that the British Industries Fairs (1920) would be held simultaneously in London, Birmingham, and in Glasgow from February 23 till March 5, 1920. The close proximity of two fairs in Glasgow, September and February, was discussed at some length by a large number of exhibitors who have booked space for the September show. The result of their deliberations was that they made the sug gestion to the Committee of the Glasgow Corporation that the September Fair should be postponed and their Assistant Chemist required immediately by large fi.m of Indiarubber manufacturers. State age, qualifications, and salary required.-Address, A. T., CHEMICAL NEWS Office, 16, Newcastle Street, Farringdon Street, London, E.C. 4. Assistant Metallurgical Chemist (21) requires Situation. Experience in both Ferrous and Non-ferrous Analyses, Case-hardening, Heat Treatment, Mechanical Testing, and castle Street, Farringdon Street, London, E.C. 4. Metallography.-Address, A. M. C., CHEMICAL NEWS Office, 16, New Chemist, three years' experience in large Tar efforts concentrated on the February show. In view of the fact that special arrangements were being made by the Board of Trade to bring foreign buyers to next year's Fair, it was considered disadvantageous from an exhi bitor's point of view to have two shows at Glasgow within a few months of each other, and that the one Fair Chemist (French) seeks Situation. Ten years' which would be a specially strong one one would be sufficient. These considerations led the Corporation Committee to come to their decision to agree to the exhibitors' suggestion, and a circular has now been issued stating that the September Fair at Glasgow has been postponed until the Spring. The classification of exhibits for the February enterprise as Glasgow will as in the past include the following:-Textiles of all descriptions; Ready made clothing, including hosiery; Hats and caps; Boots, shoes, and gloves; Carpets and upholstery material; Foodstuffs prepared and preserved; Chemicals (light and heavy); Domestic chemical products; Cardboard boxes. practice in Analysis in Research Laboratory. Specialist in Bauxite-Aluminium and Ores. Speaks fluently English, French, ard German.-Address, " Frenchman," CHEMICAL NEWS Office, 16, Newcastle Street, Farringdon Street, London, E.C.4. War with first-class Academic training. Must be well up in Organic preparations, good manipulators, and capable of carrying on investigations under the direction of the Chief. Both Senior and Junior Chemists (male or female) are required, who have completed University course. Good prospects. Commencing salary according to abilities and experience.-Address, "Midland," CHEMICAL NEWS Office, 16, Newcastle Street, Farringdon Street, London, E.C. 4. LIEBIG'S EXTRACT OF MEAT COMPANY, LTD.-At a recent Board meeting it was resolved that, subject to confirmatiou at the 54th Ordinary General Meeting of the Company to be held on July 24, an additional dividend of FOR SALE, two pairs PLATINUM WIRE 10 per cent and a bonus of 5s. per share, both free of income-tax, on the Ordinary Shares for the year ended March 31, 1919, will be payable on and after July 25 to proprietors who are registered on the Company's books on July 12 and to holders of Ordinary Share Warrants to Bearer. NOTES FROM FOREIGN SOURCES Researches on the Chemical Action in Lead Accumulators.-Ch. Féry.-The action of a lead accumulator is analogous to that of an ordinary pile; it is due to the attack of the negative, giving a plumbous sulphate, Pb2SO4, which is almost black in colour and corresponds to the plumbous oxide Pb20 which is already known to chemists. Depolarisation is due to the reduction to PbO2 of a peroxide of formula Pb2O5, which may be regarded as the anhydride of perplombic acid. This substance is black in colour, endothermic, and a powerful oxidiser. Its resistibility is 22 times less than than of PbO2. It is reduced by dry hydrogen with rise of temperature, proThe duction of PbO2, and liberation of water vapour. chemical reactions which occur during the charging and GAUZE ELECTRODES (weight of Electrodes 4 ozs. Troy), with Stand for rotating to hold 3 set Electrodes.-Offers for above to F. A. Craig, Ard-Cluan, Waterside, Londonderry. LABORATORY wanted in London, with or ANALYTICAL PRACTICE. Send particulars.-- Process for Separating Glutamic Acid from other Process of Recovering Sulphuric Acid from the The Owners of the above PATENTS are desirous of arranging, by Licence or otherwise, on reasonable terms, for the Commercial development of the Inventions. For particulars address HERBERT HADDAN and CO., Chartered Patent Agents, 31 & 32, Bedford Street, Strand, London, W.C. 2. SWANSEA TECHNICAL COLLEGE. Principal-W. MANSERGH VARLEY, M.A., D.Sc., Ph.D. discharging of the accumulator may be represented by Applications are invited for the Appointment the The Pb2+H2SO4+Pb2O5 Pb2SO4 + H2O+2PbO2. plumbous sulphate formed during the normal discharge is very rapidly transformed in air to white sulphate, owing to the presence of sulphuric acidPb2SO4+H2SO4+0=PbSO4 + H2O. Hence a discharged battery must not be allowed to stand.-Bull. Soc. Chim. de France, 1919, xxv.-xxvi., 223. of an ASSISTANT LECTURER IN CHEMISTRY. Good Degree essential, with qualifications in Inorganic and Organic Chemistry. Salary according to qualifications and experience, minimum £250. Education Offices, MARTINDALE'S BOOKS BOUGHT Apparatus and Reagents Chemical and other Scientific, Natural History, Agricultural, Gardening, &c. JOHN WHELDON & CO., 38, Great Queen Street, London, W.. 2. Telephone-Gerrard 1412. For Chemical and Bacteriological Research. SPECIALITIES: 1915 CH. CHEMICAL NEWS AND JOURNAL OF PHYSICAL SCIENCE James H. Gardiner, F.C.S. r Established (WITH WHICH IS INCORPORATED THE "CHEMICAL GAZETTE "). in the Year 1859. Published Weekly. Annual Subscription, free by post, 1 Entered at the New York Post Office as Second Class Mail Matter. Transmissible through the Post-United Kingdom, at Newspaper rate; Canada and Newfoundland, at Magazine rate. Friday, July 25, 1919. PAGE CONTENTS. CAPPER PASS & SON, Lim., LEAD ASHES, SULPHATE OF LEAD, COPPER MATTE, TIN ASHES, &c., LABORATORY wanted in London, with or without ANALYTICAL PRACTICE. Send particulars. Registered as PRICE 4d. A PARTNER is required by the Author to assist in the publication of the theory of the Constitution and Structure of the Chemical Elements (outlined in the last issue, No. 3092, p. 29), which is by far the most exact and most extensive that has ever been produced.-Address, Hawksworth Collins, CHEMICAL NEWS Office, 16, Newcastle Street, Farringdon Street, London, E.C. 4. APPRENTICE. An opening with a sound enterprising firm of Manufacturing and Commercial Chemists or Chemical Engineers is sought by ex-officer (aged 22) of broad education who has specialised in Chemistry. Fluent French. Premium can be arranged) Highest references as to parentage, education, and character. Address, "Apprentice," CHEMICAL NEWS Office, 16, Newcastle Street, Farringdon Street, London, E.C.4. Chemist, three years' experience in large Tar Products Works before taking active service, now demobilised, desires Employment in London or the Provinces.- Address, T. T., CHEMICAL NEWS Office, 16, Newcastle Street, Farringdon Street, London, E.C. 4. Address, "Bunty," CHEMICAL NEWS Office, 16, Newcastle Street, Chemist required to assist in carrying out Farringdon Street, London, E.C.4. Scientific and Technical Research Work. Candidates should preferably hold a University degree or its equivalent, and have had some previous experience in conducting independent investigations.Write. stating qualifications, age, and salary required, to " M. R. C.," care of Street's, 30, Cornhill, E.C. 3. FOR SALE, two pairs PLATINUM WIRE GAUZE ELECTRODES (weight of Electrodes 4 ozs. Troy), with Stand for rotating to hold 3 set Electrodes.-Offers for above to F. A. Craig, Ard-Cluan, Waterside, Londonderry. STAFFORDSHIRE EDUCATION COMMITTEE Applications are invited for the Post of HEAD MASTER of the Technical School, Brierley Hill (South Staffordshire). A Physical Chemist is desired, who will be willing to devote himself to the study of the Refractory Materials and cognate subjects. Works experience will be an advantage. Initial salary £400 a year. Further particulars and forms of application, which may be obtained from these offices on receipt of a stamped addressed envelope, should be returned by AUGUST 2nd. County Education Offices, GRAHAM BALFOUR, Director of Education. CHEMICAL APPARATUS Pure Chemicals for Research Work. JOHN J. CRIFFIN & SONS, LTD., KINGSWAY, LONDON, W.C The BRITISH SCIENCE GUILD The Latest Applications of Science to Industry! BRITISH SCIENTIFIC PRODUCTS EXHIBITION Patron: H.M. THE KING President: The Most Hon. THE MARQUESS OF CREWE, K.G Central Hall, Westminster, July 3- August 5 THE CHEMICAL NEWS by oxidising it by means of H2O2 to sulphate and pre Use of Br Water.-To separate solutions containing respectively 1, 2, and 3 mgrms. SO3 as Na2SO, 45 cc. HCl (1:2) were added and 5 cc. 2N. BaCl2, making a total volume of 50 cc. Any precipitates which formed were filtered off and to the filtrates bromine water added drop by drop till the solutions assumed a permanent yellow colour. The solutions were then boiled until all the Br was given off and allowed to stand five minutes. In each case a white ppt. was formed. It was suspected, however, that oxalates might be partly destroyed by bromine water and thus make it necessary to use some other oxidising agent. To ascertain this information the following experiments were made:-To separate solutions containing respectively 25 and 50 mgrms. C2O4 as K2C2O4, 45 cc. HCl (1:2) and 5 cc. 2N.BaCl2 were then added. Br water was added until a permanent yellow colour was imparted to the solutions. These were boiled and concentrated to 25 cc., made alkaline with NaOH, then acid with acetic acid. 10 cc. of 36 per cent acetic acid and 10 cc. 2N.CaCl2 were then added. A precipitate was obtained with 50 mgrms. C204, but none with 25 mgrms. C2O4. Thus bromine is unsuitable for the oxidation of sulphites to sulphates because it destroys considerable amounts of oxalates at the same time. Use of H2O2.-Since H2SO4 and H3PO4 are generally employed in the manufacture of H2O2 it was necessary for our purpose to make use of H2O2 which was found to be practically free from SO4 and PO4. Mallinkrodt's 3 per cent H2O2 was found suitable for our work as shown by the following test :-To 20 cc. 3 per cent H2O2 5 cc. of 2N. BaCl2 were added. A faint cloudiness was obtained, showing the presence of less than 1 mgrm. of either SO4 or PO4. Upon adding 5 cc. dilute HCI the cloudiness disappeared, showing that this H2O2 contained no sulphates. 1. To separate solutions containing respectively 1, 2, and 3 mgrms. SO3 as Na2SO3, 45 cc. HCI (t: 2) and 5 cc. 2N.BaCl2 were added. Any precipitate which formed was filtered off. To the filtrate 15 cc. 3 per cent H2O2 were added and the mixture evaporated to 25 cc. This insured the complete decomposition of the excess H2O2. A white precipitate was obtained in each case. 2. To separate solutions containing respectively 5, 10, 25, and 55 mgrms. C2O4, 45 cc. HCl (1 : 2), 5 cc. 2N.BaCl2, and 15 cc. 3 per cent H2O2 were added and the mixtures evaporated to 25 cc. The solutions were made alkaline with NaOH, then acid with acetic acid. An excess of 10 cc. 36 per cent acetic and 10 cc. 2N.CaCl2 were added. A white precipitate was obtained in each case. 3. It was suspected that H2O2 might destroy some tartrate. The following experiment was therefore made: -A solution containing 15 mgrms. C4H4O6 was treated according to procedure given above in Experiment 1. After concentrating to 25 cc. the solution was made alkaline with NaOH and the test for tartrate completed as given in the scheme. A good positive test was obtained. Conclusion. It is possible to detect I mgrm. sulphite cipitating the latter with BaCl2. Oxalates and tartrates are unaffected by H2O2. The hydrogen peroxide should be free of SO, and PO4. V.-Detection of Sulphites and Thiosulphates when present Together. As pointed out in Note 7 under the scheme, the test for sulphites is not conclusive if thiosulphates have been shown to be present. A method for detecting sulphites and thiosulphates in the presence of each other is given by Autenrieth and Windaus (Zeit. Ann. Chem., 1898, p. 295) based upon Table IV., which is also given by them. TABLE IV.-Solubilities in Water. It is evident from the above results that this test cannot be used as it is not sensitive enough. (b) Test Based on the Formation of a Copper-tartrate Complex. This test has recently been investigated by Curtman and Harris (Journ. Am. Chem. Soc., xxxix., 2623). Since the procedure recommended by these authors is only qualitative, it was the purpose of the following experiments to devise a method which would not only be sensitive but would at the same time afford a quantitative estimate of the amount of tartrate present. 1. Separate solutions containing increasing amounts of tartrates were made alkaline with NaOH, 2.5 cc. 25 per cent NaOH, and 3 cc. 2NCuSO4 were added, making a total volume of 15 cc. The solutions contained in testtubes were vigorously shaken for one minute, and im mediately filtered through filters prepared beforehand. To the clear filtrates 2 cc. concentrated NH4OH were added. Negative results were obtained with amounts of tartrate as high as 5 mgrms. 2. The above procedure was modified by decreasing the amount of CuSO4 from 3 cc. to 15 cc. The results obtained by this procedure showed that with 1 mgrm. C4H4O6 a faint blue coloration was obtained, while 3-5 mgrms. gave decidedly positive tests. The following experiments were made to ascertain to what extent borates, phosphates, arsenites, and ammonium salts interfered with the modified procedure, since these substances were reported in the previously mentioned paper as giving the same tests. showed that arsenites and ammonium salts respond to the test in the same manner as do tartrates. The following procedure was devised for preventing the interference of arsenites and ammonium salts. The solution to be tested was made distinctly alkaline with NaOH, and 10 cc. 25 per cent NaOH was added in excess together with 20 cc. 3 per cent H2O2. The mixture was then evaporated nearly to dryness, water (20 cc.) was added, and the solution again evaporated nearly to dryness. Ten cc. of water were then added and the mixture filtered if necessary. The solution was transferred to a test-tube and the procedure applied. The results of a series of experiments are recorded in Table XI. Colourless. No. 250 BO8. C4H106. Mgrms. I-10 50-250 II-14 250 15-16 250 17-18 Results. Mgrms. Colourless. 1-5 ΙΟ 19-24 15 5-15 Faint blue coloration (showed Decided blue coloration. Colourless. Colourless. Results. Very faint blue coloration 7-8 250 Conclusion.-(a) Borates and phosphates when present in considerable amounts interfere with the formation of the copper-tartrate complex to the extent that no less than 15 mgrms. C4H4O6 can be detected in their presence. (b) Chromates do not interfere with the test, since the difference in colour can easily be distinguished if a blank test is made at the same time. (c) Ammonium salts and arsenites interfere by giving the same test. In the proposed procedure the arsenite is oxidised to arsenate, which does not interfere with the test. The ammonium salts are decomposed by the addition of NaOH and the NH3 completely expelled by the repeated evaporation of the solution to nearly dryness. (I-VII.-To Determine to what Extent Sulphites, Thiosulphates, and Arsenites Respectively can Exist together with Chromates in Solution. Faint blue coloration(<5 mg.). 1. A solution containing 250 mgrms. CrO4 as K2CrO4 was mixed with a solution of 250 mgrms. SO3 as Na2SO3 in a total volume of 25 cc. After standing for five minutes the solution acquired a greenish yellow colour, showing that even in neutral solution chromates are reduced by sulphites. 2. Experiment I was repeated, except that after mixing the solution was made slightly acid with diluce HCl. The solution immediately turned green, showing that the chromate is reduced immediately by the sulphite in acid solution. 3. Experiment I was repeated, except that after mixing the solution was made distinctly alkaline with an excess of Na2CO3(3N) solution and boiled for five minutes. The solution remained yellow, showing that in alkaline solution the chromate is not reduced by the sulphite. The last experiment was repeated with 1000 mgrms. SO3 as Na2SO3 and 250 mgrms. CrO4 as K2CrO4. The solution Greenish yellow. remained yellow as before. It was thought that the blue colour could be better seen if the chromate were removed. Experiments were made removing the CrO, by BaCl2 before testing for tartrates as well as after completing the test. In both cases negative results were obtained, showing that it is better to test for tartrates in the presence of chromates. The difference in colour is easily seen when compared with a tube containing a solution of K2CrO4. Action of Arsenites and Ammonium Salts.-Experiments made by the above procedure with 100 mgrms. AsO3 as NazÁs03 and 100 mgrms. NH4 as NH4Cl 4. A similar series of experiments were performed, replacing the sulphite by thiosulphate. The same results were obtained, except that a yellow precipitate of sulphur was obtained in each case in which the solution was made acid. Experiments with as little as 50 mgrms. SO3 as Na2SO3 and 50 mgrms. S203 as Na2S2O3 showed them to be incompatible with CrO4 in either neutral or acid solution. 5. Two solutions, each containing 50 mgrms. As03 as NaAsO2 and 250 mgrms. CrO4 as K2CrO4, were diluted to 25 cc. The first was allowed to stand ten minutes. The solution remained yellow. It was then heated to boiling, but no change occurred. The second solution was made acid with 5 cc. dilute HCl. The yellow colour immediately |