How to Create a Vacuum in a Bell Jar
- 1). Put anything you will be experimenting with into the jar.
- 2). Put the vacuum plate on a flat surface to ensure the best seal. Place the jar into the gasket on the vacuum plate. Older bell jars with worn gaskets may require a thin strip of petroleum jelly or other grease around the jar base to maintain a proper vacuum.
- 3). Locate the 1/4-inch tubing extending from the vacuum plate. Connect the open end of the tubing to the nozzle on the hand pump.
- 4). Pump the hand pump until the pressure gauge on the plate indicates a pressure of approximately 20 negative pounds of pressure.
- 5). Note any changes to the items inside the jar.
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