Back titration with mercuric nitrate in alkaline medium

Summary Small amounts of bismuth in the order of 100 g up to 25 mg were potentiometrically determined by back titration with mercuric nitrate in alkaline media. The method gives highly accurate results and is further successfully applied for analysis of pairs of bismuth together with one of the cations of calcium, copper, cadmium, zinc, manganese, nickel, lead, aluminium and lanthanum.See also Z. analyt. Chem. 161, 401 (1958); 163, 81 (1958).     

Renewal Theorems for Singular Differential Operators

Let * be the convolution on M( ₊) associated with a second order singular differential operator L on ]0, +[. If is a probability measure on ₊ with suitable moment conditions, we study how to normalize the measures * ⁿ ; n } (resp. ) in order to get vague convergence if n+ (resp. x+). The results depend on the asymptotic drift of the operator L and on a precise study of the asymptotic behaviour of its eigenfunctions.     

Fast grey ra as a new colorimetric reagent for the microdetermination of bismuth

Fast Grey RA dye has proved to be a sensitive colorimetric reagent for microdetermination of bismuth. By its aid it is possible to determine with precision concentrations between 0.1 and 1p.p.m. in the presence of some other cations and anions, with a sensitive photometer or a Beckman spectro-photometer at a wavelength of 570 mμ. Among the interfering elements are cations of Cu, Zr, Ni, Cd,V and ferric iron. The latter element however, can be masked, to a great extent, by reduction with ascorbic acid.     

Studies on the reaction between mercury(II) and CDTA estimation of metal ions and analysis of cation mixtures

Summary Advantage was taken of the stoichiometric reaction between mercury and CDTA in urotropine buffered media to determine mercury or to back-titrate excess CDTA in the course of estimating a variety of metal ions or analyzing their binary mixtures with one of the alkaline-earth metals by selective pH. The procedures given are simple, rapid and extremely reliable.

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Zusammenfassung Die stöchiometrische Reaktion zwischen Quecksilber und CDTA in urotropingepufferter Lösung kann zur Quecksilberbestimmung oder durch Rücktitration von überschüssigem CDTA zur Bestimmung zahlreicher anderer Metallionen verwendet werden. Binäre Gemische mit Erdalkalien können durch Titration in definiertem pH-Bereich analysiert werden. Die beschriebenen Verfahren sind einfach, zuverlässig und rasch durchzuführen.

     

On the Global Integrability of Non-Negative Harmonic Functions

Let ⁺(D) be the set of all non-negative harmonic functions on a domain DR^d. Let q>0 and define L^q(D) to be the set of all Borel functions f such that |f|^q is Lebesgue-integrable on D. Let x₀D. N. Suzuki established the following:

An Analogue of Beurling–Hörmander’s Theorem Associated with Partial Differential Operators

In this paper for a positive real number α we consider two partial differential operators D and D_α on the half–plane We define a generalized Fourier transform associated with the operators D and D_α. We establish an analogue of Beurling–H?rmander’s Theorem for this transform and we give some applications of this theorem.     

The reaction of nitriles with mercaptoacetic acid. A new synthesis of thiazole derivatives

The reaction of mercaptoacetic acid with nitriles was investigated. Whereas 4-hydroxythiazole derivative could be obtained from the reaction of benzoylacetonitrile and of ethyl cyanoacetate with mercaptoacetic acid, a bithiazole derivative was obtained on treatment of benzonitrile with the same reagent. The behaviour of the synthesised thiazole derivatives towards aromatic aldehydes and hydrazines is reported.     

Extraction of some lanthanides by 12-crown-4 and 15-crown-5 from perchlorate media as ion pairs

The extraction of the trivalent lanthanides Eu, Tm and Yb(Ln) by crown ethers (CE) 12-crown-4 (12C4) and 15-crown-5 (15C5) in chloroform from perchlorate aqueous media of constant ionic strength is investigated. The effect of [H⁺], [CE] and [ClO ₄ ^– ] on the respective distribution ratio (D) is elucidated. Slope analysis of these results indicated that the extracted species are of the type Ln(OH) ₂ ⁺ ·ClO ₄ ^– (CE)₂. The extraction constants obtained are in the sequence 15C5>12C4 for the CE's and EuTm<Yb for the elements investigated. Based on the separation factors elucidated, Tm(III) and Yb(III) are separated from Eu(III) with high radiochemical purity; >99.5% by three (or four) successive extraction and strippings.