Green’s Dictionary of Slang

1. a form of treatment for syphilis [abbr. SE salivation].

c.1758		John F---g Epistle of a Reformed Rake 17: There’s Nanny Right – no, I’m mistaken, she’s just down in a Sal.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Sal, An abbreviation of salivation.
1811		Lex. Balatronicum [as cit. 1785].
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.

2. a salary.

1843		E.R. Lancaster Manager’s Daughter in Oxberry Budget of Plays I (1844) 110/1: Who does he suppose was to cut comic mugs before noblemen, without being paid double sals?
1864		G.A. Sala Quite Alone III 172: Van Post’s got him down on the pay list, and he draws his sal pretty regular.
1866		Letters by an Odd Boy 67: Rather a low sal. to begin with, but Great Expectations.
1889		Music Hall & Theatre Rev. 25 May 6/2: What a sigh when your next week’s sal. is gone and you owe a bit.
1895		C. Crowe Aus. Sl. Dict. 69: Sal, contraction for salary.

3. (W.I.) a friend.

1970

F. Collymore Notes for Gloss. of Barbadian Dial. 99: Sal. Pal.

4. see salting n.