Green’s Dictionary of Slang

a glass of spirits.

1821		‘A Real Paddy’ Real Life in Ireland 32: A right good fellow as ever took the froth of a pot, or the bead of a naggin.
a.1847		R. Barham ‘The Brothers of Birchington’ in Ingoldsby Legends (1847) 258: While as to his beads – what shame in a Knight! – / He really don’t know the wrong end from the right!
1854		E.L. Sloan ‘Mrs. Sleek’ in Bard’s Offering 70: Bill shook him, and cursed him to pluck up some spunk— / Called a glass of the lowest bead-number.
1870		Mercury (Hobart) 23 Apr. 2/5: [from the Stranraer Free Press] [...] the hard stuff [...] a bead.