From introduction: "The measurement of the thermal conductivity of liquid TF6 presented unusual difficulties because of two of its properties which necessitated working with a closed system. The properties were (1) the liquid can exist as such only above 64.05°C. at which temperature its saturated vapor pressure is 1140 mm. of mercury, and (2) the compound reacts rapidly with moist air. Also because of the liquid's extremely corrosive nature, it was necessary to design a cell of special corrosion resistant materials."