Green’s Dictionary of Slang

any form of alcoholic liquor.

1890–1904		Farmer & Henley Sl. and Its Analogues.
1895		C. Crowe Aus. Sl. Dict. 62: Purge, liquor.
1894		Civil & Milit. Gaz. (Lahore) 18 Oct. 4/3: An’ our purge is five annas a quart, Bill / Rather snide — eh? for Tommy’s rupees?
1901		Sydney Sportsman (Surry Hills, NSW) 19 June 4/2: A strong supply of willing wasters who, for a pint of purge, will accept the onus of ownership.
1914		Truth (Melbourne) 10 Jan. 9/4: He [i.e. a larrikin] and his companions were under the infleunce of a pint of purge.
1936		(con. 1900s) F. Richards Old Soldier Sahib (1965) 75: He inquired if we were fond of a drop of ‘neck-oil’, which like ‘purge’ was a nickname of beer.
1959		G. Slatter Gun in My Hand 180: ‘Have some more purge.’ He slops out some more beer into my glass.
1968		G. Slatter Pagan Game (1969) 150: Great drop of purge this [...] Down the hatch.