Oxygen Isotope Studies of Ivory Coast Tektites and Impactite Glass from the Bosumtwi Crater, Ghana

Oxygen isotope analyses were obtained for six Ivory Coast tektites, two samples of Bosumtwi Crater glass, and two new moldavites. The Ivory Coast tektites are 2 to 5 per mil richer in oxygen-18 than other known tektites, and they are similar in oxygen-18 content to the impactite glass from the nearby Bosumtwi Crater. These data are compatible with a terrestrial origin for the Ivory Coast tektites.

Oxygen Isotope Fractionation in the System Dolomite-Calcite-Carbon Dioxide

Oxygen isotopes were equilibrated between carbon dioxide and calcite at four temperatures in the range 350 degrees to 610 degrees C and between carbon dioxide and dolomite at 350 degrees and 400 degrees C. Carbon of unusual isotopic composition was used as a tracer to demonstrate the nature and extent of the exchange process. Extrapolation of these data at lower temperatures indicates that at 25 degrees C dolomite is enriched in oxygen-18 by 6.8 per mil with respect to calcite. This result indicates that those natural dolomite-calcite assemblages which show very small fractionations were not formed in isotopic equilibrium.

STUDIES OF RDX AND RELATED COMPOUNDS: VII RELATION BETWEEN RDX AND HMX PRODUCTION IN THE BACHMANN REACTION

The reactions to form RDX and HMX in Bachmann-type mixtures are comparable in respect of optimum nitric acid concentrations and in the fact that optimal amounts of acetic anhydride and ammonium nitrate are necessary for maximum yields of either explosive. The activation energies for formation of RDX and HMX were also found to be comparable, at 15 ± 1 kcal. per mole. However, withholding ammonium nitrate from the reaction mixture was found to have a more deleterious effect on RDX production than on HMX production. A mechanism is proposed which attempts in a general way to represent the relation between RDX and HMX production in the type of reaction mixtures used.

STUDIES ON RDX AND RELATED COMPOUNDS: VI. THE HOMOGENEOUS HYDROLYSIS OF CYCLOTRIMETHYLENETRINITRAMINE (RDX) AND CYCLOTETRAMETHYLENETETRANITRAMINE (HMX) IN AQUEOUS ACETONE, AND ITS APPLICATION TO ANALYSIS OF HMX IN RDX(B)

Measurements of the rates of alkaline hydrolysis of cyclotrimethylenetrinitramine (RDX) and cyclotetramethylenetetranitramine (HMX) in aqueous acetone show these two reactions to involve consecutive steps, the first of which is second order and rate controlling. Activation energies were estimated as 14 and 25 kcal. respectively. By establishing calibration curves, and controlling temperature, alkali concentration relative to concentration of explosive, and reaction time, the differential hydrolysis permits analysis of the HMX content of RDX(B) with an error of approximately ±0.2% HMX.

THE EXTRACTION AND PURIFICATION OF XENON AND KRYPTON ISOTOPES FROM NEUTRON IRRADIATED URANIUM

Both long-lived and stable isotopes of krypton and xenon are formed as the result of the slow neutron fission of uranium 235. A method is described for the extraction of these gases from massive neutron irradiated uranium metal, for separating them from contaminating gases and from each other and measuring them in a McLeod gauge, the amounts of uranium being of the order of 50 gm. and the rare gases of the order of 10−3 cc. at N.T.P. An accurate value of the ratio of fission xenon to fission krypton is given. Further experiments concern Geiger–Müller counter measurements on the long-lived krypton isotope.