Green’s Dictionary of Slang

cocaine.

1924

Chelmsford Chron. 26 Sept. 2/4: Oxspring [...] pleaded guilt to being in unlawful possession of cocaine [...] A jobmaster of Poplar, said defendant accosted him, asking ‘Do you know anyone who can do with some “S”?’ Witness replied, ‘“S,” what is “S”?’ Prisoner replied, ‘Snow’.