An experimental determination of the melting curves of argon and nitrogen into the 10000 atm region

A new apparatus for measuring melting curves at low temperatures and very high pressures is described. It is essentially a combined cryostat and high-pressure intensifier connected by a single junction at room temperature. The pressure is produced in a number of stages culminating in a single intensification stroke on to a small volume of gas maintained at low temperatures in a long steel tube. Solidification and melting are detected in this tube by means of a small steel pellet, which may be moved by an external magnetiċ field when the substance is fluid. Experiments have been carried out on argon and nitrogen. The solid-fluid equilibrium line has been extended to 8250 atm at 234° K for argon, and to 9100 atm at 180° K for nitrogen.