Ellis Stanyon's “Florin vs. Penny” in the March 1899 issue of Mahatma, Vol. 2, No. 9, p. 210, is an early example of the effect of turning a silver coin to a copper one, then back and forth several times. Next came Edward Victor's “The Changing Coin” in Magic of the Hands (1937, p. 42), followed by the Vernon routine in Stars of Magic, 1946, p. 31.