A BÃ 1\/4 chner flask can be used with a BÃ 1\/4 chner funnel for separating solids and liquids . The thick wall of the BÃ 1\/4 chner flask provides it the strength to withstand the pressure difference while holding a vacuum inside . It is primarily used together with a BÃ 1\/4 chner funnel fitted through a drilled rubber bung or an elastomer adapter ( a BÃ 1\/4 chner ring ) at the neck on top of the flask for filtration of samples .