Also known Gleichenberg law. For example, suppose gold and silver legal parity of 1:15, if the market price ratio is 1: 15.5, then the gold currency set too low, or silver overvalued. In this case, gold is undervalued become good money retreat possession. For example, people holding a unit of gold by freedom meltdown right to be exchanged for the gold in the free market, according to market parity easy to get silver pieces 15.5 Units; Then, according to the free coinage right, silver pieces to cast silver 15.5 Units, and this will be easy to get silver coins according to legal parity of 1.03. Be repeated, repeated Yi gold and silver, endless benefits. That is in meltdown and casting process, resulting in decreasing signs of gold and silver's growing role Gleichenberg law, the formation of bad money (silver) drives out good money (gold) and, more importantly, the increase in gold on the free market and silver simultaneously reducing the relative amount of supply and demand to change this, and make gold and silver markets towards parity parity statutory changes, until the market until the price ratio of 1:15.