Note:  Do not rely on this information. It is very old.

Fuller's Earth

Fuller's Earth is a clay or marl which generally occurs associated with chalk or oolite formations. It has a soft, unctuous feel, and has a specific gravity of 1-8 to 2-2. It is used in the cleansing of cloth - fulling - as it extracts the greasy materials employed in the preparation of the wool. It varies in colour from blue to yellow, and its composition generally approximates to the following: - Silica, 60 per cent.; alumina, 10 per cent.; oxides of iron, 5 per cent.; lime, 6 per cent.; magnesia and alkaline compounds, 4 per cent.; water, 15 per cent.