In-line dispersion prisms and methods of tuning for different wavelengths

Some in-line dispersion prisms have been previously devised to select a particular wavelength line of a multiple-wavelength laser. This paper considers how these prisms could be coupled and scanned so there is no deviation of the beam at any given wavelength line and no lateral displacement of the line.     

A catadioptric magnifier with two magnifications for microfiche reading

We have considered the possibility of using four internal reflections in a single lens to reduce its effective focal length by a very large factor. Hence, by using very shallow curvatures on the lens surfaces, it is possible to obtain very high visual magnification for viewing transmission objects such as microfiche. Some details of such a system are presented here, where a lower magnification is obtained for two internal reflections and a higher magnification for four internal reflections.     

On the density of various classes of groups

Let $\text{T}$ be a subset of the set of all isomorphism classes of finite groups. We consider the number F_$\text{g}$(x) of positive integers n≤x such that all groups of order n lie in $\text{T}$. When $\text{T}$ consists of the isomorphism classes of all finite groups of any of the following types, we obtain an asymptotic formula for F_$\text{g}$(x): cyclic groups, abelian groups, nilpotent groups, supersolvable groups, and solvable groups. In the course of the arguments, we also obtain, for almost all n, a lower bound for the number of groups of a given order n.     

Polarographic behaviour of zinc in sodium formate solution

Summary A polarographic determination of Zinc can be successfully performed in 1 M sodium formate solution (pH 7.0) as supporting electrolyte using 0.005% of gelatin as maximum suppressor. Well defined waves are obtained for 1–6 mM of zinc and various anions do not cause any interference. The method is also suitable for the determination of zinc and mangenese in presence of each other.

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Zusammenfassung Zur polarographischen Zinkbestimmung wird eine 1 m Natriumformiatlösung (pH 7,0) und 0,005% Gelatine als Maximumunterdrücker empfohlen. Im Bereich von 1–6 mMol Zink werden gut ausgebildete Stufen erhalten. Verschiedene Anionen stören nicht. Das Verfahren kann auch zur Bestimmung von Zink und Mangan nebeneinander angewendet werden.

     

Studies on nickel(II) complexes of N-aryl thioureas

The preparation and properties of the crystalline compounds of the type NiL ₄Cl₂, NiL ₂Cl₂ and NiLCl₂ (L=N-aryl thioureas) are described. Analytical, conductometric, magnetic and spectral data (infrared and electronic)_show that complexes of the type NiL ₄Cl₂ possess octahedral structure and those of NiL ₂Cl₂ and NiLCl₂ are characterised as distorted octahedral in solid state. The ligand field parametersD _q ,B and calculated from electronic spectral data, suggest a weak field for all the ligands. Metal sulphur bonding for all ligands is adduced from infrared and far infrared spectral studies.

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Untersuchungen an Nickel(II) Komplexen von N-Aryl-thioharnstoff Derivaten

Zusammenfassung Darstellung und Eigenschaften der kristallinen Verbindungen vom Typ NiL ₄Cl₂, NiL ₂Cl₂ und NiLCl₂ (L=N-Arylthioharnstoff) werden beschrieben. Magnetische Eigenschaften, Leitfähigkeitsmessungen, analytische und spektroskopische Daten beweisen, daß die Komplexe vom Typ NiL ₄Cl₂ oktaedrische Struktur besitzen; die Komplexe vom Typ NiL ₂Cl₂ und NiLCL₂ weisen eine verzerrt oktaedrische Geometrie auf. Die Ligandenfeld-ParameterD _q ,B und , die aus Elektronenanregungsspektren berechnet wurden, zeigen ein schwaches Feld für alle untersuchten Liganden an Aus Untersuchungen der Spektren des IR und fernen IR folgt, daß die Komplexe eine Metall—Schwefel-Bindung aufweisen.