The Double Electrophorus is a further development from the Electrophorus, capable to produce and provide both electrostatical charges by means of electrostatic influence. To achieve this state one half of the electrophorus is charged by friction. Then the metal plate is placed on top and grounded before the charge from the plate in turn is brought onto the other half of the electrophorus by a spark discharge. Through repetition, this process can be increased and both sides of the Double Electrophorus can be charged substantially.
A video on how to charge the electrophorus can be found on YouTube.
The respective electrostatic charges from the Double Electrophorus can be used to produce Lichtenberg Dust Figures. These are formed once an electric charge is brought from the electrophorus to a resin plate. The plate is then dusted with e.g. lycopodium powder. The positive and negative figures can be easily identified, the negative figures ususally showing more and thinner branches.
A video on how to produce the Lichtenberg Figures can be found on YouTube.
Lichtenberg, G. C. (1778). De Nova Methodo Naturam Ac Motum Fluidi Electrici Investigandi. Gottingae: Dieterich, Johann Christian.