JUST PUBLISHED. Containing over 700 pages and 250 Illustrations. Royal 8vo, cloth 21s. net. INDUSTRIAL AND MANUFACTURING CHEMISTRY ORGANIC. By GEOFFREY MARTIN, Ph.D. (Rostock), M.Sc. (Bristol), B.Sc. (London), F.C.S. LECTURER ON CHEMISTRY AT BIRKBECK COLLEGE, LONDON. ASSISTED BY FOURTEEN SPECIALISTS. The Editor's aim has been to cover the whole range of subjects with which the industrial chemist and manufacturer are usually concerned, and the book will serve either as a text-book or as a work of reference; it will meet the requirements of all business and practical men interested in chemical processes, of manufacturers, consulting chemists, chemical engineers, patent workers, inventors, technical lawyers, students in technical institutions, lecturers on technology, fire insurance inspectors, and others. For DRAWING CHEMICAL SKETCHES. Price 6d. DETAILED PROSPECTUS POST FREE ON APPLICATION. LONDON CROSBY LOCKWOOD AND SON, 7, Stationers' Hall Court, E.C., and 5, Broadway, Westminster, S.W. ORE CRUSHER and PULVERISER. COMPLETE COOPER'S LABORATORY APPARATUS. Price 12s. 6d. FURNISHERS 15. 9d. F. E. BECKER & CO., 17-27, HATTON WALL, E.C. LE RADIUM. PUBLIE TOUT CE QUI CONCERNE LES INSTRUCTION IN E PURE CULTIVATION OF YEAST. Physiology and Technology of Fermentations. Courses for beginners, as well as for Advanced Students in Biological Analysis of Yeast. The Laboratory possesses a numerous collection of Yeasts (Brewers', Distillers', Wine, Disease Yeasts), Moulds, and Bacteria. Manuals: ALFRED JORGENSEN, "Micro-organisms and Fermentaion," 4th edition (Charles Griffin and Co., London), and "The Practical Management of Pure Yeast" (London, "The Brewing Trade Review"). The Laboratory supplies for direct use Pure Cultures of Yeast for Breweries, Distilleries, Wine Manufactories, &c.. and performs Analyses of Yeasts, &c. Further particulars on application to the Director ALFRED JORGENSEN, The Laboratory, Copenhagen Y., Denmark. Dec. 6, 1912 FREDK. JACKSON & CO., Ltd., 14, CROSS STREET, MANCHESTER. GOODS ENTRANCE: 10, Half Moon Street. TELEGRAPHIC ADDRESS: BALANCES, Apparatus, Manchester. GENERAL CHEMICAL APPARATUS, HEMPEL and ORSAT GAS ANALYSIS THE LONDON GAS REFEREES' CAS BURETTES OF VARIOUS KINDS. ORSAT GAS ANALYSIS APPARATUS. THE ILLUSTRATED PRICE LISTS FREE ON APPLICATION. AMATEUR PHOTOGRAPHER COVERS FOR BINDING. and PHOTOGRAPHIC NEWS. Edited by F. J. MORTIMER, F.R.P.S. Price TWOPENCE-Every TUESDAY. The Leading Paper for Everyone interested in Photography. Special Articles on PICTORIAL and MODERN SCIENTIFIC PHOTOGRAPHY. The best and brightest Photographic PROFUSELY ILLUSTRATED. Office: 51, LONG ACRE, LONDON, W.C. PORCELAIN- HALDENWANGER Can be obtained from all businesses which deal in Chemical Apparatus. London; Printed and Published for the Proprietor by EDWIN JOHN DAVEY, at the Office, 16, Newcastle Street, Farringdon Street, E.C. December 6, 1912 JAN 113 LOAL LABORATORY OF HARVARD COLLEGA. THE CHEMICAL NEWS Edited by AND JOURNAL OF PHYSICAL SCIENCE S1 Wm. Crookes, O.M., F.R.S.] (WITH WHICH IS INCORPORATED THE "CHEMICAL GAZETTE"). Establish [Sixty-eight Years. Pablished Weekly Annual Sub-cription free by post £1 Entered at the New York Post Office as Second Class Mail Matter Vol. 106.-No. 2768. [Cop Friday, December 13, 1912. ARTICLES: reserved. CONTENTS. Note on the Electrolysis of Nitric Acid Solutions of Copper, by 28, ..... 287 Registered as [PRICE 44. a Newspaper. POST PRBS 4td. na DYE or TANNIN WORKS. Gentleman seeks Situation; thoroughly practical; high-class testimonials.Address, D. H., CHEMICAL NEWS Office, 16, Newcastle Street, Farringdon Street, London, E.C. For THE MURDOCH TRUST. or the Benefit of INDIGENT BACHELORS and WIDOWERS of Good Character, over fifty-five years of age, who have done "something" in the way of Promoting or Helping some branch of Science. Donations or Pensions may be granted to persons who comply with these conditions. For particulars_apply to Messrs. J. & J. TURNBULL, W.S., 58, Frederick Street, Edinburgh. 294 PLATINUM Utensils.-We supply all forms LEAD ASHES, SULPHATE OF LEAD, LEAD SLAGS, ANTIMONIAL LEAD, COPPER MATTE, TIN ASHES, &c., ORES, DROSS, or RESIDUES, containing TIN, COPPER, LEAD, and ANTIMONY. OZONE APPARATUS for the LABORATORY. 12 Page Illustrated Pamphlet, fully describing various forms of Apparatus and method of using them, Post Free to Readers of the "Chemical News. OZONAIR, Ltd., 96, VICTORIA STREET, WESTMINSTER, LONDON, S.W. LEWIS'S Circulating Annual Subscription. . from One Guinea. TECHNICAL AND SCIENTIFIC WORKS. READING ROOM OPEN DAILY, 136, GOWER STREET, LONDON, W.C. and sizes of Platinum Utensils and Apparatus for Chemical and Physical purposes. All our utensils are hammered to shape, tested, and finished in the best manner. All kinds of Platinum scrap bought for cash or taken in exchange for new.-DERBY and CO., Ltd. 14, Clerkenwell Road, London, E.C. T. TYRER & CO., Ltd, Stirling Chemical Works, STRATFORD, LONDON, E. CHEMICALS for Analysis, Research, and Technical purposes. TECHNICAL EXPERIMENTS carried out on a MANUFACTURING SCALE. Inquiries solicited from INVENTORS and PATENTEES (especially Foreign) under the New Act, 1906. To be obtained from HUGO LORENZ, Cloth, 3/6; Paper covers, 216. (Postage, 4d. extra). THE WHEAT PROBLEM: Based on Remarks made in the Presidential Address to the British Association at Bristol in 1898. REVISED WITH AN ANSWER TO VARIOUS CRITICS By SIR WILLIAM CROOKES, F.R.S. SECOND EDITION. VITH PREFACE AND ADDITIONAL Chapter, BRINGING THE With Two Chapters on the Future Wheat Supply of the OPINIONS of the PRESS. "The student of economic science and sociology will find this volume full of interesting material. The entire subject is of the profoundest interest, and an excellent pur 7-8, Idol Lane, Great Tower St., London, E.C., pose has been served by the publication of these papers in Licensed Trader in Alcohol and Spirits of Wine. Stock kept is suitable packages ready for immediate ure. a single volume."-The Eagle (Brooklyn, N.Y.). "In his bulky volume Sir William reproduces the gist of the sensational Bristol Address, and supplements it with carefully prepared answers to his chief critics and confirmatory chapters on the future wheat supply of the United States."-Morning Post. "The problem is one of importance, and Sir William Crookes presents it to us fortified by the opinions of two American experts." Manchester Guardian. "If these somewhat gloomy prognostications result in drawing the attention of chemists more seriously to what has hitherto been only an interesting laboratory problem, Sir William Crookes will have conferred an incalculable benefit on the race."-Western Morning News. "Sir William Crookes .. has propounded a problem which in the next century [written in 1899] is bound to engage the close attention not merely of agricultural experts, but of economists and statesmen."-Speaker. "The book is a useful one to all interested in the proluction of wheat both from the commercial and scientific points of view."-Knowledge. "Sir William Crookes's statistics seem to make good his alarmist statement."-British Weekly. "It is a vital question, and considering the cheap issue of the volume all interested in the feeding of the millions ought to get it and read it carefully."-Crieff Journal. "The appearance of the papers in this convenient form will be welcome to everyone who appreciates the importance of the problem."-Scotsman. CHEMICAL NEWS OFFICE, 16, NEWCASTLE ST., FARRINGDON ST., EC. SULPHUROUS ACID and SULPHITES. Liquid SO, in Syphons, for Lectures, &c. PHOSPHORIC ACID and PHOSPHATES. CARAMELS & COLORINGS for all purposes. A BOAKE, ROBERTS, & CO. (LIMITED), atford. London, 2. 112 Electrolysis of Nitric Acid Solutions of Copper. CHEMICAL NEWS. VOL. CVI., No. 2768. NOTE ON THE ELECTROLYSIS OF NITRIC ACID SOLUTIONS OF COPPER.* By J. H. STANSBIE, B.Sc., F.I.C. IN the electrolytic deposition of copper from nitric acid solutions it is practically impossible to deposit the whole of the metal upon either a rotating or stationary cathode under ordinary conditions, and in considering the results of experiments in which a copper coated cathode was caused to rotate in a nitric acid solution with no current passing, the probable cause of the failure of the current to deposit the last traces of copper from a nitric acid solution suggested itself. 283 the stationary one when purely nitric acid solutions are used. The following experiments were then made as a further test:-Five grms. of electrolytic copper were dissolved in 50 cc. of 12 nitric acid, and the solution evaporated to one fifth its bulk to decompose nitrous compounds. It was then made up to 500 cc., and the free nitric acid in 50 cc. determined. This was found to be 236 mgrms. The remaining solution was electrolysed with a rotating cathode in 50 cc. lots. Additions of free acid were made as shown in the table, and the other conditions were kept as constant as possible. The measured volume with additions was made up to 100 cc. in each case. The potential difference between the terminal of the rotor carrying the cathode and the anode = 3'2 volts. Current 15 ampères. Duration of experiment = 40 minutes. Experiment. = was The object of the preliminary experiments was to determine the difference in the rate of reaction of dilute nitric acid with copper at rest and in motion. For this purpose a platinum cathode was thickly coated with copper by electrolytic deposition. After drying and weighing rotated in 50 cc. of nitric acid (sp. gr. 1108) containing about 10 grms. of HNO3 and less than o'I mgrm. of HNO2. When the rotation was stopped the cathode was at once removed, washed, dried, and re-weighed. then immersed in a similar solution, but was allowed to remain at rest for the same length of time. The beaker was immersed in a vessel containing water at room tem perature. All the conditions were kept as constant as possible, except that the metal was rotating in the one case and at rest in the other. The following remarkable results were obtained : It was Mgrms. 6.5 780.6 15'4 3486.3 It is well known, but often overlooked, that nitrous acid plays a very important part in the dissolution of copper in nitric acid, and that the lower acid, or nitrite, accumulates in the solution. In solutions containing only traces of nitrous acid, the action is very slow at first, but gradually increases as more nitrite is formed. It this is allowed to remain on the surface of the metal the general reaction is rapidly accelerated, but if it is hurried away into the mass of the solution the reaction is retarded. This is the most obvious explanation of the results given above. Now in the ordinary electrolysis of nitric acid solutions of copper the solution is boiled, in the first instance, to decompose nitrous acid and nitrite, and to expel the products of their decomposition; but nitric acid is again reduced to nitrous acid by the current during electrolysis, and all the conditions for the dissolution of copper from the cathode are present. At first the current deposits the metal very much faster than it is re-dissolved, but finally, when only traces of metal are present in the solution, dynamic equilibrium is reached, and no further permanent deposition of the metal can take place. This furnishes another argument in favour of the rotating cathode over A Paper read before the Faraday Society, November 26, 1912, 4500 It will be seen from the table that the more or less perfect deposition of the copper depends upon the concentration of nitric acid and of nitrous acid in the solution, the smaller deposit corresponding to the greater concentration of the higher acid, while for the same concentration of the "ic" acid the smaller deposit corresponds to the greater concentration of the "ous acid. From Experiments 5 and 6 it would appear that up to 3 grms. of HNO3 per 100 cc. of solution the deposits are good, providing the nitrite keeps low; but beyond that the deposit is poor. Before the introduction of the rotating cathode the method adopted by the author was to evaporate the nitric acid solution with sulphuric acid before electrolysis, as it was found impossible to deposit the whole of the metal without getting rid of the nitric acid, on account of the low current density used. But with the rotating cathode it is sufficient to keep the nitric acid low, and add from The usual plan is to 2 to 3 cc. of strong sulphuric acid. dissolve about o'5 grm. of the metal in 10 cc. of 1.2 nitric acid, boil down to decompose nitrites, and make up to 100 cc. with addition of 2 cc. of concentrated sulphuric tion will very rarely give any coloration with sulphuretted acid. After forty minutes' electrolysis the exhausted soluhydrogen. To prevent any resolution of the metal when the circuit is broken the following simple plan has been found very effective:-A wash-bottle with a long rubber tube attached to the mouthpiece is arranged so that when the rotation is stopped a jet of water can be directed upon the cathode, while the current is gradually broken by lowering the beaker. The fixed wash-bottle with the flexible tube allows the operator to use both hands in manipulating the apparatus. The action of the sulphuric acid is probably twofold :— (a) Its ions help to carry the current and thereby to check acid to form a nitro-compound which is much less effective the formation of nitrous acid; (b) it unites with nitrous in bringing about resolution of the metal. Comparison of the results of Experiments 2, 3, and 8, 9 makes the first part of this explanation clear. The second part was suggested by the late Dr. Edward Divers in discussing the results of some experiments on the reactions of metals and alloys with nitric acid, which the author had carried out. |