Green’s Dictionary of Slang

(drugs) a medicine- or eye-dropper used by narcotics addicts as a makeshift syringe when proper hypodermics are unavailable.

1911		S.F. Call 7 May 3/6: He buys cocaine [...] he uses a pin to make the puncture and a medicine dropper for the injection ].
1936		D. Maurer ‘Argot of the Und. Narcotic Addict’ Pt 1 in AS XI:2 121/1: dropper. The inevitable medicine dropper used by the poorer class of addicts to construct a makeshift hypodermic.
1953		‘William Lee’ Junkie (1966) 64: When I turned round I noticed his dropper was full of blood.
1960		C. Cooper Jr Scene (1996) 14: He cleaned the bloody dropper.
1979		‘Iceberg Slim’ Airtight Willie and Me 66: She cooked up a spoon and drew a shot up into the dropper.
1989		(con. 1950s) Courtwright & Des Jarlais Addicts Who Survived 65: He fixed me up a little bit in a dropper.
1999		E. Bunker Mr Blue 365: Put some water in the dropper and put a fire on the needle as you squeeze.