Experiments and Observations on Electricity

Benjamin Franklin 1748

1. All objects contain a substance called an electric fire or electricity.  The total amount of this substance in the world is a constant.
2. Rubbing together of two objects results in the transfer of electricity from one object to the other.  + means a gain in electricity, - means a loss. Glass becomes electrified or gains positive when rubbed with silk.
3. Two objects electrified in the same sense, + and + or - and -, exert repulsive forces on each other.  Two objects electrified in the opposite sense, + and -, exert attractive forces on each other.
4. The mutual forces due to electrification are increased if the amount of electrification is increased or if the objects are brought closer to each other.
5. Some materials (conductors) readily conduct electricity whereas others (insulators) do not.