Green’s Dictionary of Slang

1. (US) a measure of mixed ale.

1904		C. Connors Bowery Life [ebook] De mug behind de fence, dat’s de barkeep, he twists out four scuttles an’ a torch. [...] you ought to know dat a scuttle is a mixed ale, see?
1911		T.A. Dorgan Silk Hat Harry’s Divorce Suit 27 Nov. [synd. cartoon strip] I haven’t got a jitney — I spent the last one [...] for a scuttle o’ suds and played the counter for my eats.

2. (US) a derog. term for a black person.

1983

I.L. Allen Lang. of Ethnic Conflict 47: Color Allusions, Other than ‘Black’ and ‘Negro’: scuttle.