Note 25 — Letters from Father Mateo Gisbert to the Reverend Fathers and Brothers of Veruela
Reading edition
Salt is produced by evaporation, from a method taught prior to the coming of the Spaniards by the Chinese. Sea-water, enclosed in a depression surrounded by dykes, is evaporated by the sun’s rays; when the water has disappeared, the salt deposited on the floor of the basin is gathered up and cleaned by filtration. See Census of Philippines, iv, p. 469.