Kyanite-Andalusite Equilibrium from 700{degrees} to 800{degrees}C

The metastable kyaniteandalusite equilibrium in the Al(2)SiO(5) system has been reversed at 700 degrees , 750 degrees , and 800 degrees C at elevated water pressures, with a variety of natural and synthetic kyanites and andalusites as starting materials. Sillimanite, the stable form of Al(2)SiO(5) under these conditions, did not appear. The value of the transition pressure at 750 degrees C is 6.6 +/- 0.4 kilobars, several kilobars below pressures given by several convergent previous determinations. The Al(2)SiO(5) pressure-temperature triple point now indicated lies far from the points found by others. The revised aluminum silicate phase diagram indicates that many rocks crystallized at lower pressures than formerly thought possible.     

Kaolinite Synthesis at 25{degrees}C

The addition of quercetin, an organic flavone (C(15)H(10)O(7)), to aqueous solutions containing silica and aluminum and adjusted to final pH's from 6.5 to 8.5 produced a 1 : 1 alumninosilicate precipitate which, after 6 to 16 months of aging in solution at 25 degrees C, contained as much as 5 percent well-formed kaolinite plates. Similar solutions containing no organic material produced relatively amorphous precipitates with the same composition and stability (standard free energy of formation = -897+/-1 kilocalories per mole) but with substantially smaller amounts of crystaline material even after 2 years of aging.     

Protodolomite Synthesis at 100{degrees}C and Atmospheric Pressure

Ordered protodolomite, CaMg(CO(3))(2), has been synthesized at 100 degrees C by reaction of metastable precipitated carbonates with aqueous magnesium-bearing solutions. Initial reaction products have expanded crystallographic cells, attributed to the presence of structural water. Longer reaction time produces a protodolomite approaching ideal composition and exhibiting order reflections in x-ray powder.     

Composition of Aqueous Solutions in Equilibrium with Sulfides and Oxides of Iron at 350{degrees}C

Solutions of potassium chloride (pH-buffered and 1-molal) equilibrated at 350 degrees C with pyrrhotite, pyrite, and magnetite contained approximately 1 millimole of reduced sulfur and less than 0.1 millimole of oxidized sulfur per kilogram. Similar solutions equilibrated with pyrite, magnetite, and hematite contained approximately 1 millimole of reduced sulfur, but 3 to 6 millimoles of oxidized sulfur per kilogram. Both types of solutions contained less than 0.1 millimole of iron per kilogram at pH >/= 6 and approximately 100 millimoles per kilogram at pH 2.     

Crystal Structure of Krypton Difluoride at -80{degrees}C

Krypton difluoride is tetragonal, space group P4(2)/ mnm, with two linear molecules per unit cell aligned in planes perpendicular to the tetrad axes. The alignment alternates by 90 degrees between successive planes. The kryptonfluorine bond distance is 1.89 +/- 0.02 angstroms.     

Stimulated Brillouin and Raman Scattering in Quartz at 2.1{degrees} to 293{degrees} Kelvin

Stimulated Brillouin shifts observed at 2.1 degrees K in quartz are the same as those observed at 293 degrees K. No extreme nonlinear behavior is observed. Recent anomalous results reported by Russian workers are shown to be due to the very strong stimulated Raman scattering that sets in at low temperatures.     

Flight of Winter Moths Near 0{degrees}C

Some noctuid winter moths fly at near 0 degrees C by maintaining an elevated(30 degrees to 35 degrees C) thoracic muscle temperature. Geometrid winter moths sustain themselves in free flight at subzero muscle temperatures. However, the temperature characteristics of citrate synthase and pyruvate kinase from both of these different kinds of moths and from a sphinx moth that flies with a muscles temperature of 40 degrees C are nearly identical. Furthermore, mass-specific rates of energy expenditure of both kinds of winter moths are also similar at given thoracic temperature (near 0 degrees C). The geometrids that are able to fly with a thoracic temperature near 0 degrees C do so largely because of unusually low wing-loading, which permits a low energetic cost of flight.     

Activity Coefficients of Aqueous Sodium Chloride from 15{degrees} to 50{degrees}C Measured with a Glass Electrode

Values of the mean activity coefficient of sodium chloride at 15 degrees , 250, 380 and 50 degrees C were determined for aqueous NaCl solutions of 0.01 to 1.0 molal from electromotive force measurements on the cell: (sodium-sensitive glass electrode, aqueous sodium chloride, silver chloride-silver).     

Xenon Hexafluoride: Structure of a Cubic Phase at -80{degrees}C

The crystal structure of a cubic phase of composition XeF(6) has been determined at -80 degrees C. There are no simple molecules in the complex structure which involves 1008 atoms distributed over 1600 positions per unit cell. Ions of XeF(5)+ and F- are associated in tetrameric and hexameric rings of point group symmetries 4 and 32, respectively. The structure contains right-and left-handed conformations of both tetramers and hexamers. The handedness of the tetramers is dis-ordered but the orientation is ordered. The handedness of the hexamers is ordered but the orientation is disordered.     

Dissolution of Interlayers from Intergradient Soil Clays after Preheating at 400{degrees}C

Dehydroxylated interlayers have been removed from chlorite-vermiculite-montmorillonite intergrades by boiling the preheated sample in 0.5N NaOH for 2.5 minutes. Elements extracted can be conveniently analyzed spectrophotometrically. A convenient method of estimating the amount of elements present in interlayer positions and preparing the sample for analysis for expanding and nonexpanding mineral components is thus provided.     

Thermal Properties of Meteoritic Iron from -150{degrees} to 300{degrees} Celsius

Thermal diffusivity and specific heat have been measured by the flash method on a small specimen of meteoritic iron from the Canyon Diablo fall. Measurements have been made over the temperature range -150 degrees to 300 degrees C from which thermal conductivity values have been calculated.     

Diorites from the Mid-Atlantic Ridge at 45{degrees}N

Diorites, associated with basalts, basalt breccias, and serpentinized peridotites, occur in situ on the faulted scarps of two seamounts from the western High Fractured Plateau of the Mid-Atlantic Ridgeat 45 degrees N.     

A Redox Fuel Cell That Operates with Methane as Fuel at 120{degrees}C

Platinum black efficiently catalyzes the oxidation of methane by iron(III) to generate carbon dioxide and eight equivalents of iron(II) in solutions of sulfuric acid in water. The rate of oxidation increases over 4 hours to reach approximately 4.83 x 10(-2) moles of iron(II) per gram atom of surface platinum per second. A redox fuel cell was assembled that used this reaction in a liquid reformer to generate soluble reducing equivalents of iron(II) from methane, which was electrochemically oxidized to iron(III) in the cell. A vanadium(V)-(IV)-nitric acid-O(2) redox system catalyzed the electrochemical reduction of O(2). The open-circuit voltage of the cell was 0.48 volt, and the maximum power output of the cell was 8.1 milliwatts per cubic centimeter of graphite felt electrode.     

Atom Pair Distribution Functions of Liquid Water at 25{degrees}C from Neutron Diffraction

The structure of liquid water is described by three atom pair distribution functions gOO(r), gOH(r), and gHH(r). These functions have now been derived from neutron diffraction data on four mixtures of light and heavy water. They will provide a crucial and sensitive test for proposed models of liquid water.     

Supercooling of Water to -92{degrees}C Under Pressure

The temperature at which "clean" supercooled water freezes has been determined as a function of pressure up to 3 kilobars, using a differential thermal analysis technique on subdivided water samples. The supercooling limit of such samples, -38 degrees C at normal pressure, is lowered by initial increase of pressure, reaching a minimum value of -92 degrees C at 2.00 kilobars.