bluuebunny/crossref_metadata_2025 huggingface dataset:
A Calculation of the Energy of Activation for the Racemization of 2,2′-Dibromo−4,4′-Dicarboxydiphenyl
Authors: Westheimer F. H.
Published: January 2005

In a recent article J. E. Mayer and the author presented a method of calculating the energy of activation for the racemization of optically active diphenyl derivatives from known force constants and from the van der Waals repulsion between ortho substituents. In the present paper, the calculation of this activation energy is carried through in detail for the racemization of 2–2′-dibromo−4,4′-dicarboxydiphenyl. The value obtained is 18 kcal./mole. The experimental value is not known, but the free energy of activation for the same process is 19.5 kcal./mole. In the discussion of probable errors, it is shown that the calculated energy of activation is unlikely to be in error by as much as 7 kcal./mole, and that the probable error is only about 4 kcal./mole. The racemization involves distorting the various angles and stretching the various bonds in the molecule, as well as forcing the ortho substituents to approach one another so that the distance between them is less than the sum of their van der Waals radii. In the present treatment, all these deflections and stretchings are computed; that is to say, an accurate model for the activated complex is obtained.
A Relation Between Bond Order and Covalent Bond Distance
Authors: Bernstein H. J.
Published: January 2005

A relation between covalent bond distance and bond order of the form R=R1[2/3+1/3×(n−1/n+1)p/2] is proposed and tested against the available experimental data. A suitable expression for all covalent bond distances between atoms of the first row of the periodic table of the form R=Z−A/Z−B[2/3+1/3(1/3)p/2] is also proposed. The agreement between calculated and observed values is well within the limits of the experimental errors.
On the Behavior of Pure Substances Near the Critical Point
Authors: Rice O. K.
Published: January 2005

It has been suggested several times that the phenomena of condensation could be understood by considering the vapor as a system in which molecules are associating into clusters, these obeying the ordinary laws of equilibrium. One can also consider the liquid as a system in which bubbles of vapor are forming. The present paper attempts to apply these ideas to phenomena occurring in the neighborhood of the critical point. Only thermodynamic methods are used, in conjunction with some general assumptions concerning the properties of the molecules involved. Some aspects of the surface tension of the liquid near the critical point have been considered in some detail. The highest temperature Tm at which a meniscus can exist is assumed to be the temperature at which the surface tension vanishes at the same time that the condition for equilibrium between liquid and vapor phases is fulfilled. It is concluded that the pressure-volume isotherm at Tm has a finite horizontal region, corresponding to the squeezing out of surface when the surface tension is zero. The slope of the isotherm at Tm in the vapor region outside the horizontal portion is closely related to the slope in the liquid region just to the other side of the horizontal part; these slopes approach zero as the flat part is approached. Above Tm there is still a process which may be called condensation, but no horizontal part to the isotherms. This is in contradiction to conclusions reached by Mayer and Harrison on the basis of their statistical theory of condensation, but is apparently not in real contradiction to the theory.
The Effect of Pressure on Surface Tension
Authors: Rice O. K.
Published: January 2005

The thermodynamic formula for the change of surface tension with pressure is interpreted for a one-component system and for a two-component system consisting of an inert gas over a liquid. In the latter case the effect of pressure on surface tension can be attributed in part to absorption of gas at the surface of the liquid and in part to an intrinsic decrease in density of the liquid in the neighborhood of the surface. The equations are interpreted in terms of the Gibbs adsorption isotherm. The adsorption of gas at the liquid surface has been estimated in several cases from data in the literature.
A Potentiometric Secular Equation Computer
Authors: Frost Arthur A. , Tamres Milton
Published: January 2005

An electrical computer for solving secular equations is described. The technique makes use of the linear equations from which the secular equation is derived. Each of the linear equations is successively represented by a potentiometric circuit. A series of successive approximations is carried out to arrive at the desired solutions.
Thermodynamics of Crystallization in High Polymers. I. Crystallization Induced by Stretching
Authors: Flory Paul J.
Published: January 2005

A theory of oriented crystallization in elongated polymers having network structures (e.g., in vulcanized rubber) is developed through the application of statistical mechanical procedures similar to those employed in rubber elasticity theory. Expressions are derived which, within the limitation imposed by the simplifying assumptions, relate the incipient crystallization temperature with the elongation, the degree of crystallinity with the elongation and temperature, and the retractive force at crystallization equilibrium with the elongation at constant temperature. The reciprocal of the absolute temperature for incipient crystallization is predicted to decrease linearly with a simple function of the elongation and the average number of chain segments between cross linkages. Only moderate degrees of crystallinity are predicted at equilibrium. In conformity with requirements of the second law of thermodynamics, equilibrium crystallization decreases the tension in the stretched specimen.

Apparent discrepancies between some of these predictions and various observations are attributed to severe departure from equilibrium crystallization when the polymer undergoes crystallization during the stretching process. A better approach to equilibrium should be achieved by stretching under conditions which prevent crystallization (e.g., at elevated temperature), then allowing crystallization to proceed at fixed elongation. Few experiments have been performed in this manner, but such results as are available confirm qualitatively the predictions of the theory.

Reasons for the rapid increase in tension which is observed when crystallization occurs during ordinary stretching of rubber are discussed. It is pointed out that crystalline and amorphous regions preferably should not be regarded as separate phases. Likewise, the conversion of amorphous to crystalline polymer does not conform to the definition of a phase transition.
Equilibrium Atom and Free Radical Concentrations in Carbon Monoxide Flames and Correlation with Burning Velocities
Authors: Tanford Charles , Pease Robert N.
Published: January 2005

Calculations have been made of equilibrium concentrations of hydroxyl radicals and of hydrogen and oxygen atoms in moist carbon monoxide flames. Comparison with burning velocities, measured by Jahn by the Bunsen burner method, reveals a close correlation between observed burning velocities and such calculated hydrogen atom concentrations. Only a slight correlation exists with hydroxyl radical concentrations and none at all with calculated oxygen atom concentrations. A theoretical basis for these observations will be presented in a subsequent paper.
Theory of Burning Velocity. I. Temperature and Free Radical Concentrations Near the Flame Front, Relative Importance of Heat Conduction and Diffusion
Authors: Tanford Charles
Published: January 2005

A previous paper having suggested that hydrogen atoms play an important part in combustion, an investigation is made of the relative importance of heat conduction and diffusion in establishing concentrations of hydrogen atoms near the flame front. To do this, differential equations are set up for heat transfer and for material transport. These equations are solved for two typical mixtures, one containing moist carbon monoxide, the other containing hydrogen. It is shown that the temperature falls rapidly as the distance from the flame front increases, and that the local thermal equilibrium concentration of hydrogen atoms, being a negative exponential of that temperature, falls more rapidly still. On the other hand, the local non-equilibrium concentration of hydrogen atoms, which is caused by diffusion from the flame front into unburnt gas, falls only slowly with distance. It is thus concluded that diffusion plays a more important role than heat transfer.
Separation of the Nitrogen Isotopes by the Exchange Reaction between Ammonia and Solutions of Ammonium Nitrate
Authors: Kirshenbaum Isidor , Smith James S. , Crowell Thomas , Graff Jacob , McKee Robert
Published: January 2005

The fractionation factor for the exchange reaction between ammonia and ammonium nitrate was determined as a function of the dissolved ammonia content. It was found that for a stock solution containing 59.3–59.6 percent ammonium nitrate α=−0.029 M+1.034,where α is the fractionation factor at 25°C and M the fraction (Moles NH3)/(Moles NH3+Moles NH4NO3), in solution. From these data, the equilibrium constant for the exchange reactionN14H4+(sol)+N15H3(gas)⇌N15H4+(sol)+N14H3(gas)was calculated to be 1.034, while that for the reaction N14H3(sol)+N15H3(gas)⇌N15H3(sol)+N14H3(gas)was found to be 1.005. Vapor pressure and density data were determined for the ammonia-ammonium nitrate solutions as a function of the ammonia concentration.
The Study of Reaction Intermediates by Means of a Mass Spectrometer Part I. Apparatus and Method
Authors: Eltenton G. C.
Published: January 2005

A method for coupling a reaction chamber to a Dempster-type mass spectrometer in such a manner that short lived intermediates can reach the electron beam is described. The presence of radicals is denoted by an increase in the ion current of the corresponding mass. The sensitivity of the method depends on the difference between the appearance potential of the given ion produced by electron bombardment of either reactants or end products and the ionization potential of the free radical. It is shown experimentally that excited molecules are not present in sufficient quantity to invalidate the assumption that free radicals are responsible for the changes in ion current. The method has already extended more than tenfold the pressure range in which radicals are detectable, thus bridging the gap between mirror and spectroscopic methods so that low pressure combustion phenomena may be studied.
``Structure'' in Liquids and the Relation between the Parameters of the Arrhenius Equation for Reactions in the Condensed Phase
Authors: Waring Chas. E. , Becher Paul
Published: January 2005

On the basis of the liquid state being quasi-crystalline, a modification of the transition state theory leads to a simple equation for the temperature dependence of the fluidity, which involves a characteristic frequency of molecular vibration. The parameters of the fluidity equation are shown to have a linear correlation for certain liquids. The quasi-crystalline picture is then extended to a simple collision theory of uni- and bimolecular reactions in solution, and it is shown that the known correlation of the parameters of the Arrhenius equation arises from the fluidity correlation.
Photo-Conductivity in Photographic Systems I. Dye-Sensitization of Photo-Conductivity
Authors: West W. , Carroll B. H.
Published: January 2005

Gelatino-silver halide photographic films increase in electrical conductivity on exposure to light at intensities corresponding to exposures within the normal photographic range, and above. The spectral distribution of this change in conductivity in films containing, respectively, photographic sensitizing dyes, and no dye, is found to be parallel with the spectral distribution of photographic sensitivity— the wave-lengths of maximum and minimum sensitivity in the two effects are identical and coincide with absorption maxima and minima, and there is a general parallelism in the efficiency of a dye in sensitizing the two effects to light not absorbed by the silver halide. The conclusion is drawn that the observed changes in conductivity represent a photo-conductivity originating in the photo-liberation of electrons within the silver halide, the primary act of the photographic process.

The photo-currents are proportional to the applied field up to strengths of at least 140 volts per millimeter, and at intensities of illumination within the normal photographic range and somewhat above, are proportional to the intensity. At still higher light intensities, the photo-currents verge towards a dependence on the square root of the intensity. The change in the intensity relation is interpreted as representing the passage from a situation, at low intensities, in which most of the electrons are captured by foreign traps to that, at high intensities, in which recombination with bromine atoms predominates.

It is shown that a sensitizing dye acts by causing the liberation of an electron within the conduction band of the silver halide under the stimulus of light absorbed by the dye but whether the process involves direct electron-transfer or energy-transfer is left open.
The Infra-Red Spectrum of Ketene
Authors: Halverson Frederick , Williams Van Zandt
Published: January 2005

The infra-red spectrum of gaseous ketene has been studied from 2.5μ to 25μ with a spectrometer using LiF, NaCl, and KBr prisms. A perpendicular band at 3162 cm−1 with components relatively free of perturbations has been resolved, and the intensity alternation associated with the twofold axis observed. All fundamental vibrational frequencies have been assigned. A normal coordinate treatment of the general H2XYZ molecule has been made and reasonable force constants for ketene calculated.
The Heat Capacity of Benzene Vapor. The Contribution of Anharmonicity
Authors: Scott D. W. , Waddington Guy , Smith J. C. , Huffman H. M.
Published: January 2005

The heat capacity of benzene vapor was measured at two or more pressures at each of five temperatures in the range 68° to 198°C; and values of Cpo, the heat capacity in the ideal gas state, were obtained. By assuming a moderate degree of anharmonicity of the vibrations, it was possible to obtain excellent agreement between values of Cpo calculated statistically from spectroscopic data, and the observed values. An empirical equation for the second virial coefficient of benzene vapor was obtained from the observed values of (∂Cp/∂P)T, and heat of vaporization and vapor pressure data.
The Application of Ultrasonic Waves to the Study of Electrolytic Solutions I. A Modification of Debye's Equation for the Determination of the Masses of Electrolytic Ions by means of Ultrasonic Waves
Authors: Bugosh John , Yeager Ernest , Hovorka Frank
Published: January 2005

Debye's equation for the alternating potential which should accompany the passage of ultrasonic waves through an electrolytic solution is modified and extended by the addition of terms representing corrections for relaxation forces, electrophoretic effects, thermal diffusion, and the pressure gradient associated with the material wave.
The Thermodynamic Properties of Water Substance 0° to 150°C PART VI
Authors: Keyes Frederick G.
Published: January 2005

Commitments regarding additional research on the properties of water in the region below 200°C made on the occasion of the Third International Conference on Steam Tables in 1934 have been largely completed. Correlation of all new data using James A. Beattie's determinations of the relation of the International temperature scale of 1927 to the thermodynamic scale discloses a high degree of thermodynamic consistency from 0° to 150°C between thermal data, vapor pressures, and equation of state information. The proposed vapor pressures over the temperature range are probably accurate to ±0.002°C. New measurements of vapor pressure over the range are, however, desirable but the ultimate in refinements of temperature control and pressure accuracy should be sought if the indicated discrepancies are to be resolved. Tables of vapor pressure, pressure-temperature derivatives, essential temperature-scale magnitudes, enthalpies, and entropies are given. An equation of state for steam is reported from 0° to 460°C, valid for low pressures and based on the ensemble of volume data and enthalpy pressure coefficients available.
The Adsorption of Hydrogen on Tungsten Powders
Authors: Halsey George , Taylor Hugh S.
Published: January 2005

An analysis of the extensive experimental data of Frankenburg on the adsorption of hydrogen by metallic tungsten powder between −194 and 750°C has been made, using the Fowler-Guggenheim treatment of adsorption phenomena as the mode of approach. It has not been found possible to interpret the data in terms of interaction between the adsorbed species on a uniform adsorbent surface. It is shown that the experimental data can be interpreted on the basis of a non-uniform surface without interaction, the heterogeneity of the surface being specified in terms of an exponential distribution of sites given by the distribution function N=ce−χ/χm, where χ represents the energy difference between the lowest energy state of the gas and the lowest energy of the adsorption complex. Such a distribution function yields the experimentally observed relation d lnp/d lnθ=constant at constant temperature. Such a heterogeneity is especially significant in the case of tungsten metal which hitherto has been treated as an essentially uniform surface. The quantity χm has been found to vary with the temperature. The significance of this variation has been briefly explored.
Statistical Properties of Networks of Flexible Chains
Authors: James Hubert M.
Published: January 2005

A Gaussian network is defined as a network of flexible chain segments, linked to each other and to a system of fixed points, in which each unbranching chain segment can take on a number of configurations which is a Gaussian function of the distance between its ends. Real molecular networks, such as those of rubber, can under certain circumstances be treated as Gaussian networks. The present paper carries out a systematic mathematical discussion of the statistical properties of Gaussian networks: the total number of possible configurations of the network as a function of the fixed-point coordinates, the probability of finding a given element of the network in a given position, or of finding two elements of the network in given relative positions, and so on. All probability-density functions appear as exponentials of quadratic forms, with constants explicity expressible in determinant form. An explicit reduction to a sum of squares is given for all quadratic forms occurring in the theory of coherent Gaussian networks, and an explicit general formula is found for integrals of the form ∫ −∞+∞dX1 ∫ −∞+∞dX2··· ∫ −∞+∞dXq exp{− ∑ in ∑ jnγijXiXj}.There is described a mechanical analog of a Gaussian network, by consideration of which the statistical properties of the Gaussian network can be determined. The method is applied to the discussion of the statistical properties of a Gaussian network with the connectivity of a regular cubic lattice.
Motions of Molecules in Condensed Systems. IV. The Infra-Red Spectra for Ammonium Nitrate and Thallous Nitrate
Authors: Keller William E. , Halford Ralph S.
Published: January 2005

The infra-red absorption spectra from 680 to 3600 cm−1 have been recorded for five crystalline modifications of NH4NO3 at 150°, 105°, 55°, 25°, and −40°; also the spectra from 680 to 1450 cm−1 of three modifications of TlNO3 at 170°, 100°, and 25°. Fundamental frequencies of the nitrate ion were found for NH4NO3 at 715, 830, 1050, and 1350 cm−1 (those for TlNO3 were found at approximately the same positions) and of the ammonium ion at 1430, 1760, 3100, 3200 cm−1. The spectrum of each compound remains essentially the same with change of temperature, except that in NH4NO3 at 150° and 105° the band at 715 cm−1 is absent. It is notable that bands at 1050, 1760, and 3100 cm−1, supposedly caused by symmetric vibrations, remain active in all crystal forms investigated.
Diffusion of Radioactive Copper during Oxidation of Copper Foil
Authors: Castellan Gilbert W. , Moore Walter J.
Published: January 2005

Strips of copper foil were plated with a thin deposit of radioactive copper and the specimens then oxidized in air at 800°, 900°, 1000°C. From the distribution of radioactive copper in the oxide diffusion coefficients, D, for cuprous ion in cuprous oxide were calculated. Over the temperature range D was found to be 0.0358 exp(−37,000/RT) cm2 sec.−1. The activation energy for the oxidation of copper is 39±2 kcal./mole, so that these measurements provide further evidence that diffusion of Cu+ in Cu2O is the rate-determining step in the oxidation.
Hydrocarbon Ion Appearance Potentials
Authors: Mitchell J. J. , Coleman F. F.
Published: January 2005

Discussion of the effect of impact parameter, distribution of electron energy and transition efficiency upon the appearance potential for ions from hydrocarbons in the mass spectrometer leads to the conclusion that initial ion current onset is a correct measure of the appearance potential. In order to calibrate the appearance potential voltage scale, the spectroscopic ionization potentials for seven gases were correlated with their apparent appearance potentials to give a calibration curve. Heretofore only one gas had been used to give a simple additive constant. Appearance potentials were determined for ions from six paraffins and four olefins. For methane, ethane and propane the agreement with previous determinations is excellent. For the other hydrocarbons the values reported here are higher than those reported by others. It is concluded that dissociation energies computed from these appearance potentials are greater than true bond energies because electron collision processes give rise to excited fragments. The excitation energy appears to be greater for larger molecules.
Chemical Reaction During Adiabatic Flow through a Rocket Nozzle
Authors: Altman David , Penner S. S.
Published: January 2005

An analysis has been carried out for isentropic expansion through a representative rocket nozzle. The rate of change of temperature of an element of gas with distance and time in the vicinity of the nozzle throat is discussed in some detail. By use of Daniels' rate constant for the formation of nitric oxide from nitrogen and oxygen, it is shown that the temperature changes so rapidly that the reaction 2NO⇄O2+N2 produces insignificantly small composition changes below about 2800°K when the temperature in the rocket chamber is 3000°K.
The Assignment of the Vibrational Spectra of the C4 Hydrocarbons Butyne−1, Butene−1, and Vinyl Acetylene, to the Normal Modes of Vibration of These Molecules
Authors: Sheppard N.
Published: January 2005

An attempt has been made to assign all the normal modes of vibration of the C4 hydrocarbons butyne−1, butene−1, and vinyl acetylene, in terms of frequencies observed in the infra-red and Raman spectra. It has been found to be possible to do this in a satisfactory manner which takes into account the structural similarities of these and other hydrocarbon molecules. With the help of these assignments previous data on the frequency ranges characteristic of the various hydrogen deformation modes of the groups ethyl, vinyl, and –C≡CH can be extended to include all such modes.
Spectroscopic Studies of Rotational Isomerism. IV. 2-Methyl Butane and 2,3-Dimethyl Butane
Authors: Szasz G. J. , Sheppard N.
Published: January 2005

The Raman spectra of 2-methyl butane and 2,3-dimethyl butane were investigated between room temperature and 90°K. In marked contrast to the behavior of the normal paraffins all the main lines persist in the solid phase. The slight change with temperture in the relative intensity of one line pair in liquid 2-methyl butane was investigated quantitatively with the photoelectric spectrograph. No measurable intensity changes were observed in the 2,3-dimethyl butane spectrum. The results were interpreted in terms of both a very small (<100 cal. mole−1) and a very large (1600 cal. mole−1) energy difference between the rotational isomers. Although both interpretations appear consistent with the spectroscopic results, neither affords a completely straightforward explanation of all the facts. It is shown for 2-methyl butane that accurate gaseous heat capacities would distinguish between these alternatives. The spectroscopic data on 2,3-dimethyl butane are inconsistent with a single molecular configuration possessing a center of symmetry.
The Transverse Boundary of the Random Coil
Authors: Hollingsworth C. A.
Published: January 2005

The probability density for the distance of that link (or links) which is farthest from the line joining the ends of a random coil is obtained for the case in which the number of links is large. The most probable value and the averages of that distance are determined approximately.
On Permanent Charges in Solid Dielectrics. II. Surface Charges and Transient Currents in Carnauba Wax
Authors: Gross B.
Published: January 2005

Permanent surface charges are produced in disks of carnauba wax by exposure to an external electric field. The nature of these charges is studied with a new method of analysis, which is based on the simultaneous measurement of the external current and of the induced charges on the electrodes of the capacitor containtaining the dielectric. The observed effects are explained by dielectric absorption and by transfer of charge from the electrode to the surface of the dielectric; this latter phenomenon is due to surface breakdown and continuous conduction currents. The results provide an adequate explanation for the electret.
The Magnetic Susceptibility of Organic Compounds
Authors: Broersma S.
Published: January 2005

With the object to obtain new data for the statistical analysis of hydrocarbon mixtures, measurements on diamagnetic organic compounds at room temperature have been performed. The precision was of the order of 1 per mil (10−3) of the diamagnetic effect. We checked the additivity rule and found it to be applicable within 5 per mil on the average. Mixtures were also investigated. A linear relation with the concentration was found to hold for hydrocarbon mixtures within the precision of measurement. For liquids containing electric dipole deviations up to 6 per mil were observed. We applied the results to the analysis of unknown mixtures.
The Ultraviolet Absorption and Luminescence of Decaborane
Authors: Pimentel George C. , Pitzer Kenneth S.
Published: January 2005

The ultraviolet absorption spectrum of decaborane in cyclohexane shows a broad absorption with a maximum molecular extinction coefficient of 3200±100A at wave-length 2720±50A. The luminescence of decaborane dissolved in a glass at 77°K shows a continuous fluorescence extending from 3630±50A to about 6000A with a broad maximum at 4520A. No further luminescence was observed at wave-lengths shorter than 9000A. The 0–0 transition is located at 3600±50A. The energy levels of a particle in a rectangular, hemispherical, and spherical box were used to test the applicability of a metallic model to decaborane. Agreement with the absorption spectrum and the molecular dimensions was obtained.
Polymorphism and Anion Rotational Disorder in the Alkaline Earth Carbonates
Authors: Lander J. J.
Published: January 2005

X-ray diffraction methods have been developed for the study of materials at high temperatures under controlled atmospheres, and an investigation of the high temperature phases of the alkaline earth carbonates has been made. BaCO3 was found to change from orthorhombic (aragonite type) to hexagonal (calcite type) at 803°C, and to cubic (sodium chloride type) at 976°C. SrCO3 was found to change from orthorhombic (aragonite type) to hexagonal (calcite type) at 912°C. A few experiments with mixtures, which go through similar transitions, are described.

These transitions are related to the rotational activity of the carbonate ions and consideration of the nature of the transitions leads to a description of the probable rotational behavior of these ions in the various phases.
Macroscopic Space Charge in Electrolytes during Electrolysis
Authors: Reed Charles Albert , Schriever William
Published: January 2005

Since the publication of Hittorf's famous paper in 1853 it has been assumed, in general, that macroscopic space charge does not exist in an electrolyte during electrolysis. An apparatus and procedures were developed which made possible reproducible data on potential distribution in an electrolyte. In a uniform column of electrolyte the potential rise was found to be a non-linear function of the distance from the cathode, and it was shown that this non-linearity could not have been due to concentration changes caused by the electrolysis, but must have been due to macroscopic space charges in the electrolyte. Calculations showed the space charge to be positive very close to the cathode, negative in the next quarter of the column, positive for the next nearly three-quarters of the column and negative very close to the anode.

The eight electrolytes studied were 0.0024N solutions of CuSo4, CuCl2, ZnSO4, ZnCl2, Zn(C2H3O2)2, NiSO4, NiCl2 and Al2(SO4)3. The pure metal was used for the electrodes in each case. Each column of electrolyte was 8 cm×8 cm×40 cm long, and the constant potential difference was 8.000 volts. The largest observed space charge at the end of 15 minutes was in CuSO4 at 2 mm from the anode; it was an excess of 2×106 Cu++ ions over SO4−— ions per cm3, which is an excess of only 3 Cu++ ions for every 1012 Cu++ ions originally present.

Although the space charges were all very small, they had very appreciable effects on the potential gradients, which also were calculated. The potential gradients in the different electrolytes were not constant, but had maximum deviations from constancy of from 5 to 20 percent in the explorable part of the column (to within 1 mm of each electrode). The average potential gradients in the explorable part were from 1.1 to 23 percent less than the 8/40 volt/cm. Thus Ohm's law was found not to hold even over the explorable part of the column.
The Vapor-Phase Photo Decomposition of Hydrogen Peroxide
Authors: Volman David H.
Published: January 2005

The decomposition of hydrogen peroxide vapor initiated by light of wave-length 2537A was studied. The quantum yield of the reaction was found to be 1.7±0.4, essentially independent of pressure of peroxide and intensity of absorbed light. The reaction products were water and oxygen only. The rate of the reaction was found to be independent of temperature and was not affected by the addition of oxygen, nitrogen or water to the reaction mixture. The reaction scheme proposed is H2O2+hν→2 OHOH+H2O2→H2O+HO2HO2+HO2→H2O2+O2this leads to a maximum quantum yield of 2.
Thermodynamic Properties of Oxygen Fluoride and Chlorine Fluoride from Spectroscopic Data
Authors: Potter Robert L.
Published: January 2005

Spectroscopic and electron diffraction data have been combined to make calculations of the free energy, entropy, and heat capacity of OF2 to the rigid rotator-harmonic oscillator approximation between 298.16° and 1500°K. The spectrum of ClF is known well enough to calculate these properties to the next approximation from 298.16° to 2000°K. Thermal data have been combined with these results to give the complete thermodynamic properties of these two fluorine compounds. It is pointed out that the accepted dissociation energy of F2 is too high, and calculations show that it must be close to 1.5 ev per molecule.
On the Non-Equilibrium Theory of Absolute Reaction Rates
Authors: Hulburt Hugh M. , Hirschfelder Joseph O.
Published: January 2005

The ensemble of point masses representing reaction complexes in configuration space is treated as an ideal gas by methods of exact kinetic theory. Hydrodynamic equations for the mean motion of the ensemble are derived. The theory of compressible flow is used to show that under a very wide range of conditions, the energy distribution characteristic of the reactants in a chemical reaction is maintained in the reaction complex at least until it passes through the activated state.
The Statistical Mechanical Theory of Transport Processes. III. The Coefficients of Shear and Bulk Viscosity of Liquids
Authors: Kirkwood John G. , Buff Frank P. , Green Melvin S.
Published: January 2005

A molecular theory of the coefficients of shear and bulk viscosity of monatomic liquids is developed on the basis of the general theory of transport processes presented in the first article of this series. With the use of the Lennard-Jones potential and a reasonable analytic approximation to the experimental radial distribution function, calculations of the coefficients of shear and bulk viscosity of liquid argon at 89°K have been carried out. The theory leads explicitly to ratios of the coefficients to the friction constant of the theory of Brownian motion. With a preliminary estimate of the friction constant, a value of the shear viscosity of liquid argon in moderately good agreement with experiment is obtained.
The Effect of Electric Fields on the Decomposition of Ethane by Alpha-Rays
Authors: Williams Nelson T. , Essex Harry
Published: January 2005

In the decomposition of ethane by alpha-rays the reaction is largely initiated by splitting of molecules on ionization and by splitting of molecules without ionization on electron collision. The application of even a weak electric field results in an increased ion yield in ethane, a phenomenon which has not been observed in other gases studied by this method, and this is attributed to inhibition by the field of a reaction involving ions which decreases the amount of non-condensed gas produced. The application of higher fields results in another increase in the ion yield due to the collisions of electrons accelerated by the field which cause splitting with or without attachment. At the lower pressure, a final constancy of the ion yield at high fields can be attributed to the final attachment of all of the free electrons to molecular fragments. The reaction at the higher pressure was not followed to sufficiently high values of X/p to exhibit the same high field effect.
The Infra-Red Absorption Spectra of Propane-D−1 and Propane-D−2
Authors: Friedman L. , Turkevich J.
Published: January 2005

The infra-red absorption spectra of the isomeric mono-deutero propanes have been observed. A difference in the position of the primary and secondary C–C stretching frequencies is reported. This difference places the secondary C—D frequency 45 cm−1±5 cm−1 lower than the corresponding primary C—D vibration.
Isothermal Compositional Order-Disorder. I. Superstructure Solid Solutions in a Salt System
Authors: Grenall Alexander
Published: January 2005

Solid solutions in the system, NH4Cl–MnCl2–H2O, exhibit properties characteristic of order-disorder in alloys. Disordered solid solutions are indistinguishable in structure from that of ammonium chloride. Order is revealed by superstructure formation. The familiar compositions A3B and AB appear as end-members of the ordered solid solution series. Crystal symmetry alteration from cubic to tetragonal results from ordering. Tetragonality is intimately related to the state of order. Though increase in ``solute'' content produces significant lattice distortion, superstructure unit cell volumes are constant.

Despite their unusual properties, the ordered salt solid solutions exhibit a normal Vegard's law relationship.

The salt system's features resemble those of a low temperature isotherm across Shockley's theoretical phase diagram for alloy order-disorder transformation and are regarded as experimental verification of Shockley's qualitative predictions. A concept of isothermal, compositional order-disorder is used in presenting the results.

Demonstration of a two-phase region, wherein ordered and disordered solid solutions coexist in equilibrium, provides a basis for resolving the controversy over whether the phase rule governs order-disorder transformations.

Identity of the order-disorder phenomenon in metal and salt systems was further shown by producing the disordered state of salt solutions from the ordered by thermal and cold-working methods. In both instances, order was spontaneously restored with aging at room temperature.
The Infra-Red Absorption Spectra of Some Metal Borohydrides
Authors: Price W. C.
Published: January 2005

The absorption spectra of aluminum, lithium, and sodium borohydride have been obtained in the region from 1–25μ. The aluminum borohydride was investigated as gas and an analysis of the infra-red and Raman bands fits a bridge-type structure of symmetry D3 (probably D3h). The spectra of lithium and sodium borohydrides were obtained from finely ground slurries of these materials. Their spectra indicate how the bridge structure of the H2BH2 metal groups passes over to the tetrahedral structure in a completely ionic lattic.

Using certain bond-distance force-constant relationships in conjunction with data from the diatomic hydrides and accepting electron and x-ray diffraction data for bond distances between the heavier atoms, values for the geometrical parameters are calculated for beryllium, aluminum, and sodium borohydride. These seem more plausible than any so far suggested. Observations on the electronic spectrum of aluminum borohydride have also been made down to 1000A. The diffuseness of the absorption obtained at short wave-lengths prevented any detailed interpretation.

The spectrum of a compound formed between beryllium borohydride and sodium chloride has also been obtained and a consideration of its absorption bands has given information concerning the nature of this material. A spectrum of a slurry of the methyl derivative of lithium borohydride (LiBH3CH3) indicates considerable change in the structure relative to that of lithium borohydride.

A table of frequencies of related bands in the metal and other borohydrides is given which illustrates the changes referred to above. It includes a number of boron-nitrogen hydrides and shows that the BH frequency, when it is associated with analogous electronic groups, behaves in much the same way as that of CH when it is attached to saturated, olefinic or aromatic groups.
The Theory of Flame Propagation
Authors: Hirschfelder J. O. , Curtiss C. F.
Published: January 2005

The characteristics of steady-state one-dimensional flames are expressed in terms of a set of first-order ordinary differential equations suitable for solution by differential analyzers or high speed digital computing devices. Arbitrary systems of chemical kinetics and reaction rates can be investigated. The effect of ambient temperature, pressure, heat transfer from the flame to the flame holder, diffusion of free radicals, thermal conductivity, etc., are easily estimated. The equations which we use are the ordinary hydrodynamic equations of change generalized to include the effect of the chemical reactions. In these the usual expressions for reaction rates are introduced, that is, the rate at which the composition would change in a closed vessel under the local conditions of temperature and density. Equations expressing the diffusion velocities in terms of the composition gradients are given. The flame holder has been idealized in the form of a porous plug through which the fuel can pass freely from left to right, but a semipermeable membrane prevents the product gases moving in the opposite direction. It is found that heat transfer to this flame holder is required to stabilize the position of the flame. The conditions obtained at the hot boundary are expressed parametrically in terms of the roots of a secular equation.
Thermodynamic Studies of Polyvinyl Acetate Solutions in the Dilute and Moderately Concentrated Range
Authors: Browning George V. , Ferry John D.
Published: January 2005

Osmotic pressure measurements on polyvinyl acetate solutions have provided values of the constant μ in methyl ethyl ketone, 1,2,3-trichloropropane, acetone, dioxane, and dimethyl phthalate. Modifications in techniques have permitted measurements in the first two solvents at different temperatures at concentrations (c) up to 0.07 g/cc. The osmotic pressure can be expressed as a power series in c with three terms; the coefficients of c2 and c3 are larger in trichloropropane than in methyl ethyl ketone. The partial molal heats, entropies, and free energies of dilution in these two solvents have been calculated. All are numerically greater for trichloropropane. The heats of dilution are negative; ΔH̄1/v22 is roughly constant for methyl ethyl ketone but increases somewhat with concentration for trichloropropane. The entropies of dilution are much smaller than those given by the lattice theory.
Thermal Diffusion in Binary Liquid Hydrocarbon Mixtures
Authors: Trevoy D. J. , Drickamer H. G.
Published: January 2005

Thermal diffusion coefficients have been measured for a series of binary mixtures of paraffin hydrocarbons and of paraffin hydrocarbons with benzene. The temperature dependence of the thermal diffusion coefficient is shown to be small. The results are correlated quite satisfactorily by assuming that the mobility of a molecule is inversely proportional to the product of the molecular mass and molecular cross section in the direction of flow.
Molecular Rotation in Sodium Cyanide and Sodium Nitrate
Authors: Siegel L. A.
Published: January 2005

An attempt has been made to decide between the Pauling and Frenkel hypotheses for group disorder in crystals on the basis of x-ray diffraction data.

Measurements of the line intensities of sodium cyanide showed that no decision could be reached between two models involving complete spherical rotation and a tetrahedral distribution of equilibrium positions. The 220 line was found to possess an anomalously large variation of intensity with temperature. A new rhombohedral form of sodium cyanide was found which can be produced only by quenching the cubic form from the vicinity of 300°C. The cubic and rhombohedral forms coexist from 20°C to 80°C. An ordered structure has been proposed for the rhombohedral phase.

The diffuse scattering from a single crystal of sodium nitrate has been studied, and a diffuse maximum has been found which is believed to be a result of group disorder. This maximum shows a strong angular dependence which is incompatible with the predictions of the rotation theory. The data fit a twofold disorder model for the nitrate groups, provided that the positions have an aragonite-type of coordination with the surrounding sodium atoms, rather than the calcite coordination found in the ordered structure.
Effects of Perturbations on Phosphorescence: Luminescence of Metal Organic Complexes
Authors: Yuster Philip , Weissman S. I.
Published: January 2005

Fluorescence and phosphorescence spectra, phosphorescence lifetimes, and relative ratios of intensities of fluorescence to phosphorescence of the dibenzoylmethane derivatives of the trivalent ions of Al, Sc, Y, La, Gd, and Lu have been measured. The lifetimes and intensity ratios of the various compounds differ widely, while the spectra are very similar. For instance, although the Lu and Gd compounds have practically indistinguishable phosphorescent spectra, the lifetimes of their phosphorescences differ by a factor of fifty. The results are interpreted in terms of Lewis's triplet theory of the phosphorescent state and spin-orbit perturbation of the levels. The largest effect is produced by the paramagnetic gadolinium ion. The effects produced by the non-magnetic ions depend on their nuclear charge and on their electronic structure.
Refractive Indices and Dielectric Constants of Liquids and Gases under Pressure
Authors: Rosen Joseph S.
Published: January 2005

Several interpolation formulas are given which reproduce refractive index and dielectric constant data for liquids and gases at high pressures. These formulas involve functions of the refractive indices and dielectric constants which appear in the formulas of Lorentz-Lorenz, Clausius-Mosotti, Gladstone and Dale, the empirical Eykman formula, etc. One formula shows the reciprocals of these functions to be linear in the specific volumes at various pressures. Another interpolation formula, involving the reciprocals of the same functions, contains a logarithmic term which is similar to that appearing in the Tait equation for compressibilities of liquids. The parameters involved in the Tait equations for compressibilities and in the analogous interpolation formula for refractive indices and dielectric constants are discussed.

The article also shows that the Tait equation which has been so successfully adapted to compressibility data of liquids can also be applied to gases.
A Kinetic Study of the Thermoluminescence of Lithium Fluoride
Authors: Boyd Charles A.
Published: January 2005

The isothermal decay of the thermoluminescence of single crystals of lithium fluoride activated by x-rays has been determined at various temperatures. The results are interpreted in terms of a simple reaction rate mechanism based on a picture of the thermoluminescent process similar to that of Johnson. The analysis of the isothermal decay studies is in agreement with the results of ``glow curve'' experiments on similar lithium fluoride samples where the intensity of luminescence is measured as the temperature of the crystal is heated at a constant rate.

Two principal types of electron traps in lithium fluoride are found to have trapping energies of 19,800 cal./mole and 45,300 cal./mole respectively.
The Infra-Red Spectrum and Molecular Configuration of Hydrogen Persulfide
Authors: Wilson M. Kent , Badger Richard M.
Published: January 2005

The infra-red spectrum of hydrogen persulfide has been investigated in the region 1.5 to 15μ, and vibrational assignments have been made. The perpendicular band at 2μ has been studied under high resolution and a value for one of the rotational constants has been obtained. The data strongly support a chain structure for hydrogen persulfide and probably exclude cis- or trans-planar structures, but give no very definite information regarding the azimuthal angle.
The Vibrational Spectra of Molecules and Complex Ions in Crystals. II. Benzene
Authors: Mair Robert D. , Hornig Donald F.
Published: January 2005

The infra-red spectrum of crystalline benzene has been studied at −12°C, −65°C and −170°C as well as the liquid at 28°C. The lines are extremely sharp, the mean line width for fundamentals being 7 cm−1 in the crystal. In three cases, it is less than the spectral slit width. All out-of-plane degenerate modes are split by about 10 cm−1. Selection rules are obeyed and agree with the reported x-ray structure. All ungerade fundamentals are observed directly, some for the first time. Fifty-two combination bands are observed. The frequency assignments of Ingold et al. are confirmed except for the B2u species. Evidence is cited for re-assigning ν14 from 1648 cm−1 to 1310 cm−1 and ν15 from 1110 cm−1 to 1150 cm−1. Ingold's isotopic data does not conflict with this change. Combination frequencies involving torsional lattice modes are apparently observed at −170°C.