was that the farmer in England was paying considerably more for his superphosphate that he was willing to pay. Consequently, the foreigner, particularly the Belgian and the Dutch-the Belgian more so than the Dutch-was dumping both sulphuric acid and superphosphate into England. With their permission he would just like to take them to the Continent for a few minutes, and show them how matters got so mixed up that it was sometimes very difficult to disentangle them. In For many years now Belgium and parts of Holland and Germany had been the home of the European zinc production. Belgium one might say that the production of zinc was a national industry in every sense of the word. The procedure in the past was for the Belgian to buy his Broken Hill Concentrates, bring them to Belgium, where they would be discharged right alongside the zinc roasting furnaces, and, as all that ore had to be roasted, sulphuric acid came as a by-product. That sulphuric acid the Belgian used to make into superphosphate, as he had already indicated; and it was very largely that superphosphate that reached England, to the damage of superphosphate manufacturers there, and, very largely, the same superphosphate reached the South African market here, to the detriment of the local producers of superphosphate here. All the sulphuric acid made in Belgium did not go to the manufacture of superphosphate. Even though there was a very considerable surplus that surplus went to the making of salt cake-sulphate of soda. Now they came up against another industry in Belgium-that of glass making. So they saw right away how these things were linked up together. In the making of salt cake one made a great deal of hydrochloric acid, and, at all times, hydrochloric acid, unless it was consumed on the spot, was an exeedingly difficult and ticklish thing to handle; but it was used for de-tinning, for other minor operations, and for the making of gelatine another national industry in Belgium. That gelatine was made in the following manner :- Bones-it might be human or animal bones, at any rate they were very old- were imported by the tens of thousands of tons from India and other parts of the British Empire. Those bones were treated with dilute hydrochloric acid, which dissolved out the phosphate. Some of this came back to South Africa as highgrade phosphate, and it was used at one time in Natal-he did not know whether it was to-day-for clarifying sugar syrup, for cattle lick, and other purposes. The residue contained the gelatine; they called it osein, a crude gelatine, and by subsequent processes of purification it made the table, photographic and all kinds_of_gelatine which were supplied all over the European markets. So that they would see, starting o ffwith the zinc, they had the zinc industry itself, the glass industry, the gelatine industry, and the superphosphate industry all closely linked up with one another. If losses were made in one department they could be made good in another. The calorimetry was by the method of mixtures, introducing several refinements, of which the chief were the use of fairly large charges of metal (of the order of 2 kilograms), and a device by which the hot charge was not allowed in contact with the water of the calorimeter until the latter was completely closed; this eliminates error due to production and escape of steam, with a consequent loss of heat. The device referred to consisted in the provision of a sheet metal vessel suspended by threads from the main lid of the calorimeter. The aperture through which the charge was introduced was closed by a rotating lid, in the main lid, and the crucible being introduced, was submerged after the closing of this smaller lid by means of a wire passing through an eyelet in the base of the calorimeter, and out at the top. The paper also contains values for the specific heats up to the melting point, obtained by differentiation of the temperaturetotal-heat curves. The Piezo-Electric Quartz Resonator and its Equivalent Electrical Circuit. By D. W. DYE, B.Sc., National Physical Laboratory. ABSTRACT. The quartz piezo-electric resonator is examined experimentally and theoretically with special regard to an equivalent electrical system which can represent it. It is shown that, as theoretically predicted by Butterworth, such a resonator can be represented by an inductance, a resistance and a capacity all in series. These are pictured as in parallel with another small condenser, and the whole is in series with a third condenser, the additional condensers representing air-gaps. The equations for the current in an oscillatory circuit, to which the resonator is attached, are developed and it is found that almost perfect agreement exists between the forms of current curve obtained theoretically and experimentaly. agreement is found to hold for longitudinal resonators of as low a frequency as 44,000 and for transverse resonators of as high a frequency as 15,000,000 periods a second. This It is next shown how the logarithmic decrement of the resonator may be obtained from a rectified line plotted from observation on the current in the oscillatory circuit as a function of frequency width across the crevasse which pierces the summit of the resonance curve. The methods of analysis of the equivalent mesh into its components are next developed and it is shown that this analysis can be effected by carrying out a series of observations of the current at when the air-gaps are varied by known amounts, or when the effective resistance of the oscillatory electrical circuit is given different known values. resonance The theoretical and experimental results are found to be consistent. The value of the shunting condenser is somewhat smaller than that measured at a neighbourng frequency outside the region or resonance. A possible explanation is offered. The effects on frequency of response of variation of air-gap are studied and the difference between prediction and observation is discussed. This difference is only a few parts in a hundred thousand. In the case of transverse resonators remarkable effects occur when the air-gap is varied through the regions where its length is an integral member of half-wavelengths of the supersonic air waves produced by the vibration of the quartz. The temperature coefficient of frequency of a considerable variety of resonators is examined over a range of temperatures up to 40° C. It is found that very diverse results are obtained and probable explanations are offered. The effects of displacement of the resonator from the position of centrality are examined. These are shown to be small, but not quite negligible. are The current taken by the quartz mesh is then examined in some detail theoretically, and one or two experimental curves given, together with a graphical method of deducing the cure of current from the constants of the quart. A selection of theoretical curves for the conditions under which the experiments of Cady were made have been calculated. The curves are in all respects of the shape and form experimentally found by him. A number of conclusions and suggestions terminate the paper. NOTICES OF BOOKS. Braunkohle und Ihre Chemische Verwertung. Von DR. A. FURTH. Pp. 135. Dresden and Leipzig: Theodor Steinkopff, 1926. Price, 7 marks. The coal industry has been in the forefront of almost everyone's thoughts for some months, particularly since the lockout commenced nearly two months ago. With the political aspects of the present dispute we are not concerned,but it seems as though at last it will be recognised that more scientific methods must be introduced into working practice in order to bring British mining up to the general level of progressive continental countries. The results which can be claimed to accrue from the adoption of scientific methods would obviate the case for asking the miner to remain underground for eight hours a day or to accept a lower wage. In Germany the coal is of a poorer quality than that obtained from British mines, yet by introducing highly scientific methods the Germans have reached a high state of perfection, not only in extracting the coal from the earth, but also in converting it into valuable chemical products. The distillation of brown coal and the working up of the fractions has received close attention. Increased monetary returns have succeeded the adoption of methods and procedures dictated by the results of scientific research. Refining processes are so arranged that purified products are comparatively readily obtained and all "waste" is worked up in some form or another. In this manner everything is done to lessen the cost and price of the main commodities, thus facilitating other industrial developments. All this, and much more in detail, can be inferred by a study of Dr. Furth's book in Steinkopff's valuable series of technical publications produced under the editorship of Dr. Rassow. The author has apparently studied the Patent literature very carefully -a matter of some importance so far as this subject is concerned. J. G. F. D. Die Pektinstoffe. Von DR. R. SUCHARIPA. Pp 188. Brunswick: Dr. Serger & Hempel. 1925. Price, 6 marks. Among the complex naturally occurring organic bodies whose composition has not yet been completely elucidated are the pectins or jelly-forming substances in fruits. They were discovered in 1824 by Braconnot and since then have been the subject of numerous investigations, notably by Fremy, Scheibler, and more recently Tschirch, von Fellenberg, Ehrlich, Haynes, Tutin and others. The pectins have also attracted the attention of botanists and have assumed importance in the brewing and canning industries. The early work served to show that the pectins are carbohydrate derivatives possessing acidic properties. Fellenberg and Ehrlich showed that they contained methyl ester groups and galactose together with galacturonic acid, which is an intermediate oxidation product between galactose and mucic acid. Metals, e.g., iron, may also be present, although it is now apparent that pectin is not the calcium-magnesium salt of a complex carbohydrate acid as Ehrlich supposed. The formula proposed Fellenberg is by but it should be remembered that there are at least three distinct pectin bodies-protopectin, occurring in roots, e.g., beet, and unripe fruits; soluble pectin, in ripe fruits; and pectic acid, in over-ripe fruits and in vegetables. The author mentions no less than seven distinct and characteristic varieties. In the examination of these complex substances a special technique is acquired by the investigators, but the exact nature of the substances is still by no means thoroughly understood. The author has collected together the main facts and has summarised the work (including patents) that has been done on these bodies and has presented it in a manner accessible to the general reader as well as the specialist. This is the first book devoted to the pectins and its importance cannot be over-stated in view of the rapid development in the canning trade, especially in America. It is reasonable to expect the early appearance of an English version of this work. Vacuum Practice. By L. DUMOYEER (Maître de Conférences a la Sarbonne, Paris). Translated by J. H. SMITH, M.Sc., Lecturer in Physics, University College, London. X + 228 pp. Price 12s. 6d. London: G. Bell & Sons, Ltd., York House, Portugal Street. This is a well-written book, and it was a happy suggestion of Professor Andrade that an English translation should be made. True, there are other English works on the same subject, but there is ample room for this work, especially when so carefully translated as this has been done by Mr. Smith. Particular attention has been paid to the practical as opposed to the theoretical, but this will be generally considered a good feature, especially in a work that is too short to completely cover the subject in detail. The work is well illustrated, contains an extensive bibliography, and a useful index. The Kinetics of Chemical Change in Gaseous Systems. By C. N. HINSHELWOOD, M.A., Fellow of Trinity College, Oxford. Pp. 204. Price 12s. net. Oxford: At the Clarendon Press. This work is based on lectures given in Oxford, and is, we are told, due to the interest manifested in the said lectures by many undergraduates with whom the author worked in this branch of Physical Chemistry. Not the least important part of the book is the exhaustive introduction, ON THE MODULI OF ELASTICITY APPARATUS OF MEASUREMENT. The present investigation consisted of the measurement of the moduli of elasticity and rigidity for different kinds of steel, such as carbon, nickel and cobalt steels, and that of their change by magnetisation. The absolute measurement of the moduli themselves was made by the usual methods of bending and of twisting as constantly used in our laboratory. The specimens were tested in the form of cylindrical rods, 20 cm long and 5 mm thick. THE MOTION OF ELECTRONS IN Mobilities of electrons in H2 and He at 760 mm pressure have been measured by the Rutherford alternating potential method for fields ranging from 0.5 to 46 volts/cm. The limiting mobilities for 244,774.-Heffner, L. W., and Tiddy, W.- Treatment of gas liquor and other Printed Copies of the full Published Speci- Abstract Published. are British Dyestuffs Corporation, The Latest This list of Trade Marks of interest to JUDEX. 469,197.-Chemical substances used in 460,036. Chemical substances used for |