bluuebunny/crossref_metadata_2025 huggingface dataset:
Sublimation from snow surface in southern mountain taiga of eastern Siberia
Authors: Zhang Yiensheng , Suzuki Kazuyoshi , Kadota Tsutomu , Ohata Tetsuo
Published: November 2004

Through intensive observations of snow sublimation and meteorological elements, cold season processes at the snow‐atmosphere interface were clarified for both forested and open field conditions in the taiga region of eastern Siberia. Sublimation from snow surfaces differed with atmospheric stability. During early spring a significant difference in snow sublimation was observed between slopes and valley bottoms, despite variable vegetation cover. However, during the observation period, only one episode of significant snow sublimation was observed, which was caused by strong wind and ensuing light snowmelt. The sublimation for that week was ∼50% of the sublimation observed in the study period (29 days). As atmospheric stability decreased, the effect of forest cover on snow sublimation was clear, with a significant difference between forested areas and open fields. Later in the spring, increased net all‐wave radiation did not lead to an increase in sublimation but was consumed in meltwater production. The effect of forest cover on snow sublimation can be seen from the estimated bulk transfer coefficient for latent heat. The bulk transfer coefficient was larger for a larch forest than was that of open site. In the period 13 March–22 April (48 days), total snow sublimation was 15.7, 12.1, and 10.4 mm for open field, larch forest, and larch forest on a slope, respectively. This represents 14.3%, 13.0%, and 7.6% of the maximum water‐equivalent snow cover, respectively. However, the study period was only a part of the entire snow season, so totals for the whole winter would be larger.
Analyzing the effects of complete tropical forest removal on the regional climate using a detailed three‐dimensional energy budget: An application to Africa
Authors: Snyder Peter K. , Foley Jonathan A. , Hitchman Matthew H. , Delire Christine
Published: November 2004

Previous studies have indicated how tropical deforestation can have a significant influence on regional and global climate through altered biophysical exchanges of water, energy, and momentum at the land‐atmosphere boundary. However, the mechanisms for translating a surface forcing to changes in the atmospheric thermodynamics and circulation have not received as much attention. Here we present a new moist static energy budget method for examining the regional atmospheric response to removal of tropical forests and how land surface forcing is propagated into the atmosphere. A detailed three‐dimensional grid cell energy budget approach is used within a coupled atmosphere‐biosphere model (Community Climate Model, Version 3–Integrated Biosphere Simulator (CCM3‐IBIS)) to identify how land surface forcing affects the regional climate through the vertical and horizontal movement of moist static energy. This approach allows us to clearly identify where the moist static energy budget changes, which mechanisms are responsible for the changes, and how energy moves to adjacent areas and affects rainfall. Generally, replacement of the tropical forests with bare soil in the model leads to decreased rainfall in the tropics due to regional drying, while enhanced rainfall occurs in the subtropics associated with strengthened monsoon winds importing more moisture. Interesting regional complexities emerge, notably in tropical Africa. There, removal of the forests leads to lower rainfall near the coast but enhanced rainfall in central tropical Africa. This approach provides a useful diagnostic tool for examining the implications of land use and land cover change on the regional and global atmospheric thermodynamics and circulation.
Millstone Hill coherent‐scatter radar observations of electric field variability in the sub‐auroral polarization stream
Authors: Foster J. C. , Erickson P. J. , Lind F. D. , Rideout W.
Published: November 2004

Coherent backscatter observations with the Millstone Hill UHF radar (MHR) are used to investigate spatial/temporal variations in the ionospheric sub‐auroral polarization stream (SAPS) electric field. For the 440 MHz MHR, coherent amplitude is on average linearly proportional to electric field strength. The use of both main‐beam and sidelobe returns and the great sensitivity of the MHR system permits observations spanning 3° of the SAPS region with 1‐sec temporal and 10‐km spatial resolution. For a moderately disturbed event on May 25, 2000, the SAPS channel moved steadily equatorward. Large‐scale (30 mV/m peak to peak) wave‐like oscillations in the electric field magnitude (200s–300s periodicity) were seen to propagate across the SAPS channel throughout the hour‐long event. It is suggested that such localized electric field intensifications, which exhibit many of the characteristics of the narrow SAID features described in the literature, arise as wavelike perturbations within the SAPS channel.
On the use of multiple criteria for a posteriori model rejection: Soft data to characterize model performance
Authors: Vaché Kellie B. , McDonnell Jeffrey J. , Bolte John
Published: November 2004

Land surface hydrologic models are commonly evaluated based upon the degree of correspondence between measured and modeled discharge. In this paper we illustrate significant shortcomings associated with the simple discharge based evaluation strategy. A standard conceptual hydrologic model is applied within a Monte Carlo framework to two catchments representing significantly different hydrologic regimes. Time source hydrograph separations are derived, in addition to modeled discharge, and used to more completely characterize model functioning, across the entire a priori parameter distribution. The inclusion of hydrograph separation results in improved characterization of parameter uncertainty, and in one of the cases, complete model rejection.
O3 and CO in New England: Temporal variations and relationships
Authors: Mao Huiting , Talbot Robert
Published: November 2004

We examined seasonal and interannual variability in the mixing ratios of ozone (O3) and carbon monoxide (CO) and their relationships at a rural low‐elevation site (24 m, 43.11°N, 70.95°W) and higher‐elevation site (406 m, 43.75°N, 71.35°W) in New Hampshire, United States. The data were obtained over 2 years (2001–2003) by the Atmospheric Investigation, Regional Modeling, Analysis, and Prediction (AIRMAP) program at the University of New Hampshire. An analysis of the frequency distributions of O3 and CO grouped by wind speed and direction and over four time periods of the day showed that the most polluted air masses arrived from the southeasterly and westerly wind sectors during the local afternoon hours (1800–2300 UT, −5 hours for U.S. eastern standard time (EST)). In summer within this time window a well‐defined positive O3‐CO correlation with a slope ∼0.37 existed in these air masses. Applying this relationship together with the CO emission inventory and its temporal profile from the emission model SMOKE, we estimate that 370 Mmol d−1 of O3 are exported from the northeastern United States within this time window during summer. However, over 70% of the data were obtained under weak wind conditions (<2 m s−1) when CO and O3 exhibited a dispersed relationship. An analysis using the ratio NO/NOy and the mixing ratios of NOy revealed a dominance of photochemically aged air masses with significant NOy removal accompanying high levels of O3. This result implies that elevated O3 in southern New Hampshire can largely be attributed to long‐range transport of air masses from outside the region. Furthermore, the O3‐CO relationship in each season produced a smooth lower CO boundary, which appears to represent air masses with a composition reflecting the evolutionary stages of photochemical aging and progressive phases of transport.
Constraints for flow regimes on smooth fracture surfaces
Authors: Ghezzehei Teamrat A.
Published: November 2004

In recent years, significant advances have been made in our understanding of the complex flow processes in individual fractures, aided by flow visualization experiments and conceptual modeling efforts. These advances have led to the recognition of several flow regimes in unsaturated individual fractures subjected to different initial and boundary conditions. For an idealized smooth fracture surface the most important regimes are film flow, rivulet flow, and sliding of droplets. The existence of such significantly dissimilar flow regimes has been a major hindrance in the development of self‐consistent conceptual models of flow for single fracture surfaces that encompass all the flow regimes. The objective of this study is to delineate the existence of the different flow regimes in individual fracture surfaces. For steady state flow conditions, we developed physical constraints on the different flow regimes that satisfy minimum energy configurations, which enabled us to segregate the wide range of fracture flux (volumetric flow rate per fracture width) into several flow regimes. These are, in increasing order of flow rate, flow of adsorbed films, flow of sliding drops, rivulet flow, stable film flow, and unstable (turbulent) film flow. The scope of this study is limited to wide‐aperture smooth fractures with the flow on the opposing sides of fracture being independent.
Uncertainty and data worth analysis for the hydraulic design of funnel‐and‐gate systems in heterogeneous aquifers
Authors: Cirpka Olaf A. , Bürger Claudius M. , Nowak Wolfgang , Finkel Michael
Published: November 2004

Hydraulic failure of a funnel‐and‐gate system may occur when the contaminant plume bypasses the funnels rather than being captured by the gate. We analyze the uncertainty of capturing the plumes by funnel‐and‐gate systems in heterogeneous aquifers. Restricting the analysis to two‐dimensional, steady state flow, we characterize plume capture by the values of the stream function at the boundaries of the plume and the funnels. On the basis of the covariance of the log conductivity distribution we compute the covariance matrix of the relevant stream function values by a matrix‐based first‐order second‐moment method, making use of efficient matrix‐multiplication techniques. From the covariance matrix of stream function values, we can approximate the probability that the plume is bypassing the funnels. We condition the log conductivity field to measurements of the log conductivity and the hydraulic head. Prior to performing additional measurements, we estimate their worth by the expected reduction in the variance of stream function differences. In an application to a hypothetical aquifer, we demonstrate that our method of uncertainty propagation and our sampling strategy enable us to discriminate between cases of success and failure of funnel‐and‐gate systems with a small number of additional samples.
A Spectroscopic Study of the Decomposition and Synthesis of Organic Compounds by Electrical Discharges: Electrodeless and Glow Discharges
Authors: Harkins William D. , Jackson John M.
Published: November 2004

In the chemical reactions which occur in electrical discharges through organic vapors and in the maintenance of the discharge, the simple ionization of the molecules, and the resultant formation of clusters, is found to be less important, and the breaking down into molecular, atomic and ionic fragments, more important than has heretofore been supposed. The fragments revealed by the spectroscope are CH, OH, NH, C2, CN, N2, CO, CO+, CS, S2, H2, C, C+, H, and S, and in addition H2O and NH3 are known to be formed. When the electrodeless discharge is in benzene vapor the pressure is rapidly lowered until the discharge is extinguished, but this effect is not found with the glow discharge. As compared with the electrodeless discharge, the spectrum from the glow discharge differs in the following respects: the C2 bands are much less intense and only the fourth group of Swan bands appears appreciably. The line spectrum of C is less intense, and the prominent λ4267 line of C+ disappears. The CH bands are very clear and that at λ3900 is closer in intensity to that at λ4300 than in the electrodeless discharge. The Balmer series of hydrogen is slightly more intense, and the many-line spectrum of H2, not present with the electrodeless discharge, is prominent. In general the greatest intensity of the spectrum is given by the cathode glow and the edge of the negative glow near the cathode. The Crookes dark space is a region of very low intensity. The Balmer lines are of nearly uniform intensity throughout except for a specially high intensity just at the cathode. The many line spectrum of hydrogen differs from the others in that it is scarcely visible in the cathode glow. With phenol many bands due to CO and CO+ dominate the spectrum of the glow discharge, though they are not found in the electrodeless discharge. In the electrodeless discharge the rate and nature of the reaction and the spectrum emitted are affected by the hydrogen to carbon ratio in such a way that the rate of reaction decreases as this ratio increases, and the fraction of gaseous products and the intensity of the spectra emitted by molecules which contain hydrogen increase with this ratio. Thiophene is decomposed into sulfur atoms (S), and molecules (S2), and carbon monosulfide molecules (CS) in addition to molecules of carbon (C2) and of monohydrocarbon (CH), atoms of hydrogen (H) and of carbon (C), and ions of carbon (C+) as had been shown before for the hydrocarbons. In the glow discharge both saturated and unsaturated hydrocarbons are decomposed at about the same rate to form the molecules and atoms listed above. The decomposition products from the glow unite to form brown or black solids somewhat similar to those formed in the electrodeless discharge. From the way in which the product is deposited and the intensity of the spectrum, the reaction is seen to be most rapid at the cathodeward edge of the negative glow.
The Thermal Decomposition of Ethyl Mercaptan and Ethyl Sulphide
Authors: Trenner Nelson R. , Taylor H. Austin
Published: November 2004

The thermal decompositions of ethyl mercaptan and ethyl sulphide have been studied by a static method and shown to proceed homogeneously in glass vessels which have become poisoned by products of reaction. The rate curves of both exhibit an induction period shown to be due to a reaction between ethyl and hydrogen sulphides yielding what appears to be a dimercaptan. The subsequent decomposition of this intermediate is unimolecular but complicated by a reverse reaction. The energies of activation of formation and decomposition of the intermediate are each about 40,000 calories, the rate of formation being slightly greater than the rate of decomposition at temperatures around 400°C. The unimolecular rate falls off below 150 mm which would correspond with six squared terms involved in the activation. No foreign gas has been found to maintain the rate. The existence of a complex equilibrium detracts somewhat from the certainty of interpretation of data and mechanism. A critique of similar recent work substantiates the conclusions here drawn though differing from previous interpretations.
The Influence of Ionization on the Ignition Temperature of Combustible Gases
Authors: Lewis Bernard , Kreutz C. D.
Published: November 2004

The ignition temperatures of methane-``air'' mixtures were investigated in a flow system as follows: (1) The spontaneous ignition temperature due to temperature alone was determined. (2) One of the inert gases was passed through a condensed discharge before joining the combustible gas and the change in ignition temperature noted. The individual gases were preheated to 500°C before mixing in the ignition tube which could be heated to any desired higher temperature. Ignition always occurred about 50 cm downstream from the spark chamber. The temperature at which the mixtures ignited was lower when pre-sparking was employed. The gases subjected to the spark were A, He, N2, O2. The difference between the spontaneous and pre-sparking ignition temperatures increased in the order named, being about 28°C for A and about 240°C for oxygen under the conditions of this investigation for a final mixture of 8 percent methane in ``air'' (ratio of oxygen to inert gas in final mixture being the same as in air). A post ignition phenomenon is described which is brought about by delaying the flow of the sparked oxygen for some time after cessation of the spark and then resuming the flow. Such delay times of 2½ minutes were observed. The species which cause ignition possess a long life and are rather easily removed by metal screens. It is shown that the results cannot be accounted for by nitric oxide, ozone, active nitrogen or active oxygen. It is concluded that electrically charged species or ions are responsible for the lowered ignition temperatures. A tentative explanation of the results is suggested. It is pointed out that in the ignition of combustible gas mixtures by direct action of a spark, the ions formed in the path of the spark, as well as the thermal energy liberated, play a responsible part in the ignition process.
The Free Energy, Entropy and Heat Capacity of Bromine and of Hydrogen Bromide from Spectroscopic Data
Authors: Gordon A. R. , Barnes Colin
Published: November 2004

The free energy, entropy and heat capacity of gaseous bromine and of hydrogen bromide have been computed for the temperature range 200–1600°K. The equilibrium constants for the reaction Br2=2 Br, obtained from these numbers and the spectroscopic heat of dissociation, differ from Bodenstein's values by more than his apparent experimental error. Calculations for the dissociation of hydrogen bromide give results which agree with the e.m.f. measurements of Bodenstein and Geiger, but are in definite disagreement with the experiments of von Falckenstein when the latter are corrected for the dissociation of bromine.
Complex Formation due to Polarization. II. The System Propane and Hydrogen Chloride
Authors: Glockler George , Fuller Donald L. , Roe Charles P.
Published: November 2004

Molecules of saturated hydrocarbons are rare gas-like in structure and they may be supposed to behave in many respects like rare gases. They may then be expected to show complex formation with other molecules or atoms of dipole character, depending on their own polarizability (preceding article). An experimental study of the P-V-T relations of the gaseous mixtures of propane and hydrogen chloride shows that interaction does indeed take place between these two types of molecules. The expression for the second virial coefficient as a function of composition of the gaseous mixtures, is shown to require an interaction term between unlike molecules in order to agree with experiment. This question of complex formation of saturated hydrocarbons is further discussed on the basis of Brönsted's theory of acids and bases.
On the Quantum Mechanical Stability of a Benzol Molecule
Authors: Markov M.
Published: November 2004

The Heitler-London-Rumer treatment of valence bonds is applied to the benzol molecule, considered as a system of six trivalent nitrogen-like CH groups. Partial solution of the secular equation of the thirty-fourth degree shows that this model of the benzol ring is thermodynamically unstable relative to three acetylene molecules, in disagreement with experiment. The method does not take cognizance of the directional properties of valence bonds (Slater-Pauling).
The Thermal Decomposition of Propyl Mercaptan
Authors: Taylor H. Austin , Layng Edwin T.
Published: November 2004

The thermal decomposition of normal propyl mercaptan over a temperature range from 405 to 435°C and pressures from 100 to 300 mm is homogeneous on a poisoned glass surface. The reaction is complex showing an induction period with auto-accelerating rate, ending finally in a pseudo-equilibrium involving propylene, hydrogen sulphide and isopropyl mercaptan. The energy of activation of the induction period is about 40,000 calories and that of the later reaction 39,000 calories. A mechanism, has been proposed which involves primarily the formation of propyl sulphide reacting further to form a sulphonium hydrosulphide as an unstable intermediate.
The Dielectric Constant and Absorption of Several Organic Fluids at 1.82 m
Authors: Szymanowski W. T.
Published: November 2004

For the further test of Debye's theory of anomalous dispersion, dielectric constants and absorptions were measured at λ = 1.82 m for the following fluids: ethyl alcohol, n-propyl alcohol, isopropyl alcohol, isobutyl alcohol, n-butyl alcohol, amyl alcohol, chlorobenzene, quinoline and nitrobenzene. The resonance method for undamped waves was used. The results are generally in good agreement with Debye's theory as well as with the results of Mizushima and others for fluids whose polarizations for infinite dilution do not differ greatly from those at normal concentration, as for the alcohols and chlorobenzol. For fluids like quinoline and nitrobenzene, the agreement is far from satisfactory. For these, however, when Malsch modification of Debye's theory is taken into account, a somewhat improved check is found, that for the dielectric constant being satisfactory, but that for the absorption of energy, while improved, being still far from satisfactory.
The Ground State of the Hydrogen Molecule
Authors: James Hubert M. , Coolidge Albert Sprague
Published: November 2004

The method used by Hylleraas in treating the He atom has been extended to the H2 molecule. The method consists of setting up a wave function as a series in the five variables required, electronic separation being introduced explicitly as one of the variables. The coefficients are then determined so as to produce the lowest energy. The energy found is within 0.03 v.e. of the most probable experimental value, while the form and location of the potential energy curve for various internuclear distances agree with those deduced from spectra to within similar limits. The value of the function is computed for several configurations of the electrons, and compared with other approximations. Application of the method to other problems is discussed. A method is given for the numerical solution of secular equations of high degree.
Dielectric Constant Studies. II. The Drude Method Applied to Aqueous Solutions of Potassium Chloride
Authors: Malone J. Gilbert , Case L. O. , Ferguson A. L.
Published: November 2004

This paper is an experimental comparison of several adaptations of the Drude method as applied to conducting solutions. With three distinct types of detecting device, results for the dielectric constant of water and of water-alcohol mixtures agreed within experimental error. When, however, the same apparatus was applied to measurements with KCl solutions, different results were obtained with each. This indicates that any apparent change in the dielectric constant of electrolytic solutions, as observed by the Drude method, must depend in whole or in part upon the characteristics of the apparatus.
The Heat of Formation of Binary Liquid Solutions from Their Liquid Components
Authors: Coleman J. J. , Germann Frank E. E.
Published: November 2004

It is pointed out that an equation giving the relation of the heat of formation per mol of liquid solutions from their liquid components, to temperature and composition can be used as the foundation equation for their thermodynamical theory. The empirical equation ΔH=N1(1−N1)(α+βeγN1),in which ΔH is the heat of formation per mol of the solution, N1 is the mol fraction of one of the components of the binary solution, and α, β and γ are constants or functions of temperature, is presented. There are two degenerate forms of this equation. (Eqs. (7) and (8).) There are listed values of α, β and γ (or the values of the corresponding quantities in Eqs. (7) and (8)) for 59 solutions for one temperature and sometimes for several temperatures. It is noted that according to the data assembled in the International Critical Tables, some solutions composed of ``unassociated'' liquids present a behavior more irregular than those composed of ``associated'' liquids. It is suggested that this unexpected behavior may mean that some of these data are not as precise as they are indicated to be.
Mass-Spectrograph Study of the Ionization and Dissociation by Electron Impact of n-Octane
Authors: Linder Ernest G.
Published: November 2004

A mass-spectrograph study of n-octane (C8H18) indicates that when bombarded by 120 e-volt electrons, it dissociates into a large number of small fragments, of which those containing two or three carbon atoms (and some hydrogen) are most numerous. Ions containing odd numbers of H atoms are produced in larger quantities than those containing even numbers. The octane molecule displays a greater tendency to break up than does benzene (reported in a previous paper), which is in accordance with the reactions of these compounds in gaseous electrical discharges.
Bond Energies and Mass Defects in Atomic Nuclei
Authors: Latimer W. M. , Libby W. F.
Published: November 2004

The problem of the interpretation of the mass defect curve is discussed in reference to the coupling of protons and electrons proposed by Latimer. Gamow's equation is modified by making the attractive energies the sum of the bond energies. For certain symmetrical nuclei approximate values for the mass defect may be calculated which are in good agreement with the experimental results.
Zeeman Effect in Solids
Authors: Spedding F. H.
Published: November 2004

The transverse Zeeman effect on the absorption lines of the monoclinic GdCl3–6H2O was examined at various field strengths. Photographs were made with the crystals at various temperatures. Enlarged reproductions and microphotometer curves are given. The results are discussed and explained on the assumption that if an electron is excited as a first approximation only its spin can orient in a magnetic field.
Cross-Activation in the Unimolecular Decomposition of Mixtures of Gaseous Methyl and Ethyl Ether
Authors: Steacie E. W. R.
Published: November 2004

On account of the disagreement between previous investigations of Kassel and the writer, the decomposition of mixtures of methyl and ethyl ether has been reinvestigated with greater accuracy. The cross-activation efficiency has been found to be considerably greater than that previously reported. It is, however, decidedly smaller than that for collisions between molecules of the same kind.
Lifetimes of Unstable Molecules
Authors: Rosen N.
Published: November 2004

The mechanism of the decomposition of a molecule formed by the collision between a molecule and another particle is discussed qualitatively. Calculations are then carried through to determine the lifetime of a simple linear triatomic molecule formed by the collision of an atom with a diatomic molecule. The results are applied to the short-lived molecule HO2 to determine the order of magnitude of its lifetime in a number of different states, although it does not conform strictly to the idealized conditions for which the calculation was made.
The Dipole Moments of Some Mercaptans and Sulfides
Authors: Walls W. S. , Smyth C. P.
Published: November 2004

The dipole moments of thianthrene, two thioethers and two mercaptans are measured and compared with values in the literature. The differences in moment of corresponding oxygen and sulfur compounds are attributed to inherent differences in the H–O, C–O, H–S and C–S moments and to the greater polarizability of sulfur as compared to oxygen. In contrast to the oxygen ethers, the thioethers show as much intermolecular action as the mercaptans.
Theoretical Considerations Concerning the Separation of Isotopes
Authors: Eyring Henry , Sherman Albert
Published: November 2004

The relative importance of effusion processes, the half quanta due to van der Waals forces, and half quanta associated with homopolar bonds is considered with respect to the question of the separation of isotopes. Specific reaction rate constants for various isotopic molecules in effusion processes have been calculated. It is shown that only in the neighborhood of liquid hydrogen temperatures or lower are the half quanta due to van der Waals forces important. Specific reaction rate constants involving the zero point energy of homopolar molecules have been calculated for various isotopic molecules, principally those in which a hydrogen atom is one constituent, at temperatures of 20°K, 90°K, and 273°K. The advantage of working at as low a temperature as possible is rendered apparent. Even at ordinary temperatures the differences in the constants are in general much greater than in the case of effusion or van der Waals processes. A general equation is derived relating the concentration of the light and heavy isotopes, valid for any one of the three processes considered.
Predissociation and the Crossing of Molecular Potential Energy Curves
Authors: Rice O. K.
Published: November 2004

The calculation of the width and shape of a line which is broadened because of predissociation has been extended so as to include perturbations of intermediate size. By ``perturbations of intermediate size'' we mean perturbations which are not so great that lines (of given rotational quantum number) belonging to two adjacent vibrational levels are broadened so as to overlap appreciably; they may be any size up to that limit. These calculations have been applied with certain simplifying assumptions to the case where a potential curve giving molecule formation is intersected by a repulsive curve, the curves which cross defining the unperturbed energy levels and wave functions. It is found that the discrete lines are not only broadened, but they are shifted in position, slightly distorted in shape, and there is present a series of subsidiary maxima of the absorption coefficient. The exact amount of broadening of a line depends very greatly upon its energy relative to the energy at which the potential curves cross, and in general a line which is much broadened will also be much shifted in position. In molecules we may expect to have isolated groups of rotational levels in which the central level is sharp, and the rotational levels on either side become more and more diffuse, finally fading out. The predissociation phenomena in iodine chloride are discussed on the basis of the above theory. In particular, two groups of sharp and diffuse levels, such as described, are considered and are respectively ascribed to the isotopic molecules, ICI35 and ICI37. There is some difficulty in describing the phenomena in iodine chloride quantitatively, but qualitatively the experimental results appear to accord with the theory.
The Vibration Spectra and Structure of the Cyanogen Halides
Authors: West W. , Farnsworth Marie
Published: November 2004

The Raman spectra of the cyanogen halides in the liquid state or in alcoholic solution contain 3 frequencies v1, v2, and v3. In the order chloride, bromide, iodide, v1 = 2201, 2187, 2158 cm—1; v2 = 729, 580, 470; v3 = 397, 368, 321; the order of intensities of Raman transitions is v1>v2>v3. The relative values of the frequencies indicate a linear arrangement of the nuclei in the lowest electronic state of these molecules, and the data are in accord with the structure X–C≡N rather than X–N=C.
The Free Energy of Ozone
Authors: Kassel Louis S.
Published: November 2004

The infrared spectrum of ozone is discussed. Gerhard's three fundamental frequencies, 528 cm—1, 1033 cm—1, and 1355 cm—1 are shown to be in somewhat imperfect agreement with experiment. They are nevertheless sufficiently reliable to justify a spectroscopic calculation of the free energy of ozone, in view of the unreliability of the experimental data. Ozone is found to be much less stable than experiment had shown; S298.1 = 57.0 cal./deg./mole, as compared with S273 = 86.5 based on e.m.f. measurement. The maximum partial pressure of O3 in an equilibrium mixture of O, O2, and O3 at a total pressure of 1 atm. is 1.0×10—6 atm. at 3400°K. The 1 percent ozone obtained by heating filaments to 2300°K in liquid oxygen must have been formed in the cold regions from atomic oxygen.
The Heat Capacity and Entropy of Silver Sulfate from 14 to 300°K. The Entropy of Sulfate Ion
Authors: Latimer Wendell M. , Hicks J. F. G. , Schutz Philip W.
Published: November 2004

The heat capacity of Ag2SO4 has been measured from 14 to 300°K and the entropy of the salt determined by graphical integration. By coupling this value with the entropy of solution and the entropy of silver ion, the entropy of sulfate ion in aqueous solution has been evaluated.
The Heat of Dissociation of the Carbon-Carbon Linkage
Authors: Conant J. B.
Published: November 2004

Ziegler's colorimetric measurements of the dissociation of hexaphenylethane provide information in regard to ΔF and ΔH for this process in solution. Assuming that ΔS for the dissociation of other similar compounds is approximately the same and independent of the temperature (over a short range), ΔF and ΔH of dissociation of a variety of compounds have been calculated from published data. It is suggested that the effects of substitution are approximately additive. There is evidence to indicate that the heat of activation of the association reaction of free radicals is very low; if this is the case the heats of dissociation estimated from the calculations of this paper provide information in regard to the heat of activation of the dissociation reaction.
The Raman Spectrum of Water Vapor
Authors: Rank D. H.
Published: November 2004

The Raman spectrum of water vapor at atmospheric pressure was obtained. Special precautions were taken to avoid parasitic light and a search made for the 1648 cm—1, and 984 cm—1 shifts reported by Johnston and Walker. These shifts were not observed. A line was found which might be correlated with Mecke's v(σ) but the evidence in this case is not conclusive.
Statistical Theory of Low Frequency Intermolecular Forces
Authors: Kirkwood John G.
Published: November 2004

The sum of states of a gas consisting of optically anisotropic polar molecules is shown to be substantially equal to the classical Gibbs phase integral at ordinary temperatures. A general method of obtaining the quantum correction to be applied at low temperatures is developed. The intermolecular potential energy appearing in the phase integral is semi-classical in form. The low frequency contribution arising from the permanent dipole moments of the molecules is exactly equal to their mutual electrostatic energy. The high frequency contribution is given by a modification of London's formula in which continuous functions of the molecular orientations occur instead of spatial quantum numbers.
The Nature of the Chemical Bond. VI. The Calculation from Thermochemical Data of the Energy of Resonance of Molecules Among Several Electronic Structures
Authors: Pauling Linus , Sherman J.
Published: November 2004

In the first part of this paper there is given a set of bond-energy values for single, double, and triple bonds between atoms, obtained from thermochemical data, such that the total energy of formation from separate atoms of a molecule containing given bonds is equal to the sum of the energies for those bonds. In the derivation of these values data were used only for molecules for which it is probable that one electronic structure, corresponding to one distribution of valence bonds, represents the normal state to a satisfactory degree of approximation. For other molecules more than one electronic structure of this type contributes essentially to the normal state, the energy of formation of the molecule then being larger than that for any one of the contributing structures. On comparing the energies of formation given by thermochemical data with the values calculated for various structures, it is verified that this difference is always positive or zero (to within the limits of error involved). The difference in energy is interpreted as the resonance energy of the molecule among several electronic structures, and its existence in a given case provides strong evidence that more than one structure is contributing to the normal state of the molecule, the number and importance of the contributing structures being indicated by the magnitude of the resonance energy. In this way the existence of resonance is shown for many molecules, and values found for the resonance energy are tabulated. The substances discussed include carbon dioxide, carbon disulfide, alkyl isocyanates, carboxylic acids and esters, aliphatic amines, carbonic esters, urea and related substances, benzene and benzene derivatives, naphthalene and other condensed ring systems, pyridine and related heterocyclic compounds, biphenyl, fluorene, phenylethylene, dihydronaphthalene, quinone, some ureides and purines, etc.
The Heat Capacities and Entropies of Calcium and Barium Sulfates from 15 to 300°K. The Entropy and Free Energy of Sulfate Ion
Authors: Latimer Wendell M. , Hicks J. F. G. , Schutz Philip W.
Published: November 2004

The heat capacities of BaSO4 and small precipitated crystals of CaSO4–2H2O have been measured from 15 to 300°K. The heat capacity of large naturally occurring gypsum crystals was measured from 60 to 274°K. The Cp against log T plots of the molal heat capacities of the two samples of CaSO4–2H2O differing in crystal surface by a factor of roughly 106 show slight deviations from each other. We believe these variations to be outside the limits of experimental error. However, they do not produce a change in entropy at 298.1°K. S°298.1 of CaSO4–2H2O and BaSO4 were determined to be 46.36 and 31.51 E.U. respectively with an accuracy of 0.05 percent. The final value of S°298.1 of SO4—— from this series of measurements is 3.5 E.U. The free energy of formation of SO4—— has been calculated as — 175,300 cal.
Solarization of Glass by Soft X-Rays
Authors: Kersten H. , Dwight C. H.
Published: November 2004

Window glass was solarized (colored brown) with x-rays whose wave-lengths were principally those of the K lines of copper (1.54 and 1.38A). The relative amount of light transmitted by the solarized, with respect to that transmitted by the unsolarized, part of the glass was measured with the aid of a Weston Photronic cell. The effect of x-ray tube current, voltage, time of exposure and the tendency of the solarization of fade with time, at several temperatures, were investigated.
The Lattice Energies of the Cuprous Halides
Authors: Mayer Joseph E. , Levy Ronald B.
Published: November 2004

Following exactly the method employed in the case of the silver halides the lattice energies of the cuprous halides have been calculated. The exponential constant in the empirical repulsion equation expressing the positive repulsive potential between the ions is found to be almost the same as that for the silver halides. The energies of the salts indicate that, particularly for the iodide there is not purely ionic binding. The lattice energies are calculated to be, for CuCl 216 kcal., CuBr, 208 kcal., CuI 199 kcal. The ``experimental'' values are, CuCl 221.9 kcal. CuBr 216.0 kcal. and CuI 213.4 kcal.
On the Binding Forces in the Alkali and Alkaline Earth Metals According to the Free Electron Theory
Authors: Rice O. K.
Published: November 2004

Although there have been a considerable number of attempts to work out in some detail the nature of the cohesive forces in the alkali metals, it has seemed worth while to see how far one could go with the simplest possible hypothesis, according to which the metal consists simply of singly charged positive ions in a sea of free electrons. Frenkel first showed that the fact that the electrons obey the Fermi statistics, results in an effective repulsive force which will be balanced by attractive electrical forces; but, as he pointed out, the finite size of the ions prevents this being more than a qualitative picture, and he suggested taking this into account by including repulsive forces between electrons and ions. In the present work an intrinsic ionic volume has been introduced into which the electrons are supposed to be unable to penetrate; this is simply subtracted from the atomic volume in the Fermi expression for the kinetic energy of the electrons. For the attractive potential an expression like those commonly employed to get the electrical potential of crystals is used; it involves a ``Madelung constant'' of a size about equal to those occurring in cases of uni-univalent crystals, and the same for all the alkali metals. For the alkaline earth metals appropriate modifications can be made. One can then calculate the energy of the metals from the experimental value of the atomic volume, getting excellent agreement with experiment in the case of the alkali metals, but not such good agreement in the case of the alkaline earth metals. The method appears not to be very successful in calculating the compressibilities, even in the case of the alkali metals (for which, alone, it was tried); but aside from the fact that the compressibilities at absolute zero may only be inferred from measurements around room temperature, it appears that a relatively small correction to the energy expression can give the correct compressibility without greatly upsetting the calculation of the energy. The latter then is to be considered as of significance, and gives some confidence in the essential correctness of the simple picture of the metal described above.
X-Ray Diffraction by Gaseous Benzene Derivatives
Authors: Pierce W. C.
Published: November 2004

The Debye method for the determination of interatomic distances in single molecules is applied to ortho and paradichlorbenzene. Results with monochlorbenzene are used to correct the scattering curves so as to isolate the Cl–Cl scattering. The resulting Cl–Cl curves show good agreement with theoretical curves constructed for distances of 3.0 and 6.25A, respectively. The measurements indicate a plane hexagonal benzene molecule with the chlorine atoms lying in or near the plane.
On the States of Aggregation
Authors: Herzfeld K. F. , Goeppert-Mayer Maria
Published: November 2004

The problem of investigating systematically the possible states of aggregation has not yet been attacked. It has been approached here in the hope of getting a deeper insight into the nature of the liquid state. After a discussion of the general methods, a simplified one-dimensional model is introduced. It was possible to find the exact equation of state. However, it turned out that in this case a single (gaseous) state exists. This is due to the presence of aggregates of all sizes. It is found that the existence of at least one condensed state is possible only if the change in free energy that occurs when an atom is added to a large aggregate is higher than the change that occurs in the addition of this atom to a small molecule. No progress could be made in the understanding of the liquid state.
The Raman Spectra and Molecular Constants of Phosphorus Trifluoride and Phosphine
Authors: Yost Don M. , Anderson Thomas F.
Published: November 2004

The Raman frequencies of PF3(l) were found to be ω1(1), 890 cm-1; ω2(1), 531 cm-1; ω3(2), 840 cm-1; and ω4(2), 486 cm-1, indicating a regular pyramid structure of the molecule. Three frequencies were observed for PH3(l): 2306 cm-1, 1115 cm-1 and 979 cm-1. With the aid of electron diffraction data the standard virtual entropies of PF3(g), PCl3(g), AsF3(g), and AsCl3(g) at 25°C are calculated to be 64.2, 74.7, 69.2, and 78.2 cal./deg., respectively; that of PH3(g) is estimated to be 50.5 cal./deg. These data lead to the following free energies of formation at 25°C: AsCl3(g), -62,075 cal.; PH3(g), 2750 cal.; PCl3(g), -62,220 cal.
On the Infrared and Raman Spectra of Methyl Compounds
Authors: Adel Arthur , Barker E. F.
Published: November 2004

An analysis of the resonance interaction between the vibrations v1 and 2v4 in the methyl halide molecules explains the appearance of the very intense extra band in the infrared and Raman spectra of these molecules. This degeneracy is evidently characteristic of the methyl group. A number of molecules involving the methyl group and exhibiting the phenomenon of the extra band are listed.
The Normal Frequencies of Vibration of Symmetrical Pyramidal Molecules AB3 with Application to the Raman Spectra of Trihalides
Authors: Howard J. B. , Wilson E. Bright
Published: November 2004

The symmetrical pyramidal molecule AB3 is treated by a general normal-coordinate method, six force constants being required. The convenience of the use of ``symmetry coordinates'' is illustrated in obtaining the formulas for the normal frequencies for several types of potential functions. It is found that with two constants the central force treatment and valence force treatments fit the data equally well. The four constants K, H, K′ and H′ of the potential function 2V=KΣiΔRi2+12HR02Σij′Δαij2+K′Σij′ΔRiΔRj +2H′R02(Δα12Δα23+Δα23Δα31+Δα31Δα12)for certain trihalides are obtained from Raman data. The interatomic distances calculated using these values of K in the empirical relation found by Badger for diatomic molecules agree with the distances obtained by other methods to within about 0.1A.
The Raman and Ultraviolet Absorption Spectra of Some Metal Carbonyls and Alkyls
Authors: Duncan A. B. F. , Murray John W.
Published: November 2004

The Raman spectra of nickel carbonyl, iron pentacarbonyl, lead tetramethyl, and lead tetraethyl and the ultraviolet absorption spectra of nickel carbonyl, lead tetramethyl and lead tetraethyl have been studied. The symmetry number of nickel carbonyl has been calculated. The vibrations of a mechanical model of a plane XY4 molecule have been studied. The correlation of the observed Raman lines with modes of vibration is discussed. It is concluded, from the observed spectrum and the vibrations shown by the mechanical model, that nickel carbonyl has a plane rather than a tetrahedral structure.
The Effect of Unequal Temperature Distribution on the Maximum Pressure Developed in Explosions in a Closed Vessel
Authors: Lewis Bernard , von Elbe Guenther
Published: November 2004

When a combustible gas mixture is exploded at the center of a spherical vessel, a temperature gradient is established at the moment of maximum pressure which rises from the wall to the center. The maximum pressure recorded is lower than would have been found had the temperature been equalized without heat loss. A method for calculating this difference in pressure is described. For ozone explosions it is shown to be less than 0.2 percent in weak mixtures and less than 0.5 percent in rich mixtures. For explosions of H2 and O2 with inert gases it amounts to 0.2 to 0.8 percent.
The Third Law of Thermodynamics
Authors: Rodebush W. H.
Published: November 2004

The invariance of statistical weights requires that the entropy of any phase approach zero at 0°K. The uncertainty principle, however, makes it impossible to define a state of absolute zero for a substance whose lowest energy states are closely spaced multiplets.
Analysis of Rotatory Dispersion Curves. II Configurationally Related Substituted Fatty Acids
Authors: Levene P. A. , Rothen Alexandre
Published: November 2004

The rotatory dispersion curves of substituted fatty acids of the types     COOH     |H–C–SH     |    R  and      COOH     |H–C–SO3H     |    Rhave been measured in the visible and ultraviolet regions. The results are in harmony with the rule previously reported that in members of homologous series, the total rotation of consecutive members may differ in sign, but the signs of the partial rotations remain constant.
Pressure Coefficients of Acoustic Velocity for Nine Organic Liquids
Authors: Swanson J. Chester
Published: November 2004

With a pressure supersonic interferometer especially devised for this purpose, nine organic liquids are examined at frequencies a little less than 200 kc and at temperatures varying from 22.7°C to 25.5°C for the various liquids. The acoustic velocity is measured at intervals from atmospheric pressure to a pressure of 300 kg/cm2. The values of the acoustic velocity (in meters per second) in the liquids at the pressures indicated are given below: LiquidC2H5BrC Cl4CHCl3C2H5OC2H5C5H12CS2C6H6C7H8C6H5NH2Atmospheric Pressure885.912.986.993.1005.1136.1290.1313.1640.300 kg/cm2 Pressure1000.1048.1097.1255.1281.1268.1416.1447.1745.This method is being used for the determination of the value of the specific heats at other than atmospheric pressure.