Coinage Act of 1853
The Coinage Act of 1853, 10 Stat. 160, was a piece of legislation passed by the United States Congress which lowered the silver content of the silver half dime, dime, quarter dollar, and half dollar, and authorized a three dollar gold piece. Wikipedia
Long title: An Act Amendatory of existing Laws relative to the Half Dollar, Quarter Dollar, Dime, and Half Dime