was concerned with analytical chemistry. It is regarded as likely that a meeting of the Board of this section can be arranged to coincide with the Congress.It is expected that the Congress will meet in Oxford during the second week of September, 1952. The Chairman of the Executive Committee is Mr. George Taylor, the President of the Society, and its Honorary Secretary is Mr. R. C:. Chirnside. Sir Wallace Akers has consented to act as Chairman of the Finance Committee, and Sir Robert Robinson, President of the Royal Society, continues to act as Chairman of the General Committee, and to show his interest in the successful outcome of the organisers’ efforts. TRAINING IN ANALYSIS-The Royal Society received the Report on Training in Analysis, sent to them by the Society at the end of our last year, with considerable interest; and they passed it on to the Council of the Chemical Society who appointed a special committee to consider the memorandum.The following detailed comments have been passed to the Council of the Society by the Royal Society. “The large part that has been played by analysis in the building of the present structure of chemistry is recognised. It is considered desirableMay, 19501 ANNUAL REPORT OF COUNCIL 239 that in each large University there should be one member of the Faculty who would interest himself in analytical work and give lectures on the various methods of analysis. It was thought that the establishment of a Chair of Analytical Chemistry would not by itself be the best way of raising the standard of analytical work in the country and preference was given to possible improvement in the equipment in the Universities, etc., especially of physico- chemical analytical apparatus.The advantage was recognised of letting students see and handle some of the specialised equipment. It was recommended that methods of analysis should be integrated into the general course at the Universities, and emphasis was laid on the necessity for insistence on accuracy at all stages, including that of secondary school education. The further advantage of making problems realistic was dwelt on. It was hoped that the Society might suggest analytical subjects for post-graduate research.” During the year members of the Society have undertaken the task of lecturing on a wide variety of analytical subjects to post-graduate students at a number of educational establish- ments, and it has become evident that their efforts have been appreciated. It is hoped that this work may be extended in the near future.WATER ANALYSIS-A Joint Committee, set up by the Institution of Water Engineers, on which Mr. S. E. Melling and Dr. J. H. Hamence represent the Society, has issued a report in which standard methods of analysis of water are detailed. These methods will be con- sidered for adoption by the Society as standard methods after twelve months. PRESERVATIVE REGULATIONS-During the year a Joint Committee of the Society and the Food Group of the Society of Chemical Industry was set up to consider the Preservative Regulations made by the Ministry of Health in 1925-27, which have been in existence for nearly 25 years with only slight modifications. This Committee has reported, and the Council of the Society and the Committee of the Food Group have adopted the report.The Joint Committee remarks that it is clear that in the period for which the Regulations have operated many developments have taken place in food manufacture and processing which could not have been foreseen when the Regulations were made; and these make it essential that the definition of the term “preservative” should be amended, and the application of the Regulations more precisely defined. It is admitted that it will be difficult to draw up a definition that would be generally and permanently applicable, and it is recognised that it is necessary that a more detailed schedule than now exists should be drawn up and that this schedule should be kept constantly under review. The Joint Committee has made detailed suggestions for the amendment of the Regulations. The report, as adopted, has been sent on behalf of the Society and the Food Group to the Ministries of Food and Health. the Society on this Committee, reports that it has met four times since he was appointed, and has been concerned with the XVth Conference of the International Union of Pure and Applied Chemistry, held at Amsterdam in September, 1949, and the decision to hold an International Congress on Analytical Chemistry in this country in 1952. At Amsterdam, the International Union organised itself into six autonomous sections, one of which deals with Analytical Chemistry, and this section now comprises those Commissions which are interested in branches of this aspect of chemistry. Mr. N. Strafford and Mr. R. C. Chirnside have been elected members of the Board of the section. SUMMER SCHOOL IN ANALYTICAL CHEMISTRY-The London Section of the Royal Institute of Chemistry has organised a Summer School in Analytical Chemistry to be held in London in the late summer of this year. The Council is pleased to record that it was invited to participate in the preliminary arrangements by the Committee of the London Section, and that it accepted the invitation. Attendance at the School has been confined to members of the Society and members of the Royal Institute. A very gratifying response to the anno**- fiamnn + of the project has been received. BRITISH NATIONAL COMMITTEE FOR CHEMISTRY-Dr. A. M. Ward, the representative Of GEORGE TAYLOR, President. K. A. WILLIAMS, Honorary Secretary.

ISSN:0003-2654    

DOI:10.1039/AN9507500230

出版商:RSC    

年代:1950

数据来源: RSC

摘要:

240 RUSSELL: THE FIRST BERNARD DYER MEMORIAL LECTURE [Vol. 75 The First Bernard Dyer Memorial Lecture BY SIR E. JOHN RUSSELL (Delivered at the Annual General Meeting of the Society, March 17th, 1950) THE leading scientific societies in our country have developed the praiseworthy custom of periodically suspending their normal activities for an evening and reviewing some aspects of the work of one of their distinguished leaders who, though no longer with us, lives on in the notable things he accomplished. You have decided to commemorate in this way the work of Bernard Dyer, one of the founders of your Society, and your Council has done me the honour of asking me to give the first of these lectures. I am proud to do so : I had known him for almost fifty years and had a deep respect for his high analytical attainments, his complete intellectual honesty and, like others who knew him, had great affection for him in his kindly sympathetic human nature and the friendly accessibility and helpfulness he invariably showed to younger colleagues.He was born in London on February 25th, 1856, the son of J. A. Dyer, then the News Editor of the “Daily News”; after some preliminary instruction he went in January, 1871, to the City of London School, then in Milk Street. The school was in advance of most others in its day in that it had long included science in its syllabus. Formal teaching of practical chemistry had begun in 1847* when Thomas Hall, an assistant writing master, added this to his other duties; later, in 1860, a laboratory assistant, Henry Durham, joined the school and from 1868 was promoted to help in the science teaching.Hall retired in 1868 and was succeeded by Isaac Scarf: it was under him and Durham that Dyer received his first teaching in science. Neither of these men had any university qualifications, but Scarf was described as “a fine experimenter” by G. H. J. Adlam, a later senior science master of the school. There was a certain amount of self-teaching of science in those days (my own father indulged in it, much to the sorrow of my mother, who disliked the evening conversion of our small living-room into a very smelly chemical laboratory), and both Scarf and Durham clearly had scientific knowledge and the power to impart it. The head of the school, Dr. Edwin Abbott, one of the great headmasters of the nineteenth century, had already been in charge for six years when Dyer entered; he was primarily a grammarian and a theologian: his “Shakesperian Grammar” is described as a permanent contribution to English philology, and he wrote also many theological works.]But he encouraged science teaching in the school, in spite of the violent clash between Science and Theology that had broken out at Oxford in 1860 and never quite died down. Darwin, Huxley, Lubbock and Tyndall were all in full vigour. Huxley in particular was ca.rrying on a stirring campaign for the wide- spread teaching of science. A Royal Commission had in 1863 recommended that all boys should receive instruction in some branch of natural science during part of their school life, and Dr.Abbott faithfully carried this out; the science syllabus was broad, not to say ambitious: it ranged over chemistry, physics, botany, zoology and geology. I have been unable to discover any details of the teaching or what textbooks were used: Roscoe’s “Lessons in Elementary Chemistry” was then very popular; it first appeared in 1866 and passed through fifteen editions by 1869; other elementary science books covering the school subjects were in the same series. There was, of course, no organic chemistry: indeed, a distinguished scientist of the time had described it as “a more or less circuitous route to the sink.” Whatever a modern educational expert might think of the appliances and the paper qualifications of the teachers, the results were remarkable. A vigorous intellectual life developed in the school.Dr. Lance Kramer, the present senior biology master, to whom I am indebted for much information about the school at this time, tells me that the school was then conquering Oxford and Cambridge by scholarship winning. But much more important, some outstanding scientific leaders were being produced and the school can hardly ever have had a better group of future scientists than in the time that Dyer was there. F. Gowland Hopkins, five years Dyer’s junior, entered about the same time as he did; W. H. Perkin, jun., was there, as his distinguished father had been twenty years before, and also A. G. Perkin. * The centenary of this event was celebrated by a, brilliant function at the school on November 6th, 1948.May, 19501 RUSSELL: THE FIRST BERNARD DYER MEMORIAL LECTURE 241 Dyer, however, remained only two years at the school; he left in December, 1872, and decided on agricultural chemistry as a career. The choice seems remarkable.Dyer was a Londoner born and bred, with no particular agricultural associations so far as I have been able to discover, and chemistry in those days did not offer anything like the scope of later times. A few consultants were doing some very useful work, but for the young man without capital there was little more than teaching or a post as works analyst from which he might hope for promotion into the works itself. Having decided on chemistry, the choice of agricultural chemistry was not as strange as it sounds: London in 1872 was much closer to the country than it is now.Its population was only 3.3 millions, and including Outer London, 3.9 millions: the fields were only at walking distance from any point in the city, and places like Lewisham, Stratford and others were distinct and separate villages. London also had a large animal population. Refrigerator transport of milk had not yet begun; cows were very commonly kept in the yards and stalls of the retail milk-sellers who, in the main, were small individual tradesmen, the big combines not yet having started operations. Horses were the only source of traction; the mews were actual stables. For all these animals large quantities of hay, straw, grain, roots and other fodders were needed, and farmers’ carts came rumbling in from Essex, Kent and Surrey, bringing these commodities and taking back the animal manure.All these must have been familiar sights to young Dyer on his way to and from school. Whatever the reason of his choice, at the age of seventeen he became for three years pupil-assistant to Dr. Augustus Voelcker,* the leading agricultural chemist in the country, who, as consulting chemist to the Royal Agricultural Society, received in his laboratory in Salisbury Square, Fleet Street, samples of very varied kinds for analysis and report: soils, manures, feeding stuffs, and the many other farmers’ requisites, and he was so closely in touch with practical farm problems that he knew the sort of information his clients required. There were as yet no county agricultural institutes or advisory staffs; farmers in need of advice had to go to their own societies: either their county society, if they had one, or a great society such as the Royal, the Bath and West, or the Highland.For a young man ready to take full advantage of his opportunities the training must have been admirable. Dyer was fortunate too in his fellow-workers: they included Voelcker’s two sons, John Augustus and E. W., Alfred Smetham and F. J. Lloyd. Four of them: Dyer, the two Voelckers and Smetham rose to such distinction that they became Presidents of your Society; when I came into agriculture in 1901 all five names were held in great respect by the farming com- munity. Knowing what Dyer was like in later years, one can imagine that this group of able young men must have had great times both a t work and at play; he clearly was happy there, but as to details, history is silent: Mr.Eric Voelcker has kindly looked through his grandfather’s papers but found nothing.? Then in 1877, when he was only twenty-one years of age, he took his courage in his hands, and set up quite independently as analyst at 17, Great Tower Street, where he remained till the place was destroyed by a German bomb in the great air raid in May, 1941. I shall deal only with his agricultural work, leaving others more competent to deal with his work on food and other subjects.$ He had at the time, so far as I can discover, only one official appointment, that of consulting chemist to the Devon County Agricultural Association, but his ability and his attractive personality clearly stood him in good stead, for he succeeded in establishing himself and maintaining cordial relations with his old friends, the Voelckers.He wrote easily, and, indeed, had a flair for publicity; he published six papers on Rural Water Supplies in the Agricultural Economist for 1878, followed by a rapid succession of papers in the same journal on a great variety of agricultural subjects; besides a series of twenty-one papers on Geological Sketches during the years 1881 to 1883. He ranged from crop manuring to cattle condiments; from home-brewing to disposal of rural sewage: all topics of great interest to farmers; and he wrote shrewd commonsense in language they could understand. In 1880 he became Lecturer on Agriculture at the City of London College, * Mrs. Bolton, Bernard Dyer’s daughter, tells me that he already knew Augustus Voelcker’s sons, John Augustus and E.W. The school register does not show that any boy bearing the surname Voelcker ever attended the school. j. F. Gowland Hopkins, who left the school a few years after Dyer, also spent three years in a consulting chemist’s laboratory in the city, but found the life unsatisfying and unpleasant, so abandoned the profession. It might be interesting to speculate what would have happened had he had Dyer’s good fortune. $ Reference to these is made by Mr. George Taylor in the obituary notice he prepared for the Chemical Society (J. Chem. SOC., 1948, 896-8).242 RUSSELL: THE FIRST BERNARCl DYER MEMORIAL LECTURE [Vol. 75 and gave courses there during the next eight: years. Meanwhile, he was building up a reputation in connection with food and agriculture.More and more farmers turned to him for guidance; in due course he was appointed consulting chemist to the County Agricult‘ural Societies of Essex and Leicestershire, as well a:; to many smaller agricultural organisations. He did not confine his activities to the lalioratoiy; following the example of his great teacher, Augustus Voelcker, he made field experiments on actual working farms and published his reports on them in full detail. The first that I can find were made on turnips at Rusper, near Horsham, in 1882 and 1883,* and their purpose was to compare the fertilizing values of raw coprolites with dissolved coprolites, Le., superphosphate, made from them, in each case with and without dung.The reports are on Augustus Voelcker’s lines; and included fairly full analyses of the manures as well as the so-called total analysis of the soil: the amounts of iron, aluminium, calcium, magnesium, potassium, sodium, phosphoric acid and sulphuric acid extracted by strong hydrochloric acid under specified conditions, together with sufficient agricultural detail about previous cropping and manuring to answer questions the farmer would be likely to put. Field experiments rarely come out quite in accordance with the textbook, and this one di’d not: the raw coprolites gave better results than the superphosphate. Dyer at once recognised that this was due to acidity of the soil: an obvious enough explanation now, when soil acidity has long been a prominent subject, but it could easily have been missed then when few chemists thought much about it.Another o‘bservation which did not pass into general knowledge till years afterwards, when Scott Robertson made his well-known phosphatic trials in Northern Ireland, was that farmyard manure, in spite of its low content of phosphoric acid, is a useful source of phosphate to plants and need not always be supplemented with superphosphate. The combination of farmyard manure and superphosphate was no more effective than either alone. Oats were sown on the same plots in the following year so that the residual manurial values could be ascertained. Three years later, in 1886, he made experiments on the manuring of cabbage on the same farm, and showed the great value of nitrate of soda, especially when used in conjunction with phosphate and salt.In the same year h e began his field experiments in Essex with Edward Rosling, who became a life-long friend. Essex was then changing its system of husbandry : the old carn-growing husbandry was no longer profitable and was being displaced by dairying which required large quantities of mangolds, a new crop to many of the farmers. The problems were set by the Committee of the Essex Agricultural Society-was nitrate of soda or sulphate of ammonia the better fertilizer for mangolds, and should the application be at the time of sowing or later as a top-dressing? The experimental scheme was no doubt drawn up by Dyer-the duplication and systematic order of arrangement resembled those of the Sussex experiments-and after discussion, it was finally submitted to and approved by the Special Experiments Committee of the Royal Agricultural Society.As in Sussex, oats were grown in the following year without further manuring to discover the residual values, if any, of the manures applied to the mangolds. In 1887, basic slag was tried: it was then a new fertilizer and was called “basic cinder”: it contained 17 per cent. of P,O, (37 per cent. of phosphate) and its price was forty-eight shillings per ton; its fineness was sixty-five per cent. This set of mangold and oat experiments was continued €or several years, to test an idea then current among farmers that although artificials might give a heavy crop of mangolds, they did so at the expense of the condition of the soil-the next crop, it was thought, would surely suffer.Dyer showed this was not so: the heaviest crops of mangolds were generally followed by the heaviest crops of oats; even heavy dressings of nitrate of soda given to the mangolds benefited the succeeding oat crop, probably, as he surmised, because they produced a large weight of leaves which, being ploughed in, constituted a valuable green manure. These were busy years for Dyer, for besides fulfilling his numerous professional engage- ments and building up his extensive practice, he continued his academic studies, attending courses at the Pharmaceutical Society, King’s College and the Royal College of Science; in 1886-nine years after he had set up on his o’wn account-he sat for and was awarded the BSc. degree of the London University.The records of the Sussex and Essex field experiments ended in 1891. Three years later (1894) he began, with F. W. E. Shrivell, Golden Green, Hadlow, Kent, an extensive series The plots were in duplicate, systematically arranged. Here too the mangolds were followed by unmanured oats. * J . Roy. Agric. SOC., 1884, Vol. 20.May, 19501 RUSSELL: THE FIRST BERNARD DYER MEMORIAL LECTURE 243 of trials on the manuring of market garden crops, aided by a grant from the Chilean Nitrate Committee; these were continued for a number of years and summarised in his book, “The Manuring of Market Garden Crops,” 1904. The feature common to all his field experiments is that they invariably dealt with definite questions of practical importance put to him by the farmers themselves.Dyer devised and carried out simple straightforward experiments that would give the answer. He wrote the report in language which the farmers could understand. As one of them said about his interesting paper on Catch Crops at the Farmers’ Club in November, 1888: “It is wholly practical; it commenced without any introduction and finished without any peroration,” and J. A. Voelcker, in commenting on the discussion that followed, added: “Our scientific men have become practical and I really think that you practical men are becoming scientific.”* His success among the farming community arose from his shrewd interpretation of the results of the experiments and of his own observations and gleanings on actual farms. Very few of his judgments would require much correction in the light of subsequent knowledge. His attitude to grassland in 1886 is entirely modern: “there is perhaps no crop more amenable to good treatment than grass,” he said, “and none more apt to be neglected.”f The times were hard for farmers, and he always gave a financial summary of the results, with shrewd comments: he pointed out, for example, that, if the increased crop only just paid for the fertilizer and the additional cost of handling, there was still a profit because the overheads remained the same, and therefore the cost per ton had fallen.In all these reports Dyer published the analysis of the soil as made by the old method of hydrochloric acid extraction: the so-called “total analysis.” It is significant that he does not mention the analytical data in any of his discussions, and, indeed, looking back over the figures, it is difficult to see what he could have said about them.The P,O, content of his soils varied from about 0.1 to over 0.2 per cent., but the variations had no relation to the responses of the crop to phosphatic fertilizer. Some better method was obviously needed, and as early as 1884-two years after starting his field experiments in Sussex-he began to study the general question of solvents in soil analysis; after a good deal of intermittent work, some of which he states quite candidly was tentative and disappointing, he set about a more systematic enquiry. It had early been recognised that plants can take up only a small fraction of the potassium and the phosphate present in soils.Liebig, in his classical “Chemistry in its Applications to Agriculture and Physiology” published in 1840, had discussed the breaking down of the comparatively insoluble “alkali compounds” of the soil to a more soluble state. The final solution was, he supposed, effected by acetic acid excreted by the plant root and the dissolved material then entered the root. It was, however, Daubeny: of Oxford who first clearly distinguished what he called the “active” potassic and phosphatic plant nutrients from the “dormant” compounds in his classical memoir “On the Rotation of Crops and on the Quantity of Inorganic Matters abstracted from the Soil by Various Plants under Different Circumstances,” and he suggested that the “active” nutrients could be determined by extraction with a solution of carbon dioxide, thus simulating the relations between the plant and the soil.This brilliant suggestion unfortunately could not be carried out, no adequate chemical technique being then available. Unfortunately, also, this memoir did not receive the attention it deserved, and the subject was never properly followed up: Dyer does not seem to have known about it. But the distinction thus emphasised passed into general knowledge, the names adopted being “available” and “unavailable” plant food: this simple division into two groups accorded with the nineteenth century predilection for big, broad generalisations. Liebig’s son, Hermann, had in 1872 examined some of the Rothamsted soils and showed that dilute acetic acid extracted only a little potash from the continuously unmanured Broadbank soil, but twice as much from the soil that had received potassic fertilizer on farmyard manure.P. P. Dbhbrain also used acetic acid in examining the Grignon soils and showed that it distinguished soils responding to phosphatic fertilizer from those that did not.$ Other Continental observers made similar observations. Hellriegel and Wilfarth’s proof in 1886 that this was fixed from the air by the nodule organisms was not yet widely accepted. Dyer had quite an open mind on the subject. * Some of the discussion had turned on the source of nitrogen for leguminous crops. -t “Livestock Journal and Agricultural Gazette Almanac” for 1886. C. G. B. Daubeny, Phil. Trans., 1845, 179-253. Ann. Agron., 1881, 6, 392-3; 1892, 17, 445-54.244 RUSSELL : THE FIRST BERNARD DYER MEMORIAL LECTURE These facts were no doubt well known to agricultural consulting chemists, but were not used by them; it was assumed that the available potassium and phosphate would have some relation to the total, and if this was high in amount it might be assumed that the “available” material would be adequate in quantity.It was Dyer’s great achievement that he broke away from this view and devised a workable method whereby the analyst could discriminate between the available and the non- available mineral nutrients in the soil. Characteristically enough he was not influenced by Justus Liebig’s suggestion that plants obtain their minerals by a supposed secretion of acetic acid from their roots: he may even have overlooked the suggestion, as he does not mention it.Instead, he followed up work that had been started on the Continent on the evaluation of the new phosphatic fertilizers containing no water-soluble phosphate which began coming into use in the early 1880’s; in America, the so-called precipitated phosphate; on the Continent, finely ground mineral phosphlate; and both there and here thephosphatic slag produced by the Bessemer process for making steel. Some selective solvent was needed to discriminate between the more easily soluble phosphate readily available to the plant, and the less readily soluble, and therefore, less valuable phosphate. Ammonium citrate was tried; it seems to have answered well enough for. precipitated phosphate, but was not so good for other materials.Tollens suggested citric acid* as the solvent, and this was strongly supported by Stutzer, who confirmed that in 1 per cent. solution it gave results far more in accordance with field experience than the strong ammonium citrate solution then commonly used, The choice both of acid and of strength was purely pragmatic: the reagent worked well, therefore it was the one to use. It was with this background that Dyer approached the subject of soil analysis. Here also the problem was to distinguish the available fraction of the phosphate from the total. He tried various strengths of ammonium citrate and of citric acid and found no constancy in the amount of P,O, extracted: this varied with the solvent and its concentration. So he started with the assumption then widely accepted by plant physiologists, including Sachs, their great leader, that, as Dyer put it, “plants help themselves to a part of their mineral food by means of the solvent action of their acid root sap on the particles of soil with which the rootlets come into contact.” He collected a hundred plants of twenty different natural orders, separated their fine rootlets, estimated their moisture content, crushed and then boiled them in water, estimated the acidity of the extract in terms of hydrogen by titration with phenolphthalein as indicator, and then calculated the results back on the moisture content, so arriving at the percentage acidity of the root sap.He frankly admitted that the value of the results depended on the efficacy of the extraction process, which he therefore described in considerable detail.The range of values was from 0.003 to 0.014 per cent. in terms of hydrogen, but the value he adopted was 0.013 per cent. Expressed in terms of citric acid this came to 0.91 per cent. Assuming, then, that citric acid was to be used as solvent, the strength should be 0.9 per cent. Dyer rounded this off to 1 per cent., influenced no doubt by Stutzer’s results with phosphatic fertilizers. Partly, he said, because it is “an organic acid, and in that sense kindred to other root sap acids,” partly because “it is the acid generally used by those who have attempted to determine available phosphoric acid in manures,” and partly because “it is at hand in every agricultural laboratory in a state of purity, and therefore a convenient acid.” He claimed no special scientific basis for it: “since the choice of a solvent for use in soil analysis must in the end be empirical, both as regards its form and its strength, it seemed now worth while making some effort to test the expediency of adopting a 1 per cent.citric acid solution.” Fortunately he was persona grata with both Lawes and Gilbert, and was allowed in 1889 to draw samples of the soils from the Hoos field barley plots of which the manurial and agricultural history was well known. The soils that had received no phosphate for thirty-eight years, and on which the crops were suffering from obvious phosphate starvation, contained no less than 2610 lb. of P,O, per acre (0-087 per cent.), while that of the soil manured with superphosphate contained over 4100 lb.(0.14 per cent.): a marked difference certainly, but not capable of explaining the starvation on the unrnanured plots. One per cent. citric acid, however, extracted only [Vol. 75 But why did Dyer choose citric acid? * A. Grupa and B. Tollens, B e y . dlsck. Ckem. Ges., 1880, 13, 1267; v. Ollech and B. Tollens, Jouvn. f Land., 1882, 30, 519.May, 19501 RUSSELL: THE FIRST BERNARD DYER MEMORIAL LECTURE 245 0.005 to 0408 per cent. of P,O, from the plots without phosphatic manuring-160 to 230 lb. per acre-but about six times as much4.04 per cent., lo00 to 1200 1b.-from those that had received phosphatic fertilizer. Similar results were obtained with potash determinations : the “totals” obtained by hydrochloric acid extraction (which are much less than the true totals obtained by fusion methods) were meaningless; the figures obtained by extraction with 1 per cent.citric acid accorded with the agricultural history. Various other deductions were drawn by Dyer from the analyses, perhaps the most important being the confirmation that the major part of the phosphoric acid supplied in the mineral fertilizer remains in the top nine inches of soil, and much of it in a form soluble in 1 per cent. citric acid. He was never able to account for all that had been supplied, and had to assume either that it had disappeared into the sub-soil, or had changed into a less soluble form-this latter is the view now held. He also concluded that the “alkali salts” had rendered some of the soil phosphate more soluble, or, as he later thought more probable, that the manurial phosphate entered into some sort of combination with the alkaline bases and remained in a less insoluble state than if these had been absent; also that the sodium in nitrate of soda had increased the solubility of the soil potash enabling more to be taken up by the crop, but also increasing the loss to the sub-soil.But he was careful to qualify all these deductions by pointing out that they involved the assumption that the different plots had been chemically fairly uniform at the outset. The important practical outcome of this work was his conclusion that a soil containing less than 0.01 per cent. of P,O, soluble in 1 per cent. citric acid solution might be presumed to be in need of phosphatic manuring, while if it contained 0.03 per cent.it presumably was not. If the per- centage of K,O was 0.005 or less, potassic manuring would presumably be necessary for cereals, if 0.01 per cent. or more, it presumably would not. This paper formed the major section of a thesis on which the University of London, in 1892, awarded him the degree of Doctor of Science; it was later (1894) published by the Chemical Society* and attracted a good deal of attention. Lawes and Gilbert realised the value of the work and invited Dyer to make a similarly full examination of the soils of the famous Broadbalk wheat field. He did so, and again the results obtained by the citric acid method accorded well with the field experiments. This paper was presented to the Royal Society, and so much importance was attached to it that it was published in their Philosophical Transacti0ns.t Lawes and Gilbert also invited Dyer to go to the United States in 1900 to deliver one of the periodical courses of lectures for which Lawes had made provision in the Trust Deed of the Kothamsted laboratory.$ These lectures presented the whole of the data accumulated on the Rothamsted soils, and which Lawes had long wished to be brought within “one pair of covers” as he put it.Most of the material had centred round the nitrogen problems, always Gilbert’s chief interest, and here Dyer was little more than the reporters: Gilbert laid down the lines-he was somewhat of a martinet-and all Dyer’s tact was needed to keep things going smoothly. He did so, but he once confided to me that it had been no easy task.Dyer’s own work on the phosphoric acid and potash content of the soils fills some thirty-four out of the hundred and eighty pages; it was, of course, already known in the United States, but the Department of Agriculture was then in the charge of Milton Whitney, who attached little importance to the chemical composition of the soil, but much to its physical properties. In 1890, Mr. Goschen, the then Chancellor of the Exchequer, had put a tax on whisky, the proceeds of which might be used by a county for advancing agricultural education. Several counties took advantage of this and set up agricultural colleges or institutes, and the staffs, anxious to establish contact with farmers, undertook analysis of soils, fertilizers, feeding stuffs, etc., which had hitherto been done by consulting chemists.There were some complaints about this State-aided competition : whether it took business away from the profession or whether For root crops, however, he expected the limits would be higher. Dyer’s Chemical Society paper had appeared at an opportune moment. Trans. Chem. SOC., 1894, 65, 115-67. t Phil. Trans., 1901, 194B, 235-90. $ These had to be discontinued later : at first because material and lecturers were lacking, and afterwards $ Dyer had, of course, special knowledge of this work, having contributed an important paper to the when these abounded, because the financial provision had become wholly inadequate. Chemical Society in 1895 on the Kjeldahl method of determining nitrogen.246 RUSSELL : THE FIRST BERNARD DYER MEMORIAL LECTURE it created an entirely new clientele we need not now discuss; the fact remains that these new advisers wanted analytical methods, and Dyer’s citric acid test appealed very much to them.They were living and working among farmers; their advice was critically received and severely tested, and while at times they received credit for any successes, it was long before they heard the last of any failure. A. 11. Hall and F. J. Plymen at Wye, and T. B. Wood* at Cambridge, all used Dyer’s method and found it worked satisfactorily. Hall and Plymen tried other dilute acids: as no two extracted the same amounts of P,O, and K20 they gave up the old idea of two groups of compounds, one available and the other not available, and regarded the soil as made up of a large number of compounds of varying degrees of solubility and availability, but with no sharp boundary anywhere.Dyer agreed; he did not like the expressions “available” and “una\ailable” plant food in soil; he regarded them as over-simplifications. Turning to the practical question of finding a convenient solvent, Hall and Plymen pointed out, however, that none was so useful as citric acid: others usually put the soils in the right order but extracted 1e:;s P,O, than did citric acid, making the deter- mination more difficult. It was in any case tedious enough; the extraction was in Winchester bottles and lasted a week; the bottles had to be shaken daily, and Dyer had spoken of 4-00 shakes in all; the P20a was estimated gravimetrically by 0.Hehner’s method-but in those days men worked long and cheerfully, and were thankful for a method that worked well. I t was universally adopted at all agricultural institutions. He was now caught up on another line of work. The fertilizer and feeding stuffs trades had not been free from fraud-when I first turned to agricultural chemistry in 1901, one of my revered seniors assured me that, in the lump, all fertilizer people were rogues-and in 1893 the Government passed the first Fertilizers and Feeding Stuffs Act. As advisory chemist to many agricultural bodies, Dyer became intimately acquainted with the working of this Act and the very limited extent to which it met the farmers’ problems. He was a member of the Government Advisory Committee in connection therewith, and was consulted in regard to the amendments and changes that became necessary for the framing of the new Act in 1906, of which he gave a good account in his little book written for farmers, “Fertilizers and Feeding Stuffs”; this passed through a number of editi0ns.t The 1906 Act was not entirely satisfactory, and a new one was enacted in 1926, in the framing of which Dyer played an important part.I am not qualified to discuss these Acts and their bearing on the relations of the farmers and the analyst, but fortunately this is not necessary as it has already been done by your President, Mr. George Taylor, in his very interesting -Streatfeild Memorial lecture before the Royal Institute of Chemistry in 1947. Meanwhile, investigation of the soil itself, quite apart from any immediate practical problem, had been quietly going on in Europe, the United States and this country; it was extended here when in 1906 the Goldsmiths’ Cornpany endowed a research post at Rothamsted, and still more after Mr.Lloyd George set up the Development Commission, which from 1911 onwards made grants for agricultural research, and which later blossomed out into the Agricultural Research Council. The extended investigations thus made possible showed the great complexity of the phosphorus and potassium compounds in the soil. Bassett’s early observation3 that in neutral conditions most of the inorganic phosphorus of the soil is combined with calcium in the form of hydroxyapatite (C~P,O,),Ca(OH), was broadened by D. McConnell,$ who pointed out that the OH could be replaced b:y F, Cl, CO,, 0, or to a small extent by SO,, and the Ca by Mn, Fe and others, the lattice.remaining of the same general form. Other calcium phosphates also exist in the soil as do phosphates of aluminium and iron, especially in acid conditions. Some phosphorus also is held more or less firmly by the soil colloids, and a significant proportion is an organic combination. It has long been known that some changes take place in the soil whereby soluble phosphates become insoluble, for plants are able to extract from the soil about twenty or twenty-five per cent. of the added phosphate; [Vol. 75 Dyer, having safely launched the vessel, left it to follow its course. * A. D. Hall and F. 1. Plymen. Trans. Chem. Soc., 1902, 81, 117-44; A.D. Hall and A. Amos, Ibid.. 1906, 89, 206-22; T. B. Wood; Ibid., 1896, 69, 287; T. B. Wood-and R. A. Berry, J . Agvic. Sci., 1906, 1; 114-21. t The first edition had appeared in 1894 (Crosby Lockwood): it was founded on a series of newspaper articles which had appeared in several journals and widely circulated in different parts of the country. The 6th edition appeared in 1910. Trans. Chem. SOL, 1917, 111, 620. 3 Amer. Man., 1938, 23, 1.May, 19501 RUSSELL: THE FIRST BERNARD DYER MEMORIAL LECTURE 247 what becomes of the rest is not known. The potassium compounds in the soil are, if anything, even more complex in their range. Moreover, the processes by which the plant roots take up their nutrients from the soil are much more complex than was at first thought.The old idea that they excreted from their roots an acid which attacks insoluble phosphates and potassium compounds forming soluble substances which they then absorb was displaced by the view* that only CO, was evolved from the roots. This too has had to go; it is now known that there are other secretions, even it may be acid secretions. Plants vary in their power to absorb phosphates; what is “available” to one may not be “available” to another. Lupins are among the most efficient and Prianishnikov has shown that they help others growing along with them to obtain more phosphate from the soil, apparently by making it more soluble. Further, the plant root is not simply an absorber of dissolved substances: it can also effect exchanges with soil colloids.It would be interesting but would take far too long to set out the present positionof our knowledge of these two interacting complexities, the soil as the source of the plant nutrients and the plant roots as the absorbing agents. Our concern this evening is with the prospect of finding an analytical method that will give some measure of the amount of nutrients that crops can under normal conditions obtain from the soil, remembering, however, that this is not a fixed quantity but varies to some extent with the conditions. Dyer’s method came into wide but not universal use; other solvents in steadily increasing numbers were proposed. No two of these gave the same results: and for any solvent the amount of P20, extracted depended on the concentration of the solvent and the conditions of extraction.This problem was taken up at Rothamsted by J. A. Prescott and myself,? and we found that two reactions proceeded simultaneously when dilute acids acted on soils ; the acid dissolved out phosphate, but the soil slowly absorbed it from the solution. This back action was eliminated by using a diffusion technique, and then it was found that citric, hydrochloric and nitric acids in tenth normal concentration all extracted the same quantity of P20,, whereas by the ordinary analytical process the citric acid extracted nearly twice as much as the hydrochloric and fifty per cent. more than the nitric acid. The citric acid had done this because it had reduced the absorption of the P,O, by the soil. The absorption phenomena fitted the Freund- lich equation then in vogue, and we adopted a physical explanation, though it was afterwards pointed out by E.A. Fisher that a perfectly good classical chemical explanation could be given.$ The analytical data thus recorded the difference between the amount extracted by the acid, and the amount re-absorbed by the soil. Only the direct action is wanted by the analyst; the second upsets his results. So long as he is dealing with similar soils he may assume that the reverse action is also somewhat similar so that his results will still be com- parable, but when he is dealing with different soils the reverse action may be different and he may obtain different analytical results, even though the same amounts of P205 had been extracted. We concluded, therefore, that soil analysis could be helpful when used in con- junction with a soil survey showing the areas of comparable soils, but that standards applied to one soil would not necessarily be applicable to another.The soil survey should be accompanied by field experiments to show how crops on selected soils react towards fertilisers, and these soils being analysed become standards against which the analyst can measure other soils. This procedure is now widely accepted in principle, though not always adopted in practice. Citric acid long retained its popularity because it extracted easily weighable amounts of P205 and of potassium from soils. This advantage was lost when the modern turbidimetric, colori- metric and spectrographic methods came into use. The extremely sensitive molybdenum blue reaction worked out by DenigPsS revolu tionised P,O, determinations by enabling very small quantities to be estimated with sufficient accuracy, while the flame photometer enables equally small quantities of potassium, sodium and calcium to be estimated.Alternatively, potassium can be estimated colorimetrically by the cobalt blue colour developing when Curves expressing the results could be fitted by no ordinary equation. Modern developments in technique have profoundly changed the whole subject. * F. Czapek, Jahr. wiss. Bot., 1896, 29, 321. t J . Agric. Sci., 1916, 8, 65-110. $ Trans. Farad. SOC., 1922, 17, 305-316. 5 Comfit. rend., 1920, 171, 802 (SnCI, test).248 RUSSELL: THE FIRST BERNARD DYER MEMORIAL LECTURE [Vol. 75 ammonium thiocyanate reacts with the cobaltinitrite precipitate dissolved in nitric acid.* It is difficult for the young chemist of to-day, surrounded by mechanical aids and semi- automatic devices, to realise what a profound difference they have made to chemical work.As a student I was brought up on Otto Hehner’s method of determining P206: we always hoped for about 100 or 15Omg. of the ammoinium molybdate precipitate for comfort of weighing: this meant starting with 3 to 6 mg. of P20,. Later, instead of weighing the precipitate, we dissolved it in standard alkali, titrating the excess and arranged our solutions so that 1 ml. was equal to 1 mg. of P206; this was quicker but little more delicate. But in present-day colorimetric methods the quantities measured range between 0.002 and 0.01 mg.(2 to 10 micrograms). In ordinary advisory and routine work 0.005 mg. of P20, and 0.040 mg. of K20 can be determined. The choice of so1ve:nt nowadays, therefore, depends on the con- venience of working, and citric acid, which involves long extraction, evaporation and ignition, is at an obvious disadvantage. Any solvent, even water, can extract enough material for modern methods of measurement. However, like many other scientific advances, this has not led to simplification; on the contrary a bewildering array of solvents is now in use and it is rarely possible to discover why one rather than another is adopted. Mr. G. V. Jacks, Director of the Commonwealth Bureau of Soil Science, has kindly furnished me with a formidably long list, drawn up by Mr.Brind, of methods in use in the different countries. Of the various acids for estimating available P206, 1 per cent. citric acid is still used in this country and in the Dominions, though 2 per cent. is preferred in France, the U.S.S.R. and Java. Acetic acid is much used: 0.5 per cent. in this country and in Florida for the Everglade soils; Spurway’s 0.025 N elsewhere in the United States, also Morgan’s buffered solution of sodium acetate and acetic acid at pH 4.8. Truog’s sulphuric acid 0.002 N and ammonium sulphate buffered to pH 3 is widely used, 0.2 N sulphuric acid has been adopted in Denmark in place of the former nitric acid at a final pH of 2.5; elsewhere hydrochloric acid in various strengths, e.g., 0.75 N (S. F. Thornton of Purdue), 0.3 N in the Middle West of the United States and 0.05 N at Guelph. H.Egnkr’s calcium lactate, 0.028 N , buffered at pH 3.7 with 0.01 N HClt is much used in Germany, Finland, Holland and Russia and New Zealand; but in Germany, Riehm’s modifica- tion, having twice Egner’s concentration of lactate is preferred: it is said to be better for calcareous soils, and it has entirely displaced the citric acid methods formerly used there and also the Neubauer seedling method.$ With the increasing adoption of delicate estimations, water and carbonic acid are being increasingly used: Machigin claimed that carbon dioxide gave the best results with the carbonate soils of Central Asia; it is also used in Holland and in the United States for field tests on calcareous soils. Other analysts have given up acids and use alkalis, especially for calcareous soils: potassium carbonate in India., Russia and South Africa, 0.5 N KOH in Kenya on the fertile red soils.In the case of potassium the problem is more difficult because this element occurs not only as complex silicates, some of which are attacked by dilute acids, but also in combination with the soil colloids from which it can be dislodged by exchange with another base. This exchangeable potash is certainly important in plant nutrition. Two kinds of extraction reagents are adopted: various acids, e.g., 5 per cent. glacial acetic acid at Guelph, or those used for phosphate determinations, Egnbr’s or Riehm’s reagent in Germany; and solutions of neutral salts, e.g., 10 per cent. ammonium chloride to bring out the exchangeable potash.In England several solvents are used. The citric acid method, speeded up by shorter shaking and colorimetric measurements is still widely used, but 0-5 N acetic acid is preferred in the wetter regions of the north and west. Water or Morgan’s acetic acid and sodium acetate solution are also used. I t is doubtful whether the same methods for both phosphate and potash are adopted This does not yet exhaust the list. In no country is there any uniformity of procedure. * More usually at present the potassium is precipitated with sodium cobaltinitrite and estimated by titration with permanganate or ceric sulphate. -f Medd, Centr. Anst. Fiirsiiksv. Jordbr. (Stockholm), 1932, 426. The German methods are described in “Landu.. Versuchs- u.Untersuchungsmethodik (Methoden- buch) .” Die Untersuchung von BGden, I1 Auflage, R. Harrmann, Radebeul und Berlin, 1949, Verlag Neumann. For United States methods see U.S.D.A. Circ. No. 757, 1947, “Methods of Soil Analysis”; also Misc. Pub. No. 259 (chemical quick tests) and “D:iagnostic Techniques for Soils and Crops,” American Potash Institution, Washington, D.C., 1949. Mr. Jacks tells me that the Commonwealth Bureau of Soil Science has in hand the preparation of a monograph describing all these methods. Besides all these chemical methods there is a long list of biological methods which lie outside the scope of this lecture. Bd. 1.May, 19501 RUSSELL: THE FIRST BERNARD DYER MEMORIAL LECTURE 249 in any two of the provinces into which England is divided by the Ministry of Agriculture.Discussions to secure uniformity have led to no results. This is in many ways unfortunate, though less serious than might at first appear. I t is not claimed that the analytical figures have any particular scientific interest : their purpose is to help the adviser, and any procedure giving useful information can be justified. The modern methods of colour, turbidity and flame estimation are not only rapid, but some at least lend themselves to nearly automatic recording. Already direct reading pH outfits are available, mainly based on the glass electrode; last autumn I saw in Vienna the beautiful Zeiss instrument where the analyst had little more to do than put in the soil, and the pH value was then thrown on the screen. The flame photometer used for determining K, Na, Ca, etc., has been developed by Zeiss in Germany and by Beckman in America: the solution is atomised into the flame, the relevant section of the spectrum is selected by suitable filters and the intensity measured by photo-electric colorimeters which can be calibrated in any desired units. Colorimetric and turbimetric determinations are made with an absorption colorimeter, such as Spekker’s absorptiometer (Hilger), using appropriate filters. The next stage seems obviously to be automatic recording and perhaps it is not too fanciful a dream that some of you may live to see direct reading appliances linked up with automatic type- writers, so that the analyst will need only to put the soil into one end of the machine and the typed report will come out at the other.These new methods, along with the automatic balances and automatic pipettes, have speeded up analytical determinations enormously and have vastly increased the number of analyses that can be undertaken. Dr. T. W. Walker, the Advisory Chemist to the West Midland province, tells me that in his laboratory one hundred and fifty soils are analysed daily for pH, lime requirements, available phosphate and potash. In Germany, team processes of the conveyor belt type have been worked out whereby four hundred phosphate determinations per day can be made with the help of three workers, one washer and one trolley pusher, and eight hundred with a second shaking machine and two or three more workers.* Professor G. W. Robinson, lately in charge of the small advisory area of North Wales, reported on twelve thousand soil samples in his last year of office.Mass production of soil analytical data is not attempted in the United States on the same scale as in pre-war Germany, though some of the State Experiment Stations make several thousand soil tests in a year: on the results, Missouri bases some of its recommendations for the manuring of cotton, and Illinois its recommenda- tions for manurial treatment where high yields of maize are desired. Some of the American investigators have devised not only rapid methods, but dwarf apparatus, making a suitcase laboratory for field work, but the big apparatus has prevailed. It has thus become extremely easy to amass vast numbers of figures in soil analysis: but how is one to interpret them? Taking the general run of results the responses of fertilizers are higher in soils indicated by analysis to be deficient in the corresponding nutrient.This is well shown by E. M. Crowther’s investigations on the growth of sugar beet (Table I). TABLE I ANALYSES BY CITRIC ACID METHOD AND FERTILIZER RESPONSES IN SUGAR BEET EXPERIMENTS, 1936 TO 1946 (E. M. CROWTHER) Soil analysis P 0 mg. per 100 g. (soils wit{ less than 5% CaCO,) P 1 8 18-28 28-40 41-1 72 GO, mg. per 1OOg. 3-6 6-8 8-1 1 12-26 Number of experiments 54 54 54 54 63 61 62 62 Additional sugar, cwt. per acre for superphosphate 3.7 1.6 1.1 0.5 for muriate of potash 4.7 4.4 2.0 0.8 But the chemist is commonly called upon to advise on individual soils rather than on large groups of soils, and here the indications of analysis may not always be borne out in practice.H. Rheinwald and G. Constantin, Bodenk. PJ. Emahr., 1939, 16, 1-12.250 RUSSELL: THE FIRST BERNARD DYER MEMORIAL LECTURE Wol. 75 The analyst who is working on mass production lines cannot know the soils as individuals. The problem is made more difficult by the circumstance that the supply of soil nutrients is only one of the factors in soil productiveness, and may not be the chief. American experts have expressed the view that soil analysis may furnish about ten per cent. of the information needed by an agronomist for making an intelligent recommendation regarding a soil manage- ment programme. This ten per cent., however, may be very valuable, even indispensable. Production of valuable crops such as potatoes, sugar beet, market garden crops, involves heavy manuring which in ordinary practice is not to any great extent determined by the soil nutrients, while intensive livestock production yields large quantities of manure enriched with potash and phosphates from imported feeding stuffs, also without regard to the com- position of the farm soil.It is easy to become so absorbed in the elegance of the methods and the beauty of the apparatus that one is apt to forget that the figyres have little intrinsic value: their use is for comparison with known or standard soils, so far as other conditions permit comparison to be made. The greatest value of soil analysis is realised when it is done in conjunction with field experiments, best of all a systematic series such as those in the old German Feld- verszcchsringe, where a large group of fanners carry out uniform field trials with fertilizers under the direction of a competent agronomist.* The least satisfactory arrangement is to make large numbers of analyses without adequate field controls.This is now being done in some Continental countries, and attractive lit1.le booklets are issued to each farmer, telling him how much phosphate, potash, etc., his soils contain, and how'much fertilizer he must apply to obtain satisfactory crops. The analysts plead, and no doubt correctly, that they have no time to make the necessary field experiments. In between comes the case, not uncommon in Britain, where the results are interpreted on a purely arbitrary scale based to some extent on field trials and still more or1 field observations.In advisory work,soil analysts in this country adopt the sound policy of putting the soils into categories, rather than giving figures to the farmers. Dr. Walker uses three categories: deficient, average, not deficient; other analysts use more categories: it is a question of finding the best way of conveying practical recommendations to farmers. For lime requirements, the advice is probably satisfactory, and reasonably so for phosphate; it may be less so for potash, especially in the wetter regions. During the war, advisoiy chemists in this country had the duty of deciding which fields were to be allowed additional potassic fertilizer. Thousands of soils had to be examined. In the drier English counties, where large acreages of potatoes and other potash-sensitive crops are grown, the allocations of extra potassium to soils in which analysis suggested a deficiency, played an important part in increasing crop yields.In the wetter Welsh counties the results were less certain, and chemists were not altogether happy .about them. t There can be no question, however, that the position in this country is improving: 5eld experiments of the 2 x 2 x 2 and 3 x 3 >: 3 NPK type are being extended, also trials involving differential manuring are being made, and at the same time the relevant soil analyses, Much valuable knowledge is thus accumulating. The results would gain in value and in interest if uniform analytical methods were used, as comparisons could then be made, not only within each province, but with soils in other provinces. But where methods are necessarily empirical, much latitude must be allowed. The comprehensive investigations of E. M. Crowther and his colleagues at Rothamsted on the manuring of sugar beet will, when completed, throw much light on this subject.$ We have obviously moved a long way from the ideas that formed the background of Dyer's early work to those current to-day. The general change has accorded with the change in science itself. The nineteenth century was a time of great generalisations, majestic in their comprehensiveness, magnificent in their .simplicity. So arose the idea of the simple division of soil phosphorus and potassium compounds into two groups, available and non- available. In this century the accumulation of awkward facts that could not be fitted into SO simple a scheme broke down the old generahations. Hall and Plymen pictured a great range of slightly differing compounds with no sharp dividing line. The modern idea is more complex still: the soil is viewed as the seat of many varied interactions involving colloids, micro-organisms, the plant roots and the weathering processes; with no sharp upper or lower * These were discontinued under the Hitler r6gime. f See G. W. Robinson, Chcm. and Ind., 1943, 171-74. 3 It is a pleasure to thank Dr. Crowther for much help given me in preparing this lecture.May, 19501 SUTTON AND MARKLAND : HORTVET THERMOMETERS 251 limits. We are in the stage of recognising the complexities, but not yet of expressing them in terms of mathematical equations and degrees of statistical significance as has been done for some other sciences. The soil analyst, however, has to do something: he is called on to advise the farmer and he must adopt methods that give useful answers. The methods are at present empirical, and that means that he must have close contact with field experiments to satisfy himself that they really are working well; he must have a mind sufficiently open to reject them when they cease to do so, and sufficiently alert to be able to find or devise others that will be better. His work lies largely in regions not yet tidied up by the science of the day; his equipment must always be a wide knowledge of scientific methods combined with ingenuity of invention, soundness of judgment and complete intellectual integrity. It is because Bernard Dyer possessed these qualities in so marked a degree that we honour his memory, and in the words of Ecclesiasticus, count him among those “that have left a name behind them, that their praises might be reported.” That, however, is no new situation for a consulting chemist.

ISSN:0003-2654    

DOI:10.1039/AN9507500240

出版商:RSC    

年代:1950

数据来源: RSC

摘要:

May, 19501 SUTTON AND MARKLAND : HORTVET THERMOMETERS 251 The Standardisation of Hortvet Thermometers BY R. W. SUTTON AND J. MARKLAND (Read at the meeting of the North of England Section on February 26th, 1949) SYNoPsIs-Further evidence is brought to suggest that the use of sucrose solutions forms a satisfactory basis for the standardisation of Hortvet thermo- meters. Results obtained by the use of corrections from certificates supplied by the National Physical Laboratory for two thermometers are recorded. These are less concordant than those obtained by using corrections following standardisation of the thennometers with sucrose solutions. When the National Physical Laboratory corrections for these thermo- meters were used, the freezing-point depressions for sucrose solutions were invariably smaller than those recorded by Hortvet for 7 and 10 per cent.w/v solutions, and those calculated for intermediate strength solutions by Stubbs and Elsdon. As a result, freezing-point depressions of milk measured with these thermometers by the method proposed by Aschaffenburg and Hall are at least 0.005" C. smaller than would be recorded by the method used at present. IN a previous paperl we have discussed possible sources of error in the determination of the freezing-point of milk by the Hortvet process, emphasised the need for careful work with sucrose solutions, where there is somewhat greater difficulty in obtaining concordant results, and recommended the adoption of a standard technique in making the tests. Aschaff enburg and Hall,2 working with a platinum resistance thermometer, obtained erratic results with sucrose solutions, and record that with a 10 per cent.w/v sucrose solution there was a spread in the results amounting to 0.017" C. They concluded that standardisa- tion of Hortvet thermometers by the use of sucrose solutions was unsuitable and suggested that the thennometers should be standardised at a recognised testing institution to an accuracy of at least k0.002" C. on the International Temperature Scale. Such a system would have obvious advantages and equally obvious disadvantages but, whatever the balance in these, it is our opinion that the proposal ought not to be adopted until there is sufficient evidence that it would lead to more consistent results and that it would not necessitate a change in the limits hitherto adopted as typical of genuine milk.In our earlier paperl there is evidence that differences in replicate detenninations with sucrose solutions need not be large, and in this paper we bring further evidence to suggest that, by using a carefully standardised technique, large divergencies need not arise. We also give our experience in using thermometers for which certificates were obtained from the National Physical Laboratory. The results include determinations with three thermometers, Nos. 25918, 31320 and 425505. Certificates of examination have been supplied by the National Physical Laboratory for the latter two. Thermometer No. 25918 was in regular use in our department between 1933 and 1948 but, since no certificate for this thermometer was obtained, results with it are included only in Table I which deals with the reproducibility252 SUTTON AND MARKLAND: THE STANDARDISATION OF [Vol.75 of determinations on sucrose solutions. Results with thermometer No. 425505 are not included in Table I since only one comprehensive standardisation of this thermometer has yet been made. RESULTS WITY SUCROSE SOLUTIONS FOR STANDARDISATION Following the paper by Aschaffenburg and Hall2 we have made a survey of our results with sucrose solutions in the standardisation of two thermometers during the last five years. These results are given in Table I. TABLE I RESULTS IN STANDARDISATION OF THERMOMETERS WITH SUCROSE SOLUTIONS Thermometer 259 1944 . . 1944 .. 1947 .. 1948 .. 1948 . . Totals . . 7 per cent.w/v & No. of Average deter- correc- minations tion] O c. 8 . 18 0.0059 . 42 0.0071 . 12 0.0076 . 12 0.0076 . 84 0-0070 Thermometer 31320 1944 .. . . 12 0.0006 1947 .. . . 8 0.0032 1948 .. , . 12 0.0026 1948 .. . . 10 -0*0002 Totals . . * .. 43 0.0015 9 per cent. w/v 1 No. of deter- minations Thermometer 25918 1944 .. .. 10 1944 ,. .. 1947 .. .. 1948 .. .. 18 1948 .. .. 12 Totals - . . . 40 Thermometer 31320 1944 .. .. 16 1947 . . .. 1948 .. .. 12 1948 .. .. 10 Totals . . .. 38 1 Average correc- tion] O c. 0-0091 Q 0.0114 0.0110 0.0107 0.0041 0,0027 0-0015 0-0030 7.5 per cent:. w/v 8 per cent. w/v 8.5 per cent. w/v +--7 - & No. of Average No. of Average No. of Average deter- correc- deter- correc- deter- correc- minations tion, minations tion? minations tion, O c.O c. O c. 12 0.0094 13 0.0101 12 0.0099 12 0.0080 12 0.0102 12 0.0120 12 0-0086 12 0.0099 12 0.0105 36 0,0087 37 0.0101 36 0.0108 12 0.0025 12 0-0028 15 0.0022 12 0.0027 12 0.0023 12 0.0034 10 0-0018 10 0,0021 9 0*0016 40 0.0026 34 0.0024 36 0.0024 6 0.0028 9 5 per cent. w/v 10 per cent. w/’v +--7 - No. of Average No. of Average deter- correc- deter- correc- minations tion, minations tion, O c. O c. 12 0.0104 12 0*0110 7 0.0101 12 0.0117 12 0.0123 24 0.0113 31 0.0113 17 0-0041 14 0-0038 12 0.0026 10 0.0032 10 0.0023 10 0.0016 39 0-0032 34 0.0030 The average correction is that to be added to the depression determined in order to give the depressions adopted by Hortvet for 7 and 10 per cent. w/v solutions. and those calculated by Stubbs and Elsdons for intermediate strength solutions. It will be seen that in our work we do not encounter the large irregularities reported by Aschaffenburg and Hall.Usually a repeat standardisation with any sugar solution (involving about 10 or 12 determinations) has led to very little alteration in the correction previously used. The table does not include details of the spread of individual results, but we can state that with 10 per cent. sucrose solution the extreme figures in the 31 deter- minations for thermometer No. 25918 differed by 0.006” C. and those for the 34 determinations with thermometer No. 31320 differed by 0403°C. These results were for the most part obtained using sucrose of AnalaR quality, but a few of them were obtained with sucrose of “pharmaceutical quality” when the AnalaR reagent was not obtainable. Careful analysis of this sucrose failed to reveal the presence of any impurity, and polarimetric examination indicated that it was indistinguishable from 100 per cent.pure sucrose.May, 19501 HORTVET THERMOMETERS 253 We have encountered one sample of sucrose of "laboratory reagent" grade which appeared to be unsuitable. This particular sample was first used in the preparation of a 9 per cent. w/v solution during a complete re-standardisation of thermometer No. 31320. Ten measure- ments of the freezing-point depression were made. These were in excellent agreement in themselves, but they indicated a depression smaller by 0.003" C. than was expected from the previous standardisation. Up to this point the examination of solutions of other strengths, prepared from the last of the AnalaR quality sucrose, had indicated little need for change in the corrections.The sucrose was therefore suspected. It was found to be free from moisture and ash, but on polarisation we recorded an ccB of 67.3. The results were therefore consistent with the presence of a sugar of higher molecular weight and higher specific rotation than sucrose and, although we have not as yet obtained further evidence, we think that this particular specimen may have contained a small proportion of raffinose, which is known to be a constituent of sugar beet. Soon afterwards further AnalaR sucrose was available and the freezing-point depression of a 9 per cent. w/v solution was found to be in excellent agreement with previous work.Further, we have on many occasions examined samples of milk in two different cryoscopes fitted with thermometers which had been standardised with sucrose solutions. The agreement has been good. Our records for the last 52 samples so examined show that in 45 samples the results did not differ by more than 0.002" C., in 7 samples there was a difference of 0.003" C., and on no occasion was a greater difference found. Whilst, therefore, we have ourselves been concerned to point out the possibility of errors in working with sucrose solutions, we consider that these can be kept quite small and that the method forms a satisfactory basis for the standardisation of Hortvet thermometers. RESULTS USING CORRECTIONS FROM N.P.L. CERTIFICATES After receiving certificates from the National Physical Laboratory for thermometers Nos.31320 and 425505, we applied the appropriate corrections to our readings obtained in the examination of milks and it was soon apparent that the resulting depressions were distinctly smaller than those which were recorded by application of corrections from standardisation of the thermometers with sucrose solutions. With thermometer No. 31320, the depressions were smaller by 0.005" to 0.007" C., and with thermometer No. 425505, usually by 0-005" to 0.009" C., but occasionally by as much as 0.013" C. when measuring the smaller depressions of watered milks. The explanation for these differences was readily found when corrections from the N.P.L. certificates were used in determinations of the freezing-point depressions of sucrose solutions.(1) Sucrose solution, % w/v 7.0 7.5 8.0 8.5 9.0 9.5 10.0 TABLE I1 RESULTS WITH SUGAR SOLUTIONS Readings corrected from N.P.L. certificates (2) (3) (4) (5) (6) Thermometer 31320 Thermometer 425505 \- "Hortvet" Depression Difference, Depression Difference, O c. O c. C. O c. C. 0.4220 0.4192 0.0028 0.4100 0-0120 0.4643* 0.4496 0.0047 0.4409 0-0134 0.4870* 0.4809 0.006 1 0.4757 0.0133 0.0091 0*5200* 0.5144 0.0056 0.5109 0*5532* 0.5489 0.0043 0-5473 0.0059 0.5869* 0.5816 0.0053 0.5768 0.0101 0.6210 0.6163 0-0047 0.6090 0.0120 0.0105 depressions, found, (2) o- (3), found, M0-- (5)* Average difference . . . . 0.0048 * As calculated by Stubbs and E l ~ d o n . ~ (7) Differences between two thermometers, (3) - (5) 0.0092 0.0087 0.0052 0.0035 0.0016 0.0048 0.0073 In Table I1 are given the results obtained for the sucrose solutions normally used in the Each depression is the average of at least ten With one exception, where a difference between extremes standardisation of Hortvet thermometers.closely agreeing determinations. of 0-005" C. was recorded, the spread of results in each series did not exceed 0.003" C.254 SUTTON AND MARKLAND : THE STANDARDISATION OF [Vol. 75 It is apparent from the table that the depressions are not in agreement with Hortvet's figures for 7 and 10 per cent. sucrose solutions and the calculated depressions for solutions of intermediate strength. The differences are of the same order as those previously found with milk samples. The results with the two thermometers, however, are not in agreement in themselves.With thermometer No. 31320, the depressions recorded are on the average 0.005" C. less than those previously accepted for these solutions, and with thermometer No. 425505, the depressions are on the average 0.010" C. less. From column 7 in the table it is clear that there is reasonably good agreement between the two thermometers in the results for the 9 per cent. sucrose solution, but that differences reaching 0.009" C. are found in other parts of the scale examined. It may be suggested that the differences to which we have referred so far are entirely attributable to the difficulty in working with sucrose solutions. To test this point, portions of a large sample of milk were treated with amounts of water or strong lactose solution to give mixtures having freezing-point depressions near to those of the sucrose solutions normally used for standardisation.Freezingpoint determinations were made on each sample using each thermometer. Each depression in the table is the result of duplicate determinations. Usually these were in complete agreement but where slight differences were found an average figure has been recorded. The results are shown in Table 111. r Sample RESULTS WITH MILK (2) (3) (4) 7 Thermometer No. 31320 Freezingpoint depression, O C. - I Correc- Correc- tions tions from from sugar N.P.L. solu- certi- Difference, tions ficate (2) (3), C. (5) (6) (7) Thermometer No. 425505 r 1 Freezing-point depression, O C. Lorrec- Correc- tions tions from from sugar N.P.L.solu- certi- Difference, tions ficate (5) o- (6), -A C. (8) (9) Differences between results with two thermometers, C. & Correc- Correc- tions tions from from sugar N.P.L. solu- certi- tions, ficates, (2) - (5) (3) - (6) Milk + water . . 0.425 0.420 0.005 0.423 0.412 O.OX1 +0*002 +O.OOS Milk + water . . 0.456 0.451 0.005 0,457 0.444 0.013 -0.001 +0-007 Milk + water . . 0.489 0.483 0.006 0.489 0.477 0-012 0 + 0.006 Milk +water . . 0.620 0.514 0.006 0.520 0.511 0.009 0 + 0-003 Milk .. . . 0.546 0.540 0.006 0.546 0.541 0.005 0 - 0.00 1 Milk + lactose . . 0.588 0.583 0.005 0-588 0-578 0.010 0 + 0.005 Milk + lactose . . 0.622 0.617 0.005 0.624 0.612 0,012 -0.002 f0-005 The figures in this table show that, when standardisation with sucrose solutions is relied on, the results are in.excellent agreement (column 8).On the other hand, using corrections from the N.P.L. certificates, the depressions recorded are invariably smaller and in general by amounts similar to those recorded in the examination of sucrose solutions. There is, moreover, the same indication of differences in the results obtained with the two thermometers. Again the difference is small in measuring a depression of 0.55" C., but much greater differences are to be observed in other parts of the scale. A comparison of the differences in results obtained with these two thermometers following the use of corrections obtained from N.P.L. certificates is made in Table IV. The differences, both with sucrose solutions and milk, at any level of freezing-point depression are of the same order of magnitude and, since it is generally accepted that results with milk are easy to reproduce, it is suggested that the results with sucrose solutions are equally reliable. It is true that with these particular thermometers there is good agreement in the results for depressions near to those normally recorded for genuine milk, but much larger differences are to be observed in other parts of the temperature scale where presumably the same methods were adopted to ascertain corrections.CONCLUSIONS Our experience therefore does not enable 11s to support the proposals of Aschaffenburg and Hall. From our work with two thermometers there is no evidence that the use of correc- tions from N.P.L. certificates leads to more concordant results.Indeed, our results by thisMay, 19501 HORTVET THERMOMETERS TABLE IV 255 COMPARISON OF DIFFERENCES IN RESULTS OBTAINED WITH TWO THERMOMETERS AFTER CORRECTING THE OBSERVED READINGS FROM N.P.L. CERTIFICATES Difference in depressions recorded with thermometers Nos. 31320 and 425505 Results with No. 31320 - Results with No. 425505 Approximate freezing-point < A 3 depression, Sugar solutions, Milk, O c. O c. O c. 0-42 0.45 0.49 0.52 0.55 0.59 0.62 + 0.0092 + 0.0087 + 0-0062 + 0.0035 + 0.0016 + 0.0048 + 0.0073 + 0.008 + 0.007 + 0.006 + 0.003 - 0.001 + 0.005 + 0.006 procedure, within the range of temperature normally used, compare very unfavourably with those which are obtained with the same thermometers following the application of corrections based on standardisation with sucrose solutions.Further, if the proposed method were adopted, freezing-point depressions of milk would be at least 0405" C . smaller than hitherto recorded. It would therefore be necessary to revise the limit of 0.530" C. which has for so long been adopted as the smallest depression likely to be found for genuine milk. This, to say the least, would be unfortunate. Hortvet's figures for the depressions of 7 and 10 per cent. sucrose solutions may not have been strictly correct. Elsdon and Stubbs* report that they ascertained from the Bureau of Standards that the thermometers used would be correct to k0402" to f0.005" C. However, it has always seemed to us that the acceptance of Hortvet's figures represented a sound basis for the stan4ardisation of thennometers to be used in the Hortvet cryoscope, and it is true that all our records, some of them collected with considerable care, from which the limit of 0.530" C. has emerged, have been based on the adoption of these figures. It seems to us that it would be unfortunate to have to alter the limit of 0.530" C. solely to accommodate, for the standardisa- tion of the thermometer, a different system which apparently does not provide more urlifonn results. REFERENCES 1. Sutton, R. W., Markland, J., Barraclough, A,, and Chapman, W. B., Analyst, 1960, 75, 42. 2. Aschaffenberg, R., and Hall, J. -4., Jbid., 1949, 74, 380. 3. Stubbs, J. R., and Elsdon, G. D., ]bid., 1936, 61, 455. 4. Elsdon, G. D., and Stubbs, J. R., Ibid., 1934, 59, 685. ST. MARY'S GATE COUNTY OFFICES DERBY

ISSN:0003-2654    

DOI:10.1039/AN9507500251

出版商:RSC    

年代:1950

数据来源: RSC

摘要:

256 JEWSBURY: A RAPID PHOTOMETRIC [Vol. 75 A Rapid Photometric Determination of Silicof luoride in Hydrof luoric Acid, Ammonium Fluoride, Sodium Fluoride and Soluble Coloured Fluorides BY ALAN JEWSBURY SYNoPsrs-The colorimetric silicomolybdic: acid method for the determination of silica has been adapted to the determination of small amounts of silica in hydrofluoric acid and certain fluorides of analytical reagent grade. The interference of fluoride ion is prevented by the addition of boric acid, and the colour is developed by the additic'n of nitric acid and ammonium molybdate. The influence of boric acid, concentration of fluoride ion and the effect of time on the development of the colour, to all of which the method is sensitive, have been studied. Detailed procedures are specified for deter- mining silica in ammonium fluoride over the range 0.02 to 0.8 per cent.; hydrofluoric acid (40 per cent.) 0.01 to 0-056 per cent.: hydrofluoric acid (anhydrous) 0.03 to 1.4 per cent.and sodium fluoride 0-01 to 0.7 per cent. The application of the method to coloured and insoluble fluorides is also described. A determination of silica in hydrofluoric acid and soluble fluorides can be completed in from 15 to 20 minutes. THE methods hitherto available for the determination of traces of silicofluorides in fluorides are not wholly satisfactory. There has been a long-felt need in these laboratories of a quick and accurate method for the determination of silicofluoride in fluorides of analytical reagent grades, e.g., hydrofluoric acid, ammonium fluoride and sodium fluoride.One method that has been proposedl y 2 , 3 , 4 depends on neutralising any free hydrofluoric acid under conditions that prevent hydrolysis of fluosilicic acid, subsequently hydrolysing the fluosilicic acid and titrating the liberated hydrofluoric acid. The first end-point is -9ot very distinct and for small amounts of fluosilicic acid large samples must be taken. Cade5 has proposed a method in which the hydrofluoric acid is evaporated in the presence of sodium chloride. Boric acid is added to convert any remaining sodium hydrogen fluoride to fluoboric acid and then the fluosilicic acid is converted tcl silicomolybdic acid and determined colori- metrically. Substantially the same method was proposed by Dobkina.6 Brabson et a1.' have described two methods for the determination of silica in the presence of fluoride.In the first method, which is applied more particularly to high purity hydrofluoric acid, the fluoride, after careful neutralisation, is converted by boric acid to fluoboric acid and the silica then estimated by development of the molybdenum blue colour and photometric measurement. The second method is intended for larger quantities of silica, 5 to 25mg. of SiO,, and consists in weighing the silica as the oxine salt of silicomolybdic acid. The trace methods of both Cade and Brabson are, however, subject to interference by phosphate and a determination takes about an hour.* EXPERIMENTAL Cade's method was first examined. One gram of AnalaR hydrofluoric acid was evaporated to dryness in a platinum dish with 10ml.of 2 per cent. sodium chloride solution. The residue was dissolved in 10 ml. of water, 10 ml. of 3 per cent. boric acid solution were added, followed by 1 ml. of 5 N nitric acid and 5 ml. of 10 per cent. ammonium molybdate solution. After 10 minutes, the colour was measured on the Spekker photo-electric absorptiometer with Ilford violet 601 filters in 1-cm. cells. A calibration graph had previously been prepared * During preparation of this paper, a communication by Lacroix and Labalade* has described a method for the determination of silica present in various materials including fluorides. In the presence of fluorides an excess of boric acid is added after solution of the material. The solution is then neutrahed with sodium hydroxide until added aluminium is just precipitated ,as hydroxide-this fixes the pH a t 4.6.A known quantity of sulphuric acid is then added to adjust the pH to the optimum value for development of the silicomolybdic acid colour. This method takes longer than the one proposed in this paper and possesses the disadvantage, for trace determinations, of introducing a considerable blank due to the silica in the caustic soda.May, 19501 DETERMINATION OF SILICOFLUORIDE 257 from standard silicate solutions containing sodium chloride and boric acid. The results were subsequently proved to be high and agreement between individual experiments was wanting. The results varied from 0.24 to 0.39 per cent. of 50,. By the method recom- mended below the silica figure was shown to be 0.02 per cent.Attempts were then made to remove the fluoride ion from hydrofluoric acid by adsorption on the synthetic anion exchange resin Amberlite 1R4B. This experiment was carried out in a 100-ml. silver beaker. About 0.5 g. of 40 per cent. AnalaR hydrofluoric acid was diluted to 30 ml. with water and stirred with about 15 g. of the activated resin for 10 minutes by means of a rubber-covered glass stirrer. The resin was filtered off on a Whatman No. 541 filter-paper, washed with about 50ml. of water and the filtrate made up to 100ml. This treatment not only removed the fluoride but led to loss of added silica, present in the form of silicofluoride, by adsorption on the resin. But, as silica in the form of silicate was not adsorbed by the resin, the difficulty was surmounted by removing the hydrofluoric acid and hydrolysing the silicofluoride by means of evaporation in the presence of sodium chloride.The residue from the evaporation was then dissolved in water, treated with the resin and filtered. Boric acid was finally added to form a complex with any remaining traces of fluoride and the silicomolybdic acid colour developed. Reasonable recoveries of added silica were obtained. The results are shown in Table I. TABLE I RECOVERY OF ADDED SILICA AFTER EVAPORATION AND TREATMEKT BY RESIN SiO, added, mg. . . . . 0.7 1.4 1.4 2.8 5.6 9 9 recovered, mg. . . 0.7 1.7 1.7 2-7 5.2 This method took just over an hour for a single determination, and, as a speedier one was desirable, further work was not carried out either to investigate it in greater detail or to discover the cause of interference in Cade's method that necessitated the resin treatment. The method of converting the free fluoride ion into fluoboric acid was next investigated.It was found that it was unnecessary to neutralise the free hydrofluoric acid, as Brabson7 had done, before forming the complex with boric acid. It was necessary for satisfactory development of the yellow colour due to silicomolybdic acid to control carefully the fluoride and boric acid concentrations. After investigating these conditions, methods were devised for determining silicofluoride in hydrofluoric acid, sodium fluoride and ammonium fluoride. The time for a single determination was 15 to 20 minutes. These methods are described in detail below.A method was also worked out for soluble fluorides that give coloured solutions, e g . , nickel fluoride. Time was also an important factor. THE CALIBRATION GRAPH Boric acid does not interfere with the development of the yellow coloured silicomolybdic acid. AnalaR boric acid gives a very small blank, however, and as a 4 per cent. solution proved to be the most satisfactory concentration for forming the complex with fluoride, the colour was developed in boric acid of this concentration. A standard silicate solution was prepared by diluting a weighed amount of sodium silicate of known 50, content so that 1 ml. of the diluted solution was equivalent to 0.7 mg. of 50,. The calibration graph is prepared as follows. To each of seven 50-ml. measuring cylinders add 2 g.of AnalaR boric acid and about 40 ml. of water a t 25" to 35" C. Reserve one solution for a blank and add known volumes (0.2, 0.5, 1.0, 2-0, 3.0, 4.0ml.) of the standard silicate solution to the others and dilute to 50 ml. At 25" to 35" C. add 2 ml. of 5 N nitric acid, stir, and then add 5 ml. of 10 per cent. ammonium molybdate. Plot milligrams of SiO, against drum reading difference on the Spekker absorptiometer using Ilford violet 601 filters and 4-cm. cells, after setting the instrument against water a t drum reading 1.30. In these solutions the colour developed to its full intensity in a minute or two and then remained constant until, and after, the expiration of the 10-minute period allowed before measurement. The influence of temperature within the range of normal room tem- perature is negligible.As the solutions were warmed slightly to affect reasonably rapid solution of the boric acid, the colour was always developed and measured at 25" to 35" C. Stir until dissolved. Stir and allow to stand for 10 minutes.268 JEWSBURY: A RAPID PHOTOMETRIC Fol. 75 DETERMINATION OF SILICA IN AMMONIUM FLUORIDE In order to establish the correct conditions for the determination of silica in ammonium fluoride, a series of experiments was carried out. In the first experiments, 1-g. portions of AnalaR ammonium fluoride were dissolved in water, the equivalent of 243 mg. of SiO, was added to each, together with varying amounts of AnalaR boric acid and the volume made up to 100 ml. at 25" to 36" C. Fifty ml. of this TABLE I1 DETERMINATION OF SILICA IN AMMONIUM FLUORIDE Effect of boric acid with 1 g.of sample HsBOS, SiO, found,* on 2.9 mg., 1 0.5 17.2 2 2.1 72.4 3 2.6 86.2 4 2.4 82-8 6 2.4 82-8 6 2.4 82.8 8 0.8 27.6 Recovery, calculated g- mg. % * Not corrected for the original silica content of the ammonium fluoride which contained 0.1 mg. SiO, per g. solution were taken and the silicomolybdic acid colour developed and measured 5 minutes after mixing, as described in the preparation of the calibration graph. The reasons for taking the reading after 5 minutes are discussed below. The original solution of the fluoride and boric acid was carried out in a 100-mi. silver beaker. Once the fluoborate had been formed the solution could be transferred to glass vessels without risk of the solution attacking the glass.TABLE I11 The results are shown in Table 11. (Platinum or polythene beakers are equally suitable.) DETERMINATION OF SILICA IN AMMONIUM FLUORIDE Effect of boric acid with 0.5 g. of sample Recovery calculated on 2-85 mg., % 96-5 94.7 98.2 * Not corrected for SiO, in the a.mmonium fluoride. With a 1 per cent. solution of ammonium fluoride a recovery greater than 86.2 per cent. of the silica added was not obtained even though relatively considerable amounts of boric acid were used. The recovery increased as the boric acid concentration increased, reached a maximum at about 3 per cent., and then decreased with higher concentrations of boric acid. The experiment was repeated with 0-5 g. of ammonium fluoride and 2.8 mg. of SO,. Varying amounts of boric acid were added before making up to 100ml.The results are shown in Table 111. TABLE IV DETERMINATION OF SILICA IN AMMONIUM FLUORIDE Ratio of sample to boric acid 1 : 8 Total SiO, NHP, SiO, found, present, g. mg.. mg. 0.6 2.8. 2.86 0.8 2.75 2-88 0.9 2.4: 2.89 1.0 0.8 2.90 Recovery, 98.2 95.6 83.0 27.6 %May, 19601 DETERMINATION OF SILICOFLUORIDE 259 These results were more satisfactory; the best being that in which the ratio by weight of ammonium fluoride to boric acid was as 1 : 8. But, as shown by the results in Table IV, in which this ratio was kept constant at 1 : 8, this was not the best ratio over a wide range of concentrations. The results in Tables I1 to IV show that an excess of boric acid alone is insufficient to give satisfactory conditions for the development of the silicomolybdic acid colour.It is evident that there is a maximum concentration of both boric acid and ammonium fluoride for satisfactory silica determinations. In view of this, the concentration of boric acid was fixed at 4 per cent. and experiments were carried out to find the maximum amount of ammonium fluoride that could be taken to obtain good recoveries of added silica. The results of these experiments, in which the amount of ammonium fluoride in 100 ml. of 4 per cent. boric acid containing 2.8 mg. SiO, was varied from 0.5 to 1 g., are shown in Table V. These results show that in 4 per cent. boric acid the ammonium fluoride concentra- tion must not exceed 0.7 per cent., which is the equivalent of 0.36 per cent. of fluoride ion. TABLE V To each solution 2-8 mg.silica were again added. DETERMINATION OF SILICA IN AMMONIUM FLUORIDE Optimum concentration of ammonium fluoride SO, found (corrected NH,F, for 50, in NH,F), Recovery, g. mg- % 1 2-3 82.1 0-8 2-54 90-7 0.7 2-73 97.5 0.6 2-78 99.3 0.5 2.79 99.6 E'ect of time-It had been found during the early experiments that the intensity of the yellow colour due to silicomolybdic acid varied with time in a different way from that resulting when the colour was developed in a solution containing no ammonium fluoride. The colour in the presence of ammonium fluoride developed rapidly at first, reached a maximum for a solution containing much silica after about 4 minutes, remained constant for about 3 minutes and then slowly faded. An example of this is given in Table VI.It shows the rate of colour development of a solution of 0.6 g. of ammonium fluoride in 100 ml. of 4 per cent. boric acid, to which was added 5.6 mg. of SiO,. For solutions containing less silica the time taken to reach maximum intensity of colour was less than 4 minutes, but no fading occurred within 9 minutes. All measurements on the absorptiometer were, therefore, made 5 minutes after mixing. TABLE VI DETERMINATION OF SILICA IN AMMONIUM FLUORIDE Effect of time on the colour Time, min . 2 3 4 5 7 8 10 17 Drum difference reading (1-30 -drum reading) 0.850 0-875 0-883 0.882 0.882 0.878 0.875 0-865 SiO, found, mg. 5.2 5.4 5.55 6-66 5.55 5.5 5.4 5.3 PROCEDURE- In the light of the above results, the procedure recommended for a silica determination in ammonium fluoride is as follows.Dissolve not more than 0.7 g. of ammonium fluoride in about 60 ml. of water in a silver beaker, add 4 g. of AnalaR boric acid, warming slightly, if necessary, to dissolve it. Make up to 100 ml. in a volumetric flask at 25" to 35" C . Take 60 ml., add 2 ml. of 5 N nitric acid, stir, then add 5 ml. of 10 per cent. ammonium molybdate, again stir and after 5 minutes measure the resulting colour on the Spekker absorptiometer.260 JEWSBURY: A RAPID PHOTOMETRIC [I'ol. 75 By this procedure, with 0-7 g. of ammonium fluo.ride, silica can be determined over a range of 0.02 to 0.8 per cent. If the ammonium fluoride contains more silica than 0.8 per cent., less than 0.7 g. should be taken; the remainder of the procedure being as described.Examples of the recoveries obtained by this procedure when silica was added to 0-5-g. quantities of AnalaR ammonium fluoride are shown in Table VII. TABLE TI1 DETERMINATION OF SILICA IN AMMONIUM FLUORIDE By the recommended procedure SiO, added, Yo SiO, found, * Error, Y O Y O 0.056 0.060 + 0-004 0.140 0.140 nil 0.280 0.268 - 0.012 0.560 0.540 - 0.020 0.840 0.830 - 0.010 1.120 1.120 nil * Corrected for silica in the ammonium fluoride (0.05 mg. in 0.5 g. of sample). DETERMINATION OF SILICA IN HYDROFLUORIC ACID It was found to be unnecessary to neutralise the free hydrofluoric acid if the boric acid was added before developing the silicomolybdic acid colour. The fluoborate formed did not influence the intensity of the colour if the conditions were carefully controlled, and the calibration curve already described could be used.Solutions were prepared by diluting a weighed amount of -the hydrofluoric acid solution contained in a silver beaker to about 60ml. with water. Once the added boric acid was dissolved, it was found that the solution could be transferred safely to glass vessels without contamination by silica. The solutions were made up to 100 rnl. and 50 ml. taken for development of the colour, as already described. Preliminary experiments were carried out in which about 0-5-g. quantities of 40 per cent. hydrofluoric acid were taken with 2.8 mg. of SiO, and varying amounts of boric acid. The colour was developed at 25" to 35" C . and measured after 10 minutes. A similar series was carried out with about l 6 g . of 40 per cent.hydrofluoric acid. The results are shown in Table VIII. For these experiments 40 per cent. of w/w AnalaR hydrofluoric acid was used. TABLE 'VIII DETERMINATION OF SILICA IN HYDROFLUORIC ACID Preliminary experiments 40% HF, g. 0.6 0.5 0.8 0.45 0.45 1.5 1.3 1-4 1-5 1-5 . SiO, found," mg. 2.54 2.78 2-84 2.88 2.90 2.2 2.5 2.8 2.86 2-86 * Corrected for the original silica content of the hydrofluoric acid, of 50,. Recovery, YO 90.7 99.3 101.4 102.9 103.6 78.6 89.3 100.0 102.1 102.1 which contained 0.01 per cent. I t appeared that 4 per cent. of boric acid was again a suitable concentration, at least with 2.8 mg. of SiO, present per 100 ml. of solution. So, fixing the concentration of boric acid at 4 per cent., experiments were carried out to find the maximum concentration of hydrofluoric acid that could be used, having regard to the important factor of time, to achieve a satisfactory silica determination. Efect of tiwe and hydrofluoric acid concentration-It had been noticed that time was again a very important factor and this was investigated.The results are summarised in Table I XMay, 19501 DETERMINATION OF SILICOFLUORIDE 261 and show that the time for complete development of colour depends on both the hydrofluoric acid concentration and the silica concentration. If the concentration of silica did not exceed 2-8 mg. per 100 ml., up to 1.4 g. of 40 per cent. hydrofluoric acid could be present for a satis- factory recovery after 10 minutes. If the amount of hydrofluoric acid exceeded this amount, a longer time was required for full colour development.On the other hand, when the silica concentration was 5.6 mg. per 100 ml., then although the amount of hydrofluoric acid present had not exceeded 1.4 g. the full colour did not develop even after 40 minutes. If the colour was to be measured 10 minutes after mixing, then to use the full range of the calibration graph to estimate 5-6 mg. of SO,, not more than 1 g. of 40 per cent. w/w hydrofluoric acid or 0.4g. of the anhydrous acid must be used in 100ml. of 4 per cent. boric acid. This is equivalent t o 0.38 g. of fluoride ion. TABLE IX DETERMINATION OF SILICA IN HYDROFLUORIC ACID Effect of time and acid concentration SiO, found after, minutes* A SiO, r 7 40% HF, H,I30,, added, 3 5 7 9 10 15 25 30 40 g. g. mg. 1-4 4 2.8 - 2.6 2-66 2.7 2.76 2.76 2.76 - - 2.75 - 1.6 4 2.8 0.9 4 5.6 5.46 5.62 - - 5.62 5462 - - - 1.0 4 5 6 4.4 5.1 5.3 5.4 5.5 5.5 5.5 - - 1.4 4 5.6 1.3 1.8 2.5 - 3.2 3.5 - - 4.5 - 2.5 - - - - - ' * Corrected for silica in the hydrofluoric acid. PROCEDURE- On the basis of the above experiments, the method recommended for a silica determina- tion in hydrofluoric acid is as follows.Take not more than the equivalent of 0.4 g. of the anhydrous acid in a silver beaker and dilute to about 60 ml. with water. Add 4 g. of AnalaR boric acid, warming slightly if necessary to dissolve it. Make up to 100 ml. in a volumetric flask at 25" to 35" C. Take 50 ml., add 2 ml. of 5 N nitric acid, stir, then add 5 ml. of 10 per cent. ammonium molybdate, again stir and after 10 minutes measure the colour developed on the Spekker absorptiometer.By this method, using 1 g. of aqueous 40 per cent. w/w hydrofluoric acid, silica can be determined over the range 0.01 to 0.056 per cent. or, calculated on the anhydrous acid, over the range 0.03 to 1.4 per cent. Examples of the recoveries obtained by this method when silica was added to 40 per cent. w/w AnalaR hydrofluoric acid are shown in Table X. TABLE X DETERMINATION OF SILICA I N HYDROFLUORIC ACID Recovery of added silica 40% HF taken, g* 0.6 0-55 0.55 0.6 0.6 1.0 0.9 SiO, added, 0.047 0.127 0.254 0.350 0.467 0-560 0.622 Y O SiO, found,* 0.050 0.127 0.236 0.347 0.473 0.550 0.624 Yo Error, + 0.003 nil % - 0.018 - 0.003 + 0-006 - 0.010 + 0.002 *Corrected for silica in the hydrofluoric acid (0.01%) DETERMINATION OF SILICA IN SODIUM FLUORIDE Four per cent.boric acid was again found to be satisfactory for silica determination in sodium fluoride. Preliminary experiments again showed time to be an important factor. The colour was found to develop much more rapidly than it did in the hydrofluoric acid experiments. I t reached a maximum very quickly and stayed constant for at least 5 minutes, but in less than 10 minutes it started to fade very slowly. In this determination, therefore,262 JEWSBURY: A RAPID PHOTOMETRIC [Vol. 78 all measurements were made 5 minutes after mixing. An example of the effect of time is seen in Table XI. TABLE :XI DETERMINATION OF SILICA IN SODIUM FLUORIDE Effect of time SiO, found after, minutes NaF taken, SiO, present, - A \ 40 lo 4-6 0.8 5.0 4-95 4.95 4.95 4.95 4-86 g.mg. 3 4 6 7 For these experiments a sample of sodium fluoride containing 0.1 per cent. of silica was used. The experiments shown in Table XI1 were carried out to show the maximum amount of sodium fluoride that could be taken in 100 ml. of 4 peg cent. boric acid to obtain satisfactory recovery of added silica. TABLE XI1 DETERMINATION OF SILICA IN SODIUM FLUORIDE Effect of sodium fluoride concentration Total SiO, NaF added, SiO, added, present, 50, found, Recovery, g. mg. mg. mg. % 0.6 2-8 3-4 3.3 97- 1 0.8 2.8 3.6 3.54 98.3 0.9 2.8 3.7 3.50 94-6 1.0 2- 8 3.8 2.88 75-8 1% cam be seen that 04g. of sodium fluoride (anhydrous) was the maximum amount that cauld be taken to obtain a satisfactory recotvery of silica. This is equivalent to 0.36 g.of fluoride ion. PROCEDURE- Dissolve not more than 0.8 g. of sodium fluoride in about 60 ml. of water in a silver beaker, add 4 g. of AnalaR boric acid, warming slightly to help solution. Make up to 100 ml. in a volumetric flask at 25" to 35" C. Take 50 ml., add 2 ml. of 5 N nitric acid, stir, add 5 ml. of 10 per cent. ammonium molybdate, again stir and after 5 minutes measure the colour developed on the Spekker. By this procedure silica can be determined over a range of 0.01 to 0.7 per cent. if 0.8 g. of sodium fluoride is taken. Examples of the recoveries obtained by this method when silica was added to sodium fluoride are shown in Table XIII. The procedure recommended is as follows. TABLE XI11 DETERMINATION OF SILICA IN SODIUM FLUORIDE Recovery of added silica Total SO2 N;LF taken, SiO, added, present, SiO, found, Error, g- mg- % % % 0.6 0.8 0.8 0.6 i 0.8 nil 0.10 0.10 - nil 0.10 0-10 - 1.4 0.2'75 0-270 - 0.005 2.8 0.587 0-550 - 0.017 2.8 0*4!iO 0.443 - 0.007 APPLICATION OF THE METHOD TO OTHER FLUORIDES The above results show that in general, by usihg 1OOml.of a 4 per cent. solution of boric acid, the maximum amount of fluoride that. can be taken without affecting the accuracy of the silica'determination is equivalent to 0.36 g. of fluoride ion. In the light of this know- ledge, and.bearing in mind the fact that some ions can influence the rate of development of full colour and also cause fading, the method may, with precautions, be applied generally.May, 19501 DETERMINATION OF SILICOFLUORIDE 263 For coloured fluorides a method was developed in which the coloured cation was first removed by a cation-exchange resin.The filtrate from the resin was colourless and contained hydrofluoric acid, together with the silica as hydrofluosilicic acid. There was no loss of silica by this resin treatment. The procedure adopted for nickel fluoride was as follows-0~5 g. of NiF2.4H20 and 4 g. of AnalaR boric acid were dissolved in about 60 ml. of water in a silver beaker. The solution was filtered, if necessary; log. of Amberlite 1R100H were then added and the mixture stirred for + hour. The resin was then filtered on a Whatman No. 541 filter-paper and washed with water. The filtrate, which was colourless, was made up to 100ml. The silica was determined in 50ml. by the general procedure already described.The same procedure was applied successfully to cobalt fluoride. It was necessary to know for certain purposes the silica content of magnesium fluoride. This compound is insoluble in water and is not easily soluble in cold dilute acids. The following procedure was found to be satisfactory. Half a gram of magnesium fluoride was fused in a silver beaker with 5 g. of AnalaR sodium hydroxide and kept in the liquid state for about 5 minutes. After cooling, the melt was warmed with about 50ml. of water to break it up. A few drops of phenolphthalein solution were added followed by 5 N sulphuric acid added dropwise until the solution was just permanently colourless. Four grams of AnalaR boric acid were then added and warmed until in solution.If necessary, the solution was filtered and after making up to 100 ml. the silica estimated as already described by taking 50 ml. of the dilution and making the measure- ment after 5 minutes. A blank experiment was carried out on the sodium hydroxide and the result was corrected accordingly. The main disadvantage of this method was that the silica content of the best available grade of sodium hydroxide was greater than that of the magnesium fluorides examined. INTERFERENCE Iron caused no interference as shown by adding quantities of up to 10 mg. of Fe per 100 ml. of final solution; this greatly exceeds the amount that is normally present in reagent grade fluorides. The method is subject to interference by phosphate. The author thanks the Directors of the British Drug Houses Limited for permission to publish these results and desires to record his appreciation of the encouragement he has received in this work from Mr. G. H. Osborn, F.R.I.C., A.M.I.M.M., Chief Analyst, B.D.H. Laboratory Chemicals Group. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. B.D.H. LABORATORY CHEMICALS GROUP Furman, N. H., “Scott’s Standard Methods of Chemical Analysis,’’ 5th Ed., Vol. 11, D. Van Kolthoff, I. M., and Furman, N. H., “Volumetric Analysis.” Vol. 11, John Wiley & Sons, New Manufacturing Chemists Association, Ind. Eng. Chem., A n d . Ed., 1944, 16, 483. Swinehart, C. F., and Hisik, H. F., Ibid., 1944, 16, 419. Cade. G. N., Ibid., 1945, 17, 372. Dobkina, B. M., Zavod. Lub., 1948, 14, 765. Brabson, J. A., Mattraw, H. C., Maxwell, G. E., Darrow, A., and Needham, H. F., A n d Ghem., Lacroix, S., and Labalade, M., A n d . Chim. Acta, 1949, 3, 383. Nostrand Co., New York, 1939, p. 2209. York, 1929, pp. 124-7. 1948, 20, 503. THE ANALYTICAL DEPARTMENT POOLE, DORSKT September, 1949

ISSN:0003-2654    

DOI:10.1039/AN9507500256

出版商:RSC    

年代:1950

数据来源: RSC

摘要:

May, 19501 DETERMINATION OF SILICOFLUORIDE 263 ERRATUM: February (1950) issue, pp. 71 to 73. For “phenodoxone” read “phenadoxone” throughout.

ISSN:0003-2654    

DOI:10.1039/AN9507500263

出版商:RSC    

年代:1950

数据来源: RSC