The increasing interest in the low-temperature uses of neon prompted the author to investigate one of its thermodynamic variables of state, the Joule-Thomson effect. He is now extending his range of experiments on that effect to mixtures of rare gases. The work reported here concerns isenthalpic values of neon-hefium mixtures at high pressures
JOULE-THOMSON IN NEON-HELIUM
EFFECT MIXTURES
A. GLADUNf
UP to now, only a few results of investigations of the Joule-Thomson effect in gas mixtures have been published. At low pressures, the properties of the mixtures can be calculated from the properties of the pure components. At high pressures, theoretical ideas are still incomplete and they are based mainly on the assumption of spherically symmetric potentials of the intermolecular forces. Investigation of mixtures of rare gases seems, therefore, to be of special interest; this paper is a continuation of the author's measurements ~ of the integral Joule-Thomson effect of neon. It deals with the investigation of three neon-helium mixtures and pure helium within the temperature range 55-90 ° K and at pressures up to 150 atm.
Details of the apparatus used have already been given in reference 1. Beginning at constant temperature and pressure, a gas stream was gradually expanded under reducing pressure at adiabatic conditions and the temperature of the expanded gas was taken. In this way, direct isenthalpic values were obtained.
The helium and neon concentrations of the mixtures were measured interferrometrically. The maximum error of the analysis was 0.1 per cent. During the individual runs, the composition was subject to continuous control, and no variation could be observed within the given accuracy. The nitrogen and oxygen contents were measured by gas chromotography. It was not possible to clean the mixture by adsorption on blue gel at 78 ° K, as this would have affected the concentration of neon. The original mixture contained 0.02 per cent of nitrogen and oxygen; at the end of the runs the air content rose to 0.06 per cent.