Green’s Dictionary of Slang

(drugs) amyl nitrite.

1969		R.R. Lingeman Drugs from A to Z (1970).
1974		R. Greenfield S.T.P. 316: [of a strong drug] ‘That’s bad shit, man.’ ‘Doc, doc,’ the horn player moans, slumping in his seat, [...] ‘I need an amy.’.
2001		ONDCP Street Terms 1: Amys — Amyl nitrite.