XXVlth International Congress of Industrial Chemistry XXVIth International Congress of Industrial Chemistry, which met in Paris in June, included meetings of the Analytical Section, which discussed macroanalysis, microanalysis, equipment, and laboratory apparatus. T h e secretary of the Analytical Chemistry Section is R4. D. Jouslin, Etablissements Cotelle et Foucher, 7 R u e ErnesbRenan, Issy-lee-Moulineaux (Seine), France. Abstracts of most of the papers are given here.
The precise determination of the quantity of electricity has been effected by measuring the duration of electrolysis and the utilization of supply at constant intensity. Sefram has furnished this supply, whose characteristics n e have been able t o control: the stability is of the order of 0.05% and the absolute value of the current intensity is within 0.1%.
Determination of Sulfur by Combustion. M. PONTET A N D R. BOULIN,Irsid, Saint-Germain-en-Laye, France. The authors attempted to determine the operating conditions permitting determination of sulfur by combustion in siderurgical products without corrective coefficient. Conditions of the combustion were examined. The transformation of sulfurous gas being incomplete, the final iodine titration was replaced by acidimetric titration in silver nitrate medium. Agreement with gravimetric determinations is satisfactory.
Acquaintance with polarization curves (intensity of the current of electrolysis potential of the electrode) permits a better understanding and more rational utilization of electrochemical methods of determination. We take as an example of the methods where the electrode serves as indicator of concentration: amperometry under constant tension with or without reference electrode and potentiometry at constant intensity with or without reference electrode. Starting from the properties of the polarization curves we specify the principal characteristics of these methods and the experimental conditions necessary for obtaining sufficient exactitude. We show the importance of the utilization of these curves in perfecting the determinations.
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Determination of Impurities in Lead and Lead-Tin Alloys. G. DELASSUS, Recherches Chimique de Gaz de France. The rapid and precise determination of certain impurities in lead and lead-tin alloys, used in pipes and welds, is of interest to industry because their presence is capable of altering the mechanical qualities of these metals. A rapid polarographic determination of copper, cadmium, and zinc is presented. Quantitative Analysis by X-Ray Diffraction of Mixtures of Aluminum Hydrates. R. TERTIAN AND R. HOUSSEMAINE. The authors recall the interest in determinations by physical means with the aid of x-ray diffraction, from the point of view of immediate analysis (phase determination) or chemical analysis when the usual analytical methods are unsuccessful. The principle of quantitative analysis of mixtures of crystalline powders is explained briefly, with emphasis on the importance of experimental technique. The procedures adopted and the results obtained in the case of mixtures of aluminum hydrates of two or even three components (hydrargillite. bayerite, boehmite) are described in detail. Finally, examples of applications are given: analysis of minerals or industrial products.
Importance of Polarization Curves in Perfecting Electrochemical Determinations. R. GAUGUIN, Laboratoire de Chimie Analytique de 1'Ecole Superieure de Physique et de Chimie, Paris, France.
Determination of Water Vapor by Infrared Analysis. K. F. LUFT R. GUERIN, Office National d'btudes et Recherches Aeronautiques, Chatillon, France. The method of positive filtration for the analysis of gases by their infrared absorption has been adapted to determination of water vapor, utilizing ammonia as selective gas in place of water vapor itself. With analysis tubes 50 t o 200 mm. long, it is possible to measure concentrations of water vapor from thousandths of 1X to saturation concentration at atmospheric temperature in all gases containing practically no ammonia, such as nitrogen, oxygen, hydrogen, air, carbon monoxide, and carbon dioxide. The rapidity and the accuracy of the infrared analyzer, and the low volume of gas necessary for effectuating a determination, make it possible to solve certain prohlemq of analysis which hare been difficult by current methods AND
Examination of Ancient Objects by Analytical and Microanalytical Institut de Chimie Minerale et AnalyMethods. R. STREBINQER, tique, University Technique de Vienne, Vienna, Austria.
New Procedure for Determination of Oxygenated Water in the Illuminated Cinespectrograph for Studying the Kinetics of Very Presence of Organic Peroxides. J. BARLOTAND S. MARSAULE, Brief Chemical Reactions. M. LAPORTE, Laboratoire de Recherches Poudrerie Nationale de Toulouse, Toulouse, France. Electroniques, Institut du Radium, I1 Rue Pierre Curie, Paris, The problem of the separation of oxygenated water and organic France. peroxides is often impossible to solve by the methods of analysis usually employed. The authors have found that in many cases a Volumetric Determination of Zirconium. L). B~ZJER. precise determination may be made by fixing the oxygenated water by lime in the form of calcium oxide in the presence of ethyl alcohol. The method described permits volumetric determination of zirThe oxide is titrated after filtration by permanganate. Organic conium in solution by means of two acidimetric measurements. peroxide may be measured by well-known proredures such as by The determination is easy and very rapid. There is no systematic iodine. error. The results are reproducible to about 0.5%. The method is not very selective and several metals interfere. The principle is as follows: Determination of Nitric Nitrogen by the Devarda Method. Study Measurement of Total Acid. The solution of the zirconium salt of an Alloy. L. BRISSAUD AND J. TRANCFIANT, Laboratoire Central is determined by a solution of titrated sodium. The zirconium des Poudres, 12 Quai Henri IV, Paris, France. hydroxide is precipitated a t about pH 1 to 2. At the same time free The Devarda method is in use for determining nitric nitrogen, in acid and Z r + + + + are determined. particular in organic nitrates and smokeless powders. I t is capable Hf OH- -+HzO of giving extremely precise results (relative error of about 1 in 700) if perfectly suitable reagents are employed. Zr++++ 40H- + Zr(0H)r The aluminum-copper-zinc alloy has been studied. It is shown I that to suit all the variants of the Devarda method with the same succesa it is necessary to use an alloy whose percentage composition Determination of Free Acid. To another sample is added an has a sufficiently great influence. But above all, granulometry and excess of alkaline fluoride. The zirconium is complexed, with forspecific surface must be between certain limits, which are determined. mation of zirconium fluoride, ZrFe--. Under these conditions zirconium hydroxide does not precipitate until about pH 7 to 9 (depending upon the proportion of fluoride). Free acid can then be Standardization of a Titrated Solution of Hydrochloric Acid by determined. The difference between the two measurements gives Constant-Intensity Coulometry. J. BADOZ-LAMBLING, Laboratoire the zirconium content, l Z r + + + + = 4Hf. du Professeur Charlot, Ecole Superieure de Physique et de Chimie, 10 The method has been applied to solutions of zirconium chloride Rue Vauquelin, Paris, France. and sulfate. I t is equally suited for determination of tanning prodWe have determined within 0.2y0 the titer of a solution of hydroucts with zirconium base. chloric arid by coulometric determination at constant intensity. We have in the first place specified the experimental conditions that Determination, by Heavy Water, of the Humidity of Solids Not permit obtaining a current yield of loo%, then chosen and justified Dispersible in Water. Application to the Study of Macromolecular the choice of bromophenol blue as indicator of the end of the reaction.
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