Centrifuge, SEHN truh fyooj, is an instrument used to separate two liquids mixed together, or solid particles that are mixed in a liquid. The centrifuge causes the more dense substance to move to the bottom of the container, leaving the less dense substance on top. A centrifuge usually consists of a large wheel connected to an electric motor. The mixtures to be separated are balanced in containers on each side of the wheel. When the motor is turned on, the wheel rotates rapidly and the containers swing out from the center. A smaller centrifuge consists of a small rotating top in which test tubes of material can be placed at an angle. Centrifuges turn from 800 to 6,000 times per minute.