Green’s Dictionary of Slang

1. second-rate whisky.

1892		(con. 1861-5) Morn. Call (SF) 8 May 13/4: The question is often asked how whisky became known among the soldiers of the Army of the Potomac as ‘embalming fluid’.
[1907		Wash. Times (DC) 13 Oct. 45/4: I thought Jim McKales ruse in labelling his whisky ‘Embalming Fluid’ was a pretty good one].
1922		S. Lewis Babbitt (1974) 138: Say, son, can you get us some more of this embalming fluid?
1927		(con. 1918) J.W. Thomason Red Pants 156: Me and my boyfriend will take Scotch [...] and don’t be laying any of that embalming fluid off on me.
1942		Berrey & Van den Bark Amer. Thes. Sl.

2. (US tramp) coffee.

1927		C. Samolar ‘Argot of the Vagabond’ in AS II:9 389: Other names for coffee are ink, mud, alkali and embalming fluid.
1936		Mencken Amer. Lang. (4th edn) 582: Coffee is hot-stuff, mud or embalming-fluid.
1949		Monteleone Criminal Sl. (rev. edn).

3. (drugs) phencyclidine.

1984		Abel Dict. Drug Abuse Terms.
2003		Microgram Bulletin XXXVI:8 182: On the street, PCP is commonly referred to as Angel Dust, Hog, Ozone, Rocket Fuel, Shermans, Wack, Crystal, and Embalming Fluid.

4. marijuana mixed with cocaine.

1980

E. Folb Runnin’ Down Some Lines 181: You can’t smoke too much embalmin’ fluid — no more ’n half a joint.