Water is poured into the BÃ 1\/4 chner funnel and the liquid passes through filter paper and is sucked up by a vacuum attached to the side of the BÃ 1\/4 chner flask , while the solid stays behind in the BÃ 1\/4 chner funnel . The BÃ 1\/4 chner funnel holds the sample isolated from the suction by a layer of filter paper .