To stimulate thought about heat exchange and liquid-vapor phase transitions.
Drinking bird with water cups.
The bird's head and beak are initially wetted, and the bird positioned so that its beak will dip into the water cup when it tips (whether or not the cup is there). The liquid is tri-chloro-mono-fluoro methane.
Julius Sumner Miller, Physics of the Dunking Duck, AJP 26, 42-43 (1958). Jerry L. Gaines, Dunking Duck, AJP 27, 189-190 (1959). Harry E. Stockman, Dunking Duck without Liquid, AJP 29, 335-336 (1961). Harry E. Stockman, Secret of the Dunking Duck, AJP 29, 374-375 (1961). Kemp Bennett Kolb, "Reciprocating" Engine, TPT 4, 121-122 (1966). Drinking Duck Shutter, TPT 5, 342 (1967). David L. Frank, The Drinking Bird an the Scientific Method, Journal of Chemical Education 50, No. 3, March 1973, page 211. Robert E. Wagner, Physical Chemistry of the Drinking Duck, one page, source unknown. Edmun