An unusual Victorian basket made of alum crystals

An unusual Victorian basket made of alum crystals, contained under an antique glass dome, raised on an ebonised base, circa 1860, 13in (33cm) h. This curious basket would have taken many weeks to form, growing layer upon layer of alum crystals around a wirework frame very gradually. Before the advent of chemical dyes alum was an important compound used mainly for fixing dyes in leather. Alum is a colourless astringent compound, which is a hydrated double sulphate of aluminium and potassium, and in the 19th century alum was an expensive commodity.