A Dictionary of Music and Musicians/Gong
GONG. (Fr. Tam-tam, from the Indian name.) This is a Chinese instrument, made of bronze (80 copper to 20 tin); in form, a thin round plate with the edges turned up, like a shallow sieve or tambourine. It is struck with a stick, ending in a large padded leather knob. The effect produced is an awful crash or clang, which adds considerably to the horrors of a melodramatic scene. Meyerbeer has even used it pianissimo with the orchestra, in 'Robert le Diablo' (scene of the resurrection of the nuns); and Cherubini has one stroke of it in his Requiem in C minor, absolutely solo (Dies iræ, bar 7). If a long-continued and loud noise is desired, it should first be struck very gently, and the force of the stroke gradually increased until the effect becomes almost terrific.
It is a remarkable property of the alloys of copper and tin, that they become malleable by being heated and then plunged into cold water. Gongs are thus treated after being cast, and are then hammered. This was a secret in Europe until found out some years ago by M. d'Arcet, an eminent French chemist.