Of the Latin leaches, lye and also ash with very hot water that the Romans used as whitening especially of the linen garments. Percolation, filtration of fluids through porous materials. Physical-chemical process of dissolution and extraction of soluble substances of a compound by the physical or chemical action of different liquids. This process can be natural, as in the filtration of surface water to the underground or man-induced, as in the extraction of sugar from the pulp of the beet by hot water.
