bluuebunny/crossref_metadata_2025 huggingface dataset:
Rotatory Dispersion of Configurationally Related Unsaturated Secondary Carbinols and Their Corresponding Chlorides
Authors: Levene P. A. , Rothen Alexandre
Published: January 2005

In several instances a periodic change in sign of the partial rotation of the chromophoric groups has been observed with the increase in the distance of these groups from the asymmetric carbon atom. In many unsaturated substances, the ethylenic bond is known to possess a partial rotation of significant value. It was desired to determine whether this partial rotation is subject to a periodic change in sign with the progressive increase in the distance of the double bond from the asymmetric center. The observations reported here seem to indicate that such a change exists although it is expressed less strikingly than in the case of the carbonyl group previously discussed.
The Effect of Foreign Molecules on the Absorption Coefficient of Oxygen in the Schumann Region
Authors: Schneider Edwin G.
Published: January 2005

The absorption coefficient of oxygen in the continuous band having a maximum at 1450A is not altered by the addition of 80 percent nitrogen at pressures less than 15 mm of mercury, the range covered by these experiments. The conclusion is drawn that, at least at low pressures, the absorption of oxygen in the Schumann region is not effected by collisions with foreign molecules.
A Thermodynamic Treatment of Systems, in Particular of Solutions, from the Point of View of Activity and Related Functions
Authors: Goranson Roy W.
Published: January 2005

The purpose of this paper is to present a consistent thermodynamic treatment of solutions based on activity and activity coefficient. On the basis of the argument presented interrelations of these quantities are obtained for dissociated and undissociated components. Expressions are also derived for the fugacity and activity of a component in a gas mixture.
The Deduction of Reaction Mechanisms from the Theory of Absolute Rates
Authors: Stearn Allen E. , Eyring Henry
Published: January 2005

The limitations of the simple collision theory for reactions are discussed. The Menschutkin and related reactions are shown to involve the formation of an activated complex with an electric moment of a magnitude which is calculated for the various cases. The free energy of activation for proton transfer is found from the experiments on conductance in water and the dispersion effects on polarization in ice. A partition function for liquid H2O and D2O based upon experimental quantities is given. The abnormal rapidity of the denaturation of proteins in spite of an enormous activation energy is typical of reactions, involving the simultaneous breaking of many bonds.
The Homogeneous Unimolecular Decomposition of Gaseous Alkyl Nitrites VIII. The Decomposition of Ethyl and n-Propyl Nitrites at Low Pressures Together with a General Discussion of the Results for the Entire Series
Authors: Steacie E. W. R. , Katz S.
Published: January 2005

The kinetics of the decomposition of ethyl and n-propyl nitrites have been investigated at low pressures. The results, together with those for the other members of the nitrite series, are discussed from the point of view of the Kassel theory. Attention is focused particularly on the effect of increasing molecular complexity as one ascends an homologous series, since the nitrites furnish an ideal series for such a discussion. It is concluded that the Kassel theory furnishes a complete explanation of the facts insofar as the effect of pressure on the rate is concerned. On the other hand, there is no satisfactory quantitative explanation of the increase in the high pressure rate with increasing molecular complexity. The factors which might contribute to such an increase are discussed, and it is concluded that the main factor is probably a progressive change in binding energy as one ascends an homologous series.
A Study of Long Chain Organic Compounds by Electron Diffraction
Authors: Storks K. H. , Germer L. H.
Published: January 2005

A layer of lard deposited upon a metal surface gives an electron diffraction pattern consisting of segments of diffuse inclined bands. These arise from line gratings made up of long hydrocarbon chains. The mean inclination of the axes of these chains to the surface normal is calculated to be 27°, and the separation of carbon atoms 2.50A. The saturated glyceride, tri-stearin, yields a diffraction pattern of diffuse bands parallel to the surface, unlike the diffraction pattern from lard, although the latter is predominantly a mixture of glycerides. We believe that the inclination of the long hydrocarbon chains in lard is due to lack of saturation, although this hypothesis has not been tested. Diffraction patterns from stearic acid deposited upon a metal surface also contain inclined bands. These are relatively well defined, and have inclinations which differ from one sample to another. This variation is attributed to the existence of large crystals the c axes of which are differently inclined to the plane of incidence. We calculate that this axis is always inclined 33° to the surface normal. A similar investigation of methyl stearate yields the angle 25°. For both stearic acid and methyl stearate the separation between diffraction bands corresponds to the atomic spacing 2.50A. This is in good agreement with the known distance between alternate carbon atoms in a zigzag hydrocarbon chain.
Lattice Energies, Equilibrium Distances, Compressibilities and Characteristic Frequencies of Alkali Halide Crystals
Authors: Huggins Maurice L.
Published: January 2005

Constants in the Born and Mayer exponential expression for the repulsion between two ions have been recalculated. Using these, the lattice energies and equilibrium distances between ions have been recomputed, for alkali halide crystals. Expressions have been derived and tested for the calculation of the compressibility and the characteristic maximum infrared frequency. The relation between these two quantities is shown to be approximated by an empirical equation proposed by Madelung.
A Test of the Third Law of Thermodynamics by Means of Two Crystalline Forms of Phosphine. The Heat Capacity, Heat of Vaporization and Vapor Pressure of Phosphine. Entropy of the Gas
Authors: Stephenson C. C. , Giauque W. F.
Published: January 2005

The heat capacity of solid and liquid phosphine has been measured from 15°K to its boiling point, 185.38°K. Transitions were found at 30.29, 49.43 and 88.10°K. The heats of transition are 19.6, 185.7 and 115.8 cal./mole, respectively. The transition at 49.43°K had not previously been reported. In order to obtain complete conversion to the form of phosphine which is stable below 49.43°K it was necessary to keep the unstable form near 40°K for several days. A graph showing the rate of conversion to the stable form as a function of temperature has been given. The transition at 30.29°K occurs in the form of phosphine, unstable below 49.43°K. There is also a region of abnormally high heat capacity in the supercooled form between 30.29 and 35.66°K. At the latter temperature the heat capacity decreases abruptly by 15 percent without evidence of latent heat. The melting point was found to be 139.35°K and the heat of fusion 270.4 cal./mole. The heat of vaporization at the boiling point, 185.38°K, was determined calorimetrically. The value found was 3489 cal./mole. The vapor pressure of solid and liquid phosphine was measured and the results represented by the equations: Solid phosphine 128.67 to 139.35°K; log10 P(int. cm Hg)=—895.700/T+6.86434. Liquid phosphine 139.35 to 185.56°K; log10 P(int. cm Hg) = —1027.300/T—0.0178530T+0.000029135T2+9. 73075. The entropy of the solid at 49.43°K may be obtained either from measurement on the stable or unstable form. The values are 8.14 and 8.13 cal./deg. per mole, respectively. While the extraordinarily close agreement is somewhat fortuitous, the measurements provide the most accurate existing verification of the third law of thermodynamics by means of two crystalline forms of a substance. The molal entropy of the ideal phosphine gas at the boiling point was found to be 46.39±0.1 cal./deg. per mole. The corresponding value at 298.1°K is 50.35 cal./deg. per mole. This may be compared with the value 50.5 calculated by Yost with the assistance of spectroscopic data and an estimated bond angle. The above entropy values neglect the nuclear spin entropy, R ln 16=5.509 cal./deg. per mole, which should be added to obtain the absolute entropy. The values given are the ones which should be used in ordinary thermodynamic calculations. Phosphine is known to be a symmetrical top and the two equal moments of inertia are known from its band spectrum. It has not been found possible to evaluate the other moment of inertia in this manner. However, it can be calculated from the accurate entropy determination given above. The value found is Ic=(7.9±0.8)×10-40 gram cm2. The P–H distance was found to be 1.45±0.02A and the bond angle, 98±5°.
Energy States of Solids with Particular Reference to the Energy States of Nd2(SO4)3–8H2O
Authors: Spedding F. H. , Hamlin H. F. , Nutting G. C.
Published: January 2005

The absorption spectrum of Nd2(SO4)3–8H2O crystals has been photographed at 20°, 78°, 169° and 298°K. The absorption lines occur in multiplets and originate in transitions from two low excited states as well as from the normal state. The excited levels of the basic multiplet are situated 77 and 260 cm—1 above the lowest state and undoubtedly arise through splitting of the normal state of the free Nd+++ ion in the electric field set up by its immediate neighbors in the crystal lattice. The positions of the observed levels are not in accord with conclusions of Penney and Schlapp from their study of the influence of crystal fields on the temperature variation of the paramagnetic susceptibility of Nd ion in neodymium sulfate octahydrate. Based in part upon the susceptibility measurements of Gorter and de Haas, Penney and Schlapp's work requires that the levels be at 0, 243 and 834 cm—1. If the data of Gorter and de Haas may be considered in error as regards absolute values the positions of the levels we have found are in excellent agreement with predictions of the theories of Van Vleck and Penney and Schlapp, and with the experimental results of Meyer and of Zernicke and James.
The Mercury Sensitized Reactions of Methane, Deuteromethanes and the Hydrogen Isotopes
Authors: Morikawa Kiyoshi , Benedict W. S. , Taylor Hugh S.
Published: January 2005

The interaction of methane and deuterium and of methane and methane-d4 under the influence of excited mercury have been studied. The influence of temperature, reactant concentration, light intensity and mercury concentration on the yield of deuteromethanes has been measured. Below 200° the results indicate that the production of deuteromethanes is governed by the photosensitized formation of free methyl radicals. At higher temperatures chain reactions become important and high quantum efficiencies of interaction are observed. A simultaneous process of condensation of methane to yield higher saturated hydrocarbons has been shown to occur and its kinetics and quantum efficiency studied. The condensation occurs in presence of hydrogen and its isotope. A sequence of reactions has been postulated and approximate energies of activation suggested which permit a description of the observed phenomena over the whole range of temperatures, light intensity and concentrations studied.
Raman Spectra of Amino Acids and Related Substances III. Ionization and Methylation of the Amino Group
Authors: Edsall John T.
Published: January 2005

Raman spectra have been determined for methylated amines, and the corresponding ammonium chlorides in water; also for ethylamine and its hydrochloride, and the hydrochlorides of hydroxylamine, hydrazine and trimethylamine oxide. The spectra of the hydrochlorides arise only from the positively charged ammonium ion, since the chloride ion is not attached by any covalent bond, and, therefore, is not directly involved in any of the observed vibrations. Thus the spectrum of a methylated ammonium ion is found to be exactly similar in type to that of the analogous hydrocarbon in which a C atom is substituted for the positively charged N atom. If the —CH3 and —NH3 groups are treated schematically like single atoms of the same mass, all these compounds may be represented by simple models. The characteristic frequencies of such models may be correlated with lines in the observed spectra. Qualitative polarization measurements have been made on several of the substances studied and have proved of value in assigning observed frequencies to modes of molecular vibration. Bond force constants and valence angles have been evaluated for many of the substances studied, making use of certain approximate potential functions frequently employed in describing systems of this sort. In the solution of hydrazine dihydrochloride, certain Raman lines arise from the ion +H3N–NH3+; others from +H3N–NH2. Both ions are present in appreciable concentrations, and their relative amounts are roughly what would be expected from known data on dissociation constants. The Raman spectra of the amines here studied in aqueous solution are nearly identical with those reported by other observers for the same amines as anhydrous liquids. The characteristic valence vibrations of the uncharged amino group, between 3300 and 3400 cm—1, are absent in the charged —NH3+ or NH2+ group, being apparently replaced by much weaker lines of lower frequency. The sodium salts of glycine and alanine show strong Raman lines above 3300 cm—1, which are absent in the isoelectric amino acids. This fact supplies further evidence that the amino acids exist as electrically charged dipolar ions, +H3N–R–COO—.
The Primary Oxide Film on Iron
Authors: Nelson H. R.
Published: January 2005

The identity and structure of the invisible, air-formed oxide film on iron has never been determined although the practical importance of a knowledge of its properties in the study of corrosion has been demonstrated. Electron diffraction experiments are now reported which show this film to be structurally identical with Fe3O4. In addition, it is found that the oxide has a definite orientation relationship with the underlying iron, viz., the [√210] directions in the oxide crystals are parallel to the [111] directions in the iron. Freshly abraded surfaces of electrolytic and ingot iron were investigated. Evaporated films of electrolytic iron were prepared in the diffraction camera and pictures taken before and after exposure to air show that Fe3O4 forms rapidly in dry air at room temperature. An air pressure of 10—3 mm for a few minutes gave a measurable effect. Exposure to air at atmospheric pressure for periods longer than a few minutes does not greatly strengthen the oxide pattern. The factors affecting the sensitivity of this method of examining thin films on metals are discussed.
The Properties of Paraffins. II
Authors: Aten A. H. W.
Published: January 2005

The square root in the formula of Boggia-Lera is derived in the case of the paraffins from Langmuir's ideas about the process of evaporation of liquids and van Laar's and van Arkel's rules about cohesion in liquids, combined with empirical expressions for the critical constants.
The Nature of the Crystalline Fields Present in Er2(SO4)3–8H2O
Authors: Spedding Frank H.
Published: January 2005

The splitting of the basic state of Er2(SO4)38H2O due to the presence of the crystalline fields was calculated according to the method of Van Vleck, and Penney and Schlapp. Assuming a cubic field, the basic state in the absence of a magnetic field should split into five levels with the relative separations 0, 19, 39, 85, 89 cm—1. Meehan and Nutting have located them spectroscopically at 0, 19, 41 and 85. When the potential field constant D is assumed to be the same as experimentally determined for Nd2(SO4)3–8H2O, then there are no arbitrary constants in the calculations, and the calculated over all splitting agrees with the values found within a few percent. If the true value of D could be used, the deviation would be even less. Similar calculations were made for Dy2(SO4)38H2O. While the calculated splitting is of the same order as that found experimentally, the agreement is not good. Reasons for the lack of agreement are given. The magnetic susceptibility expressions for both salts are given and the agreement with experiment in the case of Er is excellent.
Calculation of Equilibrium Constants and Activation Energies for Some Reactions Involving Various Isotopic Species of Hydrogen, Water, and Hydrogen Sulfide
Authors: Jones Tom , Sherman Albert
Published: January 2005

In part I, by means of statistical-mechanical theory, equilibrium constants are calculated for exchange reactions of the various isotopic forms of hydrogen, water and hydrogen sulfide. The calculations are made over a range of temperature and show the temperature dependence of the reactions. Part II concerns itself with the calculation of activation energies for these various reactions. The computations show that the reactions fall into three main classes. Hydrogen or deuterium, and water or hydrogen sulfide, can be expected to react by a chain mechanism at about 500°C. Water and hydrogen sulfide can be expected to react by either a chain or bimolecular mechanism around 400°C, and the isotopic forms of water or hydrogen sulfide with themselves at 200 to 300°C by a bimolecular mechanism.
Infrared Absorption Spectra of the Alcohols, Two Acids, and Their Solutions in Carbon Tetrachloride
Authors: Kinsey E. L. , Ellis J. W.
Published: January 2005

The paper describes the absorption spectra of the first eight alcohols of the aliphatic series and of formic and acetic acids in the regions extending from 0.9 to 2.2μ and from 2.0 to 4.0μ. The absorptions of the pure liquids are compared with their absorptions in carbon tetrachloride solutions. For methyl and ethyl alcohols and the two acids comparisons are also made with their vapor spectra. In every case solution in carbon tetrachloride modifies the bands characteristic of the hydroxyl group and leaves unchanged the hydrocarbon bands. The modifications are attributed to polymers or lattice structures which are partially destroyed in the solutions. Four bands near 0.96, 1.40, 1.89 and 2.1μ for the alcohols and one near 1.40μ for the acids which are present in the solution spectra are attributed to single molecules. Each of them in the solution spectra is accompanied by a broad almost continuous region of absorption on its long wave-length side, attributed to polymers, which grows stronger with increasing concentration until in the pure liquid it practically replaces the sharper bands predominating in the solution. The bands of the single molecules can still be detected, however, in each of the pure liquid alcohols. Comparison is made with the spectrum of aniline whose behavior near 1.4μ is peculiar.
The Potential Function of the Water Molecule
Authors: King G. W.
Published: January 2005

For use with frequencies corrected for anharmonicity the energy of a molecule is expressed by a complete quadratic form. Reduction of the force constants in Cartesian coordinates to an independent set by relations due to symmetry and mutual forces is carried out by a systematic matrix method which is particularly useful in correcting for anharmonicity and for finding functions of the frequencies and masses invariant in isotopic molecules. For H2O and D2O these relations being satisfied, the potential function is indeed assumed to be unchanged, all constants are computed, and compared with those of various models. In the S–P picture of the H2O molecule the H–H repulsion, ionic terms in OH bonding and exchange integrals in the angular function prove to be the values expected theoretically.
Anharmonicity Constants of the Potential Function of the Water Molecule
Authors: King G. W.
Published: January 2005

The vibrational energy levels of a polyatomic molecule with quartic terms in the potential function are determined by matrix mechanics, and the change on substitution of an isotope formulated. Applied to H2O and D2O, frequencies at the zero point are obtained that satisfy invariants calculated for harmonic motion.
Vibrations of Asymmetrical Collinear Triatomic Molecules
Authors: Rosenthal Jenny E.
Published: January 2005

Expressions are derived for the vibration frequencies of asymmetrical collinear molecules of the X2Y and XZY types. They are applied to the calculation of the frequencies of the N2O18 molecule using an appropriate approximate potential function. The ratio of the distribution functions for N2O16 and N2O18 and the value of the equilibrium constant for the reaction N2O16+H2O18⇄N2O18+H2O 16 are also given.
Thermodynamics of Gaseous Hydrocarbons: Ethane, Ethylene, Propane, Propylene, n-Butane, Isobutane, 1-Butene, Cis and Trans 2-Butenes, Isobutene, and Neopentane (Tetramethylmethane)
Authors: Pitzer Kenneth S.
Published: January 2005

It is pointed out that the assumption of completely free internal rotation in the simpler hydrocarbon molecules is probably responsible for the discrepancies between the results of previous statistical mechanical calculations and the experimental data. Using the formulas and tables of the preceding paper, calculations are presented which show that, for reasonable values of rotation restricting potentials, complete agreement can be obtained with all experimental results. The uncertainty as to the exact height and shape of these potential barriers, together with the possible errors in estimated vibration frequencies make highly precise calculations of thermodynamic functions out of the question at present. Nevertheless the general agreement with experiment indicates that the potentials and frequencies selected must be approximately correct. These molecular structure data together with the available values of heats of combustion and hydrogenation are then employed in calculations which yield thermodynamic constants and the free energy of formation as a function of the temperature in the range from 300 to 1500°K. The various calculations have been made for all of the hydrocarbons listed in the title.
On the Theory of Optical Rotatory Power
Authors: Kirkwood John G.
Published: January 2005

The Born theory of optical activity in quantum-mechanical form is simplified with the aid of certain approximations. It leads to a simple expression for the rotatory parameter of an active molecule in terms of the geometrical configuration and the polarizability tensors of its constituent groups. Optical anisotropy of the component groups and inhibited internal rotation are found to play an important role in determining rotatory power. The proposed theory has points of similarity both with the polarizability theories of Gray, de Mallemann, and Boys and also with Kuhn's specialization of Born's classical theory of optical activity. To illustrate its use, the absolute configuration and the specific rotation of d-secondary butyl alcohol are calculated.
On Transitions in Condensed Systems
Authors: Rice O. K.
Published: January 2005

In this paper there is presented a method of studying transitions in condensed phases based on the thermodynamic equation (δE/δV)T = T(δS/δV)T, which holds for low pressures. (δE/δV)T and T(δS/δV)T are plotted as functions of V, the latter for various temperatures. Intersections of these curves give the points of equilibrium and the transition points. It is shown that very general and qualitative considerations, taking into account only facts that we definitely know to be true of these curves, with one very reasonable assumption, are sufficient to indicate that as the temperature of a system is increased from absolute zero there must be at least one change of phase, which is taken to be fusion. Changes of phase due to setting in of molecular rotation in the solid are also considered. Curves of N2 and O2 are constructed from available experimental data. Finally, an equation of Eyring and Hirschfelder, which would give the trend of the function V(δS/δV)T with V for liquids, is tested by a new method, and found not to accord very well with the experimental data, especially for low boiling substances.
The Surface Tension of Deuterium Oxide and of its Mixtures with Water
Authors: Jones Grinnell , Ray Wendell A.
Published: January 2005

The surface tension, σ, of 97.8 percent deuterium oxide and of five more dilute mixtures with water has been compared with ordinary water by a modification of the capillary rise method. The results show that the relative surface tension is slightly less than that of pure water and is a linear function of the specific gravity. The data may be represented by the equation σ = 1 — 0.00501Δs, where Δs is the increase in specific gravity over ordinary water. By a slight extrapolation the surface tension of pure deuterium oxide at 25°C is estimated to be 0.999,46 of the surface tension of ordinary water at the same temperature.
The Diffusion Constant of an Electrolyte, and Its Relation to Concentration
Authors: Gordon A. R.
Published: January 2005

A semi-empirical equation is proposed which predicts for potassium chloride, sodium chloride and potassium nitrate in aqueous solution, differential diffusion constants which agree with the experimentally determined values for the three salts within the limits of error of the experiments. The relation of the effective diffusion constant determined in the Northrop-McBain diaphragm cell to the differential diffusion constant is discussed; it is shown that Cole and Gordon's rule that the effective diffusion constant measured in such a cell is equal to the differential diffusion constant for the mean concentration, is still a valid approximation even when there is a nonlinear dependence of diffusion constant on cencentration, provided the total concentration range involved is less than 0.1 N.
The Polarity of Chemical Bonds
Authors: Huggins Maurice L.
Published: January 2005

It is shown that polar bonds can be as well considered to be resonating between two covalent states as between one covalent state and an ionic state. The limitation on the number of K electrons in an isolated hydrogen atom does not prevent a hydrogen atom from being bonded at the same time to two other atoms, provided they are sufficiently electronegative. Likewise, a carbon or nitrogen atom, suitably surrounded by electronegative atoms, can hold more than four (bonding) electropairs in its valence shell. It is suggested that Pauling's ``magnetic criterion for bond type'' does not distinguish between covalent bonds and ``ionic bonds,'' but between covalent bonds of different polarity.
Electronic Activation in Crystals: The Heat Capacities of Sm2(SO4)3·8H2O and Nd2(SO4)3·8H2O from 3 to 40° Kelvin
Authors: Ahlberg J. E. , Blanchard E. R. , Lundberg W. O.
Published: January 2005

The heat capacities of the sulfate octahydrates of neodymium and samarium have been measured from 3 to 40°K. The results have been applied to the study of the electronic energy states of the rare earth ions. The electronic heat capacity of the neodymium ion in the sulfate octahydrate has been determined. The separations of the two electronic energy levels comprising the basic states of both salts have been found to be less than 1 cm—1. The presence of an electronic energy level in Nd2(SO4)3.8H2O at 77 cm—1 above that of the basic state has been substantiated. The statistical weight of this level appears to be twice that of the basic state.
Primary Photochemical Processes in Solution
Authors: Rollefson G. K. , Libby W. F.
Published: January 2005

The effect of an inert solvent on the efficiency of photodissociation processes is discussed. It is shown on theoretical considerations that under the usual experimental conditions a close analogy between reactions in solution and in the gas phase cannot be accounted for by assuming a symmetrical retardation of both the dissociation and recombination processes by the solvent. It is shown experimentally by means of the radioactive indicator method that even in the ideal case of chlorine in carbon tetrachloride the atoms produced in the photodissociation process do not react with the solvent.
The Temperature, Pressure and Volume Coefficients of the Viscosity of Fluids
Authors: Ewell Raymond H.
Published: January 2005

Since (∂η/∂T)p and (∂η/∂T)v are both positive for dilute gases and both are negative for ordinary liquids, they must be zero at some intermediate density. From data in the literature it is shown that these two coefficients do not become zero at the same state of the fluid, but that the former becomes zero at lower densities than does the latter. On this basis any state of a fluid can be placed in one of six categories, or loci, which are characterized by the signs and relative magnitudes of the two viscosity temperature coefficients. By the use of general mathematical equations relating four variables, the signs of the viscosity pressure and viscosity volume coefficients are deduced for the six loci. It is shown that the fluidity and volume of a normal liquid are linearly related for volume changes up to about 10 percent, as both properties are varied with the pressure at constant temperature, i.e., that (∂[open phi]/∂V)T is a constant. This is analogous to Batchinski's relation, according to which (∂[open phi]/∂V)p is a constant. From data in the literature it is shown that (∂[open phi]/∂V)T is about ⅔ to ¾ of (∂[open phi]/∂V)p, in agreement with relations deduced in this paper.
A Study of the Liquid State
Authors: Altar William
Published: January 2005

A theory of holes in liquids is developed to account for the thermal and mechanical properties of the liquid state. The treatment is founded on the assumption that the thermal motion of the liquid is determined by the motion of its ``surface,'' this surface, however, to be understood in a broader sense so as to include internal boundaries of which the liquid forms as many as its number of degrees of freedom will permit. An equation of state is obtained and applied to liquid argon, and very close agreement with the empirical data is reached.
Elements of the Factored Secular Equation for the Semi-Rigid Water Type Rotator, With Application to the Hydrogen Sulfide Band at 10,100A
Authors: Crawford Bryce L. , Cross Paul C.
Published: January 2005

The necessary numerical coefficients of the molecular constants in the secular equation obtained in the previous paper are tabulated up to j=12. A rapid approximate procedure for obtaining the roots of the secular equation is described. The treatment is applied to the hydrogen sulfide band at 10,100A. A slight improvement is obtained over the previous analysis which used the Wang equation classically corrected for centrifugal distortion. New molecular constants and term values are given.
Theory of Color of Organic Compounds
Authors: Sklar Alfred L.
Published: January 2005

Several structural formulae can be written for a colored compound, since the molecule usually contains an alternation of single and double bonds. The color is attributed to absorption bands corresponding to transitions between the levels which arise from a resonance among these different possible structures. A calculation is made for the levels of benzene, cyclohexadiene, fulvene, and azulene; fulvene being a yellow compound, azulene a blue one; the others, although colorless, have absorption bands in the near ultraviolet. One parameter only enters the calculation and is evaluated by data on heats of hydrogenation. The absorption bands of the molecules are then calculated without using any optical data, the results agreeing well with experiment. The calculation is amplified in the case of benzene so as to include polar structures and also triplet states in the linear combination representing the molecule. The symmetry of the states is discussed in connection with selection rules, which are found to be in agreement with the relative intensity of the band groups in benzene. An interpretation of the structure of the 2600A band is proposed which is shown to account for many properties of this band system.
Calculation of the Energy of H3 and of H3+. III
Authors: Hirschfelder J. , Diamond H. , Eyring H.
Published: January 2005

In previous communications, the energy of the triatomic hydrogen molecule and of the triatomic positive ion was calculated by the variational method for the symmetrical linear configurations. In this paper, these energies are obtained for two unsymmetrical linear configurations using the most general eigenfunction which can be formed out of 1s hydrogen-like atomic orbitals. Two of the four difficult exchange integrals which involve the coordinates of three nuclei are obtained in closed form. For the Wang plus polar states approximation, the activated state for the reaction H+H2 is found to be linear symmetrical whereas the semi-empirical calculations give an unsymmetrical activated state. The complete potential energy surface for three hydrogen atoms on a line is constructed, for this Wang plus polar states approximation. The energy of the triatomic positive ion is likewise lowest for the linear symmetrical. The complete energy surface of H2+H+ in a line is constructed and the vibration frequencies computed. The frequency of the linear symmetrical vibration for H3+ is 1.4×1014 wave no. per sec. and the frequency of the linear unsymmetrical vibration is 1.2×1014.
Chemical Applications of the Raman Effect: I. Polymerization
Authors: Hibben James H.
Published: January 2005

The Raman spectra of methyl methacrylate and similar compounds have been investigated and interpreted. The changes in the molecular constitution on polymerization indicate the disappearance of a=C––HH linkage and the like disappearance of the C=C linkage. Lower frequencies appear indicating an increased chain length and a slight decrease in the complexity of the intermediate frequency would seem to indicate an increase in the symmetry of the molecule. The force constants of the more characteristic groups are closer to the cis- than the trans-modification of the isomer. Unlike inorganic glasses, the polymer exhibits at least some sharp lines. These permit an explanation of the continuing structure present throughout the solid and the mechanism by which this structure comes into existence.
Chemical Applications of the Raman Effect: II. Common Ion Effect
Authors: Hibben James H.
Published: January 2005

It has been shown by means of the Raman effect that the ionization of homopolar compounds in dilute solution increases more rapidly than is proportional to the dilution. This ionization will be repressed by adding a common ion and such repression is proportional to the concentration of the common ion added. In mixtures of two compounds, both being homopolar and containing a common cation, there is little effect on the ionization. On the addition of a neutral salt containing an anion which may be shared with a cation already combined in homopolar linkage with another anion the equilibrium resulting is in the direction of the formation of that compound whose linkage is the most homopolar. These results indicated by means of the Raman effect cannot be observed with equal facility by any other method of approach.
The Molecular Volumes and Expansivities of Liquid Normal Hydrogen and Parahydrogen
Authors: Scott R. B. , Brickwedde F. G.
Published: January 2005

The molecular volumes at saturation of liquid normal hydrogen and parahydrogen between 14° and 20.4°K were measured with a fused quartz dilatometer, the amount of hydrogen being determined from the pressure of the gas in a calibrated flask at a measured temperature. The results are represented by the equations: V(n−H2) cm3mole−1=24.747–0.08005T+0.012716T2,V(p−H2) cm3mole−1=24.902–0.0888T+0.013104T2.At the normal boiling point of n-H2(20.38°K), V(n-H2)=28.397±0.010 and ΔV(p-n)=0.138±0.010. The expansivity of p-H2 is only slightly greater than that of n-H2. The change observed in the molecular volumes of H2 in passing from the state in which the molecules rotate (o-H2) to the state in which they do not rotate (p-H2) is opposite in direction to the change observed in other substances when passing between these two states of molecular rotation and nonrotation. The changes in ``lattice'' energies are also of opposite sign. It is shown that the random state of orientation of the axes of p-H2 molecules makes the state of nonrotating p-H2 fundamentally like that of rotation in other substances at high temperatures. The differences in the molecular volumes and ``lattice'' energies of the condensed phases of o- and p-H2 arise from a difference in the magnitude and symmetry of the intermolecular forces of repulsion. These differences in the forces of repulsion result from a difference in the distributions of the average electron density of o-H2 and p-H2 molecules arising from the difference in the rotational motion of the two varieties at low temperatures.
The Infra-Red Transmission of Several Organic Compounds Near the Melting Point
Authors: Taschek Richard , Williams Dudley
Published: January 2005

The transmission of benzophenone, desoxybenzoin, diphenyl ketone, and benzalacetophenone has been measured at various temperatures. The spectra of the compounds are affected only slightly by change of state, the most marked difference being a variation in the intensity of certain bands. Isochromatic curves for benzophenone and desoxybenzoin indicate pronounced differences in background transmission at temperatures immediately below the melting point with a rapid increase at the melting point, while those for dibenzyl ketone and benzalacetophenone show only a rapid increase in transmission on melting. The data for benzophenone and desoxybenzoin are interpreted as indicating the existence of a mesophase near the melting point.
Intensities of Electronic Transitions in Molecular Spectra I. Introduction
Authors: Mulliken Robert S.
Published: January 2005

The neglected problem of the theory of the absolute intensities of electronic transitions in molecular spectra is discussed. General equations for dipole strength, Einstein coefficients, mean lifetimes of excited states, f values, and so forth, are collected in forms convenient for use in later papers where the theory for various types of transitions will be developed and applied.
The Persistence of Molecular Vibration in Collisions
Authors: Dwyer Robert J.
Published: January 2005

The dispersion of sound is theoretically interpreted by the idea that the exchange of energy in collisions between molecular translation and rotation on one side and vibration on the other side is much slower than, for example, between the various translational degrees of freedom. It seemed desirable to find a direct optical method of observing this hypothetical effect. Apparatus has been developed in this laboratory for the purpose of investigating molecules present in very small concentration, like radicals, by their absorption spectra; with this method, relative concentrations of molecules are determined by comparing intensities of certain rotational lines. This test was applied to the higher vibrational levels of the I2 molecule. Their concentration was artificially increased beyond the small amount present in thermal equilibrium by an electric discharge of brief duration. By varying the phase between an electric switch and optical shutter, snapshots of the absorption spectrum could be taken at different intervals after the discharge was interrupted. The result was that iodine molecules raised from the ground level to the first excited vibrational level are able to persist in this level through several thousand collisions with other iodine molecules before losing their vibration.
On the Magnetic Behavior of Vanadium, Titanium and Chrome Alum
Authors: Van Vleck J. H.
Published: January 2005

As Siegert has shown, the fact that the susceptibilities of both titanium and vanadium alum conform to the ``spin-only'' formula demands that the ratio of the fourth-to the second-order part of the noncubic portion of the crystalline potential have a certain critical value. The present paper investigates whether such a ratio can result from (I) the direct effect of the ``distant'' charges, i.e., the atoms more remote than the six waters immediately surrounding the paramagnetic ion, (II) the indirect action of the remote atoms in distorting or polarizing the water cluster so that it is no longer octohedral, or (III) the Jahn-Teller effect, whereby the degeneracy of the cation has repercussions on the arrangement of the surrounding waters, so that they are not cubically grouped. It is concluded that (I) does not yield a sufficiently large splitting. That the mechanism (III) cannot alone be effective is shown by Gorter's relaxation experiments, as well as by the existence of a small splitting of the basic quartet of chrome alum which cannot be due to (III), but which is revealed by adiabatic demagnetization experiments. On the other hand, (II) does give a ratio of fourth- to second-order terms of the proper size and sign, and the corresponding departures from octohedral symmetry in the water cluster need not be large enough to contradict x-ray data. The total splitting is materially amplified by the superposition of (III) on (II). It is gratifying that a model can be found which will thus yield the rather peculiar type of crystalline potential required if the basic orbital states of titanium and vanadium are both nondegenerate, but trigonal, as shown by the susceptibility data. Furthermore, it is shown in Section IV that the model gives a splitting in chrome alum of the order of magnitude 10-1 cm-1 and sign deduced by Hebb and Purcell from the magnetization at low temperatures.
The Near Infra-Red Absorption Spectra of Pentaerythritol and Diketopiperazine Obtained with Plane Polarized Light
Authors: Ellis Joseph W. , Bath Jean
Published: January 2005

Pentaerythritol, C(CH2OH)4, a crystalline alcohol, and diketopiperazine, (CH2NHCO)2, also crystalline, have been subjected to an infra-red absorption study with plane polarized waves in the region 1–2.5μ. Pronounced pleochroism is observed, and this dependence of absorption upon the plane of vibration of the electric vector, E0, is used in identifying the bands associated with the normal vibrations of the methylene groups, CH2, in each crystal. An interesting example of Fermi resonance arises.

In pentaerythritol the appearance of pronounced absorption by perturbed OH groups when E0 oscillates along the c axis indicates that the feature of the crystalline structure, deduced from an x-ray diffraction study which orients all of the OH groups at right angles to this axis, must be modified.

The absence of the usual NH absorption near 1.50μ supports Corey's assumption of electron resonance in diketopiperazine.
The Diffusion of Gases Through Metals from a Chemical Point of View
Authors: Simons J. H. , Ham W. R.
Published: January 2005

The diffusion of gases through metals is considered from the point of view of chemical compounds between the metal or a constituent of it and the gas, all at chemical equilibrium. Without reference to the surface conditions the usual laws of diffusion are derived, and Fick's linear diffusion law is shown to be a consequence of the hypothesis. Cases are treated where one compound between the gas and metal is formed, where two compounds are formed, where one compound is formed between the metal and gas and another formed between an alloying agent and the gas, and where the same compound is formed but the metal has a transition between two forms. The theory correlates the magnitude of the exponent of the gas pressure in the diffusion isotherms with the chemical reactions within the metal. It also leads to certain consequences in regard to the magnitude of the diffusion and the energy of activation.
The Dielectric Polarization of Polar Liquids
Authors: Kirkwood John G.
Published: January 2005

An extension of the Onsager theory of dielectric polarization is presented. The local dielectric constant is approximated by the macroscopic dielectric constant of the fluid in a region outside a molecule and its first shell of neighbors rather than in the entire region exterior to the molecule. In addition to the molecular dipole moment, the average value 〈cosγ〉Av of the cosine of the angle between neighbor dipoles is a determining factor. Hindered relative rotation of neighboring molecules produces a correlation between their orientations and prevents 〈cosγ〉Av from vanishing. The theory is applied to liquid water under the assumption of tetrahedral coordination and directed bonds between neighboring molecules.
Molecular Distribution in Liquids
Authors: Kirkwood John G.
Published: January 2005

A theory of the radial distribution function in nonpolar liquids composed of spherical molecules is developed. The characteristic features of experimentally determined radial distribution functions are reproduced by the theory. A single parameter, the work of formation of a cavity of of molecular size, determines the approximate form of the distribution.
Dissociation Treatment of Condensing Systems. II
Authors: Band William
Published: January 2005

In a previous paper under the above title, in future referred to as Part I, it was shown how the theory of dissociating assemblies could be applied to an example containing only one component type of molecule which can form clusters of any size. The results were claimed as equivalent with those of Mayer (see reference 3, a and b). In a private communication Dr. Mayer has pointed out to the writer that this claim is only approximately correct, because the clusters were treated as of negligible size, excluded volumes being ignored. It is therefore necessary to regard Part I as giving a ``perfect gas analogy'' for the theory of the saturated vapor pressure curves at temperatures well below the critical value.

The present paper develops the more accurate theory by taking into account the excluded volumes and, besides the s-v-p curves, also presents a complete set of equations for the isothermals of the gas and vapor right through the critical temperature.
The Effect of Temperature on the Structure of Mercury
Authors: Boyd Robert Neilson , Wakeham Helmut R. R.
Published: January 2005

X-ray diffraction patterns of mercury at eight temperatures ranging from —36°C to 250°C have been obtained using Mo Kα radiation. The x-ray beam was diffracted from an open mercury surface using the small angle of incidence of 4° 11′, thus permitting observation of a previously unreported peak at a diffraction angle of about 10°. Fourier analyses of the intensity curves gave distribution functions showing the expected shifting and broadening of the maxima with increasing temperature. A small subsidiary peak, which changes position with temperature more rapidly than the others, occurs between the first and second main concentrations of atoms.
The Thermal Decomposition of Diacetyl
Authors: Rice F. O. , Walters W. D.
Published: January 2005

The products formed in the decomposition of diacetyl indicate an over-all reaction, CH3COCOCH3→CH4+CO+CH2=CO, followed by some decomposition and polymerization of the ketene. The reaction, as measured by pressure change, is first order and is only slightly affected by a large increase in the surface-volume ratio of the reaction vessel. The decomposition has a surprisingly high frequency factor of the order of 1017. A free radical scheme has been proposed for the decomposition but in its present form this scheme does not explain the high frequency factor.
Remarks on the Calculation of Bond Strengths
Authors: Burton Milton
Published: January 2005

The hypothesis that predissociation as evidenced by sudden broadening of the rotation lines in an absorption spectrum may be used to establish the strength of the bond involved in the associated photochemical act is re-examined. It is shown to lead to incorrect conclusions in the few cases where its use seemed applicable. New values are derived for the C–C and C–H bond strengths in various compounds. The values are consistent among themselves and with observations in reaction kinetics but show a small spread due to secondary effects of adjacent double bonds. In free acetyl and formyl radicals the bonds are much weaker than in the stable compounds.