Green’s Dictionary of Slang

milky adj.1

(UK Und.) white; thus milky duds, white clothes; milky tats, white rags.

[UK]H. Brandon Dict. of the Flash or Cant Lang. 168: The paper makers get the tats and [...] fence the milky ones with some swag chovey bloak.
[UK]‘Ducange Anglicus’ Vulgar Tongue [as cit. 1839].
[UK]Hotten Dict. of Modern Sl. etc. 62: MILKY ONES, white linen rags.
[US]Matsell Vocabulum 54: milky White.
[UK] Hotten Sl. Dict. [as cit. 1859].
[Aus]Sydney Sl. Dict. 9: The paper makers get the tats, and never tip the mots a posh, but fence the milky ones with some swag chovey bloak. / The men who pretend they are from a paper mill obtain the rags, and never pay the women (of the houses they call at) anything, and then sell the white rags to some marine store dealer.
[Aus]C. Crowe Aus. Sl. Dict. 49: Milky, white [...] Milky-Duds, white clothes.
[Aus]Argus (Melbourne) 20 Sept. 6/4: Amongst these small fry of the profession [are] the Lily prigger, snow dropper or robber of clothes lines , who gets away with a roll of snow or milky duds.

In compounds

milky way (to bliss) (n.)

1. (UK Und.) the female breasts.

Carew Caelum Brit. (Ebsworth) 139: Jupiter begins to learn to lead his own wife: I left him practising the milky way [F&H].
[UK]N. Ward London Spy VI 146: Every now and then drop’d a Lady from her Pillion, another from her Side-Saddle, some shewing the Milky-way to Bliss, others their Bugbears to the Company.
[UK]Fifteen Plagues of a Maiden-Head 3: Let your wanton Palm a little stray [...] dip thy Fingers in the milky way.
[UK] ‘Modest Obadiah’ in Fun Alive O! 52: Then surely love must blunder, / Because the Bible says ’tis good / In the milky way to wander.
[UK]Duncombe New and Improved Flash Dict. n.p.: Tet-galaxy or the milky-way, a woman’s bosom.

2. vaginal fluids.

[UK]Peeping Tom (London) 1 2/2: Within this little snug retreat / A cooling fountain plays / [...] /The stream they name’d the Milky Way, / ’Cause of its cooling pow’r.