CHEMICAL NEWS, Feb. 17, 1911 Chemistry of the Lead Chamber Process. is shown that it does not agree with the results of observa- Mr. DUDDELL remarked that he had made some experiments with insulated wires, and had found that this increased the resistance, possibly owing to condenser action. Dr. ERSKINE-MURRAY said the instrument would certainly be useful to those interested in wireless telegraphy. Major O'MEARA thought the method was well worth following up. Prof. E. WILSON drew attention to the inductive action between the two circuits, which might not be negligible in the case of a spiral. A paper on the Measurements of Energy Losses in Condensers Traversed by High Frequency Electric Oscillations," by Prof. J. A. FLEMING and Mr. G. B. DYKE, was read by Prof. FLEMING. This In this paper an arrangement of apparatus is described for the purpose of measuring the internal energy losses in condensers traversed by high-frequency (H.F.) currents. It is shown, that these energy losses in condensers may be considered as if they were due to a resistance loss in a hypothetical resistance in series with the condenser, the condenser itself being supposed to have a perfect nondissipative dielectric of the same dielectric constant. hypothetical resistance is not constant, but is a function of she condenser current. The experiments were conducted by the use of a special form of impact dischargers comprising two flat plates immersed in oil, one stationary and the other revolving at a high speed. This discharger was placed in series with a primary circuit and condenser, and H.F. oscillations were set up in the primary having any desired frequency. A secondary circuit loosely coupled consisted of a wire whose H.F. resistance could be determined, the condenser to be examined and a hot-wire ammeter and variable resistances. The measurements consisted in observing the reading of the ammeter, and then changing the current created in the secondary circuit by a small amount by adding a known resistance which altered the decrement of the circuit, but not its inductance. From these readings an equation is obtained for the hypothetical condenser resistance. It is shown that the product of the square of the secondary current A and the total resistance R of the secondary circuit is constant, and hence that the unknown condenser resistance p can be found from observations of the change in A when an additional resistance is interpolated in the condenser circuit. The energy loss in the condenser is then A2p watts. Condensers with various dielectrics, air, oil, glass, and ebonite, were examined, and the dielectric energy losses D are stated in micro watts per cubic centimetre of dielectric for given values of the electric force E. It is shown thus D can be expressed as a function of E in the form D=XEY, where X is a constant depending on the current density, and Y is a constant depending on the nature of the dielectric. For oil and air these power losses are relatively small, but for glass and ebonite large. The necessity for measuring these losses in the case of radio-telegraphic condensers is emphasised. A paper on "Some Resonance Curves taken with Impact and Spark Pall Dischargers," by Prof. J. A. FLEMING and Mr. G. B. DYKE, was read by Prof. FLEMING. In the course of the experiments described in the previous paper on the measurement of energy losses in condensers a large number of measurements had to be made with the cymometer of the frequency of oscillations in, and the inductance of, the secondary or condenser circuit. It was then an easy matter to draw complete resonance curves | 81 in each case, and this has accordingly been done with both the impact and spark ball dischargers in the primary circuit and for various resistances in the secondary circuit. The results are interesting as showing exactly what takes place in each case in the primary circuit. If we are using the spark ball discharger, and if the primary and secondary circuits are coupled with various degrees of coupling, then, for any close coupling, we find on the resonance curve three peaks which correspond respectively, as regards frequency, with the free oscillation period of the secondary and with the two-period oscillations set up by the reaction of the secondary upon the primary circuit. As the coupling is weakened the double-period oscillations die out, and only the free oscillation of the secondary survives. There is always a certain coupling, not far from 10 per cent, which gives the maximum current in the secondary circuit in the form of a free oscillation. If the secondary circuit is more highly damped, then the two period oscillations are more strongly marked, and the maximum free period oscillation has a lesser maximum value. oscillations are only apparent when the coupling exceeds If we are using an impact discharger the double-period about 30 per cent, and die away with a very little reduction in the coupling, leaving the predominant free secondary oscillation as the survivor. These curves show how very quickly the primary spark is quenched when using the impact discharger. If the maximum secondary current is set up as ordinates in terms of the coupling as abscissa we obtain curves which rise up quickly to a maximum value and fall again, and which indicate that the maximum value of the secondary current is determined both by the coupling and the secondary decrements. The two previous papers were discussed together. Mr. A. CAMPBELL observed that the curves in the second paper showed the superiority of the impact method, and remarked that, since the losses at low frequencies were so exactly proportional to the square of the voltage, it was surprising the same was not true at high frequencies. Mr. DUDDELL also expressed surprise that with low voltages the losses were not proportional to V, and drew attention to the importance of knowing exactly where all the energy losses in the secondary occurred. Mr. E. H. RAYNER remarked that a more accurate way to test the results was to plot the power factor against the voltage. Mr. ADDENBROOKE said he thought the variation of the losses with temperature was very great, and should be taken into account. Dr. ECCLES pointed out that it was only after the primary spark was quenched that it was possible for the secondary circuit to emit its natural frequency. Prof. G. W. O. Howe exhibited oscillographs showing the oscillations in the primary and secondary circuits before and after the primary spark had died down. RASCHIG, Ph.D. By F It was shown by Davy in 1812 that SO2 and the red vapour from N2O4 do not interact except in the presence of water. The formation of chamber crystals (nitrosulphonic acid) is an intermediate step in this action, and their decomposition by an excess of water liberates a fresh quantity of nitrous gases. If in addition to sulphur dioxide and nitrous gases, oxygen (or air) and water be available, the conversion of the SO2 into sulphuric acid is complete. Chamber crystals, however, can never be observed when the chambers are working normally, and the various assumptions necessarily to Davy's theory are not true in practice. The chamber gases, it is obvious from their colour, | contain more nitric oxide than is required by the relation NO+NO2. Finally, nitrosulphonic acid does not dissolve without decomposition in sulphuric acid as dilute as is found in the Glover tower, but nitrosulphonic acid, a reduction product of nitrosulphonic acid, is for some considerable time stable in sulphuric acid of sp. gr. 16; i.e., acid containing 70 per cent of H2SO4. This reduction product imparts a characteristic blue colour to its solutions, and its copper salts are coloured an intense blue. From these observations we must draw the conclusion that nitrosulphonic acid, as an intermediate product in the formation of sulphuric acid by the chamber process, must be left out of consideration, inasmuch as the process continues in concentrations of sulphuric acid from 60 per cent at the end of the chambers, to 80 per cent in the Glover tower, and in the latter case the temperatures concerned are such that even a temporary formation of nitrosulphonic acid is out of the question. The assumption is almost forced on us that in nitrosisulphonic acid we have the true intermediate product of the chamber process. All experiments lead to the conclusion that when air reacts on nitric oxide, two different substances are successively formed. The first, which is produced after a very short time, dissolves in acids or in alkalis to nitrous acid; behaves, in fact, as if it were nitrous anhydride, N2O3. The second, which demands for its complete formation about 100 times as long, dissolves in acids and alkalis, half to nitrous and half to nitric acid; behaves as though it were N2O4, and reacts with water according to the equation N2O4 + H2O = HNO2 + HNO3. It must be admitted, then, that the nitrogen compound effective in the chambers is nitrous acid, HNO2, which exists dissolved in the tiny droplets of sulphuric acid which as mist fill the chamber; and the question of the chemical nature of the chamber process narrows itself to the inquiry, how, under chamber conditions, that is to say, in presence of air, water, and much sulphuric acid of 60 to 80 per cent, does sulphur dioxide react on nitrous acid? Is nitrosisulphonic acid really formed under these circumstances? The author shows experimentally, first, that sulphur dioxide does not react on nitrosulphonic acid; second, that sulphur dioxide reacts on nitrous acid, which is dissolved in sulphuric acid of the concentrations which occur in the chambers, with formation of nitrosisulphonic acid, which later breaks up into sulphuric acid and nitric oxide. Only one question remains to be answered, though that is an important one: How is nitrosisulphonic acid, H2NSO5, formed from sulphur dioxide, SO2, and nitrous acid, HNO2? He also shows that when nitrosisulphonic acid is formed from sulphur dioxide and nitrous acid, nitric oxide gas is evolved. The remaining link of the chain is forged. The formation of sulphuric acid in the chambers occurs in this way, viz., the nitrosisulphonic acid formed dissociates into sulphuric acid and nitric oxide, and finally the nitric oxide, with air and water, becomes oxidised to nitrous acid. In the chemical sense, however, we are far from having finished. We ask further: What is the mechanism of the reaction by which, from 2 molcules of nitrous acid and I molecule of sulphur dioxide, nitrosisul phonic acid is formed? A chain of experimental evidence is adduced, which by a reduction of the processes going on in the chambers to well known and frequently observed properties of nitrogen compounds satisfies the last desire which the new theory of the chamber process still left to us. That theory can now be expressed in four equations, from the integral of which the catalyst disappears, and there remains an oxidation of sulphur dioxide by means of water and oxygen to sulphuric acid. 2NO+ H2O+0=2HNO2 H2NSO5= NO+H2SO4 SO2+O+ H2O = H2SO4 I. 2. 3. 4. abnormal conditions observed in the working of the chamber process, but by its application it was possible to predict a pecuilarity of the chamber process, namely, the possible formation of ammonia, of which no one had thought, or on the basis of the older theories could have thought. RÖNTGEN SOCIETY. PROF. WERTHEIM SALOMONSON, of Amsterdam, was the lecturer at the meeting of the Röntgen Society on February 2nd. His subject was the Induction Coil, but he restricted himself to his own oscillographic researchusing the high-frequency pattern of the Duddell instrument-upon the behaviour of coils under varying working conditions. His oscillograms were taken with various well-known coils, and with at first a mercury break working in paraffin oil or alcohol, and afterwards with a mercury jet-interrupter working in gas. He devoted attention separately to the ascending and the descending portion of the curve of the primary current as described in the oscillogram. The form of the ascending part of the curve, which denoted the increasing current strength, was principally determined, he said, by the so-called time-constant of the circuit, the self-induction being divided by the resistance. The rapidity with which the curve rose depended upon the value of the electromotive force of the battery, divided by the self-induction. The descending part of the curve, representing the fall of the current to zero in about one-thousandth of a second at the moment the circuit was broken, was of greater interest, since it was in this phase that the secondary discharge occurred, giving the spark or lighting up the X-ray tube. In all oscillograms the rapid descent of the curve was to be noted, sometimes followed by a few oscillations. His oscillographic study of the descending curve had led him, he said, to the conclusion that if the capacity of the primary condenser were varied the time taken by the primary current to fall to zero varied also; that if the capacity were gradually increased, starting from a very small value, the stopping time of the primary current lessened until a definite capacity had been reached, and that any further increase of the capacity tended to lengthen the flow of the primary current after the commencement of the break. A considerable portion of Prof. Salomonson's paper was occupied with a study of the oscillations found in the descending part of the curve. These were due chiefly to the secondary sparks, and he showed that the amplitude of the more rapid vibrations depended upon the initial phase difference between the primary and secondary circuits, with a maximum for a phase angle of 90 degrees, and a minimum when there was no phase difference. The primary spark, in his opinion, only slightly affected the intensity of the oscillations. The number of interruptions per second for the maximum secondary effect was the subject which engaged Prof. Salomonson in the concluding part of his paper. After showing that with very rapid interruptions it was of advantage to reduce their number, and with very slow interruptions to make them more frequent, he pointed out that there must be some intermediate number which gave the best results from the point of view of secondary effect. Mathematical and practical observations had led him to the belief that for coils of 10-12 inch sparking distance the average number of interruptions to be desired was twelve to thirteen per second. Of course this number was only possible with very small voltages, say, up to 18 volts. If the voltages were increased there would be some danger to the coil in reducing the number of interruptions so greatly, and it would be safer to work with a larger number. For the higher voltages, therefore, he formulated a rule, which he admitted was somewhat crude and empirical, but which might serve for practical purposes, that the most advantageous number of interruptions Not only does the new theory account for various per second for small induction coils was given by the CHEMICAL NEWS, Feb. 17, 1911 Association of Teachers in Technical Institutions. number representing the voltage, granted that the timeeconomy of the interrupter were 0.5. With larger coils the number was smaller. Some radiographs of the thorax were shown which had received exposures of about one-hundredth of a second, a specially powerful coil, the "Unipols," being used for the purpose, and the definition was everything that could be desired. CORRESPONDENCE. 83 Technical Institutions) (1) The percentage of failure in chemistry has steadily increased from 24 4 per cent in 1907 to 469 per cent in 1909. (2) The percentage of failure in chemistry in 1909 and 1910 is disproportionately high as compared with the percentage of failures in the other subjects of the group. ASSOCIATION OF TEACHERS IN TECHNICAL percentage of failures should show a corresponding minor INSTITUTIONS. To the Editor of the Chemical News. SIR,-The Council of the above Association has recently had under consideration representations from a number of members of the Association in London and Provincial Technical Institutions, part of whose duties consists in the preparation of students in day and evening classes for the Intermediate and Final B.Sc. External examinations of London University. In these representations attention has been drawn to the marked inequality of the require With respect to the above, the Council desires to point out that the educational experience goes to show that with a large number of candidates (about 700 in this case) from all parts of the country, the intellectual standard and training of the candidates, taken as a whole, will vary only to a slight extent from year to year, and therefore the variation only. Further, since the majority of the candidates take the same combination of subjects (Chemistry, Physics, Pure and Applied Mathematics) the high percentage of failures in chemistry, as compared with those in the other three subjects mentioned, cannot be justified. In this connection we would point out that there has been no alteration in the syllabus of the examination since about 1901. The Council desire to point out, with respect to the statistics relating to the External B.Sc. Pass Examination (Table II.), that in the period 1905 to 1909 the percentage of failures in chemistry is considerably higher than the TABLE I.-External Inter. B.Sc. 1906. 1908. 1909. 1907. Botany 29 17.2 45 35.6 ΙΟ 20'0 9 33'3 B. Zoology I am directed by the Council to bring the following facts to your notice, and to ask you to place the matter before the Senate and the Council for External Students for their consideration. The figures in Table I., taken from the recent University Calendars, show that there is a serious discrepancy between the requirements of the various examiners, especially in the case of chemistry, and that as a result serious injustice is there done to students and teachers. The Council desires to suggest for your consideration, and that of the Senate, that the above statistics show :- (b) That in group A (the group of subjects taken by the OBITUARY. DR. JULIUS WILHELM BRÜHL, PH.D., D.Sc., Professor of Chemistry in the University of Heidelberg. We regret to announce the death of Professor Brühl at Heidelberg on the 5th inst. The deceased was an Honorary Member of the Royal Institution, and was well known to English men of science, not only by his researches in chemistry, but, personally, by his visits to England. In 1905 he gave a Friday Evening Discourse at the Royal Institution. The subject was on the Development of Spectro-chemistry, and it was treated in a masterly manner, the development of research being reviewed since the time of Newton. The lecture was delivered in English, and all who heard it were struck by the perfect command the lecturer possessed over our language, not only in its classical and more elegant phases, but in its familiar and more colloquial aspects. To listen to Dr. Brühl's conversation few would have noticed that he was speaking a foreign language, and his knowledge of English literature | was on a par with his linguistic attainment. In the decease of Dr. Brühl, Chemistry loses a great and successful exponent and many English men of science a valued friend. posed. Sulphanilide unites with diazo-compounds in alkaline solution; with nitrous acid it yields diazobenzene nitrate, and with methyliodide dimethyl-diphenylsulphanilide. MISCELLANEOUS. New Reaction of Cupreine. -Georges Denigès.—If ammonia (1 cc.), hydrogen peroxide (1 vol.), and copper sulphate (o'r cc. of a 3-4 per cent solution) are added to 10 cc. of a 0.2 per cent solution of cupreine sulphate a green coloration is produced on shaking, and greenish blue particles are deposited. The mixture becomes a bright emerald green if an equal volume of alcohol is added, or if it is acidified with hydrochloric or acetic acid. Comptes Rendus, clxi., No. 26. Ammonia for Commercial Purposes.-Prof. Fritz Haber, who has been selected to be the Director of the Physical Chemical Research Institute that the Emperor William Society intends to establish at Dahlem, in the neighbourhood of Berlin, is known as the discoverer of a new process by means of which the nitrogen of the atmosphere is utilised directly for the production of ammonia. Prof. Haber's patents have been secured by the Baden Anilin and Soda Works, and it is stated that his process has been brought to such technical perfection there that synthetic ammonia will soon be on the market. The CHEMICAL NOTICES FROM FOREIGN practical value of the new method of producing ammonia is expected to be enormous, especially for agriculturists.— Morning Post. SOURCES. NOTE.-All degrees of temperature are Centigrade unless otherwise expressed. Berichte der Deutschen Chemischen Gesellschaft. Bromo-salts of Platinum.-A. Gutbier.-The hexabromoplatinates of aliphatic ammonium compounds, e.g., anilinium hexabromoplatinate, [C6H5.NH3]2PtBг6, may be prepared by making the ammonium bromide from the base and hydrobromic acid, and then adding it to the hydrogen platinum bromide. The precipitate can be purified by recrystallising from dilute hydrobromic acid. The compounds are mostly only slightly soluble in cold water and more soluble in warm water. They are decomposed by boiling with much water. They are relatively slightly soluble in dilute hydrobromic acid at the ordinary temperature, but are easily dissolved, giving red solutions on heating. The bases are set free from solutions by concentrated caustic soda. Ammonia gives pure yellow solutions at room temperature. Hydrazine hydrate decolorises the solutions in the cold, and sets free nitrogen and platinum on heating. Chloro-salts of Osmium.-A. Gutbier.-By decomposing sodium hexachloro-osmate with aliphatic ammonium chlorides the corresponding hexachloro-osmates of aliphatic compounds are obtained. They are much less soluble than the sodium salts, and separate in the form of crystalline yellow or red-brown precipitates. They are anhydrous and stable in air. They dissolve in cold water, but the pure aqueous solutions readily decompose. They dissolve in dilute hydrochloric acid, giving stable solutions, and are taken up by alcohol. NOTES AND QUERIES. Our Notes and Queries column was opened for the purpose of giving and obtaining information likely to be of use to our readers generally. We cannot undertake to let this colunm be the means of transmitting merely private information, or such trade notices as should legitimately come in the advertisement columns. Liquid Air Plant. -Can any reader supply names of makers of liquid air plant working on Claude's ddiabatic method?-W. E, S. MONDAY, MEETINGS FOR THE WEEK. 20th.-Royal Society of Arts, 8. (Cantor Lecture). "Brewing and Modern Science," by Prof. A. J. Brown. Society of Chemical Industry, 8. "Composition of the Acids flowing from the Thompson Displacement Apparatus for the Manufacture of Guncotton," by G. W. MacDonald. "Ammonium Sulphate and its Instability" and "Hydrolysis of Ammonium Salts," by Watson Smith. "Study of some Reactions in Gels," by E. Hatschek. "New Still-water Calorimeter," by J. H. Coste and B. R. James. TUESDAY, 21st.-Royal Institution, 3. "Heredity," by Prof. F. W. Mott, F.R.S., &c. WEDNESDAY, 22nd.-Royal Society of Arts, 8. "Water Finders," by Prof. J. Wertheimer. THURSDAY, 23rd.-Royal Institution, 3. "Problems of Animals in Captivity," by P. Chalmers Mitchell, F.R.S., &c. Royal Society. "Transmission of Flagellates Living in the Blood of certain Freshwater Fishes," by Miss M. Robertson. "Report on the Separation of Ionium and Actinium from certain Residues, and on the Production of Helium by Ionium," by Dr. B. B. Boltwood. "The Secondary y-Rays produced by B-Rays," by J. A. Gray. Specific Heat of Water and the Mechanical Equivalent of the Calorie at Temperatures from o° to 80° C., with Additional Note on the Thermoid Effect," by W. R. and W. E. Bousfield. "Measurement of Specific Inductive Capacity," by Prof. C. Niven. Moléculaire" (in French), by Prof. Jean Perrin, D.Sc. Physical, 5. "Flames at Low Temperature supported by Ozone," by The Hon. R. J. Strutt. "Movement of a Coloured Index along a Capillary Tube, and its Application to the Measurement of the Circulation of Water in a Closed Circuit," by Dr. A. Griffiths. "Optical Lever of High Power suitable for the Determination of Small Thicknesses and Displacements," by E. H. Rayner. Sulphanilide.-A. Wohl and Franz Koch.-A good yield of sulphanilide may be obtained by adding moderately FRIDAY 24th.—Royal Institution, 9. "Mouvement Brownien et Réalité dilute sulphuryl chloride to a large excess of aniline. Sulphanilide readily forms a disodium salt and mono- and diacetyl compounds. Excess of acetic acid anhydride in presence of sodium acetate splits off two molecules of diacetanilide, C6H5.N(CO.CH3)2, and sulphuric acid. In presence of free sulphuric acid aminobenzenesulphonic acid is formed. In order to nitrate sulphanilide it is necessary to exercise great caution, or else the molecule is decom SATURDAY, 25th.-Royal Institution, 3. 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