If porter be drunk out of a pewter pot, it will produce a more brisk
sensation than when it is taken out of a glass vessel, which is
ascribed to a galvanic effect. In this instance there is a combination
of one metal and two dissimilar fluids, which combination constitutes a
galvanic circle. In the act of drinking, one side of the pewter pot is
exposed to the action of the saliva, which moistens the lip, while the
other metallic side is in contact with the porter; the circuit being
thus completed, an agreeable relish is communicated to the beverage
when it comes in contact with the tongue.