Fuller's earth

[1] Primary modern uses include as absorbents for oil, grease, and animal waste (cat litter), and as a carrier for pesticides and fertilizers.

Minor uses include filtering, clarifying, and decolorizing;[1][2] as an active and inactive ingredient in beauty products; and as a filler in paint, plaster, adhesives, and pharmaceuticals.

The English name reflects the historical use of the material for fulling (cleaning and shrinking) wool, by textile workers known as fullers.

[10] Although these sites had been used since Roman times, William Smith developed new methods for the identification of deposits of fuller's earth to the south of Bath.

Cuneiform texts from Mesopotamia mention a raw material, im-bab-bár (Akkadian: 𒅎𒌓, gaṣṣu: 'gypsum, plaster'), literally "white earth", which was delivered to fullers for the finishing of cloth.

[15] While its household use and transportation by local carts in the Sindh region of Pakistan predates the 1800s, export by rail was first recorded in 1929 in British India.

In the story, an engineer is paid an outlandish sum to repair a hydraulic press, accepting his client's explanation that the potential profit from fuller's earth warrants both the expense and total secrecy.