A mode of diminishing the gold coin, practiced chiefly by the Jews, who corrode it with aqua regia. Sweating was also a diversion practised by the bloods of the last century, who styled themselves Mohocks: these gentlemen lay in wait to surprise some person late in the night, when surrouding him, they with their swords pricked him in the posteriors, which obliged him to be constantly turning round; this they continued till they thought him sufficiently sweated.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Swannery * SweetNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes