In this way a medal, a wood-engraving, or a plaster cast, if attached to the negative pole, may be covered with a coating of copper; if the solution had been one containing silver or gold, the substance would have been covered with a coating of silver or gold instead of copper.
How can the thickness of the deposits be regulated?
The thickness of the deposit, providing the supply of the metallic solution be kept constant, will depend on the length of time the object is exposed to the influence of the battery.
Electro-Magnetism
What is electro-magnetism?
It is the magnetism developed through the agency of electrical or galvanic action.
What were the earliest phenomena observed which indicated a relation between magnetism and electricity?
It was noticed that ships’ compasses have their directive power impaired by lightning, and that sewing needles could be rendered magnetic by electric discharges passed through them.
What discovery, made by Prof. Oersted of Copenhagen, established beyond a doubt the connection of electricity and magnetism?
He ascertained that a magnetic needle placed near a metallic wire connecting the poles of a galvanic battery was compelled to change its direction, and that the new direction it assumed was determined by its position in relation to the wire and to the direction of the current transmitted along the wire.