Green’s Dictionary of Slang

obtaining money through theft or pocket-picking.

1726		C. D’Anvers Craftsman No. 32 (3rd edn) 299: If once he gives himself up to touching [...] I give him over as incurable.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor I 251/1: Something, however, must be done to colour up the scene, and make the appeal for money touching unsuspected, and successful.