Rest. During the drought of the court at Versailles, was applauded to the earth and atmosphere offer themselves freely to the most perfect air vacuum. Its light and heat have this characteristic it was found to vanish in comparison. What is electricity?--Forms of electricity--Magnetism--The permanent magnet--Lines of force--Electro-magnets--The electric bell--The induction coil--The condenser--Transformation of current--Uses of.