Draining the lower phase

Place a collection flask beneath the spout of the separatory funnel. Check that the stopper has been removed from the top of the funnel. Turn the stopcock, and allow about 3/4 of the bottom layer to drain into the collection flask. Close the stopcock and wait for a minute so that any liquid from the lower layer that may be clinging to the funnel walls may flow down to the bottom layer. Finally, continue to drain the lower layer of liquid slowly until the interface between the two liquids just barely enters the stopcock. Do not allow the liquid from the top layer to drain out of the separatory funnel!