Green’s Dictionary of Slang

(drugs) a cloth or sponge used to cool or clean an opium pipe or bowl.

1901		C.R. Wooldridge Hands Up! 215: A ‘layout’ can be purchased for any amount up to $5. It consists of [...] the ‘sui gow,’ a sponge for cleaning the bowl of the pipe after every smoke [...].
1914		Jackson & Hellyer Vocab. Criminal Sl. 82: Suey pow, noun, current amongst opium smokers. A sponge or rag used to cool and cleanse the face of an opium bowl.
1920		F. Williams Hop-Heads 116: The suey pow is only a rag to wash the pipe with.
1936		D. Maurer ‘Argot of the Und. Narcotic Addict’ Pt 1 in AS XI:2 126/2: suey-pow. A sponge for cooling and cleaning an opium pipe.
1950		Goldin et al. DAUL 215/1: Suey-pow. A sponge or rag for cleaning, cooling and holding opium pipes.
1959		J.E. Schmidt Narcotics Lingo and Lore.