The Joule-Thomson Effect in Argon

The measurements employed the same apparatus as for helium and air. Slight changes were made in the compressor and the purification system. The argon was of high purity except for 0.5 percent of nitrogen. Clogging of the plug gave trouble in a limited part of the field. The vapor phase from Pyrofax gas makes an excellent low temperature bath liquid. The data for the isenthalpic curves are given in detail and plotted. The values of the Joule-Thomson coefficient, $\mu$, over the field (-150 to 300°C and 1 to 200 atm.) are calculated, tabulated, and plotted as a function of temperature and pressure. The lower branch of the inversion curve ($\mu =0\mathrm{}$) falls within the low temperature range of these measurements. The trends of the Joule-Thomson effect in argon over the measured range of temperature and pressure are exceedingly like those in air and nitrogen. Lack of specific heat data prevents the calculation of other important thermodynamic coefficients.