bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistical Mechanics of Isotope Effects on the Thermodynamic Properties of Condensed Systems
Authors: Bigeleisen Jacob
Published: January 2005

Evidence for the role of molecular structure on the difference in the thermodynamic properties of isotopic molecules in the liquid and solid states is summarized. The properties considered are vapor pressure, heats of vaporization, molal volume, and transition temperatures. It is shown that the molecular structure must be taken into consideration even for small quantum effects. In the approximation of the first quantum correction the difference in thermodynamic properties of isotopic molecules in the condensed state depends upon the atomic masses and an energy parameter associated with each atom in the molecule. The results are extended to higher-order quantum corrections for a harmonic potential. The rules of the mean are obtained directly. Various frequency distributions for the lattice modes are considered. For the case where the internal frequencies in the condensed phase are similar to the free molecule, the ordered quantum corrections can be used for T>(hvmax/12(2)½k)mol; T>(hvlattice/2πk). The role of the gas imperfection and the molal volume of the condensed phase is discussed for equilibria between gaseous and condensed phases. It is shown that the difference in molal volumes of isotopic molecules is a second-order effect. The difference in molal volumes of isotopic molecules is evaluated by an extension of Gruneisen's equation of state to molecular lattices. The results are in good agreement with available experimental data.
Exchange of Radioactive Silver and Bromide with Silver Bromide Suspensions
Authors: Langer A.
Published: January 2005

The exchange of radioactive silver and bromide ions with aqueous silver bromide suspensions was studied. It was observed that both constituents of the silver bromide lattice exchange with the ions in solution. A strong dependence of the exchange rate on the amount of surface of the precipitates used, for both the silver and the bromide was observed. A pronounced difference was found in the exchange rate for bromide if dye molecules were adsorbed on the precipitate prior to the exchange experiment. The rate for silver was not affected by the presence of the adsorbed dye molecules. A discussion of these results is included.
The Conductance of Aqueous Solutions of Potassium Bromide at Temperatures from 15° to 45°C, and the Limiting Mobility of Bromide Ion
Authors: Gunning H. E. , Gordon A. R.
Published: January 2005

The conductance of aqueous solutions of potassium bromide at concentrations from 0.0005 N to 0.01 N for temperatures from 15° to 45° C has been measured by the direct-current method previously employed for potassium and sodium chlorides. At 15°, there is a small logarithmic term required to represent the Shedlovsky function Λ′0, but for 25° and higher temperatures, Λ′0 is linear in the concentration. The limiting mobility of bromide ion is obtained from the limiting conductance and the known mobility of potassium ion; the temperature coefficients of the limiting bromide ion mobility are uniformly about 2 percent less than the corresponding values for chloride ion.
Raman Spectra of Hydrocarbons I. 1-Octene, cis+trans 2-Octene, trans−3-Octene, trans−4-Octene, 4-Octyne, and 1-Octyne
Authors: Cleveland Forrest F.
Published: January 2005

Raman frequencies, intensities and depolarization factors are reported for 1-octene, cis+trans 2-octene, trans−3-octene, trans−4-octene, 4-octyne, and 1-octyne. The experimental arrangement is described. The intensities were determined by use of a micro-densitometer. Comparison of the relative intensities obtained in the present investigation for 4-octyne with the estimated intensities obtained previously indicates that the so-called ``estimated intensities'' are in reality estimates of densities rather than of intensities. The relative intensities are based upon an arbitrary value of 1000 for the strongest line in the Raman spectrum. A high speed, Hilger E−518 glass spectrograph was used in obtaining some of the spectrograms. With this instrument, a spectrogram of carbon tetrachloride, from which eight lines could be measured, was obtained in one minute.
Atomic and Electronic Distributions in Liquid Nitrogen, Nitric Oxide, and Nitrous Oxide
Authors: Sharrah Paul C.
Published: January 2005

The monochromatic x-ray diffraction patterns for liquid nitrogen, nitric oxide and nitrous oxide have been obtained and analyzed by the Fourier integral method to obtain the atomic or electronic distributions. The diffraction patterns show one main peak and only faint peaks or plateaus at larger angles. The distribution curves show diatomic aggregates in liquid nitrogen and nitric oxide comparable to those found in the gaseous states. A linear molecule for nitrous oxide is consistent with the present data while a triangular molecule is not.
Statistical Mechanics of Cross-Linked Polymer Networks II. Swelling
Authors: Flory Paul J. , Rehner John
Published: January 2005

The interaction of solvents with cross-linked network structures, such as occur in vulcanized rubber, is subjected to a statistical mechanical treatment based on the model and procedure presented in the preceding paper. The activity of the solvent is expressed as a function of its concentration in the swollen network, and of the degree of cross-linking. The maximum degree of swelling of the network in contact with the pure solvent is related to the degree of cross-linking. The heat of interaction of the solvent with the network can be calculated from the temperature coefficient of maximum swelling. The theory leads to the conclusion that the swelling capacity should be diminished by the application of an external stress. Furthermore, the modulus of elasticity should decrease inversely with the cube root of the swelling volume.
Theory of Molecular Size Distribution and Gel Formation in Branched-Chain Polymers
Authors: Stockmayer Walter H.
Published: January 2005

The most probable distributions of molecular sizes are calculated for certain types of branched-chain polymers. The results represent an extension of the previous work of Flory, who showed that very large polymeric molecules appear suddenly at a critical extent of reaction, which is predicted to occur very nearly at the experimentally observed gel point. This transition from liquid to gel is shown to be analagous to the condensation of a saturated vapor. It is believed that the size distributions obtained herein will aid in a study of viscosity-molecular weight relationships in branched-chain polymers.
A Direct Experimental Determination of the Electron Affinity of Chlorine
Authors: McCallum Kenneth James , Mayer Joseph E.
Published: January 2005

The electron affinity of chlorine has been determined to be 85.84±1.0 kcal./mole by measureing the ratio of ions to electrons leaving a hot tungsten surface in contact with a low pressure of gas containing chlorine atoms. Both Cl2 and SnCl4 were used as carrier gases.
Statistical Lengths of Rubber-Like Hydrocarbon Molecules
Authors: Wall Frederick T.
Published: January 2005

The root mean square lengths of trans-, cis-, and random rubber-like hydrocarbon molecules are calculated. These results are compared with the maximum possible lengths of the trans- and cis-varieties and interpreted from the point of view of recent theories of rubber elasticity. It is found that the cis-structure should be more elastic than the trans-structure but the calculated difference is not large. The theory is probably sufficient to account for the properties of polychloroprene as compared to natural rubber, but stearic forces are necessary to explain the lack of elasticity in balata or gutta-percha.
The Surface Recombination of H Atoms and OH Radicals
Authors: Smith W. V.
Published: January 2005

A diffusion method of investigating surface recombination of atoms by substances of low catalytic power is presented. By this method we have evaluated the coefficient of recombination γ for H and OH on Pyrex for a temperature range of over 500°C. For smaller ranges of temperature we have found the recombination of H on a number of salts, and have found this recombination to be strongly dependent on the dryness of the surface. All salts investigated save KCl strongly recombined H when dry. Salts recombining H could not be investigated for OH recombination. However KCl, which did not recombine H, did recombine OH strongly. A number of strong dehydrogenating and dehydrating agents were tested for differences in H and OH recombination, but no difference was found.
The Electrostatic Influence of Substituents on Reaction Rates. IV.
Authors: Price Donna , Westheimer F. H.
Published: January 2005

The rates of saponification of ethyl benzoate, ethyl toluate, ethyl anisate, ethyl p-chlorobenzoate, and ethyl p-nitrobenzoate have been measured in several alcohol-water mixtures. The relative rates of saponification of the substituted benzoic esters have been compared with those computed by the Kirkwood-Westheimer theory.
The Vibration-Rotation Energies of the Linear X-Y-Z Type Molecule
Authors: Nielsen Alvin H.
Published: January 2005

The vibration-rotation energies of the linear X-Y-Z type molecule are derived according to a method suggested by Professor Harald H. Nielsen in a recent paper. By the proper substitutions the energy expressions are reduced to the ones appropriate for the XY2 type molecule, and a comparison with the work of Professor D. M. Dennison is effected.
The Influence of Hindered Molecular Rotation on the Dielectric Constants of Water, Alcohols, and Other Polar Liquids
Authors: Oster Gerald , Kirkwood John G.
Published: January 2005

The theory of dielectric polarization of polar liquids is used to calculate the dielectric constants of water and some alcohols. Quasi-rigid coordination models, based upon x-ray structural investigations, are employed in the calculation of a function g which measures the orientational correlation between neighbors in the liquid. It is pointed out that the correlation function g is closely related to the thermodynamic ``abnormality'' of polar liquids.
Detection of an Intermediate Step in the Autoxidation of Hydroquinone. Aerial Fogging of Photographic Emulsions
Authors: James T. H.
Published: January 2005

Alkaline hydroquinone solutions, oxidized in the presence of a suitable photographic material, exert a fogging action upon that material. The fogging action is due to some transitory intermediate in the oxidation process. Various possibilities are considered, and the conclusion is reached that the peroxide radical, HO2, is the fogging agent. The aerial fogging action of a number of essentially different developing agents is explained on the common basis of this intermediate.
The Quantum Yield of Diacetyl Fluorescence
Authors: Almy G. M. , Gillette P. R.
Published: January 2005

The quantum yield of fluorescence of diacetyl, excited by radiation of λ4047 and λ4358, has been measured and found to be 0.145±0.03. It is approximately independent of pressure. On the other hand, the yield with excitation of λ3650, as first observed by Henriques and Noyes, increases apparently from zero at zero pressure to nearly the value obtained for the longer wave-length excitations at a pressure of 5 cm Hg. This marked difference in pressure effect for different energies of excitation is explained by assuming that predissociation occurs at a level between those reached upon λ3650 and λ4047 excitations. By removing vibrational energy collisions can save for fluorescence a molecule excited by λ3650, but they do not play an important role in the case of molecules with excitation energy below the predissociation limit. The observed phenomena of diacetyl fluorescence can be explained in terms of a model which involves a metastable state just below the state reached on absorption. This model is compared with McMurry's predictions of states for molecules of the type of diacetyl.
The Electrical Conductivity of Lead Chromate
Authors: Lashof Theodore William
Published: January 2005

The conductivity of sintered pellets of lead chromate varies with the temperature in accordance with the Boltzmann-type law σ∝exp (−1.48 ev/kT) in the temperature range 700°C to 350°C and with the law σ∝exp (−0.60 ev/kT) at lower temperatures. At constant temperature the conductivity increases with decreasing oxygen pressure, σ∝P0−1/3.1, which indicates that lead chromate probably dissociates in accordance with the equations: 2PbCrO4→Pb(CrO2)2+Pb0+2O2 and Pb0→Pb++e. The energies of these reactions are 5.28 and 1.20 electronvolts, respectively. These same reactions would explain optical and thermal darkening as well as the conductivity, and they indicate along with transport measurements and Seebeck effect measurements that lead chromate is an excess electronic semiconductor.
Sorption of NH3 on Montmorillonitic Clay
Authors: Cornet I.
Published: January 2005

Various dry minerals were permitted to react with anhydrous ammonia under controlled conditions. When the pressures of ammonia prevailing in the sorbing system were plotted against the quantity of ammonia sorbed, typically parabolic or hyperbolic sorption isotherms were obtained with ammonium bentonite, potassium bentonite, and finely ground hydrogen bentonite. Unground hydrogen bentonite gave a complex ammonia sorption curve, in which there was a short parabolic section initially, followed by an inflection and finally a second parabolic or hyperbolic sorption section. Concurrent x-ray studies indicated that the inflection and subsequent portion of the sorption curve were accompanied by widening of the c axis spacing. The sorption and concomitant x-ray data permitted the view that the sorption of ammonia by unground hydrogen montmorillonite occurred on exterior planar surfaces, interplanar surfaces, broken bonds, corners, and edges. Data on the thermal decomposition of ammonium bentonite were consistent with this view. It was found that sorbed ammonia occupied base exchange reactive spots; physical trapping of ammonia molecules in the interplanes would not account for the lattice expansion. The data also appeared consistent with the theory that both lattice hydroxyl ions and polarization of water molecules may give rise to base exchange capacity on grinding some clay minerals.
Raman Spectra of Hydrocarbons II. 2-Methyl-1-Heptene and 6-Methyl-1-Heptene
Authors: Cleveland Forrest F.
Published: January 2005

Raman frequencies, relative intensities, and depolarization factors are listed for 2-methyl-1-heptene and 6-methyl-1-heptene. The spectrograms were made on Eastman 103-J spectroscopic plates and the intensities were obtained with the aid of a Gaertner microdensitometer. The results are compared with data obtained in a previous study of 1-octene, cis+trans 2-octene, trans−3-octene, and trans−4-octene. Polarized lines at 1643 and 3000 and depolarized (or only slightly polarized) lines at 1294, 1416, and 3078 cm−1 correspond to olefinic frequencies of the XHC=CH2 group. When the group is XYC=CH2, as for 2-methyl-1-heptene, these frequencies appear at 1653, 2978, 1303, 1414, and 3077, the depolarization factors remaining essentially unaltered. Also a line of medium intensity was observed at 1674 for 2-methyl-1-heptene; its appearance is probably due to an accidental resonance degeneracy. For the group XHC=CHY (trans), the 1416 and 3078 cm−1 frequencies are absent and the three remaining frequencies occur near 1300, 1672, and 2998, the last two being polarized as for the other groups. Both of the methyl-heptenes have more strong lines below 1200 cm−1 than did the four octenes previously studied.
Optical Sensitizing of Silver Halides by Dyes IV. The Optical Sensitizing Properties of Fluorescein Dyes in Relation to Their Spectral Absorption and Constitution
Authors: Sheppard S. E. , Lambert R. H. , Walker R. D.
Published: January 2005

A comparison of increasingly halogenated fluoresceins shows that, with increasing weight of halogen introduced, the principal visible absorption moves steadily to longer waves, as also the first ultraviolet band. At the same time the acid dissociation constants of the phenolic and carboxylic groups tend to become indistinguishable, while the solubilities of the silver compounds decline. The various structures involved in the resonance of the alkaline, hydrogen, and silver compounds are discussed. Measurements of the solubility of silver erythrosinate show this to vary with ``aging'' and particle size. The solubility of silver erythrosinate on adsorption to silver bromide is apparently lower than that of the pure compound. The adsorption is oriented, an edge-on or end-on monolayer being formed. Although not irreversible, there is a peculiar deviation from the Langmuir isotherm. The optical sensitizing appears to occur by a mechanism similar to that with basic dyes. Initially, transfer of an exciton to the silver halide seems indicated, rather than of an electron.
The Transmission Coefficient in the Theory of Absolute Reaction Rates
Authors: Hulburt Hugh M. , Hirschfelder J. O.
Published: January 2005

The activated complex theory of reaction rates is discussed critically. The transmission coefficients for a number of idealized energy surfaces have been computed quantum mechanically. It appears that curvature of the reaction path may introduce activation energy in addition to that caused by constriction and elevation of the energy valley. Except at low temperatures, this additional activation energy is almost negligible. However, it may contribute to the separation of isotopes, where small differences in activation energy are important. For systems in thermal equilibrium at room temperatures and above, the average quantum mechanical transmission coefficient is found to differ insignificantly from that calculated by classical mechanics.
An Application of Group Theory to Isomerism in General
Authors: Hill Terrell L.
Published: January 2005

By making use of Polya's theorem and the groups of symmetries of the geometrical models representing unsubstituted parent compounds, it is possible to include the various kinds of isomerism in a single discussion. The number of isomers calculated by this procedure is the total number of all types.
The Low Velocity Scattering of H+ and H3+ in Hydrogen
Authors: Simons J. H. , Fontana C. M. , Muschlitz E. E. , Jackson S. R.
Published: January 2005

The theory of the elastic scattering of a low velocity ion in a gas is examined in some detail. More precise measurements are reported on the elastic scattering of H+ and H3+ in hydrogen in the velocity range of 2 to 135 volts. The simple exponential form of a potential law is shown to change with the velocity of the ion, i.e., with distance of closest approach of the interacting particles. For H+ in H2 this is—V=−20.37×10−32r4from 2 to 24 volts (ra>1.74A)and V=−8.68×10−14r1.74from 24 to 135 volts (ra=1.74 to 1.5A).The interaction energy calculated on this basis is 3.0 electron volts instead of the 3.5 previously reported. For H3+ in H2 an average taken from 5.4 to 130 volts is V=−1.145×10−36r4.60(ra=2.12 to 1.07A);but between 10.5 and 28 volts (ra = 1.85 to 1.48A) V=−5.98×10−32r4.Both inverse fourth-power potential laws are compared with a similar law evaluated on the basis of the interaction being due solely to that of the charge on the ion interacting with the induced dipole of the hydrogen molecule. The H3+ law is seen to approximate this closely whereas the H+ law does not.
The Low Velocity Scattering of H2+ in Hydrogen. The Determination of Neutralization
Authors: Simons J. H. , Fontana C. M. , Francis H. T. , Unger L. G.
Published: January 2005

Measurements of the effective cross-sectional area for neutralization have been made for H2+ in hydrogen over a velocity range of 4 to 30 volts. As this is an electron transfer phenomenon, its measurement is of some theoretical interest. The technique of the method of measurement is discussed and possible experimental uses for it are suggested. The ability to make these measurements has enabled the elastic scattering of H2+ in hydrogen to be determined. In the range of 10 to 25 volts (ra = 2.14 to 1.70A), the potential law found is V=−10.0×10−32r4. As the constant, K, in this equation is considerably greater than an interaction based upon the polarizability of the hydrogen molecule, other forces such as those causing valence bonds must come into play in addition. Above 25 volts (ra < 1.70A) the potential law becomes V=−6.96×10−24r3.
The Scattering of Low Velocity Hydrogen Ions in Water Vapor
Authors: Simons J. H. , Francis H. T. , Muschlitz E. E. , Fryburg G. C.
Published: January 2005

The elastic scattering of H+, H2+, and H3+ in water vapor has been measured in the velocity range 2 to 130 volts. For H+ the potential law for 3 to 15 volts (ra = 2.74 to 1.77A) is V=−6.33×10−32r4. Assuming an equilibrium distance of 1.013A the proton affinity of H2O is calculated to be 6.5 electron volts. Above 15 volts (ra < 1.77A) the coefficient of r becomes very large (about 20). For H2+ in H2O between 3 and 20 volts (ra = 3.14 to 2.33A) V=−193×10−56r7. Above 20 volts the coefficient of r increases to a much larger value (about 13). H3+ in H2O shows a potential law V=−8.7×10−16r2 between 5 and 20 volts (ra = 4.27 to 2.33A). This is about what would be expected on the basis of the interaction of a dipole and a charge. Between 20 and 30 volts the coefficient of r becomes 3 and from 30 to 60 volts it is much larger (about 8). Neutralization is experienced with both H+ and H2+ in H2O but not with H3+. These neutralization cross sections are reported as a function of velocity. A design is given of a Knudsen gauge found satisfactory for the measurement of the pressure of water vapor. A new technique is described which was found necessary for the removal of insulating films on the metallic surfaces. These films are apparently carbonaceous and formed by the action of the ion beam on traces of organic compounds in the vapor. The technique used is an electric discharge in oxygen.
Photographic Development as a Catalyzed, Heterogeneous Reaction
Authors: James T. H.
Published: January 2005

Development is considered as a catalyzed reaction which takes place at the interface between the silver nuclei and the solid silver halide crystal. Silver atoms formed at the interface may migrate along the silver surface for some distance before they become incorporated into the silver lattice. An explanation of filament formation is given on this basis.
A Partition Function for Liquids from the Harmonic Oscillator Model
Authors: Matsen F. A. , Watson George M.
Published: January 2005

The energy of the molecules of a liquid in their equilibrium positions and the frequency of vibration about those positions are expressed in terms of a parameter a, the average distance between the molecules. This follows from a formulation of an average potential or spherical symmetry from an assumed force field between pairs of molecules. The ordinary thermodynamic quantities are calculated from the resultant harmonic oscillator-partition function. Order-disorder effects are neglected.
Specific Heats of Carbon Tetrafluoride from Supersonic Measurements
Authors: Byers Walter H.
Published: January 2005

Measurements of the velocity and absorption of supersonic waves in carbon tetrafluoride were made over a range of pressures for each of two different frequencies. From the dispersion and absorption curves so obtained, the specific heat for equilibrium conditions, that portion of the specific heat due to intra-molecular vibrations, and the mean lifetime of a quantum of vibrational energy were calculated.
The Structure of Liquid Carbon Tetrachloride
Authors: Bray E. E. , Gingrich N. S.
Published: January 2005

Monochromatic x-ray diffraction patterns of liquid CCl4 at 25°C and at −20°C have been analyzed to obtain radial electron density distribution curves. These curves show discrete peaks corresponding to distances between atoms in a molecule (1.7A and 2.9A at −20°C; 1.74A and 2.92A at 25°C), as well as other peaks (3.6A, 4.1A, and 6.4A at −20°C; 4.0A and 6.3A at 25°C) which are not discrete and which represent distances between atoms in different molecules.
Infra-Red and Raman Spectra of Polyatomic Molecules XVIII. Trideuteronitromethane
Authors: Wilson Thomas P.
Published: January 2005

The infra-red spectrum of trideuteronitromethane has been studied in the range 3–25μ, and the Raman spectrum has been analyzed. From this data and that obtained by Wells and Wilson on nitromethane it has been possible to determine all the fundamental frequencies except that of the torsion about the C–N bond, and to carry out a normal coordinate treatment from which a potential function fitting the observed frequencies of nitromethane and trideuteronitromethane within 2 percent has been obtained.
Infra-Red and Raman Spectra of Polyatomic Molecules. XX. Cyclobutane
Authors: Wilson Thomas P.
Published: January 2005

The infra-red spectrum of cyclobutane in the range 2 to 25μ has been obtained, together with the Raman spectrum of the same material. Analysis of these spectra, together with a normal coordinate treatment of the problem, has led to a tentative assignment of the fundamentals which explains all features of the observed spectra. Butene-1 has been identified as a product of the liquid phase photolysis of cyclopentanone.
Some Remarks on the Kinetics of Vinyl Derivative Polymerization
Authors: Abere J. , Goldfinger G. , Mark H. , Naidus H.
Published: January 2005

The various elementary steps of vinyl polymerization reactions are discussed. Activation is considered to occur by collision of an unactivated monomer either with another monomer, a catalyst, a solvent, or a polymer molecule. It is further taken into account that certain types of active nuclei can be more easily deactivated than others. Two steps of propagation are considered: normal chain growth and chain transfer. Termination of growing chains is assumed to be possible either by collision with another growing chain, with an activated monomer, with a molecule of the catalyst, or with certain chain breaking impurities. Using the assumption that for a certain period of the reaction a steady state of activated centers is maintained, equations are derived for the initial over-all rate of the reaction and for the number average polymerization degree. These equations are compared with experiments which have been carried out on the polymerization of styrene at various temperatures, monomer concentrations, and catalyst concentrations. Comparison between theory and experiments shows that in first approximation, the initial over-all rate of the reaction and the initial number average polymerization degree can be represented by the derived equations.
Equilibrium in Hydrogen-Water Systems Containing Tritium
Authors: Black James F. , Taylor Hugh S.
Published: January 2005

The equilibrium constant of the reaction HT+H2O = H2+HTO involving radioactive hydrogen (T) has been determined over the temperature range 289 to 576°K in contact with a platinum-charcoal catalyst. The results are summarized in the equations: logK=0.292 log T+336.5/T−1.055ΔF∘=+4.83T−1.34TlogT−1540ΔH∘=0.58T−1540ΔS∘=1.34logT−4.25ΔCp∘=0.58±0.05 cal./deg./moleΔHo∘=−1540±160 cal./moleI=1.055.Comparison of the experimental results with theoretical calculations by W. F. Libby indicates the correctness of these latter and confirms the assumption with respect to isotopic species that the forces acting within a molecule are unaltered by the change in nuclear mass and that any effects on the properties of the molecule are solely due to a different mass moving in the same force field.
The Use of the Exchange Between Carbon Dioxide, Carbonic Acid, Bicarbonate Ion, and Water for Isotopic Concentration
Authors: Reid Allen F. , Urey Harold C.
Published: January 2005

A study was made of the exchange of oxygen and carbon in the reactions: CO2 (dissolved)+H2O⇄H2CO3,CO2 (dissolved)+OH−⇄HCO3−.It was found that the rate of the first could be increased four or five times and the rate of the second up to 2000 times by heterogeneous catalysis. Investigation of the use of these catalyzed reactions for separation of the oxygen and carbon isotopes was carried out both by the use of a static bomb technique and by the operation of fractionating columns. The effects of different operating conditions were indicated, and the necessity for turbulent flow in the gas phase was established. Pressures from one through fifty atmospheres were tried, as the increase of CO2 pressure increases the concentration of CO2 (dissolved) and thus speeds up the exchange.

A comparison of the above method with the HCN – CN− method of separation of carbon isotopes shows the cyanide exchange to be somewhat faster and to require less time to come to production, somewhat doubtful advantages when they must be coupled with the polymerization and poisonous properties of the hydrogen cyanide, as well as with its greater cost.
The Photographic Latent Image II. Outline of the Theory
Authors: Huggins Maurice L.
Published: January 2005

A theory of the formation and growth of the photographic latent image and of the development process in the crystal containing it is outlined. It is assumed that the latent image consists of a small region of the (silver halide) crystal in which the atomic arrangement is the ``tetrahedral'' B3 type (or another closely related arrangement), stabilized by the presence of one or more photoelectrons, with or without extra silver ions.
Discrimination in Mass Spectrometer Ion Sources
Authors: Coggeshall Norman D.
Published: January 2005

An analysis is made of the collection and definition of a beam of ions by an ion source. It is found that the first slit of the source has no discriminating effect but the second slit does have. This is due to the fact that ions of certain values of initial energy, angle of velocity vector, and position of striking the plane of the first slit cannot get through the second one. An efficiency of collection of a source for ions of a certain initial energy is defined as the ratio of the number with that initial energy that get through the second slit to the number with that initial energy which get through the first slit. An expression for this efficiency is derived and it is applied to rather typical data to show how an abundance ratio obtained by taking the ratio of peak heights may be in error several percent. The method of measuring isotopic abundances is recommended wherein the focusing conditions are changed only by varying the magnetic analyzer field.
An Application of Probability Considerations to the Mechanism of the Photochemical Polymerization of Acetylene
Authors: Dunicz Bolesl/aw Ludwik
Published: January 2005

The series of experiments described in a recent paper led to an account of the mechanism of the photochemical polymerization of acetylene based upon the hypothesis that this process should be a chain reaction operating by cycles, each of them consisting of three stages, and that chain termination ought to depend upon the probability of formation of an aromatic nucleus among the polymers resulting from each particular cycle. While nothing is known of the intrinsic probabilities of the reactions postulated, the proposed mechanism seemed to offer an opportunity for quantitative treatment by the application of probability considerations. The present paper shows that if the probabilities of the formation of products of the addition and breaking of the easily dissociated single C–C bonds in the unstable products, in the respective stages of reaction, are assumed equal, quantum yields and heats of reaction may be calculated, which are in fair agreement with data found experimentally.
Butene-1 and Butene-2 Equilibrium
Authors: McCarthy W. Walter , Turkevich John
Published: January 2005

The equilibrium between butene-1 and butene-2 was attained on activated alumina at 400 and 450°C. The values obtained were found to agree with calculated results.
The Thermodynamic Properties of Gaseous Sulfur Trioxide
Authors: Stockmayer W. H. , Kavanagh G. M. , Mickley H. S.
Published: January 2005

The thermodynamic properties of sulfur trioxide in the ideal gas state are calculated from molecular data. To obtain satisfactory agreement with the equilibrium data for the reaction SO2+½O2=SO3, it is necessary to include vibrational anharmonicities, which are somewhat larger than usual because of an accidental degeneracy involving two of the normal frequencies. The standard entropy of SO3(g) at 25°C is 61.2±0.2 E.U., and its standard heat and free energy of formation from the elements are ΔH°298.16=−94.43±0.15 and ΔF°298.16=−88.48±0.20 kcal./mole.
Effect of Deformation on the Swelling Capacity of Rubber
Authors: Flory Paul J. , Rehner John
Published: January 2005

Elongation of swollen vulcanized rubber, or other polymeric materials possessing random network structures, should increase the amount of liquid absorbed (dissolved) at equilibrium with an excess of the swelling agent. According to a previously published equation relating to the thermodynamics of stretching and swelling of rubber, the relative volume of the swollen rubber at equilibrium should equal the square root of the relative stretched length. Experiments with butyl rubber vulcanizates in xylene support these predictions of theory.
The Kinetics of the Electroreduction of Acetone
Authors: Hennig Gerhart R. , Kimball George E.
Published: January 2005

The electrolytic reduction of acetone in alkaline aqueous solutions at a mercury surface has been studied with the object of determining the kinetics of the formation of isopropyl alcohol and pinacol. The reduction rate has been studied at various acetone concentrations, in varying concentrations of sodium hydroxide, in solutions of sodium sulfate, sodium chloride, barium hydroxide, and potassium hydroxide. During electrolysis the rates of formation of isopropyl alcohol and pinacol were followed continuously. It is found that at low acetone concentrations the rate of formation of isopropyl alcohol is proportional to the acetone concentration, while the rate of formation of pinacol is proportional to the square of the acetone concentration. At somewhat higher acetone concentrations the pinacol rate becomes linear in acetone concentration, and near saturation the isopropyl alcohol rate becomes practically independent of acetone concentration. At constant current density, increasing the sodium hydroxide concentration decreases the yield of isopropyl alcohol and increases the yield of pinacol (except at high concentrations of acetone and sodium hydroxide). Substitution of chloride or sulfate for hydroxide causes an increase in the alcohol rate but lowers the pinacol rate. Substitution of barium for sodium stops the reduction completely. Substitution of potassium for sodium increases both yields. Increasing the current density is accompanied by a decrease in the fraction of the current which goes into isopropyl alcohol formation and pinacol formation. It is shown that these experimental results can be explained by a modification of the mechanism proposed by Müller. The acetone is first adsorbed on the mercury with the formation of a covalent bond. The product of the adsorption may dissociate from the surface as a free radical, in which case pinacol is the final product, or it may first add on a proton and then dissociate from the surface as an ion which adds a second proton to become isopropyl alcohol.
Thermodynamics of Heterogeneous Polymers and Their Solutions
Authors: Flory Paul J.
Published: January 2005

The statistical mechanical treatment previously applied to homogeneous polymer solutions has been extended to heterogeneous polymers composed of numerous molecular species differing in polymer chain length. Entropies of mixing with solvent are derived with reference to three standard states: the oriented pure components, the disoriented pure components, and the disoriented mixture of species. The entropy of mixing with respect to the last-mentioned state is identical with that previously derived neglecting polymer heterogeneity. Upon introducing a van Laar heat of mixing term, expressions for the partial molal free energies are derived. These should be reasonably correct in view of the satisfactory agreement between observed solvent activities in polymer-solvent solutions and theory, as shown by Huggins. The relationships should be useful not only in dealing with solutions, but also in equilibria involving heterogeneous polymers in the absence of solvent. The thermodynamic equations are applied to the problem of equilibrium in the range of partial miscibility for solvent-heterogeneous polymer systems. The requisites for efficient fractionation of high polymers are discussed. The efficiency of separation depends on the ratio of the volumes of the supernatant and the precipitated phases. In order to attain a high value for this ratio, very dilute solutions must be employed. The higher the molecular weight at which separation occurs the greater the dilution required for the same sharpness of separation. The free energy expressions are also applied to the formulation of equilibrium constants to be employed in reversible polymerization-degradation processes. It is shown that concentrations should be expressed in moles per unit volume in the equilibrium constant. The equilibrium state for a polyfunctional condensation, considered as a reaction between functional groups, is not affected by the polymeric nature of the reacting species; the position of equilibrium should be the same as is found for analogous monofunctional reactants under the same conditions.
The Dielectric Properties of β-Lactoglobulin in Aqueous Glycine Solutions and in the Liquid Crystalline State
Authors: Shaw T. M. , Jansen E. F. , Lineweaver H.
Published: January 2005

The dielectric constant ε′ and loss factor ε″ of solutions of β-lactoglobulin dissolved in aqueous 0.48, 1.5, and 2.5 molar glycine, and the dielectric constant of β-lactoglobulin liquid crystals have been measured for frequencies between 0.01 and 5.0 megacycles. The data show a broader frequency range of dispersion and absorption and a smaller value of ε″max than is predicted by the Debye theory for a system characterized by a single relaxation time. The disparity between the experimental data and the Debye theory increased with the concentration of lactoglobulin and was greater than expected on the basis of the small effects of protein concentration on other physical properties of β-lactoglobulin, e.g., sedimentation constant. Dielectric constants for ``zero'' and ``infinite'' frequencies have been obtained by the Cole circular-arc method of extrapolation. The frequency dependence of ε′ and ε″ was found to be well represented by the empirical equation of Cole and Cole, ε′−iε′′=ε∞+(ε0−ε∞)/[1+(iωτ0)1−α]. In this equation ε0 and ε∞ are, respectively, the dielectric constants for zero and infinite frequencies, ω = 2π times the frequency, τ0 is a generalized relaxation time, and α is a constant, 0<α<1. For α = 0, the equation reduces to that of Debye for a system characterized by a single relaxation time. For the solutions of β-lactoglobulin α was found to range from 0.08 to 0.4, depending upon the lactoglobulin and glycine concentrations. The relaxation time varied from 7.5 to 25 × 10−8 sec. for a change in lactoglobulin concentration of 3.5 to 94.0 grams per liter. The dipole moment is estimated to be 790±26 × 10−18 e.s.u.
Note on Becker's Theory of the Shock Front
Authors: Thomas L. H.
Published: January 2005

Becker, in a classical paper, concludes that weak shocks are many free paths thick and may be treated by ordinary hydrodynamics including the effects of viscosity and thermal conductivity of the medium; that moderately strong shocks have a thickness of the order of a free path and must be treated by a direct attack on the relevant Boltzmann equation; while violent shocks have a thickness small compared with a free path and even the Boltzmann equation is no longer applicable. It is shown here that this last conclusion rests on an oversight; the thickness of a shock front is always at least of the order of magnitude of a free path, and it is to be expected that the Boltzmann equation can be applied even for the most violent shocks.
Bromination of Hydrocarbons. II. Photochemical Bromination of Ethane and Ethyl Bromide. Carbon-Hydrogen Bond Strength in Ethane
Authors: Andersen Holger C. , Van Artsdalen E. R.
Published: January 2005

The kinetics of the photochemical bromination of ethane was determined. The mechanism is very similar to the analogous brominations of hydrogen and methane: (1)     Br2+hν=Br+Br(2)   Br+C2H6=C2H5+HBr(3)  C2H5+Br2=C2H5Br+Br(4)  C2H5+HBr=C2H6+Br(5) Br+Br+M=Br2+M.Rate constants computed by assuming various efficiencies for ethane as the third body in step (5) are presented, as well as those calculated by considering heterogeneous recombination of bromine atoms. The rate of bromination of ethyl bromide is about the same as that for ethane, but its exact determination was precluded by the presence of rapidly brominated impurities. The experimental activation energy, 13.6±0.5 kcal., is quite insensitive to the several variations in mechanism discussed, and indicates a value of 98±2 kcal. for the upper limit of the strength of the C2H5–H bond. This figure is in good agreement with absolute values reported by other workers.
The Infra-Red Spectra of Bent XYZ Molecules Part I. Vibration-Rotation Energies
Authors: Shaffer W. H. , Schuman R. P.
Published: January 2005

The rotation-vibration Hamiltonian, complete to second order of approximation, is set up for the bent XYZ molecular model. The allowed energies are calculated and expressed in term-value form, E=hc(G+F); the vibrational term G is given explicitly and the elements of the secular determinant are given for evaluation of the rotational term F. The valence-force form of harmonic potential function is discussed for the bent XYY′ model and normal frequencies of HDO are calculated.
Raman Spectra of Hydrocarbons IV. 2,5-Dimethyl-1,5-Hexadiene and 2,5-Dimethyl-2,4-Hexadiene
Authors: Cleveland Forrest F.
Published: January 2005

Raman frequencies, relative intensities, and depolarization factors are given for (A) 2,5-dimethyl-1,5-hexadiene and (B) 2,5-dimethyl-2,4-hexadiene. The relative intensities and depolarization factors were obtained with the aid of a Gaertner microdensitometer. The two molecules are isomers, each containing eight carbon and fourteen hydrogen atoms. (A) contains two XYC=CH2 groups and (B) contains two XXC=CHZ groups. In (B) the double bonds are conjugated, in (A) unconjugated. The results for the five olefinic frequencies are compared with data previously obtained for nine other olefins. The data for the olefinic lines of (A) are 1297(50), 1414(430)0.74, 1651(1000)0.21, 2977(580)0.28, and 3074(220)0.78, values which are in good agreement with those obtained previously for olefins containing an XYC=CH2 group. For (B) the olefinic frequencies are 1227(75)0.46, 1663(1000)0.18, 3012(vw), and 3040(vw) (vw = very weak). The conjugation thus resulted in a lowering of these frequencies of 19, 19, 0, and 10 cm−1, respectively, from the values of the corresponding frequencies of the XYC=CHZ group in dipentene.
The Photolysis of Methylamine
Authors: Wetmore Orville C. , Taylor H. Austin
Published: January 2005

The photolysis of methylamine has been shown to proceed essentially by two consecutive first-order reactions, the first to produce hydrogen, ammonia, and CH2 : NCH3; the second a dehydrogenation of the latter at a rate approximately double the first. A mechanism involving hydrogen atoms has been postulated. These have been shown experimentally to be present and also have been shown by discharge-tube experiments to react with methylamine.
The Dependence of the Intensity of Fluorescence on the Composition of a Fluorescing Solution
Authors: Rollefson G. K. , Dodgen Harold W.
Published: January 2005

The fluorescence of solutions of fluorescein and acridone has been studied as a function of (1) the concentration of iodide added with a constant concentration of the fluorescer and (2) the concentration of the fluorescent substance. It is shown that the results are fitted much better by the equation of Stern and Volmer than by that of Perrin. In the absence of a quencher the intensity of the fluorescence observed is given by a function of the concentration which takes into account the following three effects: (1) the absorption of the exciting light by the solution, (2) the absorption of the fluorescent light, and (3) the quenching by the molecules of the fluorescent substance. No other effects needed to be considered for the substances studied.
Infra-Red Absorption of Solid Ammonium Chloride and Ammonium Bromide
Authors: Beck Clifford
Published: January 2005

According to theoretical considerations based on specific heat, dielectric constant, coefficient of expansion, and other properties, the molecules of the solid ammonium halides, at room temperature, are thought to possess rotatory motion. This rotation is expected not to exist at temperatures below the transition temperature; namely, −30.4°C for the chloride and −37.9°C for the bromide. Molecular rotation, if present, should give rise to rotational fine structure superposed on the infra-red vibrational bands of the salts. Previous workers found evidence of this, but have not resolved the fine structure. The present investigation was undertaken in the hope of resolving this fine structure, if any, and studying the changes in it resulting from lowering the temperature below the transition point. Fine structure in the 5.6-μ vibrational band of ammonium chloride and ammonium bromide was resolved. This structure was of the order of magnitude expected if the NH4 group rotating in the molecule were responsible for the fine structure. The fine structure existed practically unaltered to temperatures down to −20°C. There was considerable change between −20°C and −45°C, but then the altered fine structure persisted down to at least −60°C with little additional change.
The Mercury Photosensitized Polymerization of Acetylene
Authors: Le Roy D. J. , Steacie E. W. R.
Published: January 2005

An investigation has been made of the mercury (3P1) photosensitized polymerization of acetylene. The polymerization is inhibited by nitric oxide and it is concluded that free radicals are probably involved. The quantum yield of the uninhibited reaction is 4.5±1.2. Experiments over the range 25°C to 300°C show that the temperature coefficient of the reaction is not large. A few measurements were also made with Cd(3P1) and Cd(1P1) atoms.
Cyclotron Targets: Preparation and Radiochemical Separation. II. Krypton
Authors: Brown Sanborn C. , Irvine John W. , Livingston M. Stanley
Published: January 2005

Radioactive krypton (T=34h, e+, γ) has become a very useful gas for tracer experiments. This isotope can be made by Br79,81(d, 2n)Kr79,81. Preparation and separation of this gas have been a routine matter in this laboratory for some time and a brief description of the methods used is of interest. Two different methods will be described. Both are equally good as far as the separation of the krypton is concerned. One method involves very simple manipulation, but requires an apparatus made of monel metal, fused quartz, and Pyrex glass; the other uses only readily obtainable and inexpensive apparatus, but slightly more complicated manipulation.
Raman Spectra of Acetylenic Bromides, Iodides, and Ketones and of Some Cyclic Compounds
Authors: Murray M. J. , Cleveland Forrest F.
Published: January 2005

Raman spectra are listed for series of acetylenic bromides, iodides, and ketones, and for ascaridole, 1,3-dioxane, ethyl-p-toluenesulfonate, and for the cis- and trans−1,2-diacetoxycyclohexanes. Depolarization factors (when obtained) and relative intensities were measured by use of a Gaertner microdensitometer.