US Patent No. 525,738, granted to Gottfried Hauser of New York on September 11, 1894 (filed July 15, 1892), describes a chemical process for removing the cotton background from machine-made silk or metal embroidery. The goods are treated with a bath of aluminium chloride and an acid (sulphuric or nitric), dried, and heated so the cotton backing decays and is brushed away, leaving the silk gauze and embroidery undamaged. The aluminium chloride is said to act as a mordant that protects the embroidery colors. One sheet of drawings shows four figures of the embroidery before and after removal, followed by the specification and a single claim.