Finite thermal conductivity at the vapor-liquid critical line of a binary fluid mixture

Experimental thermal-conductivity measurements, obtained for an equimolar mixture of methane and ethane very close to the critical point, confirm that the thermal conductivity of a mixture does not diverge at the vapor-liquid critical point but crosses over to a finite limiting behavior at the critical point. A recently developed extension of the mode-coupling theory for dynamic critical phenomena in mixtures gives a good quantitative description of the experimental thermal-conductivity data.