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UCRL-3324The present work was designed to meet a need in radiochemistry for the ready separation of molybdenum and technetium and of tungsten and rhenium.The distribution coefficients for these elements on an anion exchange resin have been determined in hydrochloric and nitric acid solutions of varying concentration. These values were used to determine suitable conditions for sepa"rating these eleme.nts and recovering them in small volumes free of material which would interfere in measuring their activities.

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UCRL-11604 A spectrophotometric method for the determination of palladium is presented which utilizes the absorptivity of the tetraazidopalladium (II) complex at 315 m~-t. after extraction into n-butyl alcohol and back-extraction into water. The main factors which control the color development and extraction are discussed and the effects of some common foreign ions are shown. The method offers advantages in sensitivity, color stahility, speed and accuracy. The standard deviation over the optimum range from 1.3 to 4.6 p.p.m. is 0.03 p.p.m.

Separation of Zirconium and Hafnium with Thenoyltrifluoroacetone 3179 can be added to their discussion except to say that a completely satisfying theory of the behavior of such solutions is not yet possible, and to emphasize again the fact that interactions between the unlike molecules are involved, in addition to the type of association of the alcohol postulated by Redlich and Kister.10 Summary For the system ethanol-methylcyclohexane, densities and refractive indices have been measured at 25°. Total and partial vapor pressures have been determined at 35 and 55°. Thermodynamic con-sistency of the data was found to be satisfactory.Vapor compositions are represented by the empirical equation previously developed by the authors, to within 0.005 mole fraction. They can be represented by an equation developed by Redlich and Kister, with somewhat less accuracy, and with rather anomalous values of the equilibrium constant involved.The excess free energy, entropy and enthalpy have been calculated from the data, and exhibit a similar behavior to that of other alcohol-hydrocarbon systems.Peoria 5, Illinois