The pressures of some solid-solid transitions

A free piston gage capable of measuring pressures to 60 kb has been constructed. The basic element of the gage is a supported carbide vessel entered by a rotating piston. With this apparatus the pressures of various transitions have been determined with fair precision. We find the following pressures: Teflon, 5.43 kb; AgNO3 I-AgNO3 II, 9.78 kb; KI I-KI II, 17.48 kb; KBr I-KBr II, 17.88 kb; KCl I-KC1 II, 19.28 kb; KCN I-KCN II, 19.72 kb; Ice VI-Ice VII, 21.42 kb; AgNO3 II-AgNO3 III, 21.2 kb; Cs I-Cs II, 22.6 kb; Bi I-Bi II, 25.38 kb; Bi II-Bi III, 26.92 kb; Tl II-Tl III, 36.69 kb; Te I-Te II, 40.12 kb; Cs II-Cs III, 41.7 kb; Ba II-Ba III, 59.6 kb. These results are in close agreement with earlier measurements of discontinuities in volume made by Bridgman.