Green’s Dictionary of Slang

Dr Hall n.

[? a brandname or rhy. sl.]

(US tramp) grain alcohol and water.

[US]J. Black You Can’t Win (2000) 163: The first peddler returned in an hour with his quota of ‘Dr. Hall’ (alcohol).
[US]M.C. Sharpe Chicago May (1929) 261: White line, Dr. Hall, Mickey — alcohol.