To make a Leyden jar for collecting electrical fluid you will need:

• a small cylindrical plastic container and lid (a 35mm film canister, for example)
• a long metal nail or screw
• two small strips of aluminum foil
• some tape

Clean the container and lid.

Tape one strip of aluminum foil around the outside of the bottom third of the container.  Try to avoid having too many wrinkles in the foil.  Neatly fold the excess foil around the bottom of the container.

Tape the second strip of aluminum foil to the inside bottom third of the container.  This requires a bit of care to keep the foil as wrinkle-free and as close to the container's surface as possible.

Poke the nail or screw through the container's lid.  The head should protude about an inch above the lid.

Fill the container nearly to the top with water.

Place the lid on the container, making sure that the nail or screw is immersed in the water.

You're now ready to fill your Leyden jar with electrical fluid!

Rubbing the Plexiglas with the wool scarf will remove some electrons from the scarf thus giving the sheet of Plexiglas an excess of electrons (-).

When you place the electrophorus on the Plexiglas, the electrons in the metal pie plate (-) are quickly repelled by the excess negative charge (-) on the Plexiglas surface.  Although the pie plate is electrically neutral overall, it has become polarized:  negative charge has become concentrated on the rim of the pie plate while the bottom of the pie plate has been left with an excess of positive charge (+).

If you touch the rim of the pie plate, the electrons (-) -- eager to get as far away as possible from the excess negative charge on the Plexiglas -- will happily use your finger as an escape route.  You will feel a slight tickle and hear a faint snap as the electrons leave the pie plate. The pie plate now has an excess of positive charge (+).

You can now store some electrical fluid in your Leyden jar.

Simply pick the electrophorus up by the styrofoam handle and bring the pie plate close to the head of the nail or screw on the Leyden jar.  As the rim nears the Leyden jar, the free electrons (-) in the metal nail or screw will be attracted to the positive charge (+) of the pie plate.  You will hear another snap, and perhaps even see a small spark as the electrons jump across the gap.  The Leyden jar now has an excess of positive charge (+).

You can repeat these simple steps many times.  Each time you will increase the Leyden jar's charge.

When you want to discharge the Leyden jar, simply touch the head of the nail or screw.  Electrons in you (-) will be attracted to the positive charge stored in the Leyden jar.  In fact, the electrons are likely to move even before your finger has quite reached the Leyden jar.  As they cross the gap, you will hear a snap and feel a shock, the strength of which will depend on how much electrical fluid you were able to store in the Leyden jar.  If the room is dark, you may see a spark as well.