Mercury contact relays

ELECTRIC contacts between solid metal surfaces tend to give trouble in a number of ways. They wear down, get dirty, stick by locking or welding, and chatter. It long has been recognized that all of these difficulties might be avoided by using mercury contact surfaces instead of solid metal. However, most designs of relays and switches employing mercury have tended to be slow in operation, ordinarily being based on the motion of a fairly large quantity of mercury by gravitational acceleration.