This section is from the "A Complete Dictionary of Dry Goods" book, by George S. Cole. Also available from Amazon: A complete dictionary of dry goods and history of silk, cotton, linen, wool and other fibrous substances,: Including a full explanation of the modern processes ... together with various useful tables.
Fuller's-Earth. A species of clay, used by fullers to take grease out of cloth before they apply the soap. When good it has a greenish-white color, falls into powder in water, giving the water a milky hue, and appears to melt on the tongue like butter. It is not at present used to the extent it once was, other substances having taken its place.