Peltier Effect. Lubeck discovered in 1822 that an electric current might be produced by heating or cooling the junction of two dissimilar metals in a closed circuit, and so it was to be expected that when a current is sent from a battery, or some other source, across such a junction that point would be heated or cooled. The actual phenomenon was discovered by Peltier in 1834. If, for instance, a current be sent along a wire one half of which is of antimony and the other half of bismuth, the junction of those two metals will be heated if the current flow from the antimony to the bismuth; but the junction will be cooled if the current be reversed. This heating or cooling is known as the Peltier effect, and is proportional to the strength of the current causing it. It is to be distinguished from the heat developed in a circuit on account of its resistance, which is proportional to the square of the current and is not reversible, while the Peltier effect is reversible.