avoid loosening the stopcock plug and causing aleak. Using your right hand to operate a stopcockhandle oriented on the right side of the buret usuallyloosens the stopcock. Figure 13 shows the preferredmethod. In the figure, note that, although the stop-cock handle is on the right, it is being manipulatedwith the left hand. While turning the handle, youshould apply light pressure toward the buret withyour left hand, to prevent the plug from slipping out ofthe barrel. However, be careful not to touch your leftpalm to the stopcock or the plug could loosen. Thisprocedure leaves the right hand free to swirl the solu-tion in the receiving flask.Burets with Teflon stopcocks.When usingburets with Teflon stopcocks, you can operate thestopcock with either hand, without any risk of the plugslipping out.You should drain solution from a buret slowly sothat the film of solution on the buret wall will drainreproducibly. After you have drained the desired vol-ume, touch a glass stirring rod to the buret tip, to re-move the hanging drop. Use a wash bottle to rinsethe stirring rod with distilled water, allowing the rinsesto run into the receiving flask. After a brief pause, re-cord the final buret reading.When you are finished using the buret, drain theexcess solution and dispose of it as instructed. Rinsethe buret thoroughly with tap water, then with distilledwater. Clamp it to a ring stand with the stopcockopen, and let it drain dry.