A rubber policeman is a hand-held flexible natural-rubber scraper attached to a glass rod used in chemical laboratories to transfer residues of precipitate or solid on glass surfaces when performing gravimetric analysis. Rubber policemen also come in one-piece flexible plastic versions. They are not the same as rubber scrapers.
Rubber policemen are also used in biological labs, to transfer tissue culture cells from a plate to a suspension for e.g. splitting of cells or the preparation of cell lysates.