The popular physics demonstration experiment known as Thomson's Jumping Ring (JR) has been variously explained as a simple example of Lenz's law, or as the result of a phase shift of the ring current relative to the induced emf. The failure of the first-quadrant Lenz's law explanation is shown by the time the ring takes to jump and by levitation. A method is given for measuring the phase shift with results for aluminum and brass rings.

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An equilibrium method for the determination of the vacancy formation volume in many metals is provided by the trapping of positrons at vacancies. Utilizing a Bridgman press and angular-correlation counting techniques, the vacancy formation volume in metallic indium has been determined to be 6.1 + 0,2 cm'/mole, or 39+ 1% of the molar volume.

An independent determination has been made of the transformation pressures assigned to the high-pressure transformations in Ba and Bi which are generally used for calibration points. The metals were imbedded in NaCl, and the transitions were detected by the resistance change of the metal while the NaCl lattice parameter was simultaneously measured by x-ray diffraction. The NaCl compression values determined at the fixed points were related to pressure by reference to the semiempirical compression curve of Decker. The Ba I–II and Bi III–V transformations at room temperature were assigned thermodynamic equilibrium values of 53.3±1.2 kbar and 73.8±1.3 kbar, respectively, corresponding to NaCl linear compression values of Δa/a0=0.0510 and 0.0637, respectively. Hysteresis in the transformation pressures was investigated and sample hysteresis was separated from apparatus hysteresis. The hysteresis measurements imply a stress energy which inhibits nucleation of the new phase and causes a sizable sample hysteresis in solid-media systems.

Measurement made under hydrostatic conditions to 7 kbar of the relative thermal emf's of chromel/alumel and platinum/platinum−10% rhodium thermocouples indicates a pressure correction for platinum couples of 0.57 ± 0.03°C/kbar from about 600 to 1000°C. Chromel/alumel couples are found to be pressure dependent above about 720°C and to degrade rapidly at temperatures above 800°C. Systematic differences of unknown origin are found between pressure corrections measured with increasing and decreasing pressure.