suggested by Chatard, has been pronounced by Brearly and Ibbotson to be one of the most stable processes found in analytical chemistry. It is not interfered with by the presence of large amounts of acetic acid, lead acetate, or alkali salts (except sulphates). The paper need not be ignited separately and prolonged ignition at a much higher temperature than necessary to destroy the paper does no harm. From faintly acid solutions lead molybdate may be precipitated free from impurities in the presence of copper, cobalt, nickel, zinc, manganese, magnesium, and mercury salts. It may be readily separated from iron and chromium. Barium, strontium, uranium, arsenic, cadmium, and aluminium do not interfere if an excess of hydrochloric acid has been added to the solution followed by lead acetate and sufficient ammonium acetate to destroy the free mineral acid. The precipitate is granular, easily filtered, and washed. anadium and tungsten interfere, but may be readily separated from the molyb❘ denum." Rather (Rather, J. B., "Molybdic Acid," Jour. Assoc. Official Agr. Chem., 1915, i., 317-29; 1916, ii., 39) also referred to this method. Titration with Lead Acetate.-Titration with lead acetate is the reverse of the ammonium molybdate method for the determination of lead and has the same limitations. The colour change of the tannic acid solution is not sharp enough for use on low-grade materials. Titration with Potassium Permanganate.-Titration with potassium permanganate comprises reducing the molybdenum solution in a Jones reductor and titrating with potassium permanganate. This is a stable process and gives accurate results. The variables are easily controlled, and the method can be used for assaving high-grade as well as low-grade material. Titration with Titanium Chloride:-Titration with titanium chloride applies more generally to the determination of molybdenum in steel (Travers, M., "Nouveau dosage volumétrique du molybdène et du vanadium dans les aciers," Compt. Rend., 1917, clxv., 362; abstract in Eng. and Min. Jour., 1918, cvi., 585; and Jour. Soc. Chem. Ind., Oct. 31, 1917). Iodometric Method. By the iodometric method a mixture of molybdic acid and potassium iodide is boiled in the presence of hydrochloric acid, the volume having defined limits. Free iodine is liberated and expelled, and the molybdic acid is reduced to a definite lower oxide (Gooch, F. A., and Fairbanks, Charlotte, "The Iodometric Estimation of Molybdic Acid," Am. Jour. Sci., series 4, 1896, ii., 160; Gooch, F. A., and Pullman, O. S. jr., "The Estimation of Molybdic Acid Reduced by Hydriodic Acid," Am. Jour. Sci., series 4, 1901, xii., 449). The reaction is as follows:2MOO,+4KI+4HCI 2M0O,I+I2+4KC1+2H2O. This method finds no practical application, because of the difficulty of obtaining a quantitative reduction in accordance with the above equation (Treadwell, F. P., and Hall, W. T., "Analytical Chemistry," 3rd ed., 1912, ii., 666 67). Titration with Potassium Iodate.-In titration with potassium iodate an acid solution of the molybdenum is passed through a Jones reductor, the solution is received in a flask containing a solution of IC1 in the presence of HCl, and the molybdenum is titrated with a solution of KIO,. The reaction (Jamison, G. S., "On the Determination of Molybdenum by Potassium Iodate," Jour. Am. Chem. Soc., 1917, xxxix., 246-9) is as follows: Mo2O2+KIO,+2HCl=Mo2O,+ICI+KCl+H2O. Comments on Adaptability to Low-Grade Ores.The foregoing methods were carefully studied to determine their adaptability to the determination of molybdenum in low-grade material, the length of time necessary to complete the determination always being considered. The following comments refer to the methods in the order given :— The precipitation as sulphides was not tried out, because the method was considered too tedious and the amount of precipitated sulphides too small, as precipitated MoS, contains only 0.50 per cent Mo The conversion to some weighable form also offers too many difficulties. The precipitation as mercurous molybdate was not tried, as it offered practically the same difficulties as the preceding method. The precipitation as lead molybdate was tried out because it seemed to offer possibilities for accurate analysis of low-grade material, as the precipitate PbMoO, represents 26.15 per cent Mo. Furthermore, no special precautions are necessary in igniting the precipitate. The titration with lead acetate was tried only on low-grade material assaying less than o 15 per cent molybdenum. The method was unsatisfactory, as the insoluble lead molybdate did not form a precipitate immediately and the end point with tannic acid was not dependable. Many experiments were made with the method of reduction of the molybdenum and titration with potassium permanganate. This method is accurate, rapid, and adaptable to use with all the ores of molybdenum, regardless of the method of decomposition. However, it has certain well-defined variables that must be absolutely understood and controlled. The other methods were not tried out, as the gravimetric (PbMoO,) and the volumetric (KMnO), methods gave satisfactory results. Methods of Decomposition. -Methods of decomposition that have been suggested are as follows: Fusion with sodium peroxide (Darroch, James, and Meiklejohn, C. A., “A Rapid Method of Determining Molybdenum; Eng. and Min. Jour., 1906, lxxxii., 818); fusion with sodium or potassium carbonates or mixtures of the carbonates, with a small amount of potassium nitrate present to oxidise the sulphides (Horton, Frederick W., "Molybdenum: Its Ores and their Concentration," Bull. 111, Bureau of Mines, 1916, p. 41); fusion with potassium bisulphate (Mabee, H. C., “Molybdenum Content of Ores and Concentrates," Eng. and Min. Jour., 1918, cv., No. 18, 836); decomposition with aqua regia; decomposition with aqua regia followed by the addition of sulphuric acid and heating to fumes (Colett, E., and Eckhardt, M., "Bemerkungen zur Bestimmung des Molybdans im Molybdänglanz," Chem. Ztg., Jahrg. 33, 1909, xcvi., 968). Fusion methods offer rapid and complete decomposition of the ores. Decomposition by aqua regia is applicable to ores carrying no lead. Decomposition by aqua regia, followed by the addition of sulphuric acid and heating to fumes, is especially applicable to ores carrying lead. This is the method used for wulfenite ores. . 22 Volumetric (Potassium Permanganate) Method for Low-Grade Ore. The ore is decomposed either by acid or by fusion with Na2O, into a soluble molybdate and insoluble compounds of the other constituents of the ore. The molybdate is filtered, acid added, and the solution is passed through a Jones reductor where the MoO, is reduced to Mo,O,. The Mo,O, is then titrated with KMnO,, and the percentage of molybdenum present is calculated. aqua Procedure for Acid Decomposition.-Weigh out 05 grms. of ore, depending on its richness in molybdenum. The content of the portion taken for analysis should not exceed 0.08 grm. Mo, as explained under "Size of Sample" (prox). Decompose the sample with regia in an Erlenmeyer flask, heating for 15 minutes. Cool the solution, add 20 CC. of dilute (11) sulphuric acid, evaporate to fumes, cool again, dilute, neutralise without filtering off the insoluble matter and add 10 cc. excess of ammonium hydroxide, boil and filter and wash with hot water five times. Redissolve the precipitate into the original Erlenmeyer flask by puncturing the filter paper, washing the content into the flask and dissolving with dilute sulphuric acid. Reprecipitate, boil, filter, and wash well. The filtrate should be clear and colourless; add enough dilute sulphuric acid so that there will be present after neutralising all the ammonia, at least 125 cc. of free concentrated sulphuric acid for each 250 cc. of solution. The solution is now ready to be reduced by passing through the Jones reductor. (To be continued). REPORT FOR THE YEAR 1919 OF THE FOOD INVESTIGATION BOARD, DEPART MENT OF SCIENTIFIC AND INDUSTRIAL RESEARCH. THE Food Investigation Board beg leave to present to the Committee of the Privy Council for Scientific and Industrial Research the following Report for the year 1919. Introduction. The account of the work of the past year is set out in the following pages in sections relating to the various Committees of the Board into which it naturally falls. Only one research is, so to speak, extra territorial in that it comes under no particular Committee, namely, the research on accessory food factors, which has been carried out at the Lister Institute of Preventive Medicine. SO These mysterious substances which exert profound an influence upon digestion and assimilation are being intensively studied by a Committee specially appointed for the purpose, by the Medical Research Council and the Lister Institute. Arrangements have been made whereby the Board will be kept in close touch with the work of that Committee so that results of importance to industry may be included in the publications of the former. In the meantime, Dr. A. Harden, F.R S., of the Lister Institute, has completed a prolonged investigation of the effect of cold storage upon that accessory food factor which occurs in butter and is known either as the "growth factor," or as "fat soluble A." By the courtesy of the Colonial Consignment and Distributing Company, Ltd., butter was kept in their stores at Nelson's Wharf, Lambeth, for twelve months at -8° to -15° C., and the content of, fat soluble A determined at the close of the period. There was no material loss. Cold, therefore, preserves this accessory food factor completely. This result is of considerable scientific importance, as it makes it possible to study the influence upon the quantity of vitamine present in milk or butter, of the diet of the animal, and of the season of the year. Dr. Harriette Chick has continued her investi gation of the effect of cold storage upon the accessory food factors of fruits, and especially of the factor the absence of which from the diet causes Scurvy. The greater part of the research work has, during the year under survey, been devoted directly or indirectly to the preservation of food by cold. Though there are many ways of maintaining food in a state fit for human consumption, there is none so far which preserves its nutritive properties so completely as does cold. Of the three Committees which between them cover this field the work of the Engineering Committee differs from that of the Fruit and Vegetables Committee and the Meat Committee in its more immediate relation to practice. Determinations of the properties of insulating materials, and experiments in the equipment and construcday-to-day needs of industry. tion of refrigerated barges, come right up to the The work of the other two Committees, on the contrary, for the most part consists in an attempt to increase our knowledge of the chemistry of the ripening fruit, or of the post-mortem changes in animal tissues. It is laboratory work concerned with the fundamental science of living matter, and the applicability to industry of many of the researches is not immediate and often not obvious. This is not due to deliberate intent on the part of either Committees or research workers. It is the natural result of the state of development of the sciences concerned. Engineering is an old science. Much of the abstract work on heat engines and on heat flow was done nearly a century ago. We are now in the period of refinements of knowledge, and the application of principles established long since to special problems. Biochemistry is a young science-as it is understood now it is ten or twenty years old at the most. It is rapidly growing, but the fundamental knowledge, enormously more complex than that of the engineer, is yet far from clear. The Meat Committee and the Fruit and Vegetables Committee have at their command only this partially developed science. If their work is to be thorough, therefore, it must go deep. Investigations of this kind are of no use uniess they are as exact as the methods available permit of. To carry them out properly it is necessary to have a laboratory specially equipped for the purpose where not only the different modes of applying cold may be tested but also where the material which has been specially treated may be kept under observation for many months. Up to the present the Board have had to rely upon a small installation containing only six small chambers, or rather cupboards, placed at their disposal by the kindness of the Professor of Pathology at Cambridge. This plant has had to serve for continuous observations on moulds, on fish bacteria, on frozen meat, and on fruit. Months of work would have been lost if the temperature had got out of control at any time during the year, and the Board gladly recognise the fact that this small plant has served their workers so well owing to the devoted and anxious service of the Secretary of the Meat Committee, Mr. L. F. Newman. So small an experimental store is totally inadequate except for experiments on the smallest possible scale. It has, however, been invaluable in providing the Board with the experience necessary for the design of an experimental store fit for their work. Indeed without the experience gained during the last eighteen months it would have been impossible to design such a store. Having gained the necessary experience the Board have applied for a grant of money sufficient to build an experimental Low Temperature Research Station fully equipped for biochemical and biophysical investigations at low temperatures. The application has been granted and the University of Cambridge have presented a site for the erection of the station in close proximity to the Departments of Biochemistry, Animal Nutrition, and Botany. The investigations carried out by the Board range so widely as to render it difficult effectively to summarise them. They deal with the engineering problems of the cold storage industry, with the preservation by cold and by canning of fish, meat and fruit, with the chemistry of putrefaction, and the agents which bring it about, with the bionomics of moulds, and with the chemistry of edible oils and fats. Probably the chief needs of the fishing industry at the moment are improved methods of transport and the development of a mode of preservation capable of dealing with the excess fish landed during gluts. The Engineering Committee of the Board produced last year a report dealing with the construction of refrigerated wagons suited for this country, and the Fish Preservation Committee have just completed a report, now in the Press, upon the use of fish freezing in times of glut, based upon experiments carried out mainly at Billingsgate Market and University London. College, The Meat Committee have completed experiments upon the freezing of beef. It is a remarkable fact familiar to the industry that whereas mutton can be frozen without damage, beef cannot. The effect of freezing on the latter is so to alter the muscle substance as to cause the meat, on thawing, to exude a fluid rich in nutritive material and coloured with hæmoglobin. The new experiments prove that, provided certain precautions are taken, beef can be frozen in such a way as to preserve completely the physical and chemical qualities of the fresh meat. The experiments were carried out with small pieces of beef, and the attempt to repeat them on a commercial scale has so far failed for want of adequate apparatus. Further investigations have been postponed until the Research Station referred to above is completed. The work on putrefaction has been devoted to an analysis of the factors which determine the rate of multiplication of bacteria and limit their activities. It appears that for each species of bacteria, the rate of growth and the cessation of growth are determined by the quantity of some foodstuff which is specific for each species. The anærobic spore-bearing bacilli have been specially investigated. The study of this important group has been hampered in the past by the difficulty experienced in cultivating more than a small proportion of those shown to be present by microscopical methods. A culture medium has now been found in which these organisms grow freely. The methods commonly used for estimating the chemical changes produced by bacteria, ΟΙ enzymes, have hitherto been so laborious as to rapidly enough to follow the rate and order of render it almost impossible to make observations these changes. New methods have therefore been devised for estimating the simple products of decomposition which are both easy and accurate. Considerable progress has been made towards which grow on cold-stored meat, and special attenthe completion of a monograph of the moulds tion has been given to the "black spot infection" of beef and mutton. It is now clear that this trouble is due solely to one or more species of Cladesporium, a genus of world-wide distribution, the members of which grow chiefly upon dead vegetable tissues. Although there has been a belief in the trade for some time that certain of these there has always been some doubt as to whether moulds would develop under cold-store conditions, these growths were not due to some temporary breakdown of the plant during storage, either on board ship or elsewhere. It was, therefore, important to perform critical experiments to ascertain whether any of these fungi would develop under uniform cold-store conditions. This has been done, and it has been shown conclusively that the fungus causing "black-spot" will grow and produce spores at a temperature at least 5° C. below freezing point. So far, the "black-spot" fungus is the only one found to grow at a temperature considerably below o° C., but several others develop fairly well at freezing point. Experiments are being made upon the vitality of spores kept under cold-storage conditions for various periods. Experiments have proved that dried blood added in small amounts to the diet of pigs produces a remarkable increase in the rate of fattening. Mention was made earlier of the work of the Engineering Committee on the design of refrigerated railway wagons. The Committee have now in hand experiments directed to securing the design of refrigerated barges best suited for transferring produce from ship to store. A steel motor-driven barge is being fitted for the purpose, and will be completed for service during the hot months of the year. An apparatus of novel design for the measurement of the heat-flow through materials has been installed in triplicate at the National Physical Laboratory, and all the substances commonly used in insulation have now been tested. Considerable attention has also been given to the loss of heat by convection from plane surfaces, as practically nothing is known concerning the laws which govern it. Loss of heat by radiation has also been investigated especially in connection with the effect upon it of the nature of the radiating surface. 22, Experiments on hygrometry at low temperatures are in progress at the National Physical Laboratory and at the Physical Laboratory of the University of Bristol. Experiments on the storage of fruit have shown that by the employment of certain artificial atmospheres in the storage chambers, the life of the fruit may be greatly extended. A method of drying certain fruits which promises good results has also been worked out. The study of the respiratory metabolism of fruit at low temperatures, and of the oxidising enzymes responsible for the discoloration of certain fruits on injury has also been continued. The chemistry of the ripening process in fruit has been investigated with special reference to the changes in the pectin, and the limits of temperature within which the moulds commonly infest fruit in store will grow have been determined. The work of the Oils and Fats Committee consists, in part, of investigations begun during the war at a time when there was the possibility of an acute conflict between the demands for oils and fats for human consumption on the one hand, and for the preparation of the glycerol needed for the manufacture of explosives on the other. A process has been discovered which points to a successful synthesis of glycerol, and the physiological properties of fats in which glycerol has been replaced by other polyhydric alcohols have been determined. Experiments have been made on the production from linseed oil of an edible oil. The production of oils by vegetables has been studied, and an important monograph of the unsaturated monobasic acids related to fats has been completed. The Canned Foods Committee have completed a report, which is now in the Press, on the methods of inspection of tins, and are continuing their work on the bacteriology and chemistry of canned foods. Fish Preservation Committee. of Work under this Committee has not been on a scale commensurate with the importance of the subject, owing to the fact that the only plant available for experiments has been a small brine freezing plant, installed originally for demonstration purposes in the basement Billingsgate Market. Two research workers, Mr. G. Adair and Mr. J. Piqué, made experiments upon the rate of freezing fish in cold brine, upon the penetration of salt into the bodies of brinefrozen fish, and upon certain mechanical devices designed for the application of the process of freezing in brine to commercial practice. made full use of the plant during the many months they worked there, until the total absence of daylight, the damp and the noise made them both seriously ill. The experiments at Billingsgate were supplemented by others carried out in the Physiological Laboratory of University College, London, by the kindness of Professor W. M. Bayliss, F.R.S. They In spite of difficulties, to which no description can do justice, Mr. Adair and Mr. Piqué have carried their investigations far enough to form the basis of an interim report upon the freezing of fish, which the Committee are now completing. In addition to the work at Billingsgate, Miss I. H. Green has been engaged upon an intensive study of the bacteria which occur in herring. She has isolated, cultivated, and identified many species, and by so doing has laid a foundation for the further study of putrefactive change in these fish. In June, 1919, Miss Green visited North Wilson, of the Shields Ice and Cold Storage Shields, where, by the courtesy of Mr. George Company, she was able to make a special study of the bacterial changes in herring which had been treated in various ways. The chief results at which she arrived were : BIRMINGHAM UNIVERSITY AND RESEARCH.Towards the appeal for £500,000 to maintain and develop the work of the University of Birmingham (which was formally inauguarated on Thursday last), £200,000 was promised. Mr. Austen Chamberlain, the Chancellor of the University, stated that the Government had this year given a million pounds to the Universities. He hoped they would be able to increase the amount next year by halfa-million. The Government recognised fully the splendid services rendered during the war by the Universities, and particularly on the Science side. The Government were prepared to back their opinion of the importance of University work. The Principal, Mr. Grant Robertson, declared that a University which was not carrying on research was a crippled educational organisation. Research paid. It gave a dividend in cash, and it paid ultimately in a general and heightened national efficiency. He believed that if more money had been put into the Universities for the ten years preceding 1914, that the war would have been shortened by two years. Ist BOARD OF TRADE ANNOUNCEMENT.-Mr. L. G. Killby has been appointed Secretary to the Empire Cotton Growing Committee. He is at present Superintendent of the Department of Technology, City and Guilds of London Institute. In 1904 at Oxford, he took his B.A. degree in the Honours School of National Science, with Class Honours in Chemistry. He then became Demonstrator in Chemistry, and in 1907 was awarded the degree of B.Sc. (Oxon) for research work. He has been on the staff of the Department of Technology for 14 years. During the war Mr. Killby received a commission in the Army, and served in France as one of the chemists on water supplies in the Field, and was afterwards transferred to the Chemical Warfare Department of the Ministry of Munitions. He was mentioned in dispatches. October 22, 1920 THE FARADAY SOCIETY AND THE PHYSICAL SOCIETY OF LONDON.-A General Discussion on "The Physics and Chemistry of Colloids and their Bearing on Industrial Questions" will take place on Monday, October 25. The following is the programme:— 2.30 to 4. General Introduction "A Short Survey of the Physics and Chemistry of Colloids," by Prof. Dr The Svedberg, of the University of Upsala. Discussion on "Emulsions and Emulsification." Opener Professor F. G. Donnan, C.B.E., F.R.S. Mr. W. Clayton, M. Sc. will read a paper on "Emulsion Problems in Margarine Manufacture." Mr. S. S. Bhatuagar will read a paper on "Reversal of Phases in Emulsions and Precipitation of Suspensoids by Electrolysis—an Analogy." : 4.30 to 6.15. Discussion on "Physical Properties of Elastic Gels." Openers Mr. E. and Prof. H. R. Hatschek, F. Inst. P., Procter, D.Sc. Mr. S. C. Bradford will read a paper on "The Reversible So! gel Transformation.' Dr. J. O. W. Barratt, M.D., D.Sc., will read a paper on "The Structure of Gels." Discussion on "Glass and Pyrosols." Opener : Sir Herbert Jackson, K.B.E., F.R.S. 8 to 10. Discussion on "Non-Aqueous Systems." (a) Nitrocellulose. Opener: Sir Robert Robertson, K.B.E., F.R.S. Mr. F. Sproxton will read a paper on "Non-aqueous Colloid Systems with special reference to Nitrocellulose." Dr. Guy Barr and Mr. L. L. Bircumshaw will read a paper on "The Viscosity of some Cellulose Acetate Solutions." (b) Rubber, Opener: Mr. B. D. Porritt, speaking on "The Action of Light on Rubber." Discussion on "Precipitation in Disperse Systems." Openers Dr. R. C. Tolman and Dr. R. S. Willows, Mr. J. N. Mukherjee, M.Sc., will read a paper on "The Origin of the Charge of a Colloidal Particle and its Neutralisation by Electrolytes." Mr. W. Clayton, M.Sc., will read a paper on "Coagulation of Inorganic Suspensions by Emulsions." mose. Discussion on "Cataphoresis and Electro-EndosOpener Professor A. V. Porter, D.Sc., F.R.S. Dr. W. R. Ormandy, F.I.C. will read a paper on "Some Practical Applications of Electro-Endosmose and Cataphoresis." THE Secretary of the Department of Scientific and Industrial Research begs to announce that a license, under Section 20 of the Companies' (Consolidation) Act, 1908, has been issued by the Board of Trade to the British Electrical and Allied Industries Research Association, which has been approved by the Department as complying with the conditions laid down in the Government scheme for the encouragement of industrial research. The Association may be approached through E. B. Wedmore, Electrical Research Committee, c/o Electrical Development Association, Hampden House, 64, Kingsway, W.C.2. |