Green’s Dictionary of Slang

1. a share, a portion.

1859		Hotten Dict. of Modern Sl. etc. 97: snapps share, portion […] Old.
1864, 1867, 1870		Hotten Sl. Dict.

2. anything that will serve as a means of making money; thus looking out for snapps, waiting for a lucky break or a windfall.

1859		Hotten Dict. of Modern Sl. etc. 97: […] any articles or circumstances out of which money may be made; ‘looking out for snapps,’ waiting for windfalls, or odd jobs. Old.
1860		Hotten Dict. of Modern Sl. etc. [as cit. 1859].