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
Metal halides it a liquid at room temperature. They are usually insoluble in water, but soluble in organic solvent. Polymeric metal halides generally have melting and boiling points that are higher than monomeric metal halides, but lower than ionic metal halides. They are soluble only in the presence of a ligand which liberates discrete units. For example, palladium chloride is quite insoluble in water, but it dissolves well in concentrated sodium chloride solution: Palladium chloride is insoluble in most organic solvents, but it forms soluble monomeric units with acetonitrile and benzonitrile: The tetrahedral tetrahalides of the first-row transition metals are prepared by