(from the Greek elektron, amber). Thales (B.C. 600) observed that amber when rubbed attracted light substances, and this observation followed out has led to the present science of electricity.
“Bright amber shines on his electric throne.”
Darwin: Economy of Nature, i. 2.
Negative and positive electricity. Two opposite conditions of the electric state of bodies. At one time electricity was considered a fluid, as heat was thought to be caloric. Everybody was thought to have a certain quantity. If a body contained more than its normal quantity it was said to be positive, if less, it was said to be negative in this respect. Another theory was that there were two different electric fluids, which neutralised each other when they came in contact. Electricity is now supposed to be a mere condition, like heat and motion; but its energy is set in action by some molecular disturbance, such as friction, rupture, and chemical action. The old terms are still retained.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894