Establishment of the mercury fixed point around 0°C using volumetric method

The paper describes the determination of melting pressure of mercury around 0°C using the volume method at the National Physical Laboratory. Also described are the details of the experimental set-up and the estimation of the uncertainty in the measurement of pressure. The equilibrium pressure in the flat region of the melting curve over which bulk transformation occurs, is established by increasing/decreasing the pressure. The scatter in the obtained data for equilibrium pressures is within the limit of experimental uncertainty of the measurement of pressure. The average observed value for the melting pressure of mercury at 0·002°C is 756·93±0·25 MPa agreeing well with the reported value of Dadsonet al [1] and Molinaret al [2a, b].