Dosage du chrome,du vanadium et du molybdène par la méthode des indicateurs radioactifs

A radiochemical method for the determination of Cr, Mo, and V by means of radioactive silver is described. Using a solution of radioactive silver nitrate, a standard curve is obtained indicating the activity of the precipitate as a function of the quantity of the metal present. Unknown concentrations of Cr, Mo, or V can be easily determined if the same experimental and geometrical conditions are reproduced.     

Mise au point de la chromatographie et du dosage du tungstène

Summary The chromatographic separation and determination of tungsten has been considered in the cases in which it occurs alone in solution or accompanied by chromium, vanadium, molybdenum, and iron. Two different types of chromatographic tests have been studied: usual partition chromatography and tests according to conditions B (different solvents for saturation, development, and contamination). To achieve a precise determination of tungsten and the absence of all interference, the usual partition chromatography must be adopted. The reproducibility of the determination of tungsten in this case is of the order of ±2 to 3% for 10g of the separated element. Under the conditions of the test B, the reproducibility of the determination of separated tungsten may be just as good (±3 to 4%) if use is made of conventional references and corresponding diagrams such as we recommend. Otherwise, the stains determined in the usual manner yield a deficit of 14% with respect to the deposited tungsten. In this study, the interfering factors play a predominant role from both the quantitative and qualitative points of view. This is the first time that we have been able to accomplish the determination of individual stains of chromatographed elements, remaining on the spot, of which a portion has been dispersed in the paper during the development. The chromatogram obtained under the separating conditions is much less beautiful since it leads to the migration of only the iron and the molybdenum, but it is this which is recommended to produce a perfect determination of tungsten. In the two cases of chromatography, the excess iron is separated from the tungsten during the development.

---

Zusammenfassung Die chromatographische Trennung und Bestimmung von Wolfram in reinen Lösungen und in Gegenwart von Chrom, Vanadium, Molybdän und Eisen wurde untersucht. Hierzu wurden zwei verschiedene chromatographische Verfahren angewendet: die übliche Verteilung und eine Methode unter Anwendung verschiedener Lösungsmittel zur Sättigung, zur Entwicklung und als Zusatzmittel. Um eine genaue und störungsfreie Wolframbestimmung auszuführen, muß man die übliche Verteilungschromatographie anwenden. In diesem Falle ist die Reproduzierbarkeit der Wolframbestimmung in der Größenordnung von ±2 bis 3% für 10g des abgetrennten Elements. Bei Anwendung der zweiten Methode kann die Reproduzierbarkeit ebenfalls gut sein (± 3 bis 4%), wenn man sich eines geeigneten Standards und entsprechender, von uns empfohlener Diagramme bedient. Andernfalls ergeben die nach der üblichen Art bestimmten Chromatogrammflecken ein Defizit von 14% gegenüber dem angewandten Wolfram. Störungsfaktoren spielen hier eine vorherrschende Rolle, sowohl in qualitativer wie in quantitativer Hinsicht. Erstmalig hatten wir in diesem Falle an der Auftragstelle verbliebene Flecken eines Elementes zu bestimmen, von dem ein Teil während der Entwicklung sich auf dem Papier verteilt hatte. Das nach der üblichen Verteilungschromatographie erhaltene Chromatogramm ist zwar viel weniger schön, da nur das Eisen und das Molybdän wandern. Für eine perfekte Wolframbestimmung ist es aber zu empfehlen. Überschüssiges Eisen wird in beiden Fällen durch die chromatographische Entwicklung vom Wolfram abgetrennt.

---

---

Les techniciensG. Wantier etA. Orban ont participé aux expériences.     

Identification du mercure-I,du mercure-II et du molybdène

Résumé Dans le présent travail, on expose les réactions concernant l'identification de Hg-I, Hg-II et du Mo. Ces réactions sont basées sur la réduction de MoO₄ ^2– par Hg élémentaire en milieu d'acide chlorhydrique. Il en résulte une coloration bleue et une coloration rouge. Ces réactions sont spécifiques et elles peuvent être utilisées dans l'analyse des substances contenant ces éléments.

---

Summary This study deals with reactions serving for the identification of Hg(I), Hg(II), and Mo. These reactions are based on the reduction of MoO₄ ^2– by elementary mercury in a hydrochloric acid medium. A blue coloration results and also a red coloration. These reactions are specific and they may be employed in the analysis of samples containing these elements.

---

Zusammenfassung In der vorliegenden Arbeit werden Tüpfelreaktionen zur Bestimmung von Quecksilber(I), Quecksilber(II) und Molybdän vorgeschlagen. Diese Reaktionen beruhen auf der Reduktion von Molybdat durch elementares Quecksilber in salzsaurem Medium. Dabei entsteht eine blaue und eine rote Färbung. Die Reaktionen sind spezifisch und allgemein anwendbar.

     

Dosage du silicium par précipitation du complexe silicomolybdique jaune par la quinoléine

The authors have studied the conditions of precipitation of complex silicomolybdic yellow by quinoline from the point of view of the determination of silicon.Under the conditions that produce complete development of the complex, the precipitation is itself quantitative in the presence of an excess of quinoline, the role of which is to make the precipitate insoluble in its formation surroundings. The precipitation of free molybdate is prevented by adding the quantity of acid necessary for complexing it.The precipitate thus obtained filters without difficulty, and only needs to be dried for 1 hour at 150° in order to attain constant weight. It corresponds then exactly to the formula: SiO₂.12MoO₃.4(C₉H₇N).2H₂O.     

La Micro-Détermination du Béryllium par la fluorimétrie du complexe Morin-Be

Résumé Les conditions optimales du microdosage du Béryllium par la réaction du Morin sont déterminées (spécialement l'influence de la concentration en alcool) de même que la formule du composé fluorescent: Be₃(Mor)₂.

---

Summary The optimal conditions for the micro-determination of beryllium by Morin are determined, particularly the influence of alcohol. The fluorescent compound was found to have the composition Be₃(Mor)₂.

---

Zusammenfassung Die optimalen Arbeitsbedingungen für die Mikrobestimmung von Beryllium als Morinat wurden unter besonderer Berücksichtigung des Einflusses der Alkoholkonzentration festgelegt. Die Zusammensetzung der fluoreszierenden Verbindung entspricht der Formel Be₃(Mor)₂.

     

Dosage polarographique de la tyrosine,du tryptophane et de la phénylalanine en présence les uns des autres

A polarographic method is described for the determination of tyrosine, tryptophan and phenylalanine in mixtures, in which the animo acids are first converted to their nitro derivatives. Under suitable conditions each of these animo acids can be determined in the presence of the others.     

Les origines de la chimie organique au-delà du mythe fondateur

According to a legend, organic chemistry emerged in 1828 with the synthesis of urea performed by the German chemist Friedrich Wöhler from mineral reagents and “without the help of the kidneys”, thus ending the mysterious “vital force”. This article aims to show that this myth, invented in the nineteenth century by chemists and widely spread until today, is actually something that is certainly important, but is not enough to account for the emergence of a specialty as complex as organic chemistry. Synthesis is a fundamental component of this discipline, but its foundations lay in chemical analysis.     

Étude de la formation du complexe silicomolybdique application au dosage du silicium dans l'aluminium

The authors have examined the application of the reaction in which the yellow silicomolybdate complex is formed to the estimation of silicon.Among other things, it was established that the development of the complex is complete and rapid in the cold between pH 4.0 and pH 1.0.The rate of formation of the complex decreases rapidly above this pH but can, to a certain extent, be compensated by raising the temperature and the concentration of molybdate.The Lambert-Beer law is followed between 3650 and 5000 A only when the light is strictly monochromatic. At wave-lengths longer than 4000 A and at pH below 3, a supplementary absorption appears which is without doubt due to a chemical transformation of the molybdate in acid solution.     

Détermination spectrale du phosphore et du carbone dans les aciers par la méthode de profilage

Sans résuméLes recherches ont été effectués sous les auspices de l'I. R. S. I. A. (Institut pour l'encouragement de la Recherche Scientifique dans l'Industrie et l'Agriculture) et du C. N. R. M. (Centre National des Recherches Métallurgiques) Section Hainaut.     

Statu quo sur la méthanation du dioxyde de carbone : une revue de la littérature

This review summarizes the statu quo and the perspectives of chemical methanation. CO₂ methanation, including catalyst deactivation, reactors, mechanisms, and thermodynamics are presented. This reaction serves as a test bed for our fundamental understanding of heterogeneous catalysis and is used in various industrial processes, including the removal of oxo-compounds (CO_x) in the feed gas for the ammonia synthesis, in connection with the gasification of coal, where it can be used to produce methane from synthesis gas, and in relation to Fischer–Tropsch's synthesis. Moreover, CO₂ methanation became of interest as a renewable energy storage system based on a “power-to-gas” conversion process by SNG (synthetic natural gas) production integrating water electrolysis and CO₂ methanation as a highly effective way to store the energy produced by renewables sources. The effectiveness and efficiency of the “power-to-gas” plants strongly depends on the CO₂-methanation process.     

Étude théorique de la dynamique du réseau de PbTiO3 dans la phase quadratique

The lattice dynamics of lead titanate PbTiO₃ is discussed quantitatively using a shell model taking into account the electronic polarizabilities of the constituent ions, and including Coulomb and short-range interactions. Our calculations highlight the important role played by the anisotropic polarizability of oxygen and show good agreement between calculated and experimental dispersion curves.     

Un dosage très sélectif du nickel avec la cyclohexanedionedioxime

A method is described for the separation and determination of μg-quantities of nickel in the presence of large quantities of foreign cations, by extracting nickel-nioxime with organic solvents.     

Détermination du module d'young,de la dureté et de la contrainte d'écoulement plastique de dépôts par nano-indentation

Variable residual stresses are present in the metallic coatings of tungsten and chromium manufactured by PVD and modify the quantities measured by depth-sensing indentation instruments: depth of penetration and contact stiffness for a given load. By considering the results of experiments and numerical simulations we discuss the corrections required for improving the determination of the mechanical characteristics of such coatings.     

Phénomènes Transitoires et Influence de la Nature du Substrat dans la Déformation de la Surface Libre d'un Liquide Isolant Chargé

Abstract

On étudie l'établissement du régime final dans l'évolution électrohydrodynamique d'un liquide isolant soumis à un flux de charges dans le cas d'un substrat conducteur et dans le cas d'un substrat plus ou moins isolant; le cas d'un substrat ferroélectrique est envisagé plus particulièrement. Dans le cas d'un substrat isolant on étudie des mouvements latéraux du liquide. On montre que l'analyse de la déformation du liquide permet des études de substrats.

The establishment of the final behaviour is studied concerning the electrohydrodynamical evolution of an insulating liquid submitted to a flux of charges, for a conducting and for an insulating substrate of variable resistivity. In the case of an insulating substrate, lateral movements of the liquid are studied. One shows that analysis of the deformation of the liquid allows studies of substrates.     

Un réactif spécifique du germanium: la phénylfluorone

Based on the action of methyl fluorone on Ge(IV) the use of this reagent for the detection of germanium is described. It is necessary to treat with 6N HCl to make this reaction specific.However, another derivative of fluorone, namely phenyl fluorone, is still better for identifying Ge(IV). By placing a drop of the solution under test, previously strongly acidified (3 N to 6N in HCl), on a phenyl fluorone reagent paper and adding 2 or 3 drops of 6 N HNO₃, a. sensitive and specific reaction for germanium is obtained.The only interfering ions are those of strong oxidising agents (Ce⁺⁴, Cr⁺⁶, Mn⁺⁷, etc.) which destroy the reagents and must be eliminated in the first place.Other ions and ions of the group of the sulphides soluble in alkalisulfides do not interfere, even in the proportion of 100 parts by weight, to 1 of Ge. The limit of dilution is about 10^-5.5.     

Etude de la séparation du thorium d'avec les terres cériques

Résumé Nous avons étudié les complexes que forment les acides éthylèneglycolbis-(-aminoéthyléther)] Sr,N-tétracétique et ,-diaminodiéthylétherN,N-tétracétique, soit avec le thorium, soit avec les terres cériques et, à la suite de cette étude, nous avons pu établir une méthode d'analyse et une séparation du thorium d'avec les terres cériques qui nous a donné satisfaction.

---

Summary A study has been conducted of the complexes formed by the ethyleneglycol-bis (-amino-ethylether)-N,N-tetraacetic acid and,-diaminodiethylether-N,N-tetraacetic acid with either thorium or the ceric earths. As a result of this investigation, it was possible to set up a method of analysis and a separation of thorium from the cerium earths. These procedures have proved satisfactory.

---

Zusammenfassung Die von Äthylenglykol-bis-(-aminoäthyläther)-N,N-tetraessigsäure bzw.von ,-Diaminodiäthyläther-N,N-tetraessigsäure mit Thorium bzw. mit den Cer-Erden gebildeten Komplexe wurden untersucht. Auf Grund der Ergebnisse konnte ein Analysenverfahren und eine Trennungsmethode für Thorium und Cer-Erden entwickelt werden.

---

---

Une communication de ce travail a été faite à Graz, lors de la commémoration du centenaire de la naissance deF. Emich.