Transition to Nonmetallic Behavior in Expanded Liquid and Gaseous Metals

At high temperatures and pressures, liquid and gaseous metals exhibit a steady transition from metallic to nonmetallic behavior when the density is sufficiently reduced. All the properties are influenced by this transition, as is shown by measurement (on mercury, cesium, and potassium) of the electric conductivity, the density, the thermoelectric power, and in some cases the Hall effect, as well as the optical absorption. The continuous variation of the density over a wide range is achieved by compression or expansion above the critical temperatures of the metals, i. e. 1490 0 C for mercury, 1750 0 C for cesium, and 1925 0 C for potassium.