La séparation Lu-Yb-Tm sur échangeur de cations par l' α-ihba

The mutual separation of Lu Yb and Tm is examined with cation-exchange resin und 0.1 M αhydroxybutyric acid as eluant. When carrier amounts of ca. 1 mg of rare earths are eluted, the distribution constants are displaced and the elution peaks are asymmetrical. Quantitative separation is, however, possible at room temperature; separation requires 23 h at pH 383 but only 13 h with a pH gradient.     

La détermination rapide du calcium et du magnésium dans l'eau de mer

A rapid method is described for the determination of calcium and magnesium in sea. water. The classical gravimetric methods are very lengthy and are susceptible to errors if used for sea-water. The two alkaline earths are determined by complexometric titration using complexen III (disodium ethylenediaminetetra-acetate) as reagent and two indicators (murexide and ériochrome black T) for the determination of calcium and for the sum of Ca⁺² and Mg⁺² ions. The quantity of magnesium is obtained by difference. While the classical gravimetric methods take at least 24 hours, these two determinations can be effected in 1 hour, giving satisfactory accuracy.     

Séparation du thorium et du lanthane par échange ionique

A simple and efficient method for the separation of thorium and lanthanum by ion-exchange is described. Lanthane is eluted first of all with citric acid and then the thorium is separated with sulphuric acid as eluant. The separation is complete and the method can be applied to all the rare earth elements.     

Séparation niobium-tantale contribution à l'étude de l'électrophorése sur papier

A study has been made of the separation of Nb and Ta on a micro-scale by paper electrophoresis, using oxalic and citric complexes and different buffer solutions.A fairly good separation is obtained by using oxalic complexes and, as buffer solution, a mixture of citric acid and potassium citrate of pH 3.42 and ionic strength 0.4.Different factors influencing the displacement of ions by paper electrophorcsis have been examined. It is shown that, if saturation currents are minimized, the displacement is practically proportional to the time of electrophoresis, and more difficult separations become possible using longer strips.     

Application de l'électrolyse interne au dosage de l'Or,du Bismuth,de l'Antimoine,séparations du Bismuth,de l'Antimoine et du Plomb; séparation de l'Etain et de l'Antimoine

Résumé La méthode de l'électrolyse interne est appliquée à quelques cas particuliers.En milieu acide, l'or est séparé avec une anode d'argent. Le bismuth, séparé ou non de l'antimoine et du cuivre est déposé à partir d'une solution de thiourée dans l'acide nitrique qui permet en plus de précipiter les sels de plomb.En milieu alcalin: soude et fluorure de sodium, on obtient de beaux dépôts d'antimoine qui se sépare de l'étain.

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Summary The method of internal electrolysis is applied to some particular cases. In acid medium, gold is separated with a silver anode. Bismuth, either separated or not from antimony and copper, is precipitated by starting from a solution of thiourea in nitric acid, which furthermore permits the precipitation of lead salts. In alkaline medium: sodium hydroxide and sodium fluoride, nice deposits of antimony are obtained which are separated from tin.

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Zusammenfassung Das Verfahren der inneren Elektrolyse wurde auf einige besondere Fälle angewendet. In saurem Milieu wurde Gold mit einer Silberanode abgetrennt. Wismuth wurde nach erfolgter oder nicht erfolgter Trennung von Antimon und Kupfer aus einer salpetersauren Thioharnstofflösung abgeschieden, die sich außerdem zur Ausfällung der Bleisalze eignet. In alkalischem, Natronlauge und Natriumfluorid enthaltendem Milieu erhält man eine gute Abscheidung von Antimon, das sich so von Zinn trennen läßt.

     

Contribution á l'étude de la séparation des terres rares de fission par l'acide éthylènediaminetétraacétique

In the present paper, the authors investigate the conditions for a rapid and if possible analytical separation of a mixture Y-Eu-Pm-Ce for quantities of a few milligrams.Elution curves are given in function of the pH, which is the main influencing factor.A separation at pH 3.05 gives the best results.     

Dosage complexométrique de bromures et d'iodures en présence l'un de l'autre

Bromides and iodides are determined simultaneously by precipitation as silver halide In another aliquot, silver halides are oxidized, bromine being liberated, the iodate formed is then reduced to iodide which precipitates. The silver precipitates are treated with ammoniacal tetracyano nickelate and displaced nickel is determined complexometrically Bromide is determined by difference     

La séparation et le dosage du tungstène et du molybdène au moyen du chlorure de calcium

A rapid and simple method is described for the separation and the determination of molybdenum and tungsten. Both metals are extracted as their soluble salts, sodium molybdate and sodium tungstate, by means of an alkaline fusion (Na₂CO₃ + Na₂O₂), after which they are separated by precipitation with calcium chloride as reagent. The precipitates of calcium molybdate and calcium tungstate are filtered, washed and then decomposed by concentrated hydrochloric acid. Calcium molybdate passes completely into the filtrate while calcium tungstate leaves a precipitate of tungstic acid. By calcining this precipitate, tungstic trioxide is obtained and weighed. The tungsten content is calculated therefrom.The filtrate from tungstic acid serves for reprecipitation of calcium molybdate on making the solution alkaline and by boiling. Calcium molybdate is filtered by means of a porcelain crucible filter and then calcined. When the weight of the calcined precipitate is constant, the molybdenum content is obtained by multiplying the weight of the precipitate by the conversion factor. Results are satisfactory, separation and determination of both metals not taking more than a day's work.     

Détermination de l'ion chlorhydrique dans de l'eau condensée

The titration of chloride with Hg⁺² according to CLARKE allows the determination of lower concentrations as was possible according to MOHR. The greater sharpness of the endpoint at lower concentrations and the use of a more dilute Hg+2 solution permit a further lowering of the concentration limit down to 0.05 mg Cl^-/l, when using a calibration curve, the remarkable form of which perhaps may be attributed to the formation of HgCl₂.2HgO. This sensibility allows a suitable chloride determination in boiler condensates and the wetness determination of steam.     

Étude du dosage du phosphore et de l'arsenic dans les aciers par colorimétrie

Phosphomolybdic and arsenomolybdic acids are formed and reduced to their blue reduction products at normal temperature in the presence of certain metallic ions: bismuth, zirconium, titanium. Of these ions, the last two catalyse the reduction of molybdic acid under acid conditions favourable to the reduction of phospho- and arsenomolybdic acids. Bismuth does not bring about this last reaction. It was chosen because of its analytical applications, which are related to the estimation of phosphorus and arsenic in steels. The working methods proposed are given in an appendix.     

Séparation des isoméres de l'hexachlorocyclohexane par chromatographie en phase gaz

Hexachlorocyclohexane isomers can be separated by a glass bead technique with polypropylene glycol Niax 1025 as the stationary phase. The principal isomers separated are the γ-hexachloro-cyclohexane (Lindane isomer), the α, β, ε, and δ isomers and γ-heptachlorocyclohexane. The life of the glass bead column is short — about 20 days in constant use. A longer column life can be obtained by pretreatment of the glass beads.     

Généralisation de la méthode d'analyse de thorpe et application au dosage de l'isomère y dans l'hexachlorcyclohexane technique

The author presents a generalization of THORPE'S method for the analysis of complex mixtures and describes an application of it to the determination of the γ-isomer in technical hexachlorcyclohexane. This method has the advantage of not requiring expensive apparatus.Portions of the materials under examination are treated with CH₃OH at 20° C in such a way as to obtain, on the one hand, a solution saturated with regard to the (α + β ) isomers and, on the other hand, a solution saturated with regard to the (α + β + γ) isomers. Having determined tlie amounts of the products dissolved inthese solutions, the solubilities in CH₃OH enable the contents of the (α + β) and the γ-isomers to be calculated.     

Oxydation électrochimique de l'ion thiocyanique. Application aux dosages et ä l'étude des réactions

The author has examined the rate of reaction of the system thiocyan ate/sulphate and cyanide, by means of the current/anode potential curves obtained during the electrolytic oxidation of thiocyanate in an acid medium.Corresponding with the minimum current detectable under our experimental conditions, we find a potential which agrees well with that determined by a classical potentiométrie method, and checked chemically. Consequently, it can be used to predict the chemical reactions taking place.From these curves, the relation between the anodic potential, the intensity of the electrolytic current, and the activity of the SCN^- ions has been deduced. These methods have been applied in a new method of investigating reactions in solution, viz. the potentiometry at constant current other than zero.     

Dosage colorimétrique de faibles quantités de cérium dans l'uranium

After extraction of the iron and uranium thiocyanates by ethyl acetate, the solution is oxidised by ammonium persulphate (in the presence of silver nitrate). The absorption of this solution is measured at 360 mμ by comparison with that of an aliquot previously reduced with oxalic acid, which selectively reduces cerium and manganese to the low valences. The absorption of manganese is deduced from a measurement at 525 mμ. By this method I to 5γ/ml cerium can be determined with an error of less than 15%.     

Applications analytiques des spectres infrarouges de poudres aux composés minéraux et a l'eau de cristallisation

This sliort reviews shows tliat the infrared absorption spectra obtained from the powder method are capable to give analytically very important indications.     

Principes de l'iodimétrie absorptiométrique

A general method for the determination of oxidising or reducing agents has been investigated It is based on the measurement of the absorption of the spectrum of the 1₃^- complex Oxidizing agents may be determined by thu oxidation of iodide into I₃^-, reducing agents by reduction of I₃^-For a right application of this method one must have (a) all the iodine present in the state of 1₃^-, (b) the iodine produced by autoxidation of the iodide ion in negligible quantity Theconstants of the chief equilibria in which 13- is involved (equilibrium with I₂,I_2Br-,I₂Cl^-, IOH) and the kinetics of the autoxidation of the iodide ion in the presence and the absence of the catalyst Cu⁺² have been reinvestigated The acquned information enabled us to determine the general conditions of Applicability of this method and the realization of special analyses, The limit of detection by this method is 2.10^-7 gram equivalent of oxidizing or reducing agent per liter when absorptions are measured through a 5 cm layer.     

Dosage acidimétrique de l'ion aluminium

Acid titration of aluminium salts consists of two stages.1. Titration of the free acid. Complex ions are formed of aluminium with oxalatē of hydrofluorideions. 'I'he precipitation of aluminium hydroxide is retaided. Consequently the neutralisatiom of the free acid by the base is quite clear.2. Simultaneous titration of the acid and the aluminium ions. The solution with NaOH is neutralised until all the aluminium hydroxide is just precipitated. To avoid errors due to the formation of adsorption compounds, an excess of base is added and back-titrated with hydrochloric acid at the boiling point.These two titrations permit the determination of XXX acid and the aluminium content of the solution to approximately 0,3%.The influence of disturbing ions is studied.