摘要:

AbstractProcedures are given for the electrometric determination of vanadium in alloy steels. In tungsten‐free steels vanadium is determined by titration with ferrous sulphate under specified conditions of acidity. It is shown that this method gives low results for steels containing tungsten, due to the incomplete reduction of the vanadophosphatotungstate complex; complete reduction however takes place by boiling with excess ferrous sulphate, enabling the determination to be finshed by electrometric titration with standard permanganate. Small amounts of vanadium accompanied by large amounts of tungsten can only be determined by titration with ferrous sulphate when the amount of phosphoric acid is greatly increase

ISSN:0165-0513    

DOI:10.1002/recl.19480670102

出版商:WILEY‐VCH Verlag    

年代:1948

数据来源: WILEY

摘要:

AbstractDebye‐Scherrer photographs of silver bromide emulsions were taken before and after the emulsion had undergone a “ripening‐process” by keeping it at a temperature of about 40° C for a few hours. An increase of resolution of the Co‐Kα‐doublet of the AgBr‐line σ(H2+ K2+ L2) = 40 confirmed that the ripening‐process was accompanied by growth of the silver bromide crystals. It was further shown that this crystal growth took place in the first stage of the ripening‐process, before the soluble salts had been e

ISSN:0165-0513    

DOI:10.1002/recl.19480670103

出版商:WILEY‐VCH Verlag    

年代:1948

数据来源: WILEY

摘要:

AbstractMixed crystals of AgBr with a few % of PbBr2and of AgCl with a few % of CdCl2were prepared, partly by co‐precipitation and partly from the melt. Debije‐Scherrer photographs showed no change in lattice parameter compared with the pure silver halides. That actually mixed crystals were formed was concluded from the marked decrease in photosensitivity (colouring on exposure to ultraviolet light) as compared to that of the pure hali

ISSN:0165-0513    

DOI:10.1002/recl.19480670104

出版商:WILEY‐VCH Verlag    

年代:1948

数据来源: WILEY

摘要:

AbstractThe disintegration of silver halide crystals by irradiation with ultraviolet light manifests itself in Debije‐Scherrer photographs ofpowdered preparationsin various ways: by diminishing the discontinuous appearance of the interference lines of the non‐irradiated crystallites and by a broadening of the lines of the Kα1α2‐doublet, as shown by high‐order reflections. Also the formation of silver in a finely divided form is clearly visible.On irradiation ofsingle crystalsof silver chloride, the X‐ray photographs show the presence of silver crystallites with preferential orientations, as evident from the appearance of Debije‐interference lines with intensity maxima. This points to a formation of individual small silver crystallites with partly coinciding orientations. The exact crystallographic character of the preferred orientation and its possible connection with that of the irradiated AgCl‐crystal, has not be

ISSN:0165-0513    

DOI:10.1002/recl.19480670105

出版商:WILEY‐VCH Verlag    

年代:1948

数据来源: WILEY

摘要:

AbstractErsetzt man in der Formel eines Purin‐Derivats eines oder mehrere der Stickstoffatome des Ringsystems durch Methingruppen, so gelangt man zu Strukturtypen, für die sich durch Verwendung des Praefix „Des‐aza‐”︁ einfache Bezeichnungen ableiten lassen. Wir haben uns die Aufgabe gestellt, derartige Verbindungen zu synthetisieren und zu prüfen ob und inwieferne sie als Hemmstoffe physiologischer Prozesse wirksam sind.Die vorliegende Mitteilung beschäftigt sich mit der Synthese von 1‐Desaza‐adenin, dem von einem Imidazopyridin abgeleiteten Analogen des Adenins. Seine Darstellung hatte die Synthese des bisher ebenfalls unbekannten 2,3,4‐Triamino‐pyri

ISSN:0165-0513    

DOI:10.1002/recl.19480670106

出版商:WILEY‐VCH Verlag    

年代:1948

数据来源: WILEY

摘要:

AbstractIn der vorliegenden Arbeit wird gezeigt, dass die in der Literatur als 4(7)‐Amino‐benzimidazol beschriebene Verbindung in Wirklichkeit die Aminogruppe an Stelle 5 (bzw. 6) trägt. Das bisher unbekannte 4(7)‐Aminobenzimidazol ‐ dem wegen seiner strukturellen Beziehung zu Adenin ein gewisses Interesse zukommt ‐ wurde dargestellt und mit der isomeren Verbindung

ISSN:0165-0513    

DOI:10.1002/recl.19480670107

出版商:WILEY‐VCH Verlag    

年代:1948

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19480670109

出版商:WILEY‐VCH Verlag    

年代:1948

数据来源: WILEY

摘要:

AbstractDans ce travail, les auteurs décrivent la préparation et les propriétés d'une série de cétones provenant de réactions deFriedel‐Craftsentre les chlorures des acides hydrogénés de l'huile de chaulmoogra (acides hydnocarpique et chaulmoogrique hydrogénés) et une série d'éthers‐oxydes de monophénols, de polyphénols, et de naphtols. Certaines de ces cétones ont été réduites par la methode deClemmensen, et les éthersoxydes à longue chaîne obtenus ainsi ont été transformés en phénols libres. Les substances ainsi préparées sont très peu toxiques, et inhibent très légèrement la croissance du bacille deKoch.Des observations intéressantes ont pu être faites sur la fission hydrolytique de certaines des cétones ainsi p

ISSN:0165-0513    

DOI:10.1002/recl.19480670110

出版商:WILEY‐VCH Verlag    

年代:1948

数据来源: WILEY

摘要:

AbstractDans ce travail, les auteurs décrivent les réactions deFriedel‐Craftsentre une série de chlorures d'acides gras aliphatiques et le thionaphtène. De nombreuses cétones nouvelles ainsi que certains de leurs dérivés sont mentionnées à ce propos, et les analogies de comportement entre le thionaphtène et le naphtalène s

ISSN:0165-0513    

DOI:10.1002/recl.19480670111

出版商:WILEY‐VCH Verlag    

年代:1948

数据来源: WILEY

摘要:

AbstractA description is given of a colorimetric determination of nickel as Ni(4)dimethylglyoxime, but in contrast to the customary methods, use is made of persulphate as oxidizing agent. The influence of other metallic ions has been investigated too.It appears that, of the elements investigated Ag must be removed, while the alkaline earth metals give a sulphate precipitate which can be removed by centrifuging. The determination of Ni in the presence of Mn, Fe, Cu and Co presents the greatest difficulties. In many cases we have succeeded finally in determining nickel in the presence of these elements without removing them. Thus it is possible to determine accurately 5% Ni and over in manganese, 0.25% and over in iron, 0.05% and over in copper and 0.05% and over in cobalt.In general it has been established that the highest accuracy is obtained when full attention is paid to the following points:(1)the avoidence of ammonia(2)the regulation of the amount of dimethylglyoxime(1)the acidity of the solution.If one of these points is not in order, the degree of accuracy becomes less. This is the case in the determination of Ni in the presence of cobalt, copper, in which case the presence of ammonia is a necessary condition for the formation of the colour.It can be remarked that this method is extensively applied in our laboratory in the determination of Ni in chrome‐iron. Mo and W compound

ISSN:0165-0513    

DOI:10.1002/recl.19480670112

出版商:WILEY‐VCH Verlag    

年代:1948

数据来源: WILEY