Thermodynamic similarity and volume discontinuity during melting of simple substances

An approach to disclosing thermodynamic similarity of melting lines based on using their low-temperature asymptotics is developed. It supposes prolongation of melting lines above the ternary point to the region of negative pressures where both phases coexisting in equilibrium are metastable. The Seamon equation is used as approximation for functional bond expressing one-parametric similarity. Correlations between the parameter c, asymptotic pressure p0 and change in the volume ΔV under melting are established on the example of simple dielectric liquids and metals (Ar, In, Cs, Na, CCl4)