New Critical Point at the Vicinity of the Freezing Temperature ofK2Cs

The density, heat capacity, and electrical resistivity for the alloy K-Cs at the stoichiometric composition ${\mathrm{K}}_2$Cs have been measured through the solid and liquid states. A new singular point $T_c=258\mathrm{}$ K has been detected above the well-known freezing point $T=253.5\mathrm{}$ K. This is the rare case of a critical point being close to the solidification transition and is also the only case known of a miscibility gap in the liquid state of a mixture that exhibits full solubility below its solidus line.