MEASURING CYLINDERS

BURETTE (http://en.wikipedia.org/wiki/Burette)

A burette (also buret) is a vertical cylindrical piece of laboratory glassware with a volumetric graduation on its full length and a precision tap, or stopcock, on the bottom. It is used to dispense known amounts of a liquid reagent in experimentsfor which such precision is necessary, such as a titration experiment. Burettes are extremely accurate - a 50 cm³ burette has a tolerance of 0.1 cm³ (class B) or 0.06 cm³ (class A).

Burettes measure from the top since they are used to measure liquids dispensed out the bottom. The difference between starting and final volume is the amount dispensed

PIPETTE (http://en.wikipedia.org/wiki/Pipette)

A pipette (also called a pipet, pipettor or chemical dropper) is a laboratory instrument used to transport a measured volume of liquid.

Pipettes are commonly used in molecular biology as well as medical tests. Pipettes come in several designs for various purposes with differing levels of accuracy and precision, from single piece glass pipettes to more complex adjustable or electronic pipettes. Many pipettes types work by creating a partial vacuum above the liquid-holding chamber and selectively releasing this vacuum to draw up and dispense.

Pipettes that dispense between 1 and 1000 μl are termed micropipettes, while macropipettes dispense a greater volume of liquid. Two types of micropipettes are generally used: air-displacement pipettes and positive-displacement pipettes. In particular, piston-driven air-displacement pipettes are micropipettes which dispense an adjustable volume of liquid from a disposable tip. The pipette body contains a plunger, which provides the suction to pull liquid into the tip when the piston is compressed and released. The maximum displacement of the plunger is set by a dial on the pipette body, allowing the delivery volume to be changed. Whereas for larger volumes cylindrical pipettes, such as volumetric or graduated pipettes are used and driven by a pipette aid.

pipette image: http://images.google.com.sg/images?hl=en&q=pipette&um=1&ie=UTF-8&sa=N&tab=wi