The Mercury Melting Line Up to 1200 MPa

Abstract

The mercury melting line has been determined for pressures up to 1200 MPa. The change of electrical resistance in the mercury sample was used for detecting the equilibrium between the solid and liquid phases. Pressure measurements were made with highly stable manganin gages calibrated against two controlled clearance piston gages. Temperature measurements were made in the constant temperature bath by means of platinum resistance thermometry. Systematic errors in pressure and temperature were evaluated for all the measurements as well as the scatter due to the resolution of the equilibrium determination between the two hases of mercury. The mercury melting point at 0 C is 756.84 k 0.16 MPa which is in close agreement with the value obtained by Dadson and Greig. The experimental results are compared with previous melting lines. There are systematic differences when compared to Bogdanov's equation up to 1200 MPa but there is very close agreement with recent data obtained by Houck and Morris over the pressure range they covered. The experimental data were fitted to a third order polynomial; this equation fits the melting line data much more closely than the Simon type heretofore recommended and can be used up to 1200 MPa to increase the accuracy of a practical pressure scale based on the melting line of mercury.

A Reference Equation of State for Heavy Water

“…All experimental pressure values of Bridgman 34 were multiplied by a correction factor of 1.0102. This factor corresponds to the ratio between the melting pressure of mercury at 0 8C obtained by Bridgman 36 (749.2 MPa), which was used to calibrate the apparatus for his light and heavy water meltingpressure measurements, and the reference value reported by Molinar et al 37 (756.84 MPa).…”

Equation of State for Supercooled Water at Pressures up to 400 MPa

“…For this work, Bridgman's pressures were multiplied by the correction factor 1.0102, which follows from the current value of the mercury melting pressure. 106 Kell and Whalley 43 reported the location of the triple point as part of their investigation of the ice I-ice III phase transition line. Bignell and Bean 103 determined the triple-point pressure with metrological accuracy (0.01%).…”

Report on the First International Pressure Calibration Workshop.

“…The most recent previous effort to produce international agreement on a pressure scale is the 2nd AIRAPT IPPS Task Group Report [1], For pressure measurements below 1; 4 GPa, they recommended that a primary standard piston gauge should be used. In the absence of such a gauge, they suggested use of the mercury melting curve [2] as a secondary standard. At pressures above 1 .4 GPa, they recommended that pressures be referenced to the ruby fluorescence method [3][4][5][6][7] and the equation of state for NaCI [8][9][10].…”