Glass-to-metal seal absorb the stresses from thermal expansion mismatches. Due to its very low vapor pressure, indium finds use in glass-metal seals used in vacuum technology. Gallium is a soft metal with melting point at 30 °C. It readily wets glasses and most metals and can be used for seals that can be assembled/disassembled by just slight heating. It can be used as a liquid seal up to high temperatures or even at lower temperatures when alloyed with other metals (e.g. as galinstan). Mercury is a metal liquid at normal temperature. It was used as the earliest glass-to-metal seal and is still
Liquid-liquid critical point a higher percentage of HDL exists while below the critical pressure a higher percentage of LDL is present. The ratio "r" = LDL/(LDL + HDL) of phase amounts is determined according to the thermodynamic equilibrium of the system, which is often governed by external variables such as pressure and temperature. A discontinuity is present in "r" when crossing the liquid-liquid phase transition, which separates the LDL-rich phase from the LDL-poor phase. At any point of the liquid-liquid phase transition, including the associated liquid-liquid critical point, the ratio of LDL to HDL is exactly one ("r" = ½). The liquid-liquid critical