An apparatus was developed to measure the conductance change of electrolytes in the presence of high electric fields to a high degree of accuracy, end is described herein. The apparatus employs square wave pulse excitation to a special conductivity bridge, and permits direct observation of pulse shape on a high speed oscilloscope, as well as separate compensation of resistive and capacitive unbalance. With this apparatus, the high-field electric conductances of several solutions of biologically interesting substances were investigated and classified. The substances investigated, together with the observed increment in electric conductance at a field strength of 10⁵ volts per cm., are listed: 1. glutamine (1.25 x 10⁻⁴M), 0.56% 2. 1 (﹢) arginine monhydrochloride (2.0x10⁻⁴M), 0.48% 3. acetic acid (3.75 x 10⁻⁴M), 4.6% 4. p-amino benzoic acid (5 x 10⁻³M), 5.5% 5. sulfanilic acid (6.55 X 10⁻⁵M), 1.4% 6. 1 (﹢) glutamic acid (1.22 x 10⁻³M), 2.6% 7. glycine (0.61 M), 1.9% 8. protamine sulfate (7.9 x 10⁻⁵g/cc.) 40% 9. agar (3 x 10⁻⁴ g/cc), 37% Some of the observed results have been compared with those obtained by other methods, while the remaining substances have not been previously reported. The results were discussed in the light of available theoretical information on the high-field conductance effect in various types of electrolytes. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The cell constant of a direct current conductivity cell was measured using as a standard 0.1M and 0.01M potassium chloride solutions and specific conductivity data obtained by G. Jones and M. Prendergast. The results obtained for either of the solutions were exact to within one or two parts in ten thousand, but a difference of 0.6% existed between the two cell constant values. In order to investigate more exactly the nature of this variation, other concentrations were measured using as a standard the data obtained by T. Shedlovsky, A.S. Brown, and D.A. Maclnness. Certain factors in the design of a direct current cell have been considered and suggestions for future work offered. Studies have been made of the anodic properties of strained copper wire in the cell Cu (strained) ⃒ CuSO₄ ⃒ Cu (normal). Two copper wires were immersed in copper sulphate solution. Weights were added to one of these and the potential difference measured potentiometrically or with a vacuum tube volt-meter. The results obtained show that (1) the relaxation of this potential is approximately exponential, (2) very little potential is developed until a critical strain is applied, (3) after a certain strain has been applied the peak potential developed becomes constant with increasing strain, (4) the magnitude of the effect is dependant on the concentration of the solution, (5) the magnitude and direction (anodic or cathodic) of the potential is dependant upon the components of the electrolyte. / Science, Faculty of / Chemistry, Department of / Graduate

In recent years, several attempts have been made to develop instrumentation to aid in the measurement of soil water electrical conductivity. Each of the instruments have specific limitations. This dissertation discusses the available methods of measuring this parameter and indicates the limitations of the transducers which have been described in the literature. Also, discussed are the basic theories of operation of these transducers and definitions related to soil salinity in general. The major objective of this research was to develop a new transducer which would be a significant improvement over existing types of instrumentation. It is believed that this research has led to the development of two transducers of different geometries which can assess the soil water conductivity over a wider range of matric potential just as rapidly and accurately as the next best unit. At the same time the new transducers incorporate automatic temperature compensation which has not been done by any other field instrumentation of its type. Also presented, is the application of heat transfer theories to the diffusion of ions from the transducer to the surrounding environment, Application of this theory allows one to predict how the transducer will respond to a step change in ion concentration in an unsaturated soil system where the only process involved is diffusion. Good agreement between experimental measurements and predicted response indicates that the model may also be useful in further refinements of the transducer.

Graduation date: 1967

No description available.

Thesis (Ph. D.)--Leland Stanford Junior University, 1911. / "Reprinted from the Journal of physical chemistry, vol. 16."

(1) Developments in a.c. conductance techniques during the past ninety years have been reviewed, and a brief outline is given of the older theories regarding electrolytic polarisation. (2) A conductance bridge - incorporating the double heterodyne principle - has been constructed, capable of giving resistance readings to an accuracy of 0.01% over a range of frequencies covering the best part of 100 kc/s. It has also been found possible to calibrate the oscillator so that frequency settings can be guaranteed to an accuracy of , at least, 0.1% in the range: 2 kc/S to 50 kc/S. (3) The Wheatstone Bridge Network has been slightly modified to enable measurements at the high frequencies. (4) Resistances in the measuring arm of the bridge have been calibrated 'in situ' by the method of intercomparison. (5) A brief description is given of the modern theories regarding electrode processes and modern methods of eliminating electrode effects. (6) Two types of conductance cells, with bright Pt electrodes, have been used to carry out measurements on potassium chloride solutions: (a) Thomas- Gledhill Cell (b) Nichol-Fuoss Cell. The latter incorporates concentric, cylindrical electrodes with the lead to the outer electrode acting as an electrical shield for the lead to the inner electrode. This cell was constructed and used for the first time in this laboratory. (7) From resistance-frequency graphs plotted, it is shown that the Jones and Christian extrapolation procedure cannot be applied (with any degree of confidence) to obtain the true resistance, when measurements are effected over an extended range of frequencies. (8) The method of resistance-reactance diagrams is discussed and applied to various networks of resistances and capacitances. (9) By drawing resistance-reactance diagrams for the experimental readings obtained, equivalent circuits have been derived - for all the solutions investigated in the N-F cell, and for the approx. O.OlD solution in the T-G cell - which approximate to cell behaviour in the range: 500 c/s to 75 kc/s. The less concentrated solutions in the T-G cell show peculiar behaviour at the high frequencies. (10) Probable reasons are advanced for deviations from linearity on resistance-frequency graphs. (11) A new method is proposed for determining the true resistance of solutions measured in cells of the N-F type. Summary, p. 166-167.

The conductivities of the homologous series from tetra-methyl to tetra-n-amyl of the normal tetraalkylammonium iodides and bromides in acetonitrile at 25° C have been determined. The concentrations studied ranged from 0.006 to 0.00003 moles per litre. These salts are fairly strong electrolytes in acetonitrile. The iodides have higher conductivities and are more highly dissociated than the corresponding bromides. The conductivities decrease with increasing size of the alkyl group and the degrees of dissociation show a corresponding increase. There is a relatively large difference between the tetramethyl and tetraethyl ions and then smaller, fairly regular differences in going from tetraethyl to tetra-n-amyl. The limiting equivalent conductivities have been calculated by the methods of Shedlovsky and Fuoss. It is shown that the dissociation constants calculated by the method of Shedlovsky and those calculated by the method of Fuoss are not related in the manner predicted by these authors. Ionic conductances have been calculated by assuming that Walden's rule applies to the tetra-n-butylammonium ion. A comparison of ionic resistances in some organic solvents shows that the quaternary ammonium ions have little tendency to interact with solvent molecules. / Science, Faculty of / Chemistry, Department of / Graduate

We report diffraction experiments on some representative Fast Ion Conductors. The structures of anhydrous stoichiometric deuterium (DAl₁₁O₁₇) and silver (AgAl ₁₁O₁₇) beta aluminas have each been determined at four temperatures in the range 4 . 2K - 773K using powder neutron diffraction (PND) data. In DAl₁₁O₁₇, a strong D-O(5) hydroxyl linkage is maintained at all four temperatures .For AgAl₁₁O₁₇ at 4.2K,we have observed, for the first time in metal beta aluminas, a completely ordered cation distribution. The material, which was prepared by a new route, is accurately stoichiometric. At 298K,the silver atoms have become somewhat delocalised and by 773K they are organised in a highly diffuse manner. Single crystal neutron diffraction was used to elucidate the proton distributions in ammonium beta alumina, (NH₄) _1.25Al₁₁- 0_17.125, and the two derivatives (NH₄) _0.78H_0.25Al₁₁0₁₇ and 'HA1₁₁- 0₁₇.In the parent compound, the positions and orientations of the two independant (NH⁺₄) species are such that all protons are involved in favourable hydrogen-bonding schemes. In formation of the first derivative, one of these sites becomes completely depopulated. Our results clarify the thermal behaviour of (NH₄) _1.25Al₁₁0_17.125 and we propose schemes by which stoichiometric beta aluminas are formed from this precursor and the related (H₃0)_1+x- Al₁₁0_17.+x/2. The crystal structures of I-Ag₃PO₄(25°C and 375°C) , II-Ag₃PO₄(650°C) ,II-Na₃PO₄ (γ) (400°C) and the solid solutions Na_3(1-x)Al_xPO₄are described. The high-temperature forms are considered in relation to the fluorite structure and mechanisms for the ionic conduction of these phases are proposed. A single crystal X-ray diffraction study of β-Ag₂SO₄ (25°C) reveals that it is isostructural with thenardite, V-Na ₂SO₄.The high-temperature modifications a-Ag₂SO₄ (490°C) and α-K₂SO₄ (620°C) have been characterised using PND data. A PND experiment on silver (I) fluoride confirms that it adopts the rocksalt structure and we find no firm evidence for a significant population of defects.

No description available.