Green’s Dictionary of Slang

(Aus.) methylated spirits mixed with health salts, which give a fizzy head.

1973		Sun. Tel. (Sydney) 26 Aug. 112: Evidence was given that many Aboriginals drink ‘Northern Territory champagne’ – methylated spirits mixed with health salts [GAW4].
1979		Australian 1 Dec. 13: When the recipe for Territory champagne is ‘metho and Sal Vital’, it is hardly surprising our spirit consumption almost trebles the national average [GAW4].
1985		B. Robinson Aussie Bull 23: Some alcoholics will drink almost anything - even ‘Northern Territory Champagne’ (Metho and Sal Vital).
2006		posting at www.aussiecampovenforum.com 17 Sept. 🌐 Curry and chilli are like Northern Territory Champagne to me which is made up of Metho and Salvital either way you have it you still end up singing that Johnny Cash song.