《汉书·食货志》日:“今半两钱法重四铢,而奸或盗摩钱质而取鋊,钱益轻薄而物贵,则远方用币烦费不省。”“有司言三铢钱轻,轻钱易作奸诈,乃更请郡国铸五铢钱,周郭其质,令不可得摩取鋊。”“鋊”就是铜屑。看来当时社会上存有奸盗不法之人,挫磨半两钱盗取铜屑牟利的现象;因为半两钱系平背且多数无内外廓,銼磨后不容易看出痕迹,给不法之徒提供了作弊的条件和机会。汉武帝更铸有周廓的五铢钱,其主要目的就是防止奸盗磨钱取铜。认为钱铸上面廓,钱背铸上内外廓, “Han Shi Hui Zhi” Day: “This half-two money method weighs four baht, and rape or theft money quality and money, money is light and expensive, the remote use of the currency is not cost-effective.” “There are Secretary Samuel money light, light money easy to make treachery, but also asked the country to cast five baht money, Zhou Guo its quality, so can not be obtained from the United States.” “鋊 ” is copper scrap. At the time, it seemed that there were people in the community who had committed crimes of rape and piracy, discredited half of the money, and stolen copper scraps for profits. Because half of the money was flat and the back was mostly without inner and outer contours, it was not easy to see traces after filing, The criminals provided the conditions and opportunities for cheating. Emperor Wu of Wu made more profiles of the five baht money, its main purpose is to prevent the pirates mined copper. Think money cast on the profile, money back cast on the inside and outside the profile,