PROCEDURE:

1.    We get the schlenk tube, and smear vaseline, in order to make the parts move easily.
2.    Then, you swap up an elastic band around the schlenk tube, following the instructions of the video, so that it doesn’t move.
3.    After you get a stopper and you put it at the top of the schlenk tube to close it.
4.    To make it more secure, take another elastic band and swap it around the stopper.