CHEMICAL NEWS, Jan. 6, 1911 Physical Society's Exhibition of Apparatus 9: From our experience with both electrolytes we believe | of the new Dionic Water Tube. It is an original device for that the plain chloride is a little more satisfactory than the mixture of the chloride and fluoride in point of efficiency, and decidedly easier to manipulate. We have shown that satisfactorily high efficiencies can be obtained with it, and that efficiency is more largely a matter of careful regulation of conditions than anything else.-Chemical Engineer, xii., No. 5. PROCEEDINGS OF SOCIETIES. PHYSICAL SOCIETY. December 20th, 1910. SIXTH ANNUAL EXHIBITION OF ELECTRICAL, OPTICAL, AND OTHER PHYSICAL APPARATUS. quickly and accurately measuring the electrical resistance of a volume of water and is likely to have a wide range of usefulness; it can be used for measuring the hardness of water, the leakage of cooling water into surface condensers, sewage pollution of rivers, and many other purposes. In the demonstration given a beaker of distilled water gave a reading of 20°; the addition of one drop of sea-water sent the reading up to 80°. A great number of tests have been made of various waters; distilled water varied from 0.2° in the case of a specially pure sample prepared by Kohlrausch to 14° in a sample from a London retail chemist. Water from public supply Companies ranged from Loch Katrine water 34° to West Middlesex London supply 390°, while sea-water taken off Harwich and the Isle of Wight gave 50,000. Of course the instrument will not indicate the nature of the impurity, but one obvious application is to obtain a continuous record of the condition of a water supply. Any abnormal contamination would be at once recorded and could be investigated. THE Sixth Annual Exhibition was held at the Imperial Messrs. GRIFFIN and SONS, amongst other novelties, College of Science at South Kensington. These Ex showed a new mechanically worked Mercurial Pump of hibitions have been growing in magnitude and value since very simple construction. A vacuum tube about 14 inches their commencement six years ago, and this last effort has long and I ins. in diameter was exhausted so as to give full certainly established a record for importance. Some green phosphorescence in a few minutes. The pump was fitted thirty-six firms were represented, and no pains were spared with a novel form of McLeod gauge, in which the capacity to make the exhibits interesting and instructive. In chamber was replaced by a coiled glass tube of several addition to this demonstrations were given both in the convolutions about 6 inches in diameter fitted to the pump afternoon and evening by Professors J. A. Fleming, by a ground joint. The observation was made by trapping Silvanus P. Thompson, and R. W. Wood. The attendance a plug of mercury in this tube and rotating it so as to cause was very good, and was maintained up to a late hour. the mercury to compress the gas into the measuring tube at the end. The Council of the Physical Society are acting wisely in not allowing these "Exhibition Evenings" to become merely occasions for manufacturers to show their goods, and the demonstration of results and researches by leading physicists of the day, combined with the latest novelties in apparatus by our most active manufacturers, make the occasion of importance, as, in addition to the general interest, they bring manufacturers and workers together to the mutual advantage of both. It is impossible, as well as unnecessary, to enumerate all the exhibits, but we will draw attention to a few of the most novel : Among the exhibits of Messrs. R. and J. BECK was the Beck-Gordon Lamp for microscopical illumination. This is a device by which the light from an incandescent mantle or electric filament can be made to give a field of light with a perfectly even area of illumination. A silvered glass cylinder several inches long is mounted in front of the light, which being totally reflected along the sides emerges as a practically homogeneous disc of light. The same firm had also a number of Thorp Diffraction Gratings (celluloid casts from original Rowland rulings). These were of great beauty, and are said to be equal to the originals, and can be produced at moderate cost. The CAMBRIDGE SCIENTIFIC INSTRUMENT COMPANY had a number of novelties, among others Prof. C. T. R. Wilson's Tilted Gold Leaf Electroscope. During the evening a demonstration of the sensitiveness of this beautiful little instrument was given by Dr. G. W. C. Kaye, of the National Physical Laboratory, who showed the electrification due to the splashing of mercury. Messrs. C. F. CASELLA and Co. showed a novel form of Barometer with a tube of india-rubber, which could be coiled up and packed away in a bag when not in use. Messrs. CoSSOR and Co., the well-known tube makers, showed a new form of X-ray Tube, designed to carry heavy currents. The platinum anticathode is mounted on a massive copper rod, which projects outside the tube, ending in a multiple fin radiator to dissipate the heat formed at the target. The device for regulating the vacuum consisted in a side tube containing asbestos cloth, which is said to liberate a copious volume of dry air when in action. Messrs. ADAM HILGER and Co. gave a demonstration of Prof. Wood's method of showing the anomalous dispersion of sodium vapour with great success. Messrs. NEWTON and Co. had a new form of Mercury Dessauer" Interrupter for Induction Coils known as the " Break. This is said to be an improvement upon the various gas mercury interrupters now in general use; it gives a very rapid and clean break, and will pass a heavy current, while the construction is simple and unlikely to get out of order. The effect upon one of their "Instanta " coils was to produce a very thick flame-like discharge under perfect control. continuous Current Transformer invented by Mr. LESLIE One of the newest things in the Exhibition was a small At present this little apMILLER of Hatton Garden. paratus has only been produced in one form, but it bids fair to have a wide application. The present instrument, in the form of a polished teak box about 10 inches square, can be fitted to any continuous current lamp plug, and takes alternating current of about 10 amperes, useful for medical about half an ampère, and converts it into a low voltage cautery or lighting small lamps, &c. The current can be regulated at will, and the efficiency is said to be very high, certainly above 80 per cent. This apparatus is capable of great development. Another novelty, shown by Messrs. WRIGHT and Co., was a new Spark Coil Apparatus by Prof. Wilson. It consists of a special form of spark coil with an inductance and an interrupter driven by a small motor. The current was taken from an ordinary lamp fitting, and although the coil looked almost a toy compared with the gigantic machines now in common use, a 5-inch bulb was fully illuminated and gave a very steady and bright green illumination. MessIs. CARL ZEISS and Messrs. E. LITZ both showed beautifully arranged projection apparatus. The latter firm have introduced a quick change instrument by which the change can be made from high power microscopical projection to lantern slides or opaque objects in a few seconds. Tea and coffee were served, and the convenience of the rooms and staff of the Imperial College of Science added Messrs. EVERShed and VignolES demonstrated the action much to the success of the evening. ROYAL PHOTOGRAPHIC SOCIETY. Dr. W. SCHEFFER, the well-known photo-chemist and microscopist of Berlin, gave a demonstration of his microscopic researches upon the gelatin film of dry plates before the Royal Photographic Society on December 20th. His aim had been, he said, to discover microscopically, using a magnification of 2000 times, the first physical traces of photographic development. Premising that his physical explanations did not touch in any way upon the chemical theory of the latent image, he said that after an ordinary exposure such as one would give in taking a photograph, and a very brief development with a diluted developer, some of the silver grains in a plate were observed to be projecting fine tiny filaments. These filaments, which in some cases proceeded from a nebulous halo surrounding the grain, and in others from the grain itself, were in reality the first visible traces of the developing process. On carrying development further the developed grain would be found to increase in size and the filaments to become thicker. Certain of the grains, however, had no filaments, and these grains became increasingly delicate as develop. ment proceeded, and finally entirely disappeared. The evident function of these filamentless grains of a plate, said Dr. Scheffer, was to act as a nourishment for the black developed grains. As a matter of fact there were two kinds of grains in the plate; the first, the original grains which went directly to form the photographic image, and the second, the nourishing grains, which fed them. He then brought out the different effects produced by variations in exposure and development. In a plate which had received the correct or optimum exposure for a given development, practically all the nourishing grains disappeared after the developing process, and the formation of black developed grains was at its maximum. Overexposure entailed an over-production of the original grains bearing filaments, but these grains did not undergo much change in development, and there was a deficiency of nourishing grains. In a plate developed with diluted developer, as compared with one developed with a concentrated developer, many of the nourishing grains were left quite untouched. In the process of intensification of a plate no new grains were formed, but every black developed grain gained something in mass. In the case of reduction with ammonium persulphate those grains which belonged to a portion of the plate fully developed disappeared almost entirely, while others belonging to a portion which had had a shorter development did not disappear, but something like a wall was formed around them to protect them from the persulphate. The cutting of square sections through the film led to the unravelling of many obscure photographic processes. The photo-micrograph of the section of an under-exposed film showed that only the upper part of the gelatin was filled with black developed grain. With the longer exposure the masses of grain which had been developed were observed to go down through the whole film to the glass. The thickness of the layer of black developed grain was an exponential function of exposure. In the underdeveloped plate also the upper layers of the film only showed black developed grain, whereas with the same exposure but a longer development the masses, obeying the laws of diffusion and mass action, penetrated down to the deeper layers of the film. The same topographical phenomena were observed in comparative work upon ammonium persulphate and Farmer's reducer. In the latter there was a sharp-cut limit of action in the film. Farmer's reducer acted only in the upper part of the film and left the deeper layers untouched. Ammonium persulphate, on the other hand, affected all the grains from the top of the film to the bottom. If the velocity of action was great as compared with the velocity of diffusion, the reducer, as in the case of Farmer's, penetrated slowly and acted quickly. If the conditions were reversed, as in ammonium persulphate, there was quick penetration and comparatively slow action. Consequently, in the latter case, the grains from the top to the bottom were affected, no matter where they lay in the film. NOTICES OF BOOKS. The Fats. By J. B. LEATHES, M.A., M.B., F.R.C.S. London, New York, Bombay, and Calcutta: Longmans, Green, and Co. 1910. THIS monograph is intended for the use both of physiolɔgists and chemists who are more particularly interested in biology, and it lays emphasis upon the still unsolved problems which are awaiting the attention of trained chemists who have some knowledge of biology. The chemistry and composition of the fatty acids, their alcohols, and fatty acid esters are first fully treated, and methods of extracting them from the tissues and estimating them are then dealt with, while the processes employed in the study of them in the laboratory are described in detail. The fourth and last section of the book is devoted to the physiology of the fats and the part they play in vital phenomena, and although the book gives an excellent critical survey of the work that has already been done on this subject, it is very apparent that there is need for much further investigation, and the author shows clearly the exact directions in which more work must be performed before definite advances can be made in this branch of animal and vegetable chemistry. An Introduction to the Study of Metallurgy. By Sir W. C. ROBERTS-AUSTEN, K.Č.B., D.C.L., D.Sc., F.R.S. Sixth Edition, revised and enlarged by F. W. HARBORD, A.R.S.M., F.I.C. London: Charles Griffin and Company, Ltd. 1910. THE sixth edition of this valuable treatise on metallurgy, the merits of which have long been known to students, teachers, and practical men, has been thoroughly revised by one of Sir W. Roberts-Austen's former pupils; it has been found desirable to make a considerable number of alterations and additions, of which the most important are as follows:--The preparation of a special chapter upon alloys and the fuller treatment of the thermic properties of alloys other than steel; also the discussion of the recent rapid advance of knowledge of the theory and practice of pyrometry, in which new and accurate methods and instruments have recently been perfected. Metallography is also treated much more fully and completely, and many new types of furnaces are described, the chapters on fuels and furnaces having both undergone considerable alterations. Excellent bibliographies are appended to some of the chapters, and the text-book will clearly long retain its position as one of the foremost on metallurgy in the language. Fire Tests with Textiles. London: The British Prevention Committee. 1910. THE British Fire Prevention Committee has done a valuable work in investigating the inflammability of flannelettes and other textiles, and the results of their investigations ought to be made as widely known as possible. The object of the experiments was two-fold. Firstly, to obtain reliable data as to the relative inflammability of various materials, and to ascertain the effect of treating flannelette with a view of reducing its tendency to ignite; and, secondly, to work out the details of a trustworthy and simple standard test. For these purposes over 450 experiments were performed, and hence the conditions which should be fulfilled by a sample if it is to regarded as non-inflammable were determined. The full results of all the tests are described, and many of them are illustrated by photographs, which show very strikingly the great dif ference between flannelette and other textiles as regards inflammability, and also the marked effect of treating flannelette by the "non-flam" process. CHEMICAL NEWS Chemical Notices from Foreign Sources. The Chemists' Pocket Manual. By RICHARD K. MEADE, M.S. Second Edition. Easton, Pa.: The Chemical Publishing Co. London: Williams and Norgate. 1910. THIS pocket manual is designed more particularly for the use of the engineering and works' chemist, and contains all the tables and data which there is any likelihood of his requiring. Moreover, there are full descriptions of the quickest and most accurate methods of determining physical constants and of the usual analytical processes for the examination of metallurgical and other products. Bell's Sale of Food and Drugs Act. Fifth Edition. By THE fifth edition of this book contains all the Acts relating Photography in Colours. A Text-book for Amateurs, with II The Denver Fire-clay Company's Catalogue of Assayers' THIS fully illustrated catalogue contains many pieces of Fourteenth Edition. THE issue of an illustrated catalogue of 1020 pages is no mean task, and Messrs. Griffin and Sons are to be congratulated on having included the description of all their manufactures in one volume. It has been brought quite up to date; this is particularly noticeable in the section devoted to furnaces, radiation pyrometers, &c., where the latest electrical devices for obtaining and measuring high temperatures are shown. We may safely say that all that is needed in the way of apparatus for scientific research or teaching can be found in the book. The activity of late years in the elaboration and manufacture of science apparatus has made the issue of catalogues of this kind by dealers an absolute necessity, few years many of the devices shown will be both obselete and it has to be done with the consciousness that in a very and unneeded. This unfortunately cannot be helped, and we are quite sure that the fourteenth edition of "Scientific Handicraft" will be fully appreciated by all interested in the advance of science. The Scientist's Reference Book and Diary. Manchester : THE above diary is in narrow pocket-book form, and is VERY great advance has recently been made in the preparation of photographs in natural colours, and the most recent triumph has been the production of kinematographic pictures in which the combination of movement and coloration give an astonishingly life-like effect. These results are of great interest and value from a spectacular point of view, and the highly interesting lecture given by Prof. Stirling during the last meeting of the British Association demonstrated the value of the kinematograph as an aid in the study and teaching of natural history. Since the publication of the author's previous work on colour photography the advance has been so great that it has been found necessary to re-write the subject, and the modest little book before us, although written for the amateur, is in reality a thorough elaboration of practically all that has been done upon the subject to the present time. Commencing with Historical Notes" the evolution of colour photography is traced through the work of Goethe, Zenker, Lippmann, Young, Helmholtz, and Ives, and a whole chapter, well illustrated, is devoted to the physics of the eye, colour vision, and colour blindness. This chapter is particularly valuable; as coming from the pen of a properly qualified man, it places subsequent exposition of the science upon a thoroughly sound basis, and enables the amateur the more readily to grasp the meaning of the various operations that he will have to carry out in CHEMICAL NOTICES FROM FOREIGN the preparation of colour pictures. Up to Chapter VI. the book is devoted to the enumeration and explanation of the various discoveries that have led up to or are involved in the present day work, and numerous illustrations and diagrams are given to render the explanations as clear as possible. Chapters VII. and VIII. deal with the practical working of the various present day processes, and give elaborate and valuable details that show that the author is himself an enthusiastic worker on the subject. Chapter IX. treats of kinematography in natural colours, and shows the advance that has been made, and indicates the possibilities of developments in the near future. On the whole the book will prove invaluable to all who are working on this fascinating subject, and its perusal is likely to encourage many who have hesitated for want of knowledge to know just where to begin. It is an exceedingly handy pocket-book, and the price in red leather is Is. 6d., and in morocco 2s. 6d. SOURCES. NOTE.-All degrees of temperature are Centigrade unless other ise expressed. Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. Vol. cli., No. 19, November 7, 1910. Progressive Phosphorescence at a Low Temperature.-J. de Kowalski.-At the ordinary temperature benzene and its derivatives exhibit an ultra-violet fluorescence. When the temperature is lowered to 135° the solutions remain liquid but become more viscous, and the fluorescence extends towards the red, so that it becomes visible, although at the ordinary temperature it is invisible. At about 135° the viscous sclutions become solid, and recently at St. Enoch's Hotel, the following gentlemen being present: - Prof. A. Campion, Prof. Thos. Gray, and Prof. G. G. Henderson, Technical College; F. W. Harris, Corporation Chemical Department; D. Perry (Perry and Hope, Ltd.); Andrew Macdonald; Prof. John Ferguson and Prof. Cecil H. Desch, the University; John Traquair (W. Wotherspoon. Ltd.); John Shanks (Shanks and Co., Ltd.); W. D. Bost; W. Hatrick (W. and R. Hatrick and Co.); F. W. Bridges. Mr. F. W. Bridges, the Organising Secretary and Manager of the Exhibition, explained at some length the object and scope of the Exhibition, and the steps which had been taken up to the present by the Hon. Advisory Council to ensure the success of the Exhibition-the first of its kind. He also mentioned that a considerable number of applications for space had been received from leading firms connected with various branches of chemical industry, and the Council were desirous that Scottish firms would be well represented at the Exhibition. At the unanimous wish of those present Prof. G. G. Henderson accepted the position of Chairman of the Committee, and it was decided to hold a further meeting at the Technical College in January, 1911, and in the meantime to considerably strengthen the Committee, as it was considered most desirable that this Exhibition, which is calculated to benefit considerably the chemical industries, should be well supported by engineers and others connected with the chemical industry. A similar meeting was also held cluding:-Dr. Hans Benfey; W. H. Coleman; Jul. at the Midland Hotel, Manchester, those present in below the temperature of solidification phosphorescence, The first meeting of the Glasgow Committee was held appears. If the substance is exposed for a very short time to the action of light a bright phosphorescence of short duration appears, and its spectrum is almost identical with the fluorescence spectrum. If the exposure to the source of light is continued it will be seen that fine bands are superposed on the broad fluorescence bands, and their intensity increases with the duration of the exposure up to a limiting value. The emission spectrum of this progressive phosphorescence of an alcoholic solution is a function of the dissolved substance and varies slightly with the concentration of the solution. The bands of its spectrum differ from those of the instantaneous phosphorescence, and the relative intensity of different bands depends upon the temperature and the source of light employed. For every substance there is a temperature above which progressive phosphorescence does not appear. Preparation of Crystallised Strontium.-A. Guntz and M. Galliot. Finely powdered strontia is mixed with aluminium in the proportion given by the equation 3SrO + Al2=3Sr+Al2O3. It is then heated in a steel tube to 1000, and a vacuum is made in the porcelain tube in which it is placed, and thus about 75 per cent of the strontium used is obtained in the crystalline form. Tetranitromethane.-E. Berger.-Tetranitromethane can be obtained by the nitration of acetic anhydride if the reaction is not allowed to proceed too quickly, the temperature does not exceed 70°, and the reagents are used in the proportion of 160 grms. of pure nitric acid, 100 grms. of crystallised acetic acid, and 290 grms. of acetic anhydride. The density of tetranitromethane is 1.620 at 22°. It distils at 124-125° under 750 mm. pressure, decomposing very slightly with production of nitrous vapours, and at 21-23° under 22 mm. pressure without decomposition. Its boiling-point under 22 mm. pressure is 45-47°. When reduced by aluminium amalgam in a neutral medium it yields the same products as in an acid medium - nitrogen, ammonia, and methylamine, but no polyamines. Its heat of formation from its elements is 4'7 cals. Influence of Nitrates on Alcoholic Ferments.-E. Kayser. Fermentation is more complete in presence of manganous nitrate, and there seems to be a maximum amount of salt which induces the maximum amount of diastatic activity for each kind of yeast. Too great a quantity of nitrate hinders fermentation. Manganese nitrate acts more energetically than an equal amount of potassium nitrate. Purification of Starch.-G. Malfitano and A. N. Moschkoff.-Starch may be freed from its mineral impurities by heating with pure water, decanting off the liquid, and allowing it to congeal in a nickel vessel and then letting it melt; a liquid is thus obtained which contains the greater part of the salts and very little starch, the latter remaining in the form of flakes, which may be separated by centrifugation. The repetition of this process removes practically all the mineral matter from the starch. MISCELLANEOUS. Hubner, Secretary Manchester Section, Society of Chemical Industry; W. Beaumont Hart, Manchester Laboratory; J. H. Hoseason (Hough, Hoseason, and Co.); R. H. Clayton, Chairman Manchester Section, Society of Chemical Industry; Chas. Dreyfus (Clayton Aniline Co., Ltd.); S. W. Royse (S. W. Royse and Co.); F. W. Bridges; Mr. Bridges, Organising Secretary and W. Royse was unanimously elected Chairman of the Manchester Committee. The project commended itself favourably to all present, the opinion being freely expressed that such an Exhibition as this was wanted and would do much good to the whole industry. A large number of names were suggested of gentlemen to be invited to join the Committee, and it was agreed to hold a further meeting at the Chamber of Commerce on January 11th, 1911, when various other plans would be discussed with the view to the chemical industries of Manchester and district being well to the front at such an important Exhibition. Manager. On the proposition of Prof. Dreyfus, Mr. S. TUESDAY, 10th.-Royal Institution, 3. (Christmas Lectures, adapted Society of Public Analysts, &c.-The Anniversary Dinner of the Society will be held on Tuesday, January WEDNESDAY, 31st, at the Trocadero Restaurant, Piccadilly, W. Chemical Engineering and Industries Exhibition. -Formation of Committees in Glasgow and Manchester.-Considerable progress is being made with the arrangements for the forthcoming Chemical Engineering and Industries Exhibition to be held at the Agricultural Hall next May. The Hon. Advisory Council (of which the Chairman is Mr. Walter F. Reid, President of the Society of Chemical Industry) have decided to arrange Local Committees in the chief centres, and during the past week Committees have been formed in Glasgow and Manchester. "The THURSDAY, 12th.-Royal Society. "The Absolute Expansion of CHEMICAL NEWS, Mesothorium. 13 from thorium ores rich in uranium, as, for example, thoriTHE CHEMICAL NEWS. anite always contains mesothorium. VOL. CIII., No. 2668. MESOTHORIUM. By W. MARCKWALD. As the duration of life of radium is about 300 times that of mesothorium it is very important when studying a "radium preparation" to take into account the possibility of its containing mesothorium. As in the case I have mentioned a useless preparation was sold with the best intentions, there is also the danger of deliberate adulteration. The simplest way to test a radium preparation for mesothorium is to heat it for a short time to drive off the emanation. The preparation must then lose its y-radiating power after a few hours, completely regaining it only after the lapse of many weeks. Instead of heating it, it can of course be dissolved in water and the solution evaporated. If after the radium emanation has been driven off, and the radium C has been destroyed (which takes a few hours) there is still some y-radiation, this is due to mesothorium. The ratio of the y-radiation before and after the treatment is a measure of the proportion of radium and mesothorium in the mixture.-Berichte, xliii., 3420. IN 1907 O. Hahn (Berichte, xl., 1907, 1462, 3304) indirectly proved that thorium, on undergoing radio-active atomic disintegration, was converted into a metabolon, of which the half-constant was about five and a-half years, and which was separated from thorium during the working-up process of the preparation of the element from its ores. He called it Mesothorium. Subsequently Hahn detected this substance in the residues. He showed (Zeit. Phys. Chem., ix., 1908, 246) that mesothorium is not directly converted into radio-thorium, but that a short-lived intermediate product, mesothorium II., results (half duration of life = 6.2 hours). Recently Hahn (Lecture at the Meeting of the German Chemical Society, July 11, 1910) succeeded in concentrating the substance to such an extent that its AND AMMONIUM CARBONATE BY TITRATION. action considerably exceeded that of an equal weight of pure radium salt. The author has not published any details of the chemical properties of mesothorium I., and the method of discovering and preparing it. A short time ago I received from a chemical works a "radium preparation" which I was to investigate, determining its percentage of radium. It consisted essentially of barium chloride. Judging from its y-radiation it must have contained more than I per cent of radium chloride. But when its power of emanation was investigated it was found that the radiuin emanation evolved corresponded to only about o'2 per cent of radium. Further investigation showed that the greater part of the y-radiation (about 80 per cent) was due to mesothorium II. For if a trace of ron chloride was added to the aqueous solution of the salt and it was then made ammoniacal, the mesothorium II. was precipitated with the iron hydroxide. A strong y-radiation was emitted by the precipitate, while the barium chloride obtained by evaporating the solution had lost almost the whole of its power of emitting y-rays. But while the precipitate lost almost all its power of radiation with a half-constant of about six hours, the salt regained the greater part of its power of radiation in a day. The ammoniacal precipitate must thus contain the radiothorium formed from the mesothorium. As a matter of fact, after the decay of the mesothorium II. there remained a residue which emitted a-rays, and which gave thorium emanation. In reply to my enquiries the factory informed me that their "radium preparation" had been obtained by working up residues from ores containing uranium and thorium. Evidently mesothorium is completely analogous to radium from a chemical point of view. I have not yet succeeded in finding a reaction by which it can be separated from barium and radium. On re-crystallisation of the chloride it accumulates with the radium in the difficultly soluble crystallisations. This complete similarity of the two radio-active elements is very interesting. For up to the present no method has been found of separating by chemical reactions the four elements-thorium, radiothorium, ionium, and uranium X. Now it seems as if another group of radio-active elements of similar properties exists; to this group belong radium and mesothorium, and possibly other metabolons. The study of the chemical properties of mesothorium reveals a method of preparing it from the residues of the manufacture of thorium. It is an exact reproduction of that by which radium is obtained from uranium ore residues. Of course the mesothorium preparations obtained from monazite must contain radium, owing to the presence of uranium in them, since no method of separating these two substances is known. Moreover, the radium obtained THE ESTIMATION OF FREE AMMONIA By J. C. THOMLINSON, B.Sc. IN estimating free ammonia and ammonium carbonate in solutions containing an excess of the former a quick volumetric method may be used. Free ammonia cannot be titrated using phenolphthalein as an indicator, methyl-orange being usually used; however, when it exists in the free state, and as carbonate, by using phenolphthalein first, and titrating until the liquid assumes a transient pink coloration throughout its entire bulk, we can obtain a close approximation as to the amount of ammonium carbonate present, and by then adding methyl-orange and completing the titration estimate the total ammonia. To prove this a solution was made containing o'78 grm. free ammonia, NH3, per 100 cc., and 3.69 grms. ammonium carbonate, (NH4)2CO3, per 100 cc. To 10 cc. of this solution phenolphthalein was added, and when titrated with normal sulphuric acid as the mean of two experiments, 8.1 cc. N. H2SO4 were required. Calculated as ammonium carbonate, (NH4)2CO3, this represents 3:42 grms. (NH4)2CO3 per 100 cc. The total ammonia free and existing as carbonate in the test solution made above would be, by calculation, 2.16 grms. per 100 cc. A further titration after adding methyl-orange to 10 cc. of the liquid already titrated for carbonate gave the total amount of normal sulphuric acid solution required as 12.5 cc., representing 21 grms. total ammonia, NH3, per IOO CC. Methyl-orange commonly used as an indicator for the titration of free ammonia, although not feasible as an indicator in the presence of free carbon dioxide, can hence be used when there is an excess of ammonia in ammonium carbon solutions, and the reliability of the titration for carbonate for quick and approximate analysis may be judged from the figures given above. Royal Institution. On Tuesday next, January 17, at 3 o'clock, Prof. F. W. Mott begins a course of six lectures at the Royal Institution on "Heredity." On Thursday, January 19, at the same hour, the Astronomer Royal, Mr. F. W. Dyson, delivers the first of three lectures on "Recent Progress in Astronomy"; and on Saturday, January 21, also at 3 o'clock, Mr. Arthur Hassall commences a course of three lectures on "Problems in the Career of the Great Napoleon." The Friday Evening Discourse on January 20 will be delivered by Prof. Sir James Dewar on "Chemical and Physical Change at Low Temperatures"; on January 27, by Prof. William H. Bragg, on "Radio-activity as a Kinetic Theory of a Fourth State of Matter"; and on February 3, by Arthur E. Shipley, on "Grouse Disease." |