Green’s Dictionary of Slang

blob v.1

[var. on blab v. (1)]

1. to talk indiscreetly.

[UK]Hotten Dict. of Modern Sl. etc.
[UK]G.J. Whyte-Melville Good for Nothing (1890) 200: ‘Five minutes more and we shall run into him,’ he shouts, sitting well back on his horse, and urging him to his extreme pace, ‘when he blobs like that he’s getting beat. See how Canvas sticks to him, and the yellow dog hangs back, waiting for the turn.’.
[UK]Hotten Sl. Dict.
Eve. Teleg. (Philadelphia, PA) 22 Jan. 7/1: A farmer’s wife sometimes advises a garrulous neighbor not to ‘blob around’ so much.

2. (Aus./UK Und.) to beg by delivering some form of speechifying or patter.

[UK]Hotten Dict. of Modern Sl. etc. 7: Blob (from blab), to talk. Beggars are of two kinds ? those who screeve (introduce themselves with a fakement, or false document,) and those who blob, or state their case in their own truly ‘unvarnished’ language.
[Aus]Melbourne Punch ‘The Lay of the Lags’ 14 Mar. 1/1: Ye who screeve, and ye who blob, / Close the ken and dub the jigger, / Great’s the news for all who rob.
[UK]Hotten Sl. Dict.
[UK]Sl. Dict.

In phrases

on the blob (adv.)

by word of mouth; thus blob n., talk.

[UK](con. 1840s–50s) H. Mayhew London Labour and London Poor I 311/1: Of professional beggars there are two kinds – those who ‘do it on the blob’ (by word of mouth), and those who do it by ‘screeving’ [Ibid.] I 364/2: Pat ‘does nothing on the blob,’ that is to say (he does not follow people and speak to them on the streets). [Ibid.] IV 416/1: This ‘patter,’ or ‘blob,’ is of Plymouth [...] the bo’sen and the first le’tenant.
[Aus]Sydney Sl. Dict. 10/2: Lame Jack is pattering. He pads Pitt and George streets and the Parks, and touches coves on the blob. He blew on Sam who frisked a lobb and the same day came it on Joe for fencing the prad got on the cross.