A 26-inch 18k gold chain necklace with a 1904-S Liberty Head U.S. $20 gold piece in bezel, a collection of turn-of-the century Art Nouveau postcards from the M. M. Vienne series, and an 1878 classic Spanish bullfight scene painted on tile are just a few of the highlights in a two-day, online-only Cauldron of Curiosities timed auction planned for the weekend of Oct. 19 and 20 by Holabird Western Americana Collections, beginning at 8am Pacific time both days.