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

Gravimetric analysis

Gravimetric analysis describes a set of methods in analytical chemistry for the quantitative determination of an analyte based on the mass of a solid...

. 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

Lysis

Lysis refers to the breaking down of a cell, often by viral, enzymic, or osmotic mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a "lysate"....

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