Dead or “undead”? The curious and untidy history of Volta’s concept of“contact potential”

The long controversy surrounding electric batteries largely centers on Alessandro Volta's concept of contact potential, which emerged in the late eighteenth century. Despite the thorough rejection of Volta's original theory, the contact potential has paradoxically resurfaced in various scientific discussions, remaining relevant even in contemporary literature. This paper seeks to elucidate the reasons behind the persistent yet messy revival of the contact potential through an exploration of four key areas: dry piles, thermocouples, quadrant electrometers, and vacuum phenomena. It argues that the inconsistent survival of the contact potential stems from its significant utility in diverse experimental and theoretical contexts, although it has evaded a straightforward, unified explanation in scientific discourse. The analysis suggests that rather than allowing the concept to wither into obscurity, it would be advantageous to embrace and further develop it as a multifaceted notion intersecting multiple domains of inquiry. Overall, this work underscores the historical complexity of scientific concepts and invites a reevaluation of the enduring legacy of Volta's ideas within the field of electrochemistry.