bluuebunny/crossref_metadata_2025 huggingface dataset:
The Formation of Negative Ions in Gases Part II. CO2, N2O, SO2, H2S and H2O
Authors: Bradbury Norris E. , Tatel Howard E.
Published: November 2004

The study of electron attachment has been extended to the gases CO2, N2O, SO2, H2S and H2O. No negative ions were observed in CO2. In N2O, below X/p=2, no negative ions were formed, and the N2O molecule apparently has no electron affinity. For values of X/p>2, the electrons possessed sufficient energy to dissociate the molecule and negative ions, probably O—, were formed in increasing numbers. SO2 showed an electron affinity forming negative ions with electrons of very low velocity. The probability of attachment decreased as X/p increased until an X/p of about 13 when an increase in probability of formation was noted. This is probably due to dissociation and formation of SO—. No negative ions were observed in H2S below an X/p of 6. For greater values of X/p negative ions were formed in increasing amounts presumably by a dissociation process with the formation of HS—. A similar behavior was observed in H2O at an X/p=10, with the formation of OH—. Negative ion formation in H2O was also observed at low X/p and varied with the pressure of the gas. This is explained as being due to negative ion formation from small molecular aggregates existing near the point of condensation of the water.
A Study of the Methods of Interpretation of Electron-Diffraction Photographs of Gas Molecules, with Results for Benzene and Carbon Tetrachloride
Authors: Pauling Linus , Brockway L. O.
Published: November 2004

The reliability and accuracy of the visual method of interpreting electron-diffraction photographs, consisting in the correlation of values of (4π sin ν / 2) / λ obtained by visual measurement of rings of apparent maximum and minimum intensity with x values from a simplified theoretical curve (Eq. (7) or (8)), have been tested in the following ways: (a) The measurement and interpretation of ``artificial electron-diffraction photographs'' of bromine; (b) the comparison of electron-diffraction and bandspectral values of interatomic distances for bromine, chlorine and iodine chloride; (c) the study of microphotometer records for benzene, and comparison of results with those of the visual method; (d) the study of micro photometer records for carbon tetrachloride, and comparison with the visual method. It is concluded that the visual method when carefully applied leads to values of interatomic distances accurate to about 1 percent (probable error), or to ½ percent in favorable cases. The regular plane hexagon model of the benzene molecule is verified, the carbon-carbon distance in the ring being determined as 1.390±0.005A. The carbon-chlorine distance in the carbon tetrachloride molecule is determined as 1.760±0.005A. A brief discussion of the methods and results of other investigators is given.
Crystal Structures and Expansion Anomalies of MnO, MnS, FeO, Fe3O4 Between 100°K and 200°K
Authors: Ellefson Bennett S. , Taylor Nelson W.
Published: November 2004

(1) Determinations have been made of structure type and lattice constants of MnO, MnS, FeO and Fe3O4 at temperatures near those at which these substances show specific heat anomalies. (2) No major structure changes were apparent in the x-ray patterns. All structures are cubic at all investigated temperatures. Lattice constant data indicate similarity in the abnormal expansion behavior of MnS and FeO and of MnO and Fe3O4. (3) The specific heat and expansion anomalies are probably due to electron transitions within certain atoms in the crystal lattice and may be analogous to the behavior of metallic iron at 765°C, or of quartz at 575°C.
The Use of the Interferometer in the Isotopic Analysis of Water
Authors: Crist R. H. , Murphy G. M. , Urey H. C.
Published: November 2004

A method of analysis of mixtures of protium and deuterium oxides is presented. It consists in calibrating the apparent difference in indices of refraction of natural water and that containing higher concentrations of deuterium oxide, as obtained by a Zeiss water interferometer, against the corresponding differences in specific gravities. It is found that these two quantities are not proportional. The precision of measurement in the neighborhood of an experimentally determined specific gravity in a 40.06 mm cell is 0.01 percent.
The Emission of Alkali Atoms from Various Ammonia Catalysts
Authors: Brewer A. Keith
Published: November 2004

An apparatus is described for measuring the rate of emission of alkali as positive ions and as neutral atoms from the ammonia catalysts. The results show that when the temperature of the catalyst is first raised to the emission point the number of atoms leaving the surface far exceeds that of ions. In the course of several minutes heating the emissivity of atoms decays to a negligible value. Atom emission is much more persistent from catalysts containing Al2O3, also the temperature for equivalent ion currents is higher. Both atom and ion emission increase when sintering occurs, since the alkali can then diffuse more readily to the surface. The factors determining the ratio of atoms to ions are discussed. Under the conditions where the alkali concentration at the surface amounts to several hundredths of a molecular layer the presence of the adions will lower the work function of an appreciable fraction of the surface to a point below the ionization potential of potassium, thus permitting the potassium to escape as neutral atoms. When the alkali concentration is small, however, the work function is close to that of pure iron and the potassium can escape only in the form of ions.
The Raman Spectrum of Arsenic Trifluoride and the Molecular Constants of AsF3, AsCl3 and PCl3
Authors: Yost Don M. , Sherborne John E.
Published: November 2004

The Raman spectrum of AsF3 was found to consist of four lines with the frequencies ω1(1), 707; ω2(1), 341; ω3(2), 644; and ω4(2), 274 cm—1. The selection rules require a pyramidal molecule. Electron diffraction data for AsF3, AsCl3 and PCl3 are used to establish the bond angles. The entropies of the three trihalides were calculated, and the standard free energies of formation of AsCl3(l) and AsCl3(g) were determined to be —65,190 cal. and —62,718 cal., respectively, at 25°.
An X-Ray Study of the Structure of Liquid Benzene, Cyclohexane and Their Mixtures
Authors: Ward Herbert K.
Published: November 2004

Carefully purified benzene and cyclohexane exhibit x-ray diffraction peaks corresponding to preferred spacings of 4.68A and 5.09A, respectively, which are interpreted as the effective thicknesses of the respective rings. Mixtures of these two hydrocarbons give rise to two independent diffraction peaks indicating emulsion-type solutions, in which the disperse phase is too small to show even a Tyndall effect.
Acoustical Studies. IV. The Collision Efficiencies of Various Molecules in Exciting the Lower Vibrational States of Ethylene, Together with Some Observations Concerning the Excitation of Rotational Energy in Hydrogen
Authors: Richards William T. , Reid James A.
Published: November 2004

The velocity of sound in pure ethylene has been determined at various pressures, temperatures and frequencies. It is concluded that equilibrium is attained between the various states of the vibrational energy on every effective collision, but that a considerable activation energy of collision is required for the conversion of translational into vibrational energy. Collisions with argon, helium, and nitrogen molecules have no appreciable effect on the vibrational energy of the ethylene molecule. Collisions with hydrogen molecules are about ten times as effective as ethylene-ethylene collisions in producing transitions in the lower vibrational energy states of ethylene. Hydrogen shows a dispersive region at ultrasonic frequencies which is apparently due to the failure of the rotational energy transitions to follow the acoustical cycle. It has been found necessary to suppose that ethylene-hydrogen collisions are about twenty times as effective as hydrogen-hydrogen collisions in exciting the rotational energy of hydrogen molecules.
The Separation of the Hydrogen Isotopes by Electrolysis. Part I
Authors: Topley B. , Eyring H.
Published: November 2004

The equilibrium constants of the reactions H2O+2D=D2O+2H and H2O+D2O=2HDO are calculated and from these an expression is obtained for the electrolytic separation coefficient, valid when zero-point energy and tunnelling are negligible in the activated state. The change in this coefficient with increase in concentration of the heavy isotope is calculated. Experimental values have been determined for the separation coefficient at different metallic cathodes, ranging from 7.6 to 2.8. Local concentration disturbances round the cathode are not in general important, but may be the cause of the poor separation found with platinum black. The importance of half-quanta in the activated state is discussed. The experimental results considered in the light of the calculations indicate that tunnelling is not very important in the electrolytic separation. The vapor pressures of liquids containing isotopes are considered.
The Mutual Repulsive Potential of Closed Shells
Authors: Bleick Willard E. , Mayer Joseph E.
Published: November 2004

A method is developed for representing, in terms of a small number of integrals, the mutual potential of two ions or atoms having a rare gas electron configuration. The accuracy is the usual first approximation of the Heitler-London method. The integrals are evaluated for two like atoms, and numerical calculations made for two neon atoms. The total (repulsive) potential at R=1.8×10-8 cm is 344×10-14 erg; at R=2.3×10-8 cm, 35×10-14 erg; and at R=3.2×10-8 cm, 0.4×10-14 erg.
The Experimental Determination of the Heat Capacity of Explosive Gases by a New Method
Authors: Lewis Bernard , von Elbe Guenther
Published: November 2004

A method is described for determining the heat capacity of explosive gases at temperatures up to several hundred degrees above room temperature, by exploding the gas whose heat capacity is to be determined in a spherical bomb. The same data are required as are needed to determine the heat capacity of the burned gas by the explosion method, namely, the maximum pressure developed in the explosion, the initial temperature and initial pressure, the composition of the gas mixture, and the heat of reaction. Equations have been developed, and the method is described in detail. The method is particularly useful for the determination of heat capacities of easily decomposed gases, such as O3 and Cl2O, for which the flow method is unsuitable. An interesting consequence of the method is that it permits simultaneous determination of the heat capacity of carbon dioxide at high and low temperatures by exploding mixtures of gaseous ozone and carbon dioxide.
The Raman Spectra and Molecular Constants of the Hexafluorides of Sulfur, Selenium and Tellurium
Authors: Yost Don M. , Steffens Carsten C. , Gross Siegfried T.
Published: November 2004

The Raman spectra of the gaseous and liquid hexafluorides of sulfur, selenium and tellurium were determined (Table I). Three lines for each substance were observed and this is the number permitted by the selection rules for a regular octahedral molecule. Frequency formulae based on central forces were derived, and these, together with the appearance of the spectra, were used to assign the observed frequencies to the proper modes of vibration. Estimates of the magnitudes of the forbidden frequencies were made. A provisional value of —238,000 cal. is given for the free energy of formation of SF6 (g) at 25°.
The Mercury Photosensitized Decomposition of the Deuteroammonias
Authors: Jungers Joseph C. , Taylor Hugh S.
Published: November 2004

A method of preparation of ammonias in which one, two and three hydrogens are replaced by deuterium has been devised. It reveals that the preparation of magnesium nitride from magnesium and ammonia yields amido- or imido-compounds as intermediate stages of great stability. The physical properties of deuteroammonia preparations have been studied. Ultraviolet absorption spectra reveal the presence of all three substituted deuteroammonias in the preparations studied. The mercury photosensitized decomposition of trideuteroammonia is more than ten times slower than the corresponding reaction of ammonia. It is also inhibited much more strongly by deuterium than is ammonia decomposition by hydrogen. Increasing deuterium content of ammonia decreases the rate of sensitized decomposition. The kinetics of decomposition are qualitatively similar but quantitatively different. The quantitative results are compared with data on quenching of fluorescence of mercury resonance radiation by the several gases in question and lead to important conclusions concerning the nature of the collisions involved in the decomposition process.
Acid-Base Reactions Involving Deuterium
Authors: Wynne-Jones W. F. K.
Published: November 2004

From measurements of the rate of neutralisation of a pseudo-acid, nitroethane, in heavy water, a comparison is made of the relative rates of ionisation of protium and deuterium atoms, the ratio being approximately 10 : 1. It is shown that these relative rates are of great importance in the study of catalysis by acids and bases in heavy water and some conclusions may be drawn with regard to the mechanism of the inversion of sucrose and of the mutarotation of glucose. These results also have a bearing on the question of deuterium-protium exchange in compounds when dissolved in water.
Heat Capacity Curves of the Simpler Gases. VI. Rotational Heat Capacity Curves of Molecular Deuterium and of Deuterium Hydride. The Equilibrium Between the Ortho and Para Forms of Deuterium. Free Energy, Total Energy, Entropy, Heat Capacity and Dissociation of H2H2 and of H1H2, to 3000°K1
Authors: Johnston Herrick L. , Long Earl A.
Published: November 2004

Heat capacities, entropies, free energies, total energies and dissociation constants have been calculated for H2H2 and for H1H2, to 3000°K, by reliable methods and are listed in tabular form. The ortho-para equilibrium in H2H2 has been considered for both the gaseous and the solid states. The solid state equilibrium has been discussed from the point of view of its bearing on the application of the third law of thermodynamics. The rotational heat capacity curves of the various forms of H2H2 and that of H1H2 are shown graphically and are compared with the rotational heat capacity curve of ordinary hydrogen and with the hypothetical rotational specific heats of gaseous nitrogen. The heavy molecules, H2H2 and H1H2, dissociate to only about one-half the extent of H1H1 below 3000°K. The three hydrogen molecules are compared with respect to the influences of molecular stretching and of anharmonic vibration in the high temperature heat capacities. We also include tables which show the distributions of molecules among the vibrational levels as a function of the temperature.
The Theory of Moderate Deviations from van't Hoff's Law
Authors: Coleman J. J. , Germann F. E. E.
Published: November 2004

A sketch of the application of van der Waals notions to the study of deviations from van't Hoff's law made by A. A. Noyes is given and a modification of the theory is introduced. An osmotic pressure equation is then deduced from a heat of formation equation. The new theory is shown to be, at least formally, in harmony with the old. Both theories result in an equation of the van der Waals type for osmotic pressures. This constitutes an extension of van't Hoff's very useful analogy between dilute solutes and gases.
Note on Electric Moments and Infrared Spectra, and the Structure of CO
Authors: Mulliken Robert S.
Published: November 2004

The desirability of measurements of infrared intensities in order to determine electric moments as functions of interatomic distances is illustrated by a discussion of available data on HCl, HI, CO and H2O. Some new information on the structure of CO is obtained.
The Crystal Structure and Magnetic Susceptibility of Caesium Argentous Auric Chloride, Cs2AgAuCl6, and Caesium Aurous Auric Chloride, Cs2AuAuCl6
Authors: Elliott Norman
Published: November 2004

The triple salts Cs2AgAuCl6 and Cs2AuAuCl6 have been investigated by means of magnetic susceptibility measurements and x-ray powder photographs in order to obtain information regarding the general nature of these compounds. Both compounds were found to be diamagnetic. X-ray powder-photographic data lead to a cubic structural unit with a0=5.33A for both crystals. The observed intensity values are in general agreement with the perovskite structure. Small discrepancies, however, suggest that the atomic arrangement varies slightly from the ideal perovskite structure. The detailed nature of the distortion was not determined. The bearing of these results on the valence type of the substances is discussed.
The Quenching of Mercury Resonance Radiation by Compounds Containing Deuterium
Authors: Evans Meredith G.
Published: November 2004

The quenching of mercury resonance radiation by hydrogen, deuterium, ammonia, deutero-ammonia, water vapor and heavy water vapor has been measured. It has been possible to correlate the differences in quenching efficiencies between the heavy and ordinary compounds with the changes in the vibrational level of the molecules which are brought about by the introduction of deuterium atoms. The quenching cross sections obtained fall on the general type of resonance curve.
The Infrared Absorption of Solutions of Hydroxides and Hydrolyzing Salts
Authors: Plyler E. K. , Gordy Walter
Published: November 2004

Absorption bands have been found at 3.65μ and 5.2μ in aqueous solutions of NaOH, KOH and LiOH. Solutions of ZnCl2, ZnBr2, NH4C2H3O2, Na2CO3, NaC2H3O2, Na2B4O7, Na2SiO3 and Al2(SO4)3 were studied in the region from 2.8μ to 6μ and bands were observed at about 3.45μ, 4.5μ, 5.2μ and 5.6μ. The solutions which are acid in reaction had intense bands at 3.6μ and 5.2μ, while the basic solutions gave a strong band at 5.6μ. This variation in intensity indicates that the absorption bands are due to undissociated molecules bound to water molecules. The band at 4.5μ is probably due to water which has been modified by the ions. The hydroxides showed the absorption bands at 3.6μ and 5.2μ when 0.1N solution was used.
The Quantum Mechanics of Unsaturated and Aromatic Molecules: A Comparison of Two Methods of Treatment
Authors: Wheland G. W.
Published: November 2004

A comparison is made of two quantum-mechanical methods of treatment of unsaturated and aromatic organic molecules. The HLSP treatment, which is based upon the use of Slater valence-bond eigenfunctions, seems to give results in somewhat better general agreement with experiment than the HMH, which is based upon the use of molecular orbitals of the Hund-Mulliken type. The latter, however, can be extended to a wider variety of problems. The problems considered include the energy relations among hydrocarbons, the dissociation of aryl substituted ethanes, the electron-affinity of free radicals and the acid strength of hydrocarbons.
The Theory of the Structure of Hydrogen Peroxide and Hydrazine
Authors: Penney W. G. , Sutherland G. B. B. M.
Published: November 2004

The method of electron pairs has been applied to determine the most stable configuration for the atoms in the molecules HO–OH and H2N–NH2. The calculations show that free rotation cannot occur in either of these molecules at ordinary temperatures and that the only stable forms are those in which the azimuth of one-half of the molecule with respect to the other is approximately 90°. The essential feature of the argument is that the electrons of the two central atoms arrange themselves to form the strongest possible bonds and in so doing render the charge density on these atoms unsymmetrical about the axis of the molecule. The interaction of the two electronic clouds is the dominant factor in determining the azimuth of one group relative to the other; all other types of interaction have been estimated to shift the equilibrium position only slightly, i.e., probably from 90° to 100°.
The Dipole Moments of the Methyl and Ethyl Halides
Authors: Smyth C. P. , McAlpine K. B.
Published: November 2004

The dielectric constants of the vapors of the methyl and ethyl halides have been measured in order to obtain accurate values for their dipole moments. The increase in moment from the methyl to the ethyl halide accords with the previously advanced hypothesis of an inductive effect, but the change in the increase with change in the halogen involved points to the influence of an additional factor. The change in moment from compound to compound is compared with the change in the Raman frequency associated with the carbon-halogen bond.
On the Theory of Flame Propagation
Authors: Lewis Bernard , von Elbe Guenther
Published: November 2004

A new theory of flame propagation in slow inflammation is proposed which considers that the highly energized atoms or radicals formed in the flame front play a more important rôle than heat conductivity in bringing the unburned gas to the reacting state. A small number of atoms or radicals diffuse over into the unburned phase, there initiating the chemical reaction. This and other considerations allow one to propose that the sum of thermal and chemical energy per unit mass of gas in all layers from the burned phase to the unburned phase is constant. The fundamental equation for the velocity V of the flame is derived simply from the fact that the number of molecules of combustible gas entering the reaction zone (flame front) in unit time equals the number reacting in the zone in the same time. If the flame front extends from xu to xb and the unburned gas enters it at a rate just sufficient to maintain the flame front stationary, then for 1cm¯2 cross section the equation reads: VNc(u)= ∫ TuTb−∂Nc∂tdxdTdTwhere V is the flame speed which is identical with the volume of unburned gaseous mixture (under initial conditions) entering the reaction zone per sec.; Nc(u) is the concentration of combustible gas in molecules/cc in the unburned phase; and Tb and Tu are temperatures of the completely burned and unburned gases at xb and xu, respectively. This equation, in addition to the postulates that the sum of thermal and chemical energy per unit mass remains constant and that the rate of change of concentration of the various gas constituents in an elementary layer due to mass flow, diffusion and chemical reaction is zero, allows a solution of the problem. The theory is applied to explosions of mixtures of ozone gas and oxygen. Ozone decomposes to oxygen, with evolution of heat. With the help of the postulate that the total energy per unit mass is constant, the terms ∂Nc/∂t and dx/dT can be expressed as functions of temperature alone, and the above equation can be solved. In view of certain simplifications the calculated velocities are considered to be in satisfactory agreement with the experimental velocities. The theory furnishes knowledge of the structure of the flame front. A particular explosion is analyzed. The width of its flame front is shown to be about 10-3 cm. The temperature distribution, the distribution of the concentrations of various molecular and atomic species, and the rate of reaction throughout the flame front are given. The authors add an appendix, which includes a critical analysis of the essential differences between the present theory and previous theories of other investigators.
The Infrared Absorption of Alcoholic Solutions of Hydroxides
Authors: Plyler E. K. , Williams F. D.
Published: November 2004

Bands have been observed at 0.76μ, 0.95μ, 1.05μ, 1.27μ, 1.30μ, 1.73μ, 1.89μ, 2.30μ, 2.60μ, 3.80μ and 5.20μ in alcoholic solutions of hydroxides. Solutions of NaOH and KOH gave the same positions for the bands. It was found that if the bands at 3.80μ and 5.20μ were considered as fundamentals, the remaining bands could be classified as harmonics. The similarity of the observed bands of the alcoholic solutions to the bands of aqueous solutions is mentioned.
Raman Spectrum of Fluorobenzene
Authors: Crawford F. W. , Nielsen J. Rud
Published: November 2004

The Raman spectrum of fluorobenzene has been investigated with a Hilger E1 quartz spectrograph, the following frequency shifts being obtained: 241, 517, 613, 804, 829, 997, 1009, 1157, 1220, (1265), (1414), 1496, (1561), 1599, 3076 and 3677 cm—1. Relative intensities were measured with a Zeiss three-prism glass spectrograph and a Moll microphotometer.
Caesium Nitrate and the Perovskite Structure
Authors: Waldbauer Louis , McCann D. C.
Published: November 2004

1. The crystal structure of dysanalyte has been verified. 2. The crystal structure of CsNO3 has been determined. 3. The so-called perovskite structure as a type of cubic symmetry is based on a mineral which is very probably not cubic but is orthorhombic. 4. The term ``perovskite structure'' should be discontinued.
Families of Thermodynamic Equations. I The Method of Transformations by the Characteristic Group
Authors: Koenig F. O.
Published: November 2004

Attention is called to the fact that certain important equations of thermodynamics such as the two Gibbs-Helmholtz equations may be grouped into families, but that a precise definition of such families has hitherto been lacking. For the case of a single phase of k components in equilibrium a method is given for splitting a certain class of equations, the ``f11-equations,'' into families in a precise manner as follows. The f11-class of equations is defined by means of four ``basic'' equations and two ``basic'' assumptions, and involves the 2k+8 variables E, H, F, A, V, S, P, T, μi, ni. For the f11-equations there is in turn defined a number of ``standard forms'' which depend upon the introduction of absolute value signs in a certain way. Then the ``characteristic group,'' a substitution group of the eighth order on the letters E, H, F, A, V, —S, —P, T, μi, ni is generated by a series of geometrical operations on a square. The theorem is stated that the transformation of any f11-equation in standard form by any element of the characteristic group yields an f11-equation in standard form. No formal proof of this theorem is given, but its correctness is sufficiently demonstrated by systematic verification. The theorem leads immediately to the definition of a family of f11-equations as the totality of distinct f11-equations resulting from the transformation of a given f11-equation in standard form by all the elements of the characteristic group. It is found that every f11-equation is a member of one and only one f11-family. The method increases the number of fundamental equations readily available and emphasizes the symmetry of these equations.
Addition of Symmetrical Diatomic Molecules to Benzene
Authors: Sherman Albert , Sun C. E. , Eyring Henry
Published: November 2004

The reaction of hydrogen and benzene to form 1,2-dihydrobenzene is considered, and the activation energy of the reaction is calculated with various assumptions concerning directed valence. It is shown that one may calculate approximate heats of reactions by considering exchange integrals only between electrons on neighboring atoms in a molecule, but this is not possible in calculating activation energies. The hydrogenation of benzene is considered as an eight electron problem, and the system serves to illustrate the degree of simplification of the secular equation arising from the symmetry of the system. The matrix elements of the factored equation are calculated. Activation energies of the reactions involved in the adsorption of H2 and C6H6 on Ni have been calculated and lead one to expect that the reaction might be achieved more easily catalytically.
Wave Mechanical Treatment of the Molecule Li2+
Authors: James Hubert M.
Published: November 2004

The Li2+ molecule has been treated by methods previously applied to the study of Li2 by the writer. It appears that the dissociation energy of Li2+ must be greater than that of Li2, and is probably 1.30±0.05 e.v. The ratio of one- to two-electron bond strengths appears to be greater with Li2 than with H2 because the bonding wave functions are more diffuse. The inner shells play a deterring role in the binding in Li2+ similar to that found in Li2. The Heitler-London wave function has been compared with the much more accurate series function, and the general character of the satisfactory molecular orbital is noted. The form of the variational process used here appears to be particularly suitable for the treatment of one-electron bonds, and simple functions may be used to give highly satisfactory results, as illustrated by the cases of Li2+ and H2+.
The Pressure-Volume-Temperature Relations of the Liquid, and the Phase Diagram of Heavy Water
Authors: Bridgman P. W.
Published: November 2004

The pressure-volume-temperature relations of both liquid D2O and H2O are measured between —20° and 95°C and up to 12,000 kg/cm2, and the transition parameters of the liquid and solid modifications of D2O in the range between —60° and +20°C and up to about 9000 kg/cm2. An unstable modification of solid D2O, for which the designation IV is proposed, is found in the field of stability of V. Reference to the original work on H2O shows that the corresponding modification of H2O also exists. In general the properties of H2O and D2O covered by these measurements are very much alike, and differ in the direction suggested by the greater zero-point energy of H2O: the molar volume of D2O is always greater than that of H2O at the same pressure and temperature, and the transition lines of D2O always run at higher temperatures. In finer detail, however, the differences between the two waters do not vary regularly, and probably other considerations than of zero-point energy alone are necessary for a complete explanation.
Precision Determination of Lattice Constants
Authors: Jette Eric R. , Foote Frank
Published: November 2004

In Part I the theoretical and experimental conditions which must be satisfied in order to determine lattice constants with a precision of a few parts per hundred thousand are discussed with particular application to the symmetrical focusing type of camera. Cohen's method of calculation of lattice constants for the elimination of ``drift'' and experimental errors is applied. Methods are developed for the evaluation of standard errors and fiduciary limits of results from a single film and from a set of films. The usefulness of x-ray targets made of alloys rather than pure elements for the purpose of securing a larger number and better distribution of lines is indicated. The influence of the number and Miller indices of diffraction lines on the values of lattice constants in noncubic systems is shown. The importance of the methods of sample preparation for precision work is emphasized. In Part II, precision measurements on Al, Ni, Ag, Au, Si, Fe, Mo, W, Mg, Zn, Cd, Sb, Bi and Sn are reported for materials of a high degree of purity. The fiduciary limits of these lattice constants vary between 2 and 7 parts per hundred thousand and are so chosen that the probability of the correct value lying between the stated limits is 19 out of 20.
The Vapor Pressure of Barium
Authors: Rudberg Erik , Lempert Joseph
Published: November 2004

The vapor pressure of barium has been determined for temperatures from 525 to 750°C by a method based on molecular effusion. The metal was obtained by decomposition of barium azide in vacuum. The evaporated deposits were determined by microtitration to about 10—8 mole. The values obtained for the pressure range from 5×10—5 to 2×10—2 mm. They are well represented by the equation: log p (in mm) = 6.99 — 8980/T. This corresponds to a latent heat of evaporation of 4.09×104 cal. mole.
Electronic Structures of Molecules XIII. Diborane and Related Molecules
Authors: Mulliken Robert S.
Published: November 2004

The electronic structure of diborane (B2H6), which is known to have a nuclear arrangement similar to that of ethane but which has two less electrons, is determined. It is shown that there must be eleven low energy electron states (some singlet, some triplet), belonging to three electron configurations. To account for the colorless diamagnetic character of B2H6, it must be that all or most of these eleven states fall within an energy range of 1.5 volts or less, with the lowest state, somewhat accidentally, probably of 1A1 type. Derivatives of B2H6 have similar structures. According to the present method there is nothing particularly anomalous about these structures. The structures here arrived at are in general agreement with the suggestions of Sidgwick and Pauling that the three H atoms in each BH3 in B2H6 are held by two electron-pair bonds and one one-electron bond, although according to the present method one would say that the H atoms are held by two [s] and three [π] bonding electrons, a total of five, shared equally by the three H's. The present method shows clearly that in, e.g., B2H2(CH3)4, there is no reason to suppose that the B–H bonds have fewer electrons per bond than the B–C bonds, the number being 5/3 in each case. Equal energy for B2R6 and 2 BR3 would mean equal effective strength of B–R and B–B bonds. It is noted that the B–B bond is a remarkably strong one. Reasons why BCl3 does not form B2Cl6 are discussed. The desirability of magnetic susceptibility and perhaps molecular weight determinations, if possible at elevated temperatures, for some of the types BR3 and B2R6 is pointed out.
The Linear Thermal Expansion of Sodium Tungstate Between 20° and 600°
Authors: Austin J. B. , Pierce R. H. H.
Published: November 2004

(1) The linear thermal expansion of anhydrous sodium tungstate has been determined between 20° and 600°C by means of an interferometer, with results given by the following equations: v=v20[1+53.194(t−20)10−6+41.5(t−20)210−9],Δl/l20=17.73(t−20)10−6+13.83(t−20)210−9,αm=17.73×10−6+13.83(t−20)10−9,αt=17.73×10−6+27.66(t−20)10−9.(2) The results show that at atmospheric pressure the salt is trimorphous. Modification III is stable on heating up to 585° at which temperature it transforms to II with an increase in volume of 17.4 percent. Form II is stable over a very short temperature interval, whose exact extent could not be determined, and then transforms to Na2WO4 I with a decrease in volume of 0.12 percent.
A Generalized Thermodynamic Notation
Authors: McKay H. A. C.
Published: November 2004

It has recently been shown by Koenig that, as a result of the symmetry of the fundamental relations of thermodynamics, thermodynamic equations can be grouped into families. In the present paper a generalized notation is described which leads to an elegant method of writing down from one generalized equation all the members of a family; in particular, the signs of the various terms are very easily manipulated. The question of the number of members of a family is considered, and a method is given for obtaining the generalized equation when any one member of a family is known. Finally the extension of the method to problems of capillarity, magnetization, etc., is shown to be very readily carried out.
The Electron Affinity of Iodine from Space-Charge Effects
Authors: Glockler George , Calvin Melvin
Published: November 2004

The electron affinity of iodine atoms has been determined by a direct method in which only iodine atoms and electrons were involved. The value so obtained is 74.6 k-calories, which is in good agreement with values obtained by other methods. The concentration of the several ions of different masses (I— and E—) have been calculated from their effect on space charge. It has been established that iodine has no effect on the thermionic emission of tungsten.
The Absolute Rate of Homogeneous Atomic Reactions
Authors: Eyring Henry , Gershinowitz Harold , Sun Cheng E.
Published: November 2004

The absolute rate of the recombination of three hydrogen atoms is calculated entirely theoretically. The manner in which rotation determines the dimensions of the activated complex in cases having little or no activation energy is discussed. The theoretical data are in good agreement with the experimental rates of Steiner and of Amdur. An immediate consequence of the theory is that energy transfer occurs most effectively among particles which can react with each other, free atoms being more efficient than molecules. A qualitative application of potential surfaces to the problem of energy transfer as met in velocity of sound experiments and in experiments on maintenance of high pressure rates of unimolecular reactions is made.
A Summary of Experimental Activation Energies of Elementary Reactions Between Hydrogen and the Halogens
Authors: Morris J. Carrell , Pease Robert N.
Published: November 2004

Existing experimental data on reactions between hydrogen and the halogens have been analyzed to give values of the activation energies of the intermediate reactions involved. These are compared with calculated values due to Eyring and Wheeler.
The Principal Magnetic Susceptibilities of K3Fe(CN)6
Authors: Howard J. B.
Published: November 2004

The magnitudes, anisotropy and temperature dependence of the principal magnetic susceptibilities of K3Fe(CN)6 are calculated by the method of crystalline potentials, and prove to be in good agreement with experiment. The assumption is made that the interatomic forces in the Fe(CN)6--- complex destroy Russell-Saunders coupling. This results in a susceptibility corresponding to one free electron spin with a contribution, except at very low temperatures, from the unquenched orbital angular momentum. The effect of the latter is sufficient to make the susceptibility at room temperature almost twice as large as the value which would be obtained if the spin alone were considered. The superposition of a small rhombic crystalline field suffices to produce the large observed magnetic anisotropy. The behavior of the susceptibility of K3Fe(CN)6 is in sharp contrast to the higher effective magneton numbers and magnetic isotropy of many ferric compounds, such as the sulphates. In these the ground state of Fe+++ is the normal state of the free ion, namely a 6S state, so that five spins contribute to the susceptibility. Although the calculations ostensibly use the method of crystalline potentials, they are really based on general group properties and so apply even if the bonds in the cyanide are covalent, as they probably are, rather than ionic.
The Molecular Structure of Nickel Carbonyl
Authors: Brockway L. O. , Cross Paul C.
Published: November 2004

Electron diffraction by the vapor of Ni(CO)4 leads to a molecular model in which the four carbonyl groups have a tetrahedral arrangement about the nickel atom with the distances Ni – C = 1.82±0.03A and C – O = 1.15A. These distances are compatible with resonance between two electronic structures in which the C – O bond resonates between triple and double electron pair bonds and the Ni – C bond between single and double electron pair bonds. Nickel carbonyl is the first quadricovalent compound of neutral nickel whose structure has been determined, and its tetrahedral configuration is contrasted with the square arrangement of bonds in the quadricovalent compounds of divalent nickel ion.
The Structure of Caesium Enneachlordiarsenite, Cs3As2Cl9
Authors: Hoard J. L. , Goldstein Leonard
Published: November 2004

Cs3As2Cl9 is shown to have a hexagonal unit of structure with a0 = 7.37A, c0 = 8.91A, containing one molecule. The atomic arrangement is based upon closest-packing of caesium and chlorine, with D32 — C 3 2 as the most probable space-group, but the amount of distortion from the closest-packed positions is not large enough to permit of the unambiguous elimination of D3d3 — C 3̄ m. A structure based upon D32 accounts well for observed intensity data. Arsenic is shown definitely by the intensity data to have only a pseudo-coordination number of six, and the structure may be qualitatively described as containing AsCl3 molecules embedded in an environment of caesium and chloride ions in such a way that all large atoms fit into an approximately closest-packed arrangement. This is the first structure of this type to be discovered. The ratio of 3Cl per Cs is a particularly happy one for structures of this kind, and a study of this structure gives much insight into the existence and stability of the related group of compounds discussed in the Introduction.
The Critical Constants of Propane
Authors: Beattie James A. , Poffenberger Noland , Hadlock Canfield
Published: November 2004

The critical constants of propane (C3H8) are: tc = 96.81±0.01°C, pc = 42.01±0.02 normal atmospheres, vc = 0.195 liter per mole (4.43 cc per gram), dc = 5.13 moles per liter (0.226 gram per cc). The uncertainty in the critical volume and density is 1 percent.
The Absorption Spectrum of Acetone Vapor in the Far Ultraviolet
Authors: Duncan A. B. F.
Published: November 2004

The absorption spectrum of acetone has been photographed down to 850A. Discrete bands were found above 1300A but only continuous absorption between 1300 and 850A. The bands are described and a qualitative interpretation is given of the complete spectrum. One Rydberg series was found, converging to an ionization potential of 10.20 volts.
Chemical Identification of the Radioelements Produced from Carbon and Boron by Deuteron Bombardment
Authors: Yost Don M. , Ridenour L. N. , Shinohara K.
Published: November 2004

Chemical experiments were made on the radioactive substances resulting from the bombardment of carbon and boron by deuterons. Carbon is shown to yield an isotope of nitrogen and boron an isotope of carbon. The nitrogen so formed has a half-life of 10.5 minutes while that found by Curie and Joliot on bombardment of boron with alpha-particles has a half-life of 14 minutes. These facts are discussed.
The Liquid ``Structure'' of Methyl Alcohol
Authors: Zachariasen W. H.
Published: November 2004

Fourier integral analyses of the x-ray diffraction patterns of liquid nonyl and methyl alcohol are made. From these the radial distribution of atoms around any one atom is obtained. On the basis of the radial distribution curves, conclusions are drawn concerning the molecular configuration in the liquid. For nonyl alcohol this analysis confirms the results of Warren. In the case of methyl alcohol the analysis gives strong indication of hydrogen binding (dipole binding) between oxygen atoms of neighboring molecules. The short ``life'' of a given intermolecular bond in the liquid is emphasized. It is pointed out that the application of the ordinary Bragg equation to the peaks in the diffraction pattern of a liquid has no justification.
The Photodissociation of Some Polyatomic Molecules
Authors: Hukumoto Yosisige
Published: November 2004

A continuous absorption spectrum without a neighboring band spectrum and a convergence limit was investigated in the region of the ultraviolet of a number of polyatomic molecules: Halogen alkyls, alcohols, mercaptans, cyan compounds and other miscellaneous compounds. The energy of dissociation was, in each case, calculated from the absorption edge, considering the probable mechanism of the photodissociation process. Some remarks are given on the relationship between the dissociation energy of the bond and the structure of the molecule. Finally, some consideration is given to the Raman effects and infrared spectra as related to the bond energy of the molecules.
The Acidities of Ketones and the Mechanism of Prototropic Change
Authors: Watson H. B. , Nathan W. S. , Laurie L. L.
Published: November 2004

The observation of acidity in the brominated acetones is attributed to coordination of carbonyl carbon and hydroxyl ion, the process being preceded by electromeric change to the semipolar form. Acid- and base-catalyzed prototropy is regarded as involving a similar electromeric change, brought about by interaction with the catalyst, and followed by transformation of the semipolar form either to ketone or to enolic ion. The measured velocity will thus be dependent upon (a) the rate of reaction of ketone and catalyst, and (b) the proportion of the semipolar form which changes to enol. The application of this view, in conjunction with the conception of quantum-mechanical resonance as developed by Pauling, renders possible the satisfactory interpretation of a number of observations relating to the prototropic changes of carbonyl compounds.
The Rotation of Molecules in Crystals
Authors: Nielsen Harald H.
Published: November 2004

The problem of the rotation of molecules in crystals has been generalized to embrace also polyatomic configurations. Two models, of which the homo- and heteropolar diatomic molecules are special cases, are considered. The potential energy expressions are taken to be harmonic functions of the coordinates, satisfying the symmetry of the model under consideration. Two limiting cases exist; one where the crystal fields are small and effecting the motion of the top only slightly; the other where the crystal fields are large, restraining the top to rotate principally about its axis of symmetry, which will oscillate isotropically about its position of equilibrium. The eigenvalues of the problem are approximated for small fields by applying Schrödinger perturbation theory to the rotator and for large fields by applying Schrödinger perturbation theory to the isotropic oscillator in two dimensions. The connection of the eigenvalues for extreme values of the field is considered in detail. The eigenfunctions may on the rotator side be expanded in terms of the hypergeometric functions, and on the oscillator side in terms of associated Laguerre polynomials.
The Crystal Structure of Diaspore
Authors: Ewing F. J.
Published: November 2004

The parameters in diaspore are redetermined, and the structure is discussed from the standpoint of the coordination theory. The existence and location of hydrogen bonds in the structure are established, and representative formulas are proposed.
On the Normal Vibration Frequencies of NH3, PH3 and AsH3
Authors: Howard J. B.
Published: November 2004

It is shown that the assumption of valence forces for NH3, PH3 and AsH3 leads to the conclusion that the high frequency, degenerate normal vibration, although theoretically active, does not appear as a fundamental in the infrared spectra of these compounds. This conclusion follows from the fact that the remaining three fundamentals, all of which have been observed, can be accounted for satisfactorily with proper values of the two constants of the potential function for valence forces. The values calculated for this absent frequency with the same force-constants are 3450 cm—1, 2340 cm—1 and 2125 cm—1 for NH3, PH3 and AsH3, respectively. The frequency for NH3 may be fixed more precisely at 3470 cm—1 if we interpret the 4417 cm—1 band as a combination band involving this frequency and the 950 cm—1 frequency. Other evidence is given in support of a value for the frequency in the neighborhood of 3450 cm—1. There is, however, the difficulty of explaining why the predicted frequencies are not observed. The 4417 cm—1 band is probably to be ascribed to the fourth fundamental in case this fundamental does actually appear. If this is the case, then there is an extreme departure from valence forces in NH3 and probably likewise in PH3 and AsH3. Frequencies are computed for NH2D, ND2H and ND3 to provide a means of testing the value predicted upon the assumption of valence forces for the fourth fundamental in NH3.