HOW AN ELECTRIC BATTERY GENERATES ELECTRICITY

The above simple voltaic battery, or cell, consists of a plate of copper and one of zinc dipping into a vessel containing dilute sulphuric acid to twenty of water by volume. When these plates are joined externally by a wire or other conductor a current flows from the copper plates, called the positive pole of the battery, to the zinc plate, called the negative pole of the battery. This is due to the fact that a difference of potential is set up between the plates on immersion in the acid, in consequence of which an electro-motive force is generated that drives the current round the circuit. The potential between the plates is maintained by the chemical action now going on in the cell. This action results in the gradual consumption of the zinc plate with formation of zinc sulphate and evolution of hydrogen at the copper plate. In a short time the current in the circuit falls off in consequence of local action and polarization.

[Large illustration] (433 kB)

What is electrotyping, or electro-metallurgy?

It is the art or process of depositing, from a metallic solution, through the agency of galvanic electricity, a coating or film of metal upon some other substance.

Upon what principles is it accomplished?

The process is based on the fact, that when a galvanic current is passed through a solution of some metal, as a solution of sulphate of copper (sulphuric acid and copper), decomposition takes place; the metal is separated in a metallic state, and attaches itself to the negative pole, or to any substance that may be attached to the negative pole; while the acid or other substance before in combination with the metal, goes to, and is deposited on the positive pole.