An evaluation of proposed platinum group element contents in the parental magmas of the Bushveld complex

Samples collected by the authors and representing three proposed parental magmas of the Bushveld complex were analyzed for their platinum group element (PGE) contents by three different laboratories. Results differ strongly between laboratories, but imply that the parental magmas may have had flatter chondrite normalized patterns and an overall lower content than previously reported. It seems, however, that the Bushveld magmas were enriched in PGE's relative to average mafic rocks. A clear difference between the three magma types could not be substantiated. At present the PGE content of proposed parental melts of the Bushveld complex must be considered to be insufficiently known to warrant any quantitative models.     

Wie der Gesundheitsingenieur seine Zusammenarbeit mit dem Biologen sieht

Ohne Zusammenfassung     

Nepheline Solid Solution in the System NaAISiO4-KAISiO4-SiO2

The limit of solid solution of SiO₂ in nephelines has been determinedat 700? C and a water pressure of 15, 000 lb/sq. in. X-ray dataare given for the determination of the composition of nephelinesin equilibrium with alkali feldspar at 700? C. The break in the plot of lattice parameters against chemicalcomposition for nephelines in the system NaAISiO₄–KAISiO₄(Tuttle & Smith, 1958) is found to persist in the ternarysystem and occurs when six out of the eight alkali atom sitesare filled by Na.     

An improved model of the condensation nucleus counter with stereo-photomicrographic recording

Summary A new model of the condensation nucleus counter with stereo-photomicrographic recording is described which is distinguished by perfect symmetry in its construction, reduced turbulence, two separate microscopes with photographic attachments and a novel dark-field illumination which eliminates completely fogging of the graticule even after prolonged use of the instrument. A view-finder microscope permits observations of the graticule so that the instrument can also be used for counting nuclei by eye. When the graticule is removed the droplets can be photographed in space stereoscopically.The use of the counter and its accessories is described and the dimensions and range of the instrument given.

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Zusammenfassung Es wird ein neues Model des Kondensationskernzählers mit stereo-photomikrographischer Registrierung beschrieben, welches sich durch vollkommene Symmetrie der Konstruktion, reduzierte Turbulenz, zwei gesonderte Mikroskope mit photographischen Zusatzeinrichtungen und einer neuartigen Dunkelfeldbeleuchtung auszeichnet, welche das Beschlagen der Zählplatte, selbst nach langem Gebrauche des Instrumentes, völlig eliminiert. Ein Suchermikroskop gestattet die Beobachtung des Zählglases, so dass das Instrument auch als Kernzähler für Augenbeobachtungen gebraucht werden kann. Wenn die Zählplatte entfernt wird, können die Tröpfchen im Raume stereoskopisch photographiert werden.Der Gebrauch des Kernzählers und seines Zugehörs wird beschrieben, sowie die Dimensionen des Instrumentes und der mit ihm mögliche Umfang der Kernzählungen angegeben.

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The research reported in this article has been sponsored and supported in part by the Geophysics Research Directorate of the Air Force Cambridge Research Center, Air Research and Development Command, United States Air Force, under Contract AF 61(052)-26, through the European Office, ARDC in Brussels.     

The atmospheric electric fog effect at de bilt

Summary In a polluted area, conductivity measurements do not provide significantly better fog forecasts than result from the trend of synoptic reports.