Abstract
The triple point of highly pure argon was measured by means of the step heating programming technique, where the base line temperature in each step was estimated from the transient temperature of a partially overheated sample cooling asymptotically toward a stable temperature. Thus obtained melting curve was assumed to represent the equilibrium temperature for the fraction melted at each step. The depression of the melting point and the purity of the sample were estimated from the result by using the equation of Van't Hoff.
The obtained values of the purity of the sample and the depression of the melting point are 99.99916mol% and 0.42mK respectively, and the value of the triple point of pure argon was estimated as 83.7962K on the IPTS-68.
